47 results on '"Khan, Imtiaz"'
Search Results
2. List of Contributors
- Author
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Ajioka, James W., primary, Ajzenberg, Daniel, additional, Alexander, James, additional, Asai, Takashi, additional, Bogyo, Matthew, additional, Boothroyd, John C., additional, Butcher, Barbara A., additional, Bzik, David J., additional, Carruthers, Vern B., additional, Cesbron-Delauw, Marie-France, additional, Chaudhary, Kshitiz, additional, Coppens, Isabelle, additional, Dardé, Marie-Laure, additional, Denkers, Eric Y., additional, Dubey, Jitender P., additional, Dubremetz, Jean-François, additional, Feagin, Jean E., additional, Ferguson, David J.P., additional, Fox, Barbara A., additional, Gazzinelli, Ricardo T., additional, Gross, Uwe, additional, Gubbels, Marc-Jan, additional, Halonen, Sandra K., additional, Harb, Omar S., additional, Henriquez, Fiona L., additional, Honda, Andrea, additional, Hunter, Christopher A., additional, Jacot, Damien, additional, Khaliq, Farzana, additional, Khan, Imtiaz A., additional, Kim, Kami, additional, Knoll, Laura J., additional, Latkany, Paul, additional, Lebrun, Maryse, additional, Lindsay, David S., additional, Lüder, Carsten G.K., additional, McLeod, Rima, additional, Meissner, Markus, additional, Montoya, José G., additional, Mordue, Dana G., additional, Moreno, Silvia N.J., additional, Morrissette, Naomi, additional, Mullins, Jeremi, additional, Ochiai, Eri, additional, Pace, Douglas A., additional, Parsons, Marilyn, additional, Pereira, Lucas Borges, additional, Petersen, Eskild, additional, Prasad, Sheela, additional, Radke, Joshua B., additional, Reese, Michael L., additional, Reichard, Utz, additional, Roberts, Craig W., additional, Roos, David S., additional, Sa, Qila, additional, Seeber, Frank, additional, Sheiner, Lilach, additional, Sibley, L. David, additional, Sinai, Anthony P., additional, Soldati-Favre, Dominique, additional, Striepen, Boris, additional, Su, Emily, additional, Su, Chunlei, additional, Sullivan, William J., additional, Suzuki, Yasuhiro, additional, Tomavo, Stanislas, additional, Tomita, Tadakimi, additional, Van Tubbergen, Christine, additional, Ward, Gary, additional, Wastling, Jonathan M., additional, Weiss, Louis M., additional, White, Michael W., additional, Xia, Dong, additional, and Yolken, Robert, additional
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- 2014
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3. Adaptive Immunity and Genetics of the Host Immune Response
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Roberts, Craig W., primary, Prasad, Sheela, additional, Khaliq, Farzana, additional, Gazzinelli, Ricardo T., additional, Khan, Imtiaz A., additional, and McLeod, Rima, additional
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- 2014
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4. Contributors
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Ajioka, James W., primary, Ajzenberg, Daniel, additional, Alexander, James, additional, Asai, Takashi, additional, Behnke, Michael S., additional, Boothroyd, John, additional, Butcher, Barbara, additional, Buzoni-Gatel, Dominique, additional, Bzik, David J., additional, Carruthers, Vern B., additional, Cesbron-Delauw, Marie-France, additional, Chaudhary, Kshitiz, additional, Dardé, Marie Laure, additional, Denkers, Eric, additional, de Souza, Wanderley, additional, Donald, Robert G.K., additional, Dubey, J.P., additional, Dubremetz, Jean-François, additional, Dunn, Joe Dan, additional, Esquivel, Adrian, additional, Fang, Jianmin, additional, Feagin, Jean E., additional, Ferguson, David J.P., additional, Fox, Barbara A., additional, Gazzinelli, Ricardo T., additional, Gross, Uwe, additional, Halonen, Sandra, additional, Kasper, Lloyd H., additional, Khan, Imtiaz A., additional, Kim, Kami, additional, Latkany, Paul, additional, Lebrun, Maryse, additional, Liesenfeld, Oliver, additional, Lindsay, David S., additional, McLeod, Rima, additional, Miranda, Kildare, additional, Moreno, Silvia N.J., additional, Nowakowska, Dorota, additional, Parsons, Marilyn, additional, Petersen, Eskild, additional, Radke, Jay R., additional, Reichard, Utz, additional, Roberts, Craig W., additional, Rohloff, Peter, additional, Schaap, Dick, additional, Sibley, L. David, additional, Smith, Judith, additional, Soldati, Dominique, additional, Striepen, Boris, additional, Sullivan, William J., additional, Suzuki, Yasuhiro, additional, Templeton, Thomas J., additional, Tomavo, Stanislas, additional, Vermeulen, Arno N., additional, Wang, Xisheng, additional, Wastling, Jonathan M., additional, Weiss, Louis M., additional, Wen, Xiangshu, additional, and White, Michael W., additional
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- 2007
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5. Small Animal PET Enables Parametric Mapping of Saturation Kinetics at the 5-HT1A Receptor
- Author
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Gunn, Roger N., primary, Hume, Susan P., additional, Hirani, Ella, additional, Khan, Imtiaz, additional, and Opacka-Juffry, Jolanta, additional
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- 2001
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6. Luteolin, a flavonoid, as an anticancer agent: a review
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Imran, Muhammad, Rauf, Abdur, Abu-Izneid, Tareq, Nadeem, Muhammad, Shariati, Mohammad Ali, Khan, Imtiaz Ali, Imran, Ali, Orhan, Ilkay Erdogan, Rizwan, Muhammad, Atif, Mihammad, Gondal, Tanweer Aslam, Mubarak, Mohammad S, Imran, Muhammad, Rauf, Abdur, Abu-Izneid, Tareq, Nadeem, Muhammad, Shariati, Mohammad Ali, Khan, Imtiaz Ali, Imran, Ali, Orhan, Ilkay Erdogan, Rizwan, Muhammad, Atif, Mihammad, Gondal, Tanweer Aslam, and Mubarak, Mohammad S
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- 2019
7. Thymoquinone: a novel strategy to combat cancer: a review
- Author
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Imran, Muhammad, Rauf, Abdur, Khan, Imtiaz Ali, Shahbaz, Muhammad, Qaisrani, Tahira Batool, Fatmawati, Sri, Abu-Izneid, Tareq, Imran, Ali, Rahman, Khaliq Ur, Gondal, Tanweer Aslam, Imran, Muhammad, Rauf, Abdur, Khan, Imtiaz Ali, Shahbaz, Muhammad, Qaisrani, Tahira Batool, Fatmawati, Sri, Abu-Izneid, Tareq, Imran, Ali, Rahman, Khaliq Ur, and Gondal, Tanweer Aslam
- Published
- 2018
8. Exploration of thiazine Schiff bases as promising urease inhibitors: Design, synthesis, enzyme inhibition, kinetic analysis, ADME/T evaluation, and molecular docking studies.
- Author
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Khan Y, Solangi M, Khan KM, Ullah N, Iqbal J, Hussain Z, Khan IA, Salar U, and Taha M
- Abstract
Urease catalyzes the hydrolysis of urea, leading to an increase in stomach pH and supporting Helicobacter pylori survival, which is linked to several gastrointestinal disorders. In this study, thiazine-based Schiff bases were explored as promising urease inhibitors. Various spectroscopic techniques characterized the synthetic library of thiazine Schiff bases 2-36 and also evaluated for their inhibitory activities against urease. The derivatives demonstrated significant inhibitory potential with IC
50 values ranging from 0.14 ± 0.08 to 3.66 ± 0.21 μM, outperforming the standard inhibitor thiourea (IC50 = 19.43 ± 0.18 μM). Structure-activity relationship (SAR) studies revealed that specific substitutions (type and positions) on the aryl ring significantly affect the inhibition potential. The most potent derivative, compound 7, possessed 2-methoxy-5-trifluoromethyl substitutions and exhibited an IC50 of 0.14 ± 0.08 μM. Enzyme kinetics studies revealed that the most potent derivatives function as competitive inhibitors. Additionally, molecular docking studies provided insights into the binding interactions between the molecule and the urease active site, highlighting key residues involved in inhibitor binding. These findings highlight the therapeutic potential of thiazine-based Schiff bases as urease inhibitors and provide insights for the development of new anti-ulcer agents., Competing Interests: Declaration of competing interest The authors declare no conflict of interest, financial or otherwise. No writing assistance was utilized in the production of this manuscript., (Copyright © 2024 Elsevier B.V. All rights reserved.)- Published
- 2024
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9. Advances in MXene-based technologies for the remediation of toxic phenols: A comprehensive review.
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Afridi MN, Zafar Z, Khan IA, Ali I, Bacha AU, Maitlo HA, Qasim M, Nawaz M, Qi F, Sillanpää M, Lee KH, and Asif MB
- Abstract
The pressing global issue of organic pollutants, particularly phenolic compounds derived primarily from industrial wastes, poses a significant threat to the environment. Although progress has been made in the development of low-cost materials for phenolic compound removal, their effectiveness remains limited. Thus, there is an urgent need for novel technologies to comprehensively address this issue. In this context, MXenes, known for their exceptional physicochemical properties, have emerged as highly promising candidates for the remediation of phenolic pollutants. This review aims to provide a comprehensive and critical evaluation of MXene-based technologies for the removal of phenolic pollutants, focusing on the following key aspects: (1) The classification and categorization of phenolic pollutants, highlighting their adverse environmental impacts, and emphasizing the crucial need for their removal. (2) An in-depth discussion on the synthesis methods and properties of MXene-based composites, emphasizing their suitability for environmental remediation. (3) A detailed analysis of MXene-based adsorption, catalysis, photocatalysis, and hybrid processes, showcasing current advancements in MXene modification and functionalization to enhance removal efficiency. (4) A thorough examination of the removal mechanisms and stability of MXene-based technologies, elucidating their operating conditions and stability in pollutant removal scenarios. (5) Finally, this review concludes by outlining future challenges and opportunities for MXene-based technologies in water treatment, facilitating their potential applications. This comprehensive review provides valuable insights and innovative ideas for the development of versatile MXene-based technologies tailored to combat water pollution effectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)
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- 2024
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10. Design and discovery of urease and Helicobacter pylori inhibitors based on benzofuran/benzothiophene-sulfonate and sulfamate scaffolds for the treatment of ureolytic bacterial infections.
- Author
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Hashem O, Zaib S, Zaraei SO, Javed H, Kedia RA, Anbar HS, Khan I, Ravi A, El-Gamal MI, and Khoder G
- Subjects
- Humans, Drug Design, Helicobacter Infections drug therapy, Helicobacter Infections microbiology, Microbial Sensitivity Tests, Structure-Activity Relationship, Drug Discovery, Urease antagonists & inhibitors, Urease metabolism, Helicobacter pylori drug effects, Helicobacter pylori enzymology, Sulfonic Acids chemistry, Sulfonic Acids pharmacology, Molecular Docking Simulation, Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents chemistry, Enzyme Inhibitors pharmacology, Enzyme Inhibitors chemistry, Benzofurans chemistry, Benzofurans pharmacology, Thiophenes chemistry, Thiophenes pharmacology
- Abstract
A series of sulfonate and sulfamate derivatives bearing benzofuran or benzothiophene scaffold exhibited potent inhibitory effect on urease enzyme. Most of the derivatives exhibited significantly higher potency than thiourea, the standard inhibitor. Compound 1s was identified as the most potent urease inhibitor with an IC
50 value of 0.42 ± 0.08 μM, which is 53-fold more potent than thiourea, positive control (IC50 = 22.3 ± 0.031 μM). The docking results further revealed the binding interactions towards the urease active site. Phenotypic screening revealed that compounds 1c, 1d, 1e, 1f, 1j, 1n, and 1t exhibit high potency against H. pylori with MIC values ranging from 0.00625 to 0.05 mM and IC50 values ranging from 0.0031 to 0.0095 mM, much more potent than the positive control, acetohydroxamic acid (MIC and IC50 values were 12.5 and 7.38 mM, respectively). Additional studies were performed to investigate the toxicity of these compounds against the gastric epithelial cell line (AGS) and their selectivity profile against E. coli, and five Lactobacillus species representative of the gut microflora. Permeability characteristics of the most promising derivatives were investigated in Caco-2 cell line. The results indicate that the compounds could be targeted in the GIT only without systemic side effects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)- Published
- 2024
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11. Design and discovery of anthranilamide derivatives as a potential treatment for neurodegenerative disorders via targeting cholinesterases and monoamine oxidases.
- Author
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Zaib S, Khan I, Ali HS, Younas MT, Ibrar A, Al-Odayni AB, and Al-Kahtani AA
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- Humans, Structure-Activity Relationship, Drug Discovery, Cholinesterases metabolism, Cholinesterases chemistry, Molecular Dynamics Simulation, Cholinesterase Inhibitors chemistry, Cholinesterase Inhibitors pharmacology, ortho-Aminobenzoates chemistry, ortho-Aminobenzoates pharmacology, Monoamine Oxidase metabolism, Monoamine Oxidase chemistry, Molecular Docking Simulation, Monoamine Oxidase Inhibitors chemistry, Monoamine Oxidase Inhibitors pharmacology, Drug Design, Neurodegenerative Diseases drug therapy, Neurodegenerative Diseases enzymology
- Abstract
Neurodegenerative diseases with progressive cellular loss of the central nervous system and elusive disease etiology provide a continuous impetus to explore drug discovery programmes aiming at identifying robust and effective inhibitors of cholinesterase and monoamine oxidase enzymes. We herein present a concise library of anthranilamide derivatives involving a palladium-catalyzed Suzuki-Miyaura cross-coupling reaction to install the diverse structural diversity required for the desired biological action. Using Ellman's method, cholinesterase inhibitory activity was performed against AChE and BuChE enzymes. In vitro assay results demonstrated that anthranilamides are potent inhibitors with remarkable potency. Compound 6k emerged as the lead candidate and dual inhibitor of both enzymes with IC
50 values of 0.12 ± 0.01 and 0.49 ± 0.02 μM against AChE and BuChE, respectively. Several other compounds were found as highly potent and selective inhibitors. Anthranilamide derivatives were also tested against monoamine oxidase (A and B) enzymes using fluorometric method. In vitro data revealed compound 6h as the most potent inhibitor against MAO-A, showing an IC50 value of 0.44 ± 0.02 μM, whereas, compound 6k emerged as the top inhibitor of MAO-B with an IC50 value of 0.06 ± 0.01 μM. All the lead inhibitors were analyzed for the identification of their mechanism of action using Michaelis-Menten kinetics experiments. Compound 6k and 6h depicted a competitive mode of action against AChE and MAO-A, whereas, a non-competitive and mixed-type of inhibition was observed against BuChE and MAO-B by compounds 6k. Molecular docking analysis revealed remarkable binding affinities of the potent inhibitors with specific residues inside the active site of receptors. Furthermore, molecular dynamics simulations were performed to explore the ability of potent compounds to form energetically stable complexes with the target protein. Finally, in silico ADME calculations also demonstrated that the potent compounds exhibit promising pharmacokinetic profile, satisfying the essential criteria for drug-likeness. Altogether, the findings reported in the current work clearly suggest that the identified anthranilamide derivatives have the potential to serve as effective drug candidates for future investigations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)- Published
- 2024
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12. Identification of isobenzofuranone derivatives as promising antidiabetic agents: Synthesis, in vitro and in vivo inhibition of α-glucosidase and α-amylase, computational docking analysis and molecular dynamics simulations.
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Zahra S, Zaib S, and Khan I
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- Rats, Animals, Acarbose, Molecular Dynamics Simulation, alpha-Glucosidases metabolism, Molecular Docking Simulation, alpha-Amylases, Glycoside Hydrolase Inhibitors pharmacology, Hypoglycemic Agents pharmacology, Diabetes Mellitus, Experimental drug therapy
- Abstract
Diabetes mellitus, one of the major health challenges of the 21st century, is associated with numerous biomedical complications including retinopathy, neuropathy, nephropathy, cardiovascular diseases and liver disorders. To control the chronic hyperglycemic condition, the development of potential inhibitors of drug targets such as α-glucosidase and α-amylase remains a promising strategy and focus of continuous efforts. Therefore, in the present work, a concise library of isobenzofuranone derivatives (3a-q) was designed and synthesized using Suzuki-Miyaura cross-coupling approach. The biological potential of these heterocyclic compounds against carbohydrate-hydrolyzing enzymes; α-glucosidase and α-amylase, was examined. In vitro inhibitory results demonstrated that the tested isobenzofuranones were considerably more effective and potent inhibitors than the standard drug, acarbose. Compound 3d having an IC
50 value of 6.82 ± 0.02 μM was emerged as the lead candidate against α-glucosidase with ⁓127-folds strong inhibition than acarbose. Similarly, compound 3g demonstrated ⁓11-folds higher inhibition strength against α-amylase when compared with acarbose. Both compounds were tested in vivo and results demonstrate that the treatment of diabetic rats with α-amylase inhibitor show more pronounced histopathological normalization in kidney and liver than with α-glucosidase inhibitor. The Lineweaver-Burk plot revealed an uncompetitive mode of inhibition for 3d against α-glucosidase whereas compound 3g exhibited mixed inhibition against α-amylase. Furthermore, in silico molecular docking and dynamics simulations validated the in vitro data for these compounds whereas pharmacokinetics profile revealed the druglike properties of potent inhibitors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)- Published
- 2024
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13. Fabrication and evaluation of anticancer potential of diosgenin incorporated chitosan-silver nanoparticles; in vitro, in silico and in vivo studies.
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Zaib S, Shah HS, Khan I, Jawad Z, Sarfraz M, Riaz H, Asjad HMM, Ishtiaq M, Ogaly HA, Othman G, and Ahmed DAEM
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- Animals, Mice, Silver, Chitosan chemistry, Metal Nanoparticles, Diosgenin pharmacology, Diosgenin chemistry, Antineoplastic Agents pharmacology, Antineoplastic Agents chemistry, Nanoparticles chemistry
- Abstract
The discovery of effective therapeutic approaches with minimum side effects and their tendency to completely eradicate the disease is the main challenge in the history of cancer treatment. Fenugreek (FGK) seeds are a rich source of phytochemicals, especially Diosgenin (DGN), which shows outstanding anticancer activities. In the present study, chitosan-silver nanoparticles (ChAgNPs) containing Diosgenin (DGN-ChAgNPs) were synthesized and evaluated for their anticancer activity against breast cancer cell line (MCF-7). For the physical characterization, the hydrodynamic diameter and zeta potential of DGN-ChAgNPs were determined to be 160.4 ± 12 nm and +37.19 ± 5.02 mV, respectively. Transmission electron microscopy (TEM) showed that nanoparticles shape was mostly round with smooth edges. Moreover, DGN was efficiently entrapped in nanoformulation with good entrapment efficacy (EE) of ~88 ± 4 %. The in vitro anti-proliferative activity of DGN-ChAgNPs was performed by sulforhodamine B (SRB) assay with promising inhibitory concentration of 6.902 ± 2.79 μg/mL. DAPI staining, comet assay and flow cytometry were performed to validate the anticancer potential of DGN-ChAgNPs both qualitatively and quantitatively. The percentage of survival rate and tumor reduction weight was evaluated in vivo in different groups of mice. Cisplatin was used as a standard anticancer drug. The DGN-ChAgNPs (12.5 mg/kg) treated group revealed higher percentage of survival rate and tumor reduction weight as compared to pure DGN treated group. These findings suggest that DGN-ChAgNPs could be developed as potential treatment therapy for breast cancer., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)
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- 2024
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14. Discovery of druggable potent inhibitors of serine proteases and farnesoid X receptor by ligand-based virtual screening to obstruct SARS-CoV-2.
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Zaib S, Rana N, Ali HS, Hussain N, Areeba, Ogaly HA, Al-Zahrani FAM, and Khan I
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- Animals, Humans, Serine Proteases, Furin, Cathepsin B, Ligands, Pandemics, Virus Internalization, Mammals, SARS-CoV-2, COVID-19
- Abstract
The coronavirus, a subfamily of the coronavirinae family, is an RNA virus with over 40 variations that can infect humans, non-human mammals and birds. There are seven types of human coronaviruses, including SARS-CoV-2, is responsible for the recent COVID-19 pandemic. The current study is focused on the identification of drug molecules for the treatment of COVID-19 by targeting human proteases like transmembrane serine protease 2 (TMPRSS2), furin, cathepsin B, and a nuclear receptor named farnesoid X receptor (FXR). TMPRSS2 and furin help in cleaving the spike protein of the SARS-CoV-2 virus, while cathepsin B plays a critical role in the entry and pathogenesis. FXR, on the other hand, regulates the expression of ACE2, and its inhibition can reduce SARS-CoV-2 infection. By inhibiting these four protein targets with non-toxic inhibitors, the entry of the infectious agent into host cells and its pathogenesis can be obstructed. We have used the BioSolveIT suite for pharmacophore-based computational drug designing. A total of 1611 ligands from the ligand library were docked with the target proteins to obtain potent inhibitors on the basis of pharmacophore. Following the ADMET analysis and protein ligand interactions, potent and druggable inhibitors of the target proteins were obtained. Additionally, toxic substructures and the less toxic route of administration of the most potent inhibitors in rodents were also determined computationally. Compounds namely N-(diaminomethylene)-2-((3-((1R,3R)-3-(2-(methoxy(methyl)amino)-2-oxoethyl)cyclopentyl)propyl)amino)-2-oxoethan-1-aminium (26), (1R,3R)-3-(((2-ammonioethyl)ammonio)methyl)-1-((4-propyl-1H-imidazol-2-yl)methyl)piperidin-1-ium (29) and (1R,3R)-3-(((2-ammonioethyl)ammonio)methyl)-1-((1-propyl-1H-pyrazol-4-yl)methyl)piperidin-1-ium (30) were found as the potent inhibitors of TMPRSS2, whereas, 1-(1-(1-(1H-tetrazol-1-yl)cyclopropane-1‑carbonyl)piperidin-4-yl)azepan-2-one (6), (2R)-4-methyl-1-oxo-1-((7R,11S)-4-oxo-6,7,8,9,10,11-hexahydro-4H-7,11-methanopyrido[1,2-a]azocin-9-yl)pentan-2-aminium (12), 4-((1-(3-(3,5-dimethylisoxazol-4-yl)propanoyl)piperidin-4-yl)methyl)morpholin-4-ium (13), 1-(4,6-dimethylpyrimidin-2-yl)-N-(3-oxocyclohex-1-en-1-yl)piperidine-4-carboxamide (14), 1-(4-(1,5-dimethyl-1H-1,2,4-triazol-3-yl)piperidin-1-yl)-3-(3,5-dimethylisoxazol-4-yl)propan-1-one (25) and N,N-dimethyl-4-oxo-4-((1S,5R)-8-oxo-5,6-dihydro-1H-1,5-methanopyrido[1,2-a][1,5]diazocin-3(2H,4H,8H)-yl)butanamide (31) inhibited the FXR preferentially. In case of cathepsin B, N-((5-benzoylthiophen-2-yl)methyl)-2-hydrazineyl-2-oxoacetamide (2) and N-([2,2'-bifuran]-5-ylmethyl)-2-hydrazineyl-2-oxoacetamide (7) were identified as the most druggable inhibitors whereas 1-amino-2,7-diethyl-3,8-dioxo-6-(p-tolyl)-2,3,7,8-tetrahydro-2,7-naphthyridine-4‑carbonitrile (5) and (R)-6-amino-2-(2,3-dihydroxypropyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (20) were active against furin., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)
- Published
- 2023
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15. Pyrimidine-morpholine hybrids as potent druggable therapeutics for Alzheimer's disease: Synthesis, biochemical and in silico analyses.
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Zaib S, Younas MT, Khan I, Ali HS, McAdam CJ, White JM, Jaber F, Awwad NS, and Ibrahium HA
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- Humans, Molecular Structure, Acetylcholinesterase metabolism, Morpholines pharmacology, Morpholines chemistry, Pyrimidines pharmacology, Pyrimidines therapeutic use, Molecular Docking Simulation, Structure-Activity Relationship, Cholinesterase Inhibitors pharmacology, Cholinesterase Inhibitors therapeutic use, Cholinesterase Inhibitors chemistry, Alzheimer Disease drug therapy, Alzheimer Disease metabolism
- Abstract
The identification of effective and druggable cholinesterase inhibitors to treat progressive neurodegenerative Alzheimer's disorder remains a continuous drug discovery hunt. In this perspective, the present study investigates the design and discovery of pyrimidine-morpholine hybrids (5a-l) as potent cholinesterase inhibitors. Palladium-catalyzed Suzuki-Miyaura cross-coupling reaction was employed to introduce the structural diversity on the pyrimidine heterocyclic core. A range of commercially available boronic acids was successfully coupled showing a high functional group tolerance. In vitro cholinesterase inhibitory potential using Ellman's method revealed significantly strong potency. Compound 5h bearing a meta-tolyl substituent at 2-position of pyrimidine ring emerged as a lead candidate against AChE with an inhibitory potency of 0.43 ± 0.42 µM, ∼38-fold stronger value than neostigmine (IC
50 = 16.3 ± 1.12 µM). Compound 5h also showed the lead inhibition against BuChE with an IC50 value of 2.5 ± 0.04 µM. The kinetics analysis of 5h revealed the non-competitive mode of inhibition against AChE whereas computational modelling results of potent leads depicted diverse contacts with the binding site amino acid residues. Molecular dynamics simulations revealed the stability of biomolecular system, while, ADME analysis demonstrated druglikeness behaviour of potent compounds. Overall, the investigated pyrimidine-morpholine scaffold presented a remarkable potential to be developed as efficacious anti-Alzheimer's drugs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)- Published
- 2023
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16. Triazolothiadiazoles and triazolothiadiazines as potent α-glucosidase inhibitors: Mechanistic insights from kinetics studies, molecular docking and dynamics simulations.
- Author
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Ullah S, Waqas M, Halim SA, Khan I, Khalid A, Abdalla AN, Makeen HA, Ibrar A, Khan A, and Al-Harrasi A
- Abstract
Diabetes mellitus has been considered as a serious health problem worldwide due its high prevalence rate and associated complications. In this context, the current research work aims at exploring new structural leads for the treatment of a major metabolic disorder, diabetes mellitus type 2. The outcomes of our prior studies on a diverse set of triazolothiadiazole and triazolothiadiazine derivatives and their therapeutic potential, encouraged us to explore their anti-diabetic competency by targeting the key carbohydrate catabolic enzyme, α-glucosidase. Therefore, all these analogues were examined to reveal their contribution towards this severe metabolic issue. Interestingly, all the tested compounds (2a-2l and 3a-3p) exhibited several times more potent α-glucosidase inhibitory activities (IC
50 in the range of 2.44-219.93 μM) as compared to marketed drug, acarbose (IC50 = 873.34 ± 1.67 μM). Furthermore, their mechanism of action was investigated through in vitro kinetics studies which revealed compounds 3a, 3d, 3o, and 2k as competitive inhibitors, and 3f as a mixed type inhibitor of α-glucosidase. In addition, in silico molecular docking and molecular dynamics simulations were applied to observe the mode of interaction of the active hits within the binding pocket of α-glucosidase. Both docking and simulation results favored our in vitro mechanistic analysis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)- Published
- 2023
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17. Designing multi-epitope monkeypox virus-specific vaccine using immunoinformatics approach.
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Zaib S, Rana N, Areeba, Hussain N, Alrbyawi H, Dera AA, Khan I, Khalid M, Khan A, and Al-Harrasi A
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- Animals, Vaccines, Subunit chemistry, Vaccines, Subunit genetics, Molecular Docking Simulation, Computational Biology methods, Epitopes, B-Lymphocyte, Monkeypox virus
- Abstract
Background: Monkeypox virus is an enveloped DNA virus that belongs to Poxviridae family. The virus is transmitted from rodents to primates via infected body fluids, skin lesions, and respiratory droplets. After being infected with virus, the patients experience fever, myalgia, maculopapular rash, and fluid-filled blisters. It is necessary to differentiate monkeypox virus from other poxviruses during diagnosis which can be appropriately envisioned via DNA analysis from swab samples. During small outbreaks, the virus is treated with therapies administered in other orthopoxviruses infections and does not have its own specific therapy and vaccine. Consequently, in this article, two potential peptides have been designed., Methods: For the purpose of designing a vaccine, protein sequences were retrieved followed by the prediction of B- and T-cell epitopes. Afterward, vaccine structures were predicted which were docked with toll-like receptors. The docked complexes were analyzed with iMODS. Moreover, vaccine constructs nucleotide sequences were optimized and expressed in silico., Results: COP-B7R vaccine construct (V1) has antigenicity score of 0.5400, instability index of 29.33, z-score of - 2.11-, and 42.11% GC content whereas COP-A44L vaccine construct (V2) has an antigenicity score of 0.7784, instability index of 23.33, z-score of - 0.61, and 48.63% GC content. It was also observed that COP-A44L can be expressed as a soluble protein in Escherichia coli as compared to COP-B7R which requires a different expression system., Conclusion: The obtained results revealed that both vaccine constructs show satisfactory outcomes after in silico investigation and have significant potential to prevent the monkeypox virus. However, COP-A44L gave better results., Competing Interests: Competing interests There are no conflicts to declare., (Copyright © 2022. Published by Elsevier Ltd.)
- Published
- 2023
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18. Discovery of potent and selective dual cholinesterases and β-secretase inhibitors in pomegranate as a treatment for Alzheimer's disease.
- Author
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Yousof Ali M, Zaib S, Jannat S, and Khan I
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- Humans, Amyloid Precursor Protein Secretases, Aspartic Acid Endopeptidases metabolism, Amyloid beta-Protein Precursor metabolism, Amyloid beta-Protein Precursor therapeutic use, Molecular Docking Simulation, Cholinesterases, Amyloid beta-Peptides metabolism, Pomegranate, Alzheimer Disease drug therapy
- Abstract
Pomegranate (Punica granatum L.) extract has been reported to inhibit cholinesterase and the β-site amyloid precursor protein cleaving enzyme 1 (BACE1); however, most of its constituents' potential inhibition of these enzymes remains unknown. Thus, we investigated the anti-Alzheimer's disease (anti-AD) potential of 16 ellagitannin and gallotannin, and nine anthocyanin derivatives' inhibition of BACE1, AChE, and BChE, and gallagic acid inhibited both the best. Further, a kinetic study identified different modes of inhibition, and a molecular docking simulation revealed that active compounds inhibited these three enzymes with low binding energy through hydrophilic and hydrophobic interactions in the active site cavities. Gallagic acid and castalagin decreased Aβ peptides secretion from neuroblastoma cells that overexpressed human β-amyloid precursor protein significantly by 10 μM. Further, treatment with gallagic acid and castalagin reduced BACE1 and APPsβ expression levels significantly without affecting amyloid precursor protein (APP) levels in the amyloidogenic pathway. Co-incubation of Aβ42 with gallagic acid reduced Aβ42-induced intracellular reactive oxygen species (ROS) production significantly. Our results suggest that pomegranate constituents, specifically gallagic acid, may be useful in developing therapeutic treatment modalities for AD., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)
- Published
- 2022
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19. Immune responses to Toxoplasma gondii.
- Author
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Khan IA and Moretto M
- Subjects
- CD8-Positive T-Lymphocytes, Humans, Immunity, Innate, Infant, Newborn, Monocytes, Toxoplasma physiology
- Abstract
Toxoplasma gondii is an obligate intracellular parasite that can cause severe complications in the newborn and immunocompromised individuals. The parasite evokes a strong innate immune response in the infected hosts which is followed by a robust adaptive immunity. In the last few years, importance of innate immune mechanisms dependent on the role of MyD-88 independent pathways, inflammatory monocytes and innate lymphocyte have been identified. However, notwithstanding the strong immune response to the parasite, the chronic infection persists in the host. The inability to prevent chronic infection can be attributed to aberration in the memory CD8 T cell response caused by an increased expression of inhibitory receptors that leads to their dysfunctionality., (Copyright © 2022. Published by Elsevier Ltd.)
- Published
- 2022
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20. New acetylphenol-based acyl thioureas broaden the scope of drug candidates for urease inhibition: synthesis, in vitro screening and in silico analysis.
- Author
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Zahra U, Zaib S, Saeed A, Rehman MU, Shabir G, Alsaab HO, and Khan I
- Subjects
- Structure-Activity Relationship, Helicobacter pylori drug effects, Helicobacter pylori enzymology, Humans, Computer Simulation, Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents chemistry, Anti-Bacterial Agents chemical synthesis, Phenols chemistry, Phenols pharmacology, Phenols chemical synthesis, Drug Evaluation, Preclinical, Urease antagonists & inhibitors, Urease chemistry, Urease metabolism, Thiourea chemistry, Thiourea pharmacology, Molecular Docking Simulation, Enzyme Inhibitors pharmacology, Enzyme Inhibitors chemistry, Enzyme Inhibitors chemical synthesis
- Abstract
Helicobacter pylori urease remains a validated drug target for the eradication of pervasive chronic stomach infection that leads to severe human health diseases such as gastritis and stomach cancer. The increased failure of current treatment protocols because of resistance to broadband antibiotics, severe side effects and low compliance underscore the need for a targeted eradication therapy. Therefore, in the present research, we have developed a new series of acetylphenol-based acyl thioureas that can potentially provide a new template for drug candidates to inhibit urease enzyme. Newly synthesized compounds 7a-j were evaluated for urease inhibitory strength using thiourea as a positive control. In vitro inhibitory results revealed that all the tested compounds were significantly potent than the standard drug. The most active lead 7f competitively inhibited the enzyme and displayed an IC
50 value of 0.054 ± 0.002 μM, a ~413-fold strong inhibitory potential than thiourea (IC50 = 22.3 ± 0.031 μM). Various insightful structure-activity relationships were developed showing the key structural requirements for potent inhibitory effects. Molecular docking analysis of 7f inside the active pocket of urease suggested several important interactions with amino acid residues such as ILE411, MET637, ARG439, GLN635, ALA636 and ALA440. Finally, pharmacokinetic properties suggested that the tested derivatives are safe to develop as low-molecular-weight drugs to treat ureolytic bacterial infections., (Copyright © 2021 Elsevier B.V. All rights reserved.)- Published
- 2022
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21. Discovery of urease inhibitory effect of sulfamate derivatives: Biological and computational studies.
- Author
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Zaib S, Tayyab Younas M, Zaraei SO, Khan I, Anbar HS, and El-Gamal MI
- Subjects
- Anti-Bacterial Agents chemical synthesis, Anti-Bacterial Agents chemistry, Dose-Response Relationship, Drug, Enzyme Inhibitors chemical synthesis, Enzyme Inhibitors chemistry, Helicobacter pylori enzymology, Kinetics, Microbial Sensitivity Tests, Models, Molecular, Molecular Structure, Structure-Activity Relationship, Sulfonic Acids chemical synthesis, Sulfonic Acids chemistry, Urease metabolism, Anti-Bacterial Agents pharmacology, Drug Discovery, Enzyme Inhibitors pharmacology, Helicobacter pylori drug effects, Sulfonic Acids pharmacology, Urease antagonists & inhibitors
- Abstract
The discovery of life-changing medicines continues to be the driving force for the rapid exploration and expansion of chemical space, enabling access to innovative small molecules of medicinal importance. These small molecules remain the backbone for modern drug discovery. In this context, the treatment of ureolytic bacterial infections inspires the identification of potent and effective inhibitors of urease, a promising and highly needed target for H. pylori eradication. The present study explores the evaluation of sulfamate derivatives for the inhibition of urease enzyme. The tested compounds showed remarkable inhibitory effect and high level of potency. Compound 1q emerged as the lead inhibitor with an IC
50 value of 0.062 ± 0.001 µM, ∼360-fold more potent than thiourea (IC50 = 22.31 ± 0.031 µM). The assessment of various contributing factors towards the inhibition profile allowed for the establishment of diverse structure-activity relationships. Kinetics studies revealed the competitive mode of inhibition of compound 1q while molecular modeling analysis identified various crucial binding interactions with ARG609, ARG439, HIS519, HIS492, HIS593, ALA440, and ALA636 in the active pocket of the enzyme. Finally, the calculated pharmacokinetic properties suggest a promising profile of our potent sulfamate-based urease inhibitors., (Copyright © 2021 Elsevier Inc. All rights reserved.)- Published
- 2022
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22. Metal oxide and carbon nanomaterial based membranes for reverse osmosis and membrane distillation: A comparative review.
- Author
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Khan AA, Maitlo HA, Khan IA, Lim D, Zhang M, Kim KH, Lee J, and Kim JO
- Subjects
- Distillation, Membranes, Artificial, Osmosis, Silicon Dioxide, Nanostructures, Water Purification
- Abstract
Commercial membranes typically suffer from fouling and wetting during membrane distillation (MD). In contrast, reverse osmosis (RO) can be subject to the fouling issue if applied for highly saline feed solutions containing foulants (e.g., organics, oils, and surfactants). Among the diverse treatment options, the nanomaterial-based membranes have recently gained great interest due to their advantageous properties (e.g., enhanced flux and roughness, better pore size distribution, and higher conductivity). This review focuses on recent advances in the mechanical properties, anti-fouling capabilities, salt rejection, and economic viability of metal oxide (SiO
2 , TiO2 , and ZnO) and carbon nanomaterial (graphene oxide/carbon nanotube)-based membranes. Current challenges in applying nanomaterial-based membranes are also discussed. The study further describes the preparation methods, mechanisms, commercial applications, and economical feasibility of metal oxide- and carbon nanomaterial-based membrane technologies., (Copyright © 2021 Elsevier Inc. All rights reserved.)- Published
- 2021
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23. Design of a novel multiple epitope-based vaccine: An immunoinformatics approach to combat SARS-CoV-2 strains.
- Author
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Naveed M, Tehreem S, Arshad S, Bukhari SA, Shabbir MA, Essa R, Ali N, Zaib S, Khan A, Al-Harrasi A, and Khan I
- Subjects
- China, Computational Biology, Epitopes, B-Lymphocyte, Humans, Molecular Docking Simulation, Spike Glycoprotein, Coronavirus, COVID-19, SARS-CoV-2
- Abstract
Background: Since the SARS-CoV-2 outbreak in December 2019 in Wuhan, China, the virus has infected more than 153 million individuals across the world due to its human-to-human transmission. The USA is the most affected country having more than 32-million cases till date. Sudden high fever, pneumonia and organ failure have been observed in infected individuals., Objectives: In the current situation of emerging viral disease, there is no specific vaccine, or any therapeutics available for SARS-CoV-2, thus there is a dire need to design a potential vaccine to combat the virus by developing immunity in the population. The purpose of present study was to develop a potential vaccine by targeting B and T-cell epitopes using bioinformatics approaches., Methods: B- and T-cell epitopes are predicted from novel M protein-SARS-CoV-2 for the development of a unique multiple epitope vaccine by applying bioinformatics approaches. These epitopes were analyzed and selected for their immunogenicity, antigenicity scores, and toxicity in correspondence to their ability to trigger immune response. In combination to epitopes, best multi-epitope of potential immunogenic property was constructed. The epitopes were joined using EAAAK, AAY and GPGPG linkers., Results: The constructed vaccine showed good results of worldwide population coverage and promising immune response. This constructed vaccine was subjected to in-silico immune simulations by C-ImmSim. Chimeric protein construct was cloned into PET28a (+) vector for expression study in Escherichia coli using snapgene., Conclusion: This vaccine design proved effective in various computer-based immune response analysis as well as showed good population coverage. This study is solely dependent on developing M protein-based vaccine, and these in silico findings would be a breakthrough in the development of an effective vaccine to eradicate SARS-CoV-2 globally., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2021
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24. Utilization of the common functional groups in bioactive molecules: Exploring dual inhibitory potential and computational analysis of keto esters against α-glucosidase and carbonic anhydrase-II enzymes.
- Author
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Khan I, Khan A, Halim SA, Khan M, Zaib S, Al-Yahyaei BEM, Al-Harrasi A, and Ibrar A
- Subjects
- Carbonic Anhydrase Inhibitors chemical synthesis, Carbonic Anhydrase Inhibitors pharmacology, Chemical Phenomena, Chemistry Techniques, Synthetic, Enzyme Activation drug effects, Glycoside Hydrolase Inhibitors chemical synthesis, Glycoside Hydrolase Inhibitors pharmacology, Humans, Kinetics, Models, Molecular, Molecular Conformation, Molecular Structure, Structure-Activity Relationship, Carbonic Anhydrase II chemistry, Carbonic Anhydrase Inhibitors chemistry, Esters chemistry, Glycoside Hydrolase Inhibitors chemistry, Ketones chemistry, alpha-Glucosidases chemistry
- Abstract
Diabetes mellitus, a progressive chronic disease, characterized by the abnormal carbohydrate metabolism is associated with severe health complications including long term dysfunction or failure of several organs, cardiovascular and micro-angiopathic problems (neuropathy, nephropathy, retinopathy). Despite the existence of diverse chemical structural libraries of α-glucosidase inhibitors, the limited diabetic treatment due to the adverse side effects such as abdominal distention, flatulence, diarrhoea, and liver damage associated with these inhibitors encourage the medicinal research community to design and develop new and potent inhibitors of α-glucosidase with better pharmacokinetic properties. In this perspective, we demonstrate the successful integration of common functional groups (ketone & ester) in one combined pharmacophore which is favorable for the formation of hydrogen bonds and other weaker interactions with the target proteins. These keto ester derivatives were screened for their α-glucosidase inhibition potential and the in vitro results revealed compound 3c as the highly active inhibitor with an IC
50 value of 12.4 ± 0.16 μM compared to acarbose (IC50 = 942 ± 0.74 μM). This inhibition potency was ~76-fold higher than acarbose. Other potent compounds were 3f (IC50 = 28.0 ± 0.28 μM), 3h (IC50 = 33.9 ± 0.09 μM), 3g (IC50 = 34.1 ± 0.04 μM), and 3d (IC50 = 76.5 ± 2.0 μM). In addition, the emerging use of carbonic anhydrase inhibitors for the treatment of diabetic retinopathy (a leading cause of vision loss) prompted us to screen the keto ester derivatives for the inhibition of carbonic anhydrase-II. Compound 3b was found significantly active against carbonic anhydrase-II with an IC50 of 16.5 ± 0.92 μM (acetazolamide; IC50 = 18.2 ± 1.23 μM). Compound 3a also exhibited comparable potency with an IC50 value of 18.9 ± 1.08 μM. Several structure-activity relationship analyses depicted the influence of the substitution pattern on both the aromatic rings. Molecular docking analysis revealed the formation of several H-bonding interactions through the ester carbonyl and the nitro oxygens of 3c with the side chains of His348, Arg212 and His279 in the active pocket of α-glucosidase whereas 3b interacted with His95, -OH of Thr197, Thr198 and WAT462 in the active site of carbonic anhydrase-II. Furthermore, evaluation of ADME properties suggests the safer pharmacological profile of the tested derivatives., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)- Published
- 2021
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25. Optimization of preoxidation to reduce scaling during cleaning-in-place of membrane treatment.
- Author
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Khan IA, Lee YS, and Kim JO
- Abstract
This study investigated the potential for reducing scaling during chemical cleaning of polyvinylidene fluoride membranes by optimizing preoxidation dose and pH. Membranes were fouled by a solution containing inorganic foulants (aluminum, iron, and manganese), humic acid, and kaolin at a Ca
+2 strength of 0.5 mM and varying the preoxidation dose. Energy-dispersive spectroscopy was used to verify the presence of inorganic foulants after cleaning. Fourier-transform infrared spectroscopy revealed changes in CCl and C-F functional groups, with bond vibrations at 542 cm-1 and 1199 cm-1 , respectively. Minimum irreversible fouling of 5.4% and maximum flux recovery of 88.8% of the initial value were associated with a preoxidation dose of 1.5 mg/L and pH 8.5. A decrease in amount of aluminum from 5.79 ± 0.021 mg to 3.85 ± 0.054 mg in the presence of humic acid with a removal efficiency greater than 60% was due to alteration of the feed solution, as revealed by mass-balance analysis. Membrane characterization and fouling reversibility analysis confirmed that preoxidation of the feed solution produced less scaling during chemical cleaning. The cake layer fouling contribution was determined by fitting results of Hermia's fouling model analysis, with 1.34-1.85 times lower total fouling indices and 3-5.5 times lower chemically irreversible fouling indices at pH 8.5 and a preoxidation dose of 1.5 mg/L., (Copyright © 2020. Published by Elsevier B.V.)- Published
- 2020
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26. Synthetic and medicinal chemistry of phthalazines: Recent developments, opportunities and challenges.
- Author
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Zaib S and Khan I
- Subjects
- Chemistry, Pharmaceutical, Disease, Humans, Molecular Structure, Phthalazines chemical synthesis, Phthalazines chemistry, Drug Development, Phthalazines pharmacology
- Abstract
Fused diaza-heterocycles constitute the core structure of numerous bioactive natural products and effective therapeutic drugs. Among them, phthalazines have been recognized as remarkable structural leads in medicinal chemistry due to their wide application in pharmaceutical and agrochemical industries. Accessing such challenging pharmaceutical agents/drug candidates with high chemical complexity through synthetically efficient approaches remains an attractive goal in the contemporary medicinal chemistry and drug discovery arena. In this review, we focus on the recent developments in the synthetic routes towards the generation of phthalazine-based active pharmaceutical ingredients and their biological potential against various targets. The general reaction scope of these innovative and easily accessible strategies was emphasized focusing on the functional group tolerance, substrate and coupling partner compatibility/limitation, the choice of catalyst, and product diversification. These processes were also accompanied by the mechanistic insights where deemed appropriate to demonstrate meaningful information. Moreover, the rapid examination of the structure-activity relationship analyses around the phthalazine core enabled by the pharmacophore replacement/integration revealed the generation of robust, efficient, and more selective compounds with pronounced biological effects. A large variety of in silico methods and ADME profiling tools were also employed to provide a global appraisal of the pharmacokinetics profile of diaza-heterocycles. Thus, the discovery of new structural leads offers the promise of improving treatments for various tropical diseases such as tuberculosis, leishmaniasis, malaria, Chagas disease, among many others including various cancers, atherosclerosis, HIV, inflammatory, and cardiovascular diseases. We hope this review would serve as an informative collection of structurally diverse molecules enabling the generation of mature, high-quality, and innovative routes to support the drug discovery endeavors., (Copyright © 2020 Elsevier Inc. All rights reserved.)
- Published
- 2020
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27. Exploring biological efficacy of coumarin clubbed thiazolo[3,2-b][1,2,4]triazoles as efficient inhibitors of urease: A biochemical and in silico approach.
- Author
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Khan I, Khan A, Ahsan Halim S, Saeed A, Mehsud S, Csuk R, Al-Harrasi A, and Ibrar A
- Subjects
- Binding Sites, Catalytic Domain, Enzyme Inhibitors chemical synthesis, Models, Molecular, Molecular Structure, Protein Binding, Structure-Activity Relationship, Triazoles chemical synthesis, Coumarins chemistry, Enzyme Inhibitors chemistry, Enzyme Inhibitors pharmacology, Thiazoles chemistry, Triazoles chemistry, Triazoles pharmacology, Urease chemistry
- Abstract
Combating several pathological conditions associated with ureolytic enzyme (urease) remains a formidable challenge because of the lack of effective and safe drug therapies. In this regard, the development of potent inhibitors of urease could be considered as a promising remedy. Herein, we report a new library of structurally diverse hybrid heteroaromatics featuring coumarin and thiazolotriazole motifs in one combined unit. These new chemical scaffolds accessed through the integration approach were shown to inhibit the enzyme urease from jack bean at variable efficacies. An initial structure-activity relationship analysis guided through the variation of several functional groups at the aryl ring connected to the thiazole core revealed compound 6o (IC
50 = 4.35 ± 0.18 µM) as the most potent inhibitor. The inhibitory strength of 6o was 5-fold compared to thiourea (standard; IC50 = 20.8 ± 0.59 µM). In the molecular docking analysis, 6o was stabilized in the active pocket through various binding interactions. The presence of an amino moiety at the meta position of the phenyl ring facilitates hydrogen bonding with the sulfhydryl group of Cys322 (2.11 Å) in addition to an interaction observed between the thiazole sulfur and nickel atoms present in the active site. Moreover, this amino group also interacts with the carbonyl oxygen of Ala366 at a distance of 2.75 Å. The chromenone moiety of compound 6o is stabilized by the side chains of various amino acid residues including Ala279, Thr301, Pro303, Thr304, His315 and Met367., (Copyright © 2019 Elsevier B.V. All rights reserved.)- Published
- 2020
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28. Robust therapeutic potential of carbazole-triazine hybrids as a new class of urease inhibitors: A distinctive combination of nitrogen-containing heterocycles.
- Author
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Ibrar A, Kazmi M, Khan A, Halim SA, Saeed A, Mehsud S, Al-Harrasi A, and Khan I
- Subjects
- Canavalia enzymology, Carbazoles chemistry, Dose-Response Relationship, Drug, Enzyme Inhibitors chemical synthesis, Enzyme Inhibitors chemistry, Heterocyclic Compounds chemical synthesis, Heterocyclic Compounds chemistry, Molecular Structure, Nitrogen chemistry, Nitrogen pharmacology, Structure-Activity Relationship, Triazines chemistry, Urease metabolism, Carbazoles pharmacology, Enzyme Inhibitors pharmacology, Heterocyclic Compounds pharmacology, Triazines pharmacology, Urease antagonists & inhibitors
- Abstract
The inhibition of urease enzyme is very important as it plays a key role in the treatment of several urinary and gastrointestinal tract infections. This enzyme provides a suitable environment for Helicobacter pylori at the low pH of the stomach, a causative agent of gastric and peptic ulcer that may lead to cancer. In agriculture, the high urease content causes environmental and economic problems. In this pursuit, given the well-established importance of integrated pharmacophores in medicinal chemistry and to explore new inhibitors of urease featuring two distinct heterocyclic functionalities, we herein report a facile synthesis of carbazole-triazine hybrids (3a-j). These new propeller-shaped chemical scaffolds were evaluated for their urease inhibitory potential in order to identify suitable leads. The initial structure-activity survey work guided through in vitro bioactivity results recognized 3e and 3f as new starting point hits incorporating bulky iodo (3e) and strong electron-withdrawing nitro (3f) groups at the para-position of aryl amine component. The potent compounds (3e &3f) exhibited the highest activity with IC
50 values of 5.6 and 6.7 µM, respectively. In the molecular docking analysis, these compounds depicted excellent binding interactions with the active site residues. The key interactions observed include hydrogen bonding, π-π interactions, π-cation and nickel atom coordination to the triazine nitrogen of both inhibitors., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2019 Elsevier Inc. All rights reserved.)- Published
- 2020
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29. Probing the high potency of pyrazolyl pyrimidinetriones and thioxopyrimidinediones as selective and efficient non-nucleotide inhibitors of recombinant human ectonucleotidases.
- Author
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Andleeb H, Hameed S, Ejaz SA, Khan I, Zaib S, Lecka J, Sévigny J, and Iqbal J
- Subjects
- Alkaline Phosphatase antagonists & inhibitors, Alkaline Phosphatase chemistry, Alkaline Phosphatase metabolism, Antineoplastic Agents chemical synthesis, Antineoplastic Agents metabolism, Antineoplastic Agents pharmacology, Barbiturates chemical synthesis, Barbiturates metabolism, Catalytic Domain, Cell Line, Tumor, Drug Design, Enzyme Assays, Enzyme Inhibitors chemical synthesis, Enzyme Inhibitors metabolism, GPI-Linked Proteins antagonists & inhibitors, GPI-Linked Proteins chemistry, GPI-Linked Proteins metabolism, Humans, Kinetics, Microbial Sensitivity Tests, Molecular Docking Simulation, Molecular Structure, Phosphoric Diester Hydrolases chemistry, Phosphoric Diester Hydrolases metabolism, Protein Binding, Pyrazoles chemical synthesis, Pyrazoles metabolism, Pyrophosphatases antagonists & inhibitors, Pyrophosphatases chemistry, Pyrophosphatases metabolism, Structure-Activity Relationship, Thiones chemical synthesis, Thiones metabolism, Barbiturates pharmacology, Enzyme Inhibitors pharmacology, Pyrazoles pharmacology, Thiones pharmacology
- Abstract
With the aim to discover novel, efficient and selective inhibitors of human alkaline phosphatase and nucleotide pyrophosphatase enzymes, two new series of pyrazolyl pyrimidinetriones (PPTs) (6a-g) and thioxopyrimidinediones (PTPs) (6h-n) were synthesized in good chemical yields using Knoevenagel condensation reaction between pyrazole carbaldehydes (4a-g) and pharmacologically active N-alkylated pyrimidinetrione (5a) and thioxopyrimidinedione (5b). The inhibition potential of the synthesized hybrid compounds was evaluated against human alkaline phosphatase (h-TNAP and h-IAP) and ectonucleotidase (h-NPP1 and h-NPP3) enzymes. Most of the tested analogs were highly potent with a variable degree of inhibition depending on the functionalized hybrid structure. The detailed structure-activity relationship (SAR) of PPT and PTP derivatives suggested that the compound with unsubstituted phenyl ring from PPT series led to selective and potent inhibition (6a; IC
50 = 0.33 ± 0.02 µM) of h-TNAP, whereas compound 6c selectively inhibited h-IAP isozyme with IC50 value of 0.86 ± 0.04 µM. Similarly, compounds 6b and 6h were identified as the lead scaffolds against h-NPP1 and h-NPP3, respectively. The probable binding modes for the most potent inhibitors were elucidated through molecular docking analysis. Structure-activity relationships, mechanism of action, cytotoxic effects and druglikeness properties are also discussed., (Copyright © 2019. Published by Elsevier Inc.)- Published
- 2019
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30. One-pot four-component synthesis of thiazolidin-2-imines using Cu I /Zn II dual catalysis: A new class of acetylcholinesterase inhibitors.
- Author
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Shehzadi SA, Khan I, Saeed A, Larik FA, Channar PA, Hassan M, Raza H, Abbas Q, and Seo SY
- Subjects
- Acetylcholinesterase chemistry, Acetylcholinesterase metabolism, Binding Sites, Catalysis, Cholinesterase Inhibitors metabolism, Copper chemistry, Humans, Imines metabolism, Inhibitory Concentration 50, Molecular Conformation, Molecular Docking Simulation, Structure-Activity Relationship, Thermodynamics, Thiazoles chemistry, Zinc chemistry, Cholinesterase Inhibitors chemical synthesis, Imines chemistry
- Abstract
An efficient one-pot four-component strategy involving aldehydes, amines, alkynes and isothiocyanates has been developed to access a novel series of thiazolidine-2-imines (5a-x). This process operates under the action of a cooperative catalysis composed of Cu(I) and Zn(II) delivering the desired five-membered heterocyclic compounds in good to excellent yields. Notably, this transformation avoids the use of pre-formed imines or propargylamines and proceeds via an intramolecular 5-exo-dig hydrothiolation reaction of the in situ formed propargyl thiourea. Furthermore, the biological application of these motifs was demonstrated in terms of their strong acetylcholinesterase (AChE) inhibitory activity where compound 5s was identified as the lead AChE inhibitor with an IC
50 value of 0.0023 ± 0.0002 μM, 88-folds stronger inhibition than standard drug (neostigmine methyl sulphate; IC50 = 0.203 ± 0.004 μM). Molecular docking analysis reinforced the in vitro biological activity results revealing the formation of several useful interactions of the potent lead with amino acid residues in the active site of the enzyme., (Copyright © 2018 Elsevier Inc. All rights reserved.)- Published
- 2019
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31. Optimization of membrane modification using SiO 2 for robust anti-fouling performance with calcium-humic acid feed in membrane distillation.
- Author
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Khan AA, Khan IA, Siyal MI, Lee CK, and Kim JO
- Subjects
- Calcium, Humic Substances, Membranes, Membranes, Artificial, Distillation, Silicon Dioxide metabolism, Water Purification
- Abstract
The goal of this study was to prepare a robust anti-wetting and anti-fouling polyethersulfone (PES) membrane for the rejection of a highly saline (NaCl and CaCl
2 ·2H2 O) feed solution containing humic acid (HA) in direct contact membrane distillation (DCMD). Response surface methodology (RSM) was used to determine the optimum formulation of the used materials. The variable factors selected were polydimethyl siloxane (PDMS) and silica (SiO2 ); liquid entry pressure (LEP) and contact angle (CA) were selected as responses. Scanning electron microscopy (SEM) analysis confirmed the SiO2 deposition and Fourier-transform infrared spectroscopy (FTIR) test evidenced the new functional groups i.e., Si-OH, siloxane, and C-F bond vibrations at 3446, 1099 cm-1 , and 1150-1240 cm-1 respectively on the membrane surface. The average roughness (Ra) was increased four times for the coated membranes (0.202-0.242 µm) as compared to that for pristine PES membrane (0.053 µm). The optimum PES-13 membrane exhibited consistent flux of 12 LMH and salt rejection (> 99%) with anti-fouling characteristic in DCMD using the feed solution of 3.5 wt% NaCl + 10 mM CaCl2 ·2H2 O + 10 mg L-1 HA. The PES-13 membrane may therefore be a key membrane for application in DCMD against CaCl2 ·2H2 O-containing salty solutions with HA., (Copyright © 2018 Elsevier Inc. All rights reserved.)- Published
- 2019
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32. A new entry into the portfolio of α-glucosidase inhibitors as potent therapeutics for type 2 diabetes: Design, bioevaluation and one-pot multi-component synthesis of diamine-bridged coumarinyl oxadiazole conjugates.
- Author
-
Kazmi M, Zaib S, Ibrar A, Amjad ST, Shafique Z, Mehsud S, Saeed A, Iqbal J, and Khan I
- Subjects
- Coumarins chemical synthesis, Coumarins chemistry, Diabetes Mellitus, Type 2 metabolism, Diamines chemistry, Dose-Response Relationship, Drug, Glycoside Hydrolase Inhibitors chemical synthesis, Glycoside Hydrolase Inhibitors chemistry, Kinetics, Molecular Docking Simulation, Molecular Structure, Oxadiazoles chemical synthesis, Oxadiazoles chemistry, Saccharomyces cerevisiae enzymology, Structure-Activity Relationship, Coumarins pharmacology, Diabetes Mellitus, Type 2 drug therapy, Diamines pharmacology, Drug Design, Glycoside Hydrolase Inhibitors pharmacology, Oxadiazoles pharmacology, alpha-Glucosidases metabolism
- Abstract
Diabetes mellitus (DM), a chronic multifarious metabolic disorder resulting from impaired glucose homeostasis has become one of the most challenging diseases with severe life threat to public health. The inhibition of α-glucosidase, a key carbohydrate hydrolyzing enzyme, could serve as one of the effective methodology in both preventing and treating diabetes through controlling the postprandial glucose levels and suppressing postprandial hyperglycemia. In this context, three series of diamine-bridged bis-coumarinyl oxadiazole conjugates were designed and synthesized by one-pot multi-component methodology. The synthesized conjugates (4a-j, 5a-j, 6a-j) were evaluated as potential inhibitors of glucosidases. Compound 6f containing 4,4'-oxydianiline linker was identified as the lead and selective inhibitor of α-glucosidase enzyme with an IC
50 value of 0.07 ± 0.001 μM (acarbose: IC50 = 38.2 ± 0.12 μM). This inhibition efficacy was ∼545-fold higher compared to the standard drug. Compound 6f was also emerged as the lead molecule against intestinal maltase-glucoamylase with good inhibition strength (IC50 = 0.04 ± 0.02 μM) compared to acarbose (IC50 = 0.06 ± 0.01 μM). Against β-glucosidase enzyme, compound 6 g was noted as the lead inhibitor with IC50 value of 0.08 ± 0.002 μM. Michaelis-Menten kinetic experiments were performed to explore the mechanism of inhibition. Molecular docking studies of the synthesized library of hybrid structures against glucosidase enzyme were performed to describe ligand-protein interactions at molecular level that provided an insight into the biological properties of the analyzed compounds. The results suggested that the inhibitors could be stabilized in the active site through the formation of multiple interactions with catalytic residues in a cooperative fashion. In addition, strong binding interactions of the compounds with the amino acid residues were effective for the successful identification of α-glucosidase inhibitors., (Copyright © 2018 Elsevier Inc. All rights reserved.)- Published
- 2018
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33. Exploration of thioxothiazolidinone-sulfonate conjugates as a new class of aldehyde/aldose reductase inhibitors: A synthetic and computational investigation.
- Author
-
Andleeb H, Tehseen Y, Jabeen F, Khan I, Iqbal J, and Hameed S
- Subjects
- Aldehyde Reductase isolation & purification, Aldehyde Reductase metabolism, Animals, Binding Sites, Catalytic Domain, Cattle, Enzyme Inhibitors chemistry, Enzyme Inhibitors metabolism, Inhibitory Concentration 50, Lens, Crystalline enzymology, Molecular Docking Simulation, Protein Isoforms antagonists & inhibitors, Protein Isoforms isolation & purification, Protein Isoforms metabolism, Structure-Activity Relationship, Aldehyde Reductase antagonists & inhibitors, Enzyme Inhibitors chemical synthesis, Sulfonic Acids chemistry, Thiazoles chemistry
- Abstract
In the present study, the pharmacophore integration methodology provided an efficient access to a new library of thioxothiazolidinone-sulfonate conjugates (8a-r) from easily available synthetic precursors. The approach was excellently high yielding with flexible structural sites for chemical modifications. The designed hybrid scaffolds were assessed for aldehyde/aldose reductase inhibition activities. The results for the in vitro bioassays were promising with the identification of compound 8e as the lead and selective candidate for ALR2 inhibition with an IC
50 value of 0.468±0.003µMas compared to 3.1±0.2µM for the standard (sorbinil), whereas compound 8o demonstrated high inhibitory potency for both ALR2 and ALR1 enzymes. Molecular modeling analysis of the potent compounds provided further insight into the biological properties where detailed binding mode analysis revealed that the conjugates (8a-r) were found stabilized in the active site of the enzymes through the development of a number of interactions with catalytic residues., (Copyright © 2017 Elsevier Inc. All rights reserved.)- Published
- 2017
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34. Exploration of aroyl/heteroaroyl iminothiazolines featuring 2,4,5-trichlorophenyl moiety as a new class of potent, selective, and in vitro efficacious glucosidase inhibitors.
- Author
-
Kazmi M, Zaib S, Amjad ST, Khan I, Ibrar A, Saeed A, and Iqbal J
- Subjects
- Dose-Response Relationship, Drug, Glycoside Hydrolase Inhibitors chemical synthesis, Glycoside Hydrolase Inhibitors chemistry, Humans, Hypoglycemic Agents chemical synthesis, Hypoglycemic Agents chemistry, Molecular Docking Simulation, Molecular Structure, Structure-Activity Relationship, Thiazoles chemical synthesis, Thiazoles chemistry, Glycoside Hydrolase Inhibitors pharmacology, Hypoglycemic Agents pharmacology, Thiazoles pharmacology, alpha-Glucosidases metabolism
- Abstract
A series of iminothiazolines (4a-j) featuring 2,4,5-trichlorophenyl moiety and aroyl/heteroaroyl substituents has been prepared from readily accessible thioureas. In-vitro screening against glucosidase enzymes showed highly specific inhibition of α-glucosidase with a marked dependence of the potency upon the nature of the aroyl/heteroaroyl substituents. The most potent representatives, bearing ortho-tolyl and bulky naphthyl groups displayed the highest inhibitory potential with IC
50 value of 0.15±0.01µM compared to standard drug acarbose (IC50 =38.2±0.12µM). Several other derivatives (4c, 4d, 4i and 4j) were also significantly powerful and selective inhibitors of α-glucosidase. Binding interactions of potent compounds 4b, 4c, 4h and 4i with α-glucosidase were explored by molecular docking simulation. These results clearly identified a new class of structural leads which can be further investigated for the development of promising α-glucosidase inhibitors for the prevention of diabetes mellitus., (Copyright © 2017 Elsevier Inc. All rights reserved.)- Published
- 2017
- Full Text
- View/download PDF
35. Symmetrical aryl linked bis-iminothiazolidinones as new chemical entities for the inhibition of monoamine oxidases: Synthesis, in vitro biological evaluation and molecular modelling analysis.
- Author
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Abbas N, Zaib S, Bakht SM, Ibrar A, Khan I, Batool S, Saeed A, and Iqbal J
- Subjects
- Drug Discovery, Humans, Imines chemical synthesis, Imines chemistry, Imines pharmacology, Molecular Docking Simulation, Monoamine Oxidase chemistry, Monoamine Oxidase Inhibitors chemical synthesis, Thiazolidines chemical synthesis, Monoamine Oxidase metabolism, Monoamine Oxidase Inhibitors chemistry, Monoamine Oxidase Inhibitors pharmacology, Thiazolidines chemistry, Thiazolidines pharmacology
- Abstract
The multifactorial nature of Parkinson's disease necessitates the development of new chemical entities with inherent ability to address key pathogenic processes. To this end, two series of new symmetrical 1,2- and 1,4-bis(2-aroyl/alkoylimino-5-(2-methoxy-2-oxoethylidene)-4-oxo-thiazolidin-3-yl)benzene derivatives (3a-g and 5a-e) were synthesized in good yields by the cyclization of 1,2- and 1,4-bis(N'-substituted thioureido)benzene intermediates with dimethyl acetylenedicarboxylate (DMAD) in methanol at ambient temperature. The bis-iminothiazolidinone compounds were investigated in vitro for their inhibition of monoamine oxidase (MAO-A & MAO-B) enzymes with the aim to identify new and distinct pharmacophores for the treatment of neurodegenerative disorders like Parkinson's disease. Most of the designed compounds exhibited good inhibitory efficacy against monoamine oxidases. Compound 5a was identified as the most potent inhibitor of MAO-A depicting an IC
50 value of 0.001μM, a 4-fold stronger inhibitory strength compared to standard inhibitor (clorgyline: IC50 =0.0045μM). Molecular docking studies provided insights into enzyme-inhibitor interactions and a rationale for the observed inhibition towards monoamine oxidases., (Copyright © 2016 Elsevier Inc. All rights reserved.)- Published
- 2017
- Full Text
- View/download PDF
36. Coumarin-thiazole and -oxadiazole derivatives: Synthesis, bioactivity and docking studies for aldose/aldehyde reductase inhibitors.
- Author
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Ibrar A, Tehseen Y, Khan I, Hameed A, Saeed A, Furtmann N, Bajorath J, and Iqbal J
- Subjects
- Aldehyde Reductase metabolism, Animals, Cattle, Coumarins chemistry, Dose-Response Relationship, Drug, Enzyme Inhibitors chemical synthesis, Enzyme Inhibitors chemistry, Molecular Structure, Oxadiazoles chemistry, Structure-Activity Relationship, Thiazoles chemistry, Aldehyde Reductase antagonists & inhibitors, Coumarins pharmacology, Enzyme Inhibitors pharmacology, Molecular Docking Simulation, Oxadiazoles pharmacology, Thiazoles pharmacology
- Abstract
In continuation of our previous efforts directed towards the development of potent and selective inhibitors of aldose reductase (ALR2), and to control the diabetes mellitus (DM), a chronic metabolic disease, we synthesized novel coumarin-thiazole 6(a-o) and coumarin-oxadiazole 11(a-h) hybrids and screened for their inhibitory activity against aldose reductase (ALR2), for the selectivity against aldehyde reductase (ALR1). Compounds were also screened against ALR1. Among the newly designed compounds, 6c, 11d, and 11g were selective inhibitors of ALR2. Whereas, (E)-3-(2-(2-(2-bromobenzylidene)hydrazinyl)thiazol-4-yl)-2H-chromen-2-one 6c yielded the lowest IC50 value of 0.16±0.06μM for ALR2. Moreover, compounds (E)-3-(2-(2-benzylidenehydrazinyl)thiazol-4-yl)-2H-chromen-2-one (6a; IC50=2.94±1.23μM for ARL1 and 0.12±0.05μM for ARL2) and (E)-3-(2-(2-(1-(4-bromophenyl)ethylidene)hydrazinyl)thiazol-4-yl)-2H-chromen-2-one (6e; IC50=1.71±0.01μM for ARL1 and 0.11±0.001μM for ARL2) were confirmed as dual inhibitors. Furthermore, compounds 6i, 6k, 6m, and 11b were found to be selective inhibitors for ALR1, among which (E)-3-(2-(2-((2-amino-4-chlorophenyl)(phenyl)methylene)hydrazinyl)thiazol-4-yl)-2H-chromen-2-one (6m) was most potent (IC50=0.459±0.001μM). Docking studies performed using X-ray structures of ALR1 and ALR2 with the given synthesized inhibitors showed that coumarinyl thiazole series lacks the carboxylate function that could interact with the anionic binding site being a common ALR1/ALR2 inhibitors trait. Molecular docking study with dual inhibitor 6e also suggested plausible binding modes for the ALR1 and ALR2 enzymes. Hence, the results of this study revealed that coumarinyl thiazole and oxadiazole derivatives could act as potential ALR1/ALR2 inhibitors., (Copyright © 2016 Elsevier Inc. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
37. Exploration of the impact of stereochemistry on the identification of the novel translocator protein PET imaging agent [(18)F]GE-180.
- Author
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Chau WF, Black AM, Clarke A, Durrant C, Gausemel I, Khan I, Mantzilas D, Oulie I, Rogstad A, Trigg W, and Jones PA
- Subjects
- Animals, Brain diagnostic imaging, Contrast Media chemistry, Contrast Media pharmacokinetics, Drug Stability, Humans, Isotope Labeling, Male, Materials Testing, Radiopharmaceuticals chemistry, Radiopharmaceuticals pharmacokinetics, Rats, Rats, Sprague-Dawley, Reproducibility of Results, Sensitivity and Specificity, Stereoisomerism, Structure-Activity Relationship, Tissue Distribution, Brain metabolism, Carbazoles chemistry, Carbazoles pharmacokinetics, Carrier Proteins metabolism, Molecular Imaging methods, Positron-Emission Tomography methods, Receptors, GABA-A metabolism
- Abstract
Introduction: The tricyclic indole compound, [(18)F]GE-180 has been previously identified as a promising positron emission tomography (PET) imaging agent of the translocator protein (TSPO) with the potential to aid in the diagnosis, prognosis and therapy monitoring of degenerative neuroinflammatory conditions such as multiple sclerosis. [(18)F]GE-180 was first identified and evaluated as a racemate, but subsequent evaluations of the resolved enantiomers have shown that the S-enantiomer has a higher affinity for TSPO and an improved in vivo biodistribution performance, in terms of higher uptake in specific brain regions and good clearance (as described previously). Here we describe the additional biological evaluations carried out to confirm the improved performance of the S-enantiomer and including experiments which have demonstrated the stability of the chiral centre to chemical and biological factors., Materials and Methods: GE-180 and the corresponding radiolabelling precursor were separated into single enantiomers using semi-preparative chiral supercritical fluid chromatography (SFC). A detailed comparison of the individual enantiomers and the racemate was carried out in a number of biological studies. TSPO binding affinity was assessed using a radioligand binding assay. Incubation with rat hepatic S9 fractions was used to monitor metabolic stability. In vivo biodistribution studies up to 60 min post injection (PI) in naïve rats were carried out to monitor uptake and clearance. Achiral and chiral in vivo metabolite detection methods were developed to assess the presence of metabolite/s in plasma and brain samples, with the chiral method also determining potential racemisation at the chiral centre., Results: Evaluation of the chiral stability of the two enantiomers to metabolism by rat S9 fractions, showed no racemisation of enantiomers. There were notable differences in the biodistribution between the racemate and the R- and S-enantiomers. All compounds had similar initial brain uptake between 0.99 and 1.01% injected dose (id) at 2 min PI, with S-[(18)F]GE-180 showing significantly greater retention than the R-enantiomer at 10 and 30 min PI (P<0.05). S-[(18)F]GE-180 uptake to the TSPO-expressing olfactory bulbs was 0.45% id (SD ± 0.17) at 30 min PI in comparison to RS-[(18)F]GE-180 or R-[(18)F]GE-180 levels of 0.41% id ± 0.09 and 0.23% id ± 0.02 respectively, at the same timepoint (P > 0.05). The signal-to-noise ratio (ratio olfactory bulb to striata binding) were similar for both RS-[(18)F]GE-180 and S-[(18)F]GE-180 (3.2 and 3.4 respectively). Initial uptake to the lungs (an organ with high TSPO expression) was more than 3-fold greater with S-[(18)F]GE-180 than R-[(18)F]GE-180, and significantly higher at 10 and 30 min PI (P < 0.05). Furthermore lung uptake of S-[(18)F]GE-180 at 2 and 10 min PI was also significant when compared to the racemate (P < 0.05). The majority of the radioactivity in the rat brain following administration of RS-[(18)F]GE-180 or S-[(18)F]GE-180 was due to the presence of the parent compound (91% ± 1.5 and 94% ± 2.0 of total radioactivity at 60 min PI respectively). In contrast at 60 min PI for the plasma samples, the parent compounds accounted for only 28% ± 1.2 and 21% ± 4.6 of total radioactivity for RS-[(18)F]GE-180 and S-[(18)F]GE-180 respectively. Chiral assessment confirmed that the S-enantiomer was chirally stable in vivo, with no stereochemical conversion in brain and plasma samples up to 60 min PI., Conclusions: Developing racemic radiotracers, as for racemic therapeutics, is a considerable challenge due to differences of the enantiomers in pharmacokinetics, efficacy and potential toxicity. We have shown that the enantiomers of the promising racemic PET ligand [(18)F]GE-180 do not share identical performance, with S-[(18)F]GE-180 demonstrating higher TSPO affinity, higher brain uptake and better retention to the high TSPO-expressing lungs. Furthermore, S-[(18)F]GE-180 has also been shown to be enantiomerically stable in vivo, with no observed conversation of the eutomer to the distomer. As a single enantiomer, S-[(18)F]GE-180 retains the beneficial characteristics of the racemate and is a promising imaging agent for imaging neuroinflammation in vivo., (Copyright © 2015 Elsevier Inc. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
38. IL-7 and IL-15 do not synergize during CD8 T cell recall response against an obligate intracellular parasite.
- Author
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Bhadra R and Khan IA
- Subjects
- Adoptive Transfer, Animals, CD8-Positive T-Lymphocytes cytology, CD8-Positive T-Lymphocytes parasitology, Female, Interferon-gamma immunology, Mice, Mice, Inbred C57BL, Mice, Knockout, Survival Analysis, Toxoplasma physiology, Toxoplasmosis, Animal parasitology, Antigens, Protozoan immunology, CD8-Positive T-Lymphocytes immunology, Interleukin-15 immunology, Interleukin-7 immunology, Toxoplasma immunology, Toxoplasmosis, Animal immunology
- Abstract
Long-term protection against Toxoplasma gondii is dependent on robust CD8(+) T cell immunity. In the absence of this response, the host is unable to maintain chronicity, which results in recrudescence of infection and possible death. Factors needed for the persistence of protective CD8(+) T cells against the parasite need to be evaluated. Previous studies from our laboratory have reported that synergism between γ chain cytokines like IL-7 and IL-15 is critical for the generation of CD8(+) T cell response needed for protection during acute infection. In this study we report that the situation is different during the recall response where CD8(+) T cell response is almost entirely dependent on IL-15, with IL-7 at best playing a minor role. In the absence of IL-15, CD8(+) T cells fail to respond optimally to parasitic re-challenge and hosts are unable to control their replication, which leads to their death. Thus T. gondii infection may represent a unique situation where CD8(+) T cell response during secondary challenge is primarily dependent on IL-15 with other γ chain cytokines having nominal effect. These findings provide important information regarding factors involved in the generation of protective immunity against T. gondii with strong implications in developing immunotherapeutic agents against the pathogen., (Copyright © 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)
- Published
- 2012
- Full Text
- View/download PDF
39. Nonoperative management of contained retrohepatic caval injury.
- Author
-
Khan IR, Hamidian Jahromi A, Khan FM, and Youssef AM
- Subjects
- Female, Fluid Therapy, Hematoma therapy, Hemodynamics, Humans, Lacerations, Liver diagnostic imaging, Middle Aged, Retroperitoneal Space, Tomography, X-Ray Computed, Treatment Outcome, Vascular System Injuries diagnostic imaging, Vascular System Injuries physiopathology, Vena Cava, Inferior diagnostic imaging, Vena Cava, Inferior physiopathology, Wounds, Gunshot diagnostic imaging, Wounds, Gunshot physiopathology, Liver injuries, Vascular System Injuries therapy, Vena Cava, Inferior injuries, Wounds, Gunshot therapy
- Abstract
Traumatic inferior vena cava (IVC) injuries are associated with high mortality rates, despite all improvements in the technical skills and prehospital and hospital care. Selective conservative management of the penetrating abdominal injuries involving IVC has not been widely discussed before. Here, we report a case of a young female with a single gunshot wound to her abdomen, who presented to our level 1 trauma center 10 minutes after injury and was hemodynamically stable. A computed tomographic scan revealed a large liver laceration with a trajectory through the liver and the IVC. The IVC was surrounded by a moderate amount of fluid, consistent with a contained retroperitoneal hematoma. We discuss the outcome of nonoperative management of this patient along with a review of the literature., (Published by Elsevier Inc.)
- Published
- 2012
- Full Text
- View/download PDF
40. Acute aortic occlusion in a child secondary to lap-belt injury treated with thromboendarterectomy and primary repair.
- Author
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West CA Jr, Johnson LW, Doucet L, Shah M, Khan I, and Heldmann M
- Subjects
- Acute Disease, Aorta, Abdominal diagnostic imaging, Aorta, Abdominal injuries, Aortic Diseases diagnostic imaging, Aortic Diseases etiology, Aortography methods, Arterial Occlusive Diseases diagnostic imaging, Arterial Occlusive Diseases etiology, Child, Female, Humans, Ischemia etiology, Lower Extremity blood supply, Lumbar Vertebrae injuries, Spinal Fractures etiology, Thrombosis diagnostic imaging, Thrombosis etiology, Tomography, X-Ray Computed, Treatment Outcome, Vascular System Injuries diagnostic imaging, Vascular System Injuries etiology, Accidents, Traffic, Aorta, Abdominal surgery, Aortic Diseases surgery, Arterial Occlusive Diseases surgery, Endarterectomy, Seat Belts adverse effects, Thrombosis surgery, Vascular System Injuries surgery
- Abstract
Abdominal aortic injury as a result of blunt trauma is a rare event and has been described in few children. A 6-year-old girl presented with acute bilateral lower extremity ischemia, and a triad of acute aortic occlusion, intra-abdominal visceral injury, and a lumbar chance fracture after sustaining a seat belt injury from a motor vehicle collision. An emergency aortic thromboendarterectomy and primary repair were performed. This represents one of the few reports of acute traumatic aortic thrombosis in a child and highlights the surgical treatment of acute abdominal aortic injury in a pediatric patient., (Copyright © 2011 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
41. Simultaneous arterial and venous ultrasound-assisted thrombolysis for phlegmasia cerulea dolens.
- Author
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Khan IR, Reeves JG, Riesenman PJ, and Kasirajan K
- Subjects
- Aged, Angioplasty, Balloon instrumentation, Anticoagulants administration & dosage, Catheterization, Peripheral, Female, Humans, Infusions, Intra-Arterial, Infusions, Intravenous, Limb Salvage, Phlebography, Stents, Stockings, Compression, Thrombectomy, Thrombophlebitis diagnostic imaging, Treatment Outcome, Fibrinolytic Agents administration & dosage, Thrombolytic Therapy methods, Thrombophlebitis drug therapy, Ultrasonography, Interventional
- Abstract
Phlegmasia cerulea dolens is a rare condition in which an extensive deep venous thrombus can partially or completely occlude venous outflow from the affected extremity. Clinical presentation is typically characterized by extremity edema, cyanosis, and pain. This condition is associated with a high rate of extremity amputation and mortality. Although numerous therapies have been described, there is no generalized treatment consensus and less invasive forms of therapy continue to evolve. We report a case of phlegmasia cerulea dolens in a patient who presented with concomitant arterial and venous thrombosis of the affected extremity. The patient's condition was successfully treated using combined ultrasound-assisted intra-arterial and intravenous catheter-directed thrombolysis., (Copyright © 2011 Annals of Vascular Surgery Inc. Published by Elsevier Inc. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
42. Reoperations after surgery for lumbar spinal stenosis.
- Author
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Javalkar V, Cardenas R, Tawfik TA, Khan IR, Bollam P, Banerjee AD, and Nanda A
- Subjects
- Aged, Aged, 80 and over, Aging physiology, Bone Screws, Cohort Studies, Device Removal, Female, Humans, Internal Fixators, Kaplan-Meier Estimate, Magnetic Resonance Imaging, Male, Middle Aged, Myelography, Patient Selection, Postoperative Complications epidemiology, Postoperative Complications surgery, Retrospective Studies, Risk Factors, Survival Analysis, Tomography, X-Ray Computed, Decompression, Surgical, Orthopedic Procedures, Reoperation, Spinal Stenosis surgery
- Abstract
Objective: To study the indication for reoperations after lumbar decompression, the factors predisposing to redo operations, and the effect of prior instrumentation on developing adjacent level stenosis requiring reoperation., Methods: Kaplan-Meier analysis was used to compare the median interval to first reoperation. Cox regression was used for multivariate analysis of time to first reoperation., Results: Of 335 patients who underwent surgery for lumbar spinal stenosis, 63 (18%) underwent instrumentation in addition to decompression. There were 50 reoperations performed in 44 patients (13%). Of these 50 reoperations, 26 were at the same level, 14 were at the same level plus an adjacent level, and 10 were at an adjacent level. In 21 reoperations, the indication was adjacent level spinal stenosis; in 16, adjacent level spinal stenosis plus instability; in 9, instability alone; and in 4, disc problem. The risk of reoperation was higher among male patients (hazard ratio [HR] 1.2, 95% confidence interval [CI] 0.586-2.635) and in patients with prior instrumentation (HR 1.7, 95% CI 0.684-4.640). There was no statistical association between prior instrumentation and subsequent risk of reoperation (P = 0.12). There was no association between prior instrumentation and development of adjacent level stenosis requiring reoperation (P = 0.473)., Conclusions: Many patients with spinal stenosis undergo instrumentation because of instability. Most patients in this study underwent reoperation at the same level, and the most common pathology was spinal stenosis. The risk of reoperation was lower in older patients (≥65 years old). Although there was a trend that the risk of reoperation was higher among patients with prior instrumentation, it did not reach statistical significance. In this study, there was no association between prior instrumentation and adjacent level stenosis requiring reoperation. These findings need to be evaluated further in randomized trials., (Published by Elsevier Inc.)
- Published
- 2011
- Full Text
- View/download PDF
43. Reactive nitrogen and oxygen species, and iron sequestration contribute to macrophage-mediated control of Encephalitozoon cuniculi (Phylum Microsporidia) infection in vitro and in vivo.
- Author
-
Didier ES, Bowers LC, Martin AD, Kuroda MJ, Khan IA, and Didier PJ
- Subjects
- Animals, Female, Macrophages, Peritoneal metabolism, Mice, Peritoneum immunology, Peritoneum microbiology, Reactive Nitrogen Species toxicity, Reactive Oxygen Species toxicity, Survival Analysis, Encephalitozoon cuniculi immunology, Encephalitozoonosis immunology, Iron metabolism, Macrophages, Peritoneal immunology, Reactive Nitrogen Species metabolism, Reactive Oxygen Species metabolism
- Abstract
Encephalitozoon cuniculi (Phylum Microsporidia) infects a wide range of mammals, and replicates within resting macrophages. Activated macrophages, conversely, inhibit replication and destroy intracellular organisms. These studies were performed to assess mechanisms of innate immune responses expressed by macrophages to control E. cuniculi infection. Addition of reactive oxygen and nitrogen species inhibitors to activated murine peritoneal macrophages statistically significantly, rescued E. cuniculi infection ex vivo. Mice deficient in reactive oxygen species, reactive nitrogen species, or both survived ip inoculation of E. cuniculi, but carried significantly higher peritoneal parasite burdens than wild-type mice at 1 and 2 weeks post inoculation. Infected peritoneal macrophages could still be identified 4 weeks post inoculation in mice deficient in reactive nitrogen species. L-tryptophan supplementation of activated murine peritoneal macrophage cultures ex vivo failed to rescue microsporidia infection. Addition of ferric citrate to supplement iron, however, did significantly rescue E. cuniculi infection in activated macrophages and further increased parasite replication in non-activated macrophages over non-treated resting control macrophages. These results demonstrate the contribution of reactive oxygen and nitrogen species, as well as iron sequestration, to innate immune responses expressed by macrophages to control E. cuniculi infection., (Copyright © 2010 Institut Pasteur. Published by Elsevier SAS. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF
44. Giant pararenal abdominal aortic aneurysm.
- Author
-
West CA Jr, Khan IR, Doucet L, Boudreaux MB, and Johnson LW
- Subjects
- Aged, Aortic Aneurysm, Abdominal diagnostic imaging, Aortitis diagnostic imaging, Aortography methods, Humans, Male, Tomography, X-Ray Computed, Treatment Outcome, Aortic Aneurysm, Abdominal surgery, Aortitis surgery, Blood Vessel Prosthesis Implantation
- Abstract
Inflammatory aortic aneurysms are unusual vascular lesions and most commonly involve the infrarenal segment of the abdominal aorta. These complex aneurysms represent a challenge to the vascular surgeon and become even more difficult as the extent of the aneurysm and size of the inflammatory mass increase. Although well described, few cases of giant inflammatory aneurysms are reported. In this case, we review the clinical presentation and surgical management of a patient with a giant pararenal abdominal aortic aneurysm and highlight an uncommon morphologic pattern of aortic disease and provide a review of relevant literature., (Copyright © 2010 Annals of Vascular Surgery Inc. Published by Elsevier Inc. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF
45. Purified PTP1 protein induces antigen-specific protective immunity against Encephalitozoon cuniculi.
- Author
-
Moretto MM, Lawlor EM, Xu Y, Khan IA, and Weiss LM
- Subjects
- Animals, CD8 Antigens genetics, CD8-Positive T-Lymphocytes immunology, Encephalitozoonosis immunology, Female, Immunity, Cellular, Mice, Mice, Inbred C57BL, Mice, Knockout, Carrier Proteins immunology, Encephalitozoon cuniculi, Encephalitozoonosis prevention & control, Fungal Proteins immunology, Fungal Vaccines immunology
- Abstract
Microsporidiosis poses a problem for immunocompromised individuals including patients with HIV infection as well as those with organ transplantation. Recent reports from Africa have suggested that microsporidiosis with diarrhea is an independent risk factor for malnutrition in children. Previous studies from our laboratory have demonstrated that CD8(+) T cells are an essential component of protective immunity against the microsporidium Encephalitozoon cuniculi. Mutant mice lacking this T cell subset or cytotoxic function are unable to clear the infection and ultimately succumb to the disease. However, information regarding the antigens involved in the elicitation of CD8(+) T cell response is not available. In this study, we report that immunization of animals with Encephalitozoon hellem polar tube protein 1 (rEhPTP1) induces a strong T cell response in vaccinated animals. Splenic dendritic cells pulsed with rEhPTP1 are able to induce E. cuniculi specific CD8(+) T cell response with no effect on the CD4(+) T cell subset. This is the first report identifying a protein capable of inducing CD8(+) T cell immunity, which is conserved in other microsporidial species of human importance.
- Published
- 2010
- Full Text
- View/download PDF
46. Multiple hereditary exostoses as a rare nonatherosclerotic etiology of chronic lower extremity ischemia.
- Author
-
Khan I, West CA Jr, Sangster GP, Heldmann M, Doucet L, and Olmedo M
- Subjects
- Angiography, Digital Subtraction, Arterial Occlusive Diseases diagnosis, Arterial Occlusive Diseases surgery, Constriction, Pathologic, Exostoses, Multiple Hereditary complications, Exostoses, Multiple Hereditary pathology, Female, Humans, Intermittent Claudication diagnosis, Intermittent Claudication surgery, Ischemia diagnosis, Ischemia surgery, Middle Aged, Saphenous Vein transplantation, Tomography, X-Ray Computed, Treatment Outcome, Ultrasonography, Doppler, Duplex, Vascular Surgical Procedures, Arterial Occlusive Diseases genetics, Exostoses, Multiple Hereditary genetics, Intermittent Claudication genetics, Ischemia genetics, Lower Extremity blood supply, Popliteal Artery diagnostic imaging, Popliteal Artery surgery, Tibia pathology
- Abstract
Nonatherosclerotic etiologies of arterial insufficiency are uncommon but important causes of chronic lower extremity ischemia. We report a patient with multiple hereditary exostoses (MHE) presenting with lifestyle-limiting lower extremity claudication and popliteal artery occlusion secondary to a large osteochondroma. The presence of MHE with associated osteochondroma resulting in arterial occlusion is a rare condition. Management strategies for treating large osteochondromas adjacent to or with vessel involvement in asymptomatic patients remain undefined.
- Published
- 2010
- Full Text
- View/download PDF
47. Femororenal arteriovenous graft: a viable option for hemodialysis access.
- Author
-
Khan AR, Blackwell LM, Stafford SJ, Thompson AD, Romero RJ, Goodier CD, Kwan D, Khan IR, Schellack JV, and Perkowski PE
- Subjects
- Adult, Blood Vessel Prosthesis, Femoral Vein diagnostic imaging, Femoral Vein physiopathology, Humans, Kidney Failure, Chronic diagnostic imaging, Kidney Failure, Chronic surgery, Male, Phlebography, Polytetrafluoroethylene, Prosthesis Design, Renal Veins diagnostic imaging, Renal Veins physiopathology, Vascular Patency, Arteriovenous Shunt, Surgical, Blood Vessel Prosthesis Implantation instrumentation, Femoral Vein surgery, Kidney Failure, Chronic therapy, Renal Dialysis, Renal Veins surgery
- Abstract
There has been a significant increase in the number of patients with end-stage renal disease. The limited number of kidney transplants necessitates that most patients become dependent upon chronic dialysis. Due to the numerous complications associated with temporary access catheters, permanent arteriovenous access is more beneficial for long-term vascular access. However, with the restricted availability of sites for permanent vascular access, it is important to have a variety of possibilities. In this case report, we present an alternative choice for an arteriovenous graft, left common femoral artery to left renal vein, in a patient with limited vascular access options.
- Published
- 2008
- Full Text
- View/download PDF
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