78 results on '"Robert W. Huigens"'
Search Results
2. First-in-class multifunctional TYMS nonclassical antifolate inhibitor with potent in vivo activity that prolongs survival
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Maria V. Guijarro, Patrick C. Kellish, Peter E. Dib, Nicholas G. Paciaroni, Akbar Nawab, Jacob Andring, Lidia Kulemina, Nicholas V. Borrero, Carlos Modenutti, Michael Feely, Elham Nasri, Robert P. Seifert, Xiaoping Luo, Richard L. Bennett, Daniil Shabashvili, Jonathan D. Licht, Robert McKenna, Adrian Roitberg, Robert W. Huigens III, Frederic J. Kaye, and Maria Zajac-Kaye
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Therapeutics ,Medicine - Abstract
Although thymidylate synthase (TYMS) inhibitors have served as components of chemotherapy regimens, the currently available inhibitors induce TYMS overexpression or alter folate transport/metabolism feedback pathways that tumor cells exploit for drug resistance, limiting overall benefit. Here we report a small molecule TYMS inhibitor that i) exhibited enhanced antitumor activity as compared with current fluoropyrimidines and antifolates without inducing TYMS overexpression, ii) is structurally distinct from classical antifolates, iii) extended survival in both pancreatic xenograft tumor models and an hTS/Ink4a/Arf null genetically engineered mouse tumor model, and iv) is well tolerated with equal efficacy using either intraperitoneal or oral administration. Mechanistically, we verify the compound is a multifunctional nonclassical antifolate, and using a series of analogs, we identify structural features allowing direct TYMS inhibition while maintaining the ability to inhibit dihydrofolate reductase. Collectively, this work identifies nonclassical antifolate inhibitors that optimize inhibition of thymidylate biosynthesis with a favorable safety profile, highlighting the potential for enhanced cancer therapy.
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- 2023
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3. Molecular characterization of myotonic dystrophy fibroblast cell lines for use in small molecule screening
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Jana R. Jenquin, Alana P. O’Brien, Kiril Poukalov, Yidan Lu, Jesus A. Frias, Hannah K. Shorrock, Jared I. Richardson, Hormoz Mazdiyasni, Hongfen Yang, Robert W. Huigens, III, David Boykin, Laura P.W. Ranum, John Douglas Cleary, Eric T. Wang, and J. Andrew Berglund
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Biochemistry ,Small molecule ,Molecular physiology ,Science - Abstract
Summary: Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are common forms of adult onset muscular dystrophy. Pathogenesis in both diseases is largely driven by production of toxic-expanded repeat RNAs that sequester MBNL RNA-binding proteins, causing mis-splicing. Given this shared pathogenesis, we hypothesized that diamidines, small molecules that rescue mis-splicing in DM1 models, could also rescue mis-splicing in DM2 models. While several DM1 cell models exist, few are available for DM2 limiting research and therapeutic development. Here, we characterize DM1 and DM2 patient-derived fibroblasts for use in small molecule screens and therapeutic studies. We identify mis-splicing events unique to DM2 fibroblasts and common events shared with DM1 fibroblasts. We show that diamidines can partially rescue molecular phenotypes in both DM1 and DM2 fibroblasts. This study demonstrates the potential of fibroblasts as models for DM1 and DM2, which will help meet an important need for well-characterized DM2 cell models.
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- 2022
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4. Efficacy data of halogenated phenazine and quinoline agents and an NH125 analogue to veterinary mycoplasmas
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Marissa A. Valentine-King, Katherine Cisneros, Margaret O. James, Robert W. Huigens, and Mary B. Brown
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Veterinary mycoplasmas ,Drug evaluation ,Quinoline ,NH125 analogue ,Phenazine ,Nitroxoline ,Veterinary medicine ,SF600-1100 - Abstract
Abstract Background Mycoplasmas primarily cause respiratory or urogenital tract infections impacting avian, bovine, canine, caprine, murine, and reptilian hosts. In animal husbandry, mycoplasmas cause reduced feed-conversion, decreased egg production, arthritis, hypogalactia or agalactia, increased condemnations, culling, and mortality in some cases. Antibiotics reduce transmission and mitigate clinical signs; however, concerning levels of antibiotic resistance in Mycoplasma gallisepticum and M. capricolum isolates exist. To address these issues, we evaluated the minimum inhibitory concentrations (MICs) of halogenated phenazine and quinoline compounds, an N-arylated NH125 analogue, and triclosan against six representative veterinary mycoplasmas via microbroth or agar dilution methods. Thereafter, we evaluated the minimum bactericidal concentration (MBC) of efficacious drugs. Results We identified several compounds with MICs ≤25 μM against M. pulmonis (n = 5), M. capricolum (n = 4), M. gallisepticum (n = 3), M. alligatoris (n = 3), M. agassizii (n = 2), and M. canis (n = 1). An N-arylated NH125 analogue, compound 21, served as the most efficacious, having a MIC ≤25 μM against all mycoplasmas tested, followed by two quinolines, nitroxoline (compound 12) and compound 20, which were effective against four and three mycoplasma type strains, respectively. Nitroxoline exhibited bactericidal activity among all susceptible mycoplasmas, and compound 21 exhibited bactericidal activity when the MBC was able to be determined. Conclusions These findings highlight a number of promising agents from novel drug classes with potential applications to treat veterinary mycoplasma infections and present the opportunity to evaluate preliminary pharmacokinetic indices using M. pulmonis in rodents as an animal model of human infection.
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- 2020
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5. Pyrazine and Phenazine Heterocycles: Platforms for Total Synthesis and Drug Discovery
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Robert W. Huigens, Beau R. Brummel, Srinivasarao Tenneti, Aaron T. Garrison, and Tao Xiao
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pyrazine ,phenazine ,heterocyclic chemistry ,total synthesis ,medicinal chemistry ,Organic chemistry ,QD241-441 - Abstract
There are numerous pyrazine and phenazine compounds that demonstrate biological activities relevant to the treatment of disease. In this review, we discuss pyrazine and phenazine agents that have shown potential therapeutic value, including several clinically used agents. In addition, we cover some basic science related to pyrazine and phenazine heterocycles, which possess interesting reactivity profiles that have been on display in numerous cases of innovative total synthesis approaches, synthetic methodologies, drug discovery efforts, and medicinal chemistry programs. The majority of this review is focused on presenting instructive total synthesis and medicinal chemistry efforts of select pyrazine and phenazine compounds, and we believe these incredible heterocycles offer promise in medicine.
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- 2022
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6. A Highly Potent Class of Halogenated Phenazine Antibacterial and Biofilm-Eradicating Agents Accessed Through a Modular Wohl-Aue Synthesis
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Hongfen Yang, Yasmeen Abouelhassan, Gena M. Burch, Dimitris Kallifidas, Guangtao Huang, Hussain Yousaf, Shouguang Jin, Hendrik Luesch, and Robert W. Huigens
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Medicine ,Science - Abstract
Abstract Unlike individual, free-floating planktonic bacteria, biofilms are surface-attached communities of slow- or non-replicating bacteria encased within a protective extracellular polymeric matrix enabling persistent bacterial populations to tolerate high concentrations of antimicrobials. Our current antibacterial arsenal is composed of growth-inhibiting agents that target rapidly-dividing planktonic bacteria but not metabolically dormant biofilm cells. We report the first modular synthesis of a library of 20 halogenated phenazines (HP), utilizing the Wohl-Aue reaction, that targets both planktonic and biofilm cells. New HPs, including 6-substituted analogues, demonstrate potent antibacterial activities against MRSA, MRSE and VRE (MIC = 0.003–0.78 µM). HPs bind metal(II) cations and demonstrate interesting activity profiles when co-treated in a panel of metal(II) cations in MIC assays. HP 1 inhibited RNA and protein biosynthesis while not inhibiting DNA biosynthesis using 3H-radiolabeled precursors in macromolecular synthesis inhibition assays against MRSA. New HPs reported here demonstrate potent eradication activities (MBEC = 0.59–9.38 µM) against MRSA, MRSE and VRE biofilms while showing minimal red blood cell lysis or cytotoxicity against HeLa cells. PEG-carbonate HPs 24 and 25 were found to have potent antibacterial activities with significantly improved water solubility. HP small molecules could have a dramatic impact on persistent, biofilm-associated bacterial infection treatments.
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- 2017
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7. Chemical Reactions of Indole Alkaloids That Enable Rapid Access to New Scaffolds for Discovery
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Robert W. Huigens III, Derek A. Leas, and Daniel C. Schultz
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Biomaterials ,Materials Science (miscellaneous) ,Organic Chemistry ,Catalysis - Abstract
This graphical review provides a concise overview of indole alkaloids and chemical reactions that have been reported to transform both these natural products and derivatives to rapidly access new molecular scaffolds. Select biologically active compounds from these synthetic efforts are reported herein.
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- 2023
8. Design, Synthesis, and Evaluation of Carbonate-Linked Halogenated Phenazine-Quinone Prodrugs with Improved Water-Solubility and Potent Antibacterial Profiles
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Tao Xiao, Ke Liu, Qiwen Gao, Manyun Chen, Young S. Kim, Shouguang Jin, Yousong Ding, and Robert W. Huigens
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Infectious Diseases - Published
- 2023
9. Transcript Profiling of Nitroxoline-Treated Biofilms Shows Rapid Up-regulation of Iron Acquisition Gene Clusters
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Ke Liu, Yasmeen Abouelhassan, Yanping Zhang, Shouguang Jin, and Robert W. Huigens III
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Methicillin-Resistant Staphylococcus aureus ,Infectious Diseases ,Bacteria ,Biofilms ,Iron ,Multigene Family ,Nitroquinolines ,Up-Regulation - Abstract
Bacterial biofilms are surface-attached communities of slow- or non-replicating cells embedded within a protective matrix of biomolecules. Unlike free-floating planktonic bacteria, biofilms are innately tolerant to conventional antibiotics and are prevalent in recurring and chronic infections. Nitroxoline, a broad-spectrum biofilm-eradicating agent, was used to probe biofilm viability. Transcript profiling (RNA-seq) showed that 452 of 2594 genes (17.4%) in methicillin-resistant
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- 2022
10. A Modular Synthetic Route Involving N-Aryl-2-nitrosoaniline Intermediates Leads to a New Series of 3-Substituted Halogenated Phenazine Antibacterial Agents
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Robert W. Huigens, Yousong Ding, Kyle H. Rohde, Ke Liu, Yasmeen Abouelhassan, José A. Lemos, Shivani Kundra, Hongfen Yang, Michaelle Chojnacki, Guangtao Huang, Hendrik Luesch, Dimitris Kallifidas, Paul M. Dunman, Shouguang Jin, Peilan Zhang, and Marisa A. Fuse
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0303 health sciences ,biology ,medicine.drug_class ,Phenazine ,Antibiotics ,Biofilm ,Pathogenic bacteria ,medicine.disease_cause ,biology.organism_classification ,01 natural sciences ,0104 chemical sciences ,Microbiology ,Mycobacterium tuberculosis ,010404 medicinal & biomolecular chemistry ,03 medical and health sciences ,chemistry.chemical_compound ,chemistry ,Staphylococcus aureus ,Drug Discovery ,medicine ,Molecular Medicine ,Structure–activity relationship ,Bacteria ,030304 developmental biology - Abstract
Pathogenic bacteria demonstrate incredible abilities to evade conventional antibiotics through the development of resistance and formation of dormant, surface-attached biofilms. Therefore, agents that target and eradicate planktonic and biofilm bacteria are of significant interest. We explored a new series of halogenated phenazines (HP) through the use of N-aryl-2-nitrosoaniline synthetic intermediates that enabled functionalization of the 3-position of this scaffold. Several HPs demonstrated potent antibacterial and biofilm-killing activities (e.g., HP 29, against methicillin-resistant Staphylococcus aureus: MIC = 0.075 μM; MBEC = 2.35 μM), and transcriptional analysis revealed that HPs 3, 28, and 29 induce rapid iron starvation in MRSA biofilms. Several HPs demonstrated excellent activities against Mycobacterium tuberculosis (HP 34, MIC = 0.80 μM against CDC1551). This work established new SAR insights, and HP 29 demonstrated efficacy in dorsal wound infection models in mice. Encouraged by these findings, we believe that HPs could lead to significant advances in the treatment of challenging infections.
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- 2021
11. Evolution of Resistance to Phenazine Antibiotics in Staphylococcus aureus and Its Role During Coinfection with Pseudomonas aeruginosa
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Hongfen Yang, Zheng Fan, Xinwen Zhang, Xiaolei Pan, Bo Fang, Fan Yang, Tongtong Fu, Baolin Sun, Zhao Cai, Liang Yang, Wuihui Wu, Zhihui Cheng, Robert W. Huigens, Fang Bai, Zhuo Yue, and Yongxin Jin
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0301 basic medicine ,Chemistry ,Pseudomonas aeruginosa ,030106 microbiology ,Mutant ,Phenazine ,Repressor ,medicine.disease_cause ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,Infectious Diseases ,Pyocyanin ,Staphylococcus aureus ,medicine ,Efflux ,Pathogen - Abstract
In the niches that Staphylococcus aureus and Pseudomonas aeruginosa coinhabit, the later pathogen produces phenazine antibiotics to inhibit the growth of S. aureus. Recently, a group of halogenated phenazines (HPs) has been shown to have potent antimicrobial activities against Staphylococci; however, no HP-resistant mutant has been reported. Here, we demonstrate that S. aureus develops HP-resistance via single amino acid change (Arg116Cys) in a transcriptional repressor TetR21. RNA-seq analysis showed that the TetR21R116C variation caused drastic up-regulation of an adjacent gene hprS (halogenated phenazine resistance protein of S. aureus). Deletion of the hprS in the TetR21R116C background restored bacterial susceptibility to HP, while hprS overexpression in S. aureus conferred HP-resistance. The expression of HprS is under tight transcriptional control of the TetR21 via direct binding to the promoter region of hprS. The R116C mutation in TetR21 significantly reduced its DNA binding affinity. Moreover, natural phenazine antibiotics (phenazine-1-carboxylic acid and pyocyanin) and a HP analog (HP-22) are ligands for the TetR21, regulating its repressor activity. Combining homology analysis and LC-MS/MS assay we demonstrated that HprS is a phenazine efflux pump. To the best of our knowledge, we provide the first report of phenazine efflux pump in S. aureus. Interestingly, the TetR21R116C variation has been found in some clinical S. aureus isolates, and a laboratory strain of S. aureus with TetR21R116C variation showed enhanced growth competitiveness toward P. aeruginosa and promoted coinfection with P. aeruginosa in the host environment, demonstrating significance of the mutation in host infections.
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- 2021
12. Targeting bacterial biofilms with persister-killing agents
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Robert W. Huigens
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Pharmacology ,Staphylococcus aureus ,Chemistry ,Biofilm ,Microbial Sensitivity Tests ,Streptomyces ,Anti-Bacterial Agents ,Microbiology ,Retinoids ,Biofilms ,Depsipeptides ,Drug Discovery ,Staphylococcus epidermidis ,Phenazines ,Molecular Medicine - Published
- 2021
13. Re-Engineering of Yohimbine’s Biological Activity through Ring Distortion: Identification and Structure–Activity Relationships of a New Class of Antiplasmodial Agents
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Claribel Murillo-Solano, Robert W. Huigens, Srinivasarao Tenneti, Nicholas G. Paciaroni, Debopam Chakrabarti, David L. Perry, Verrill M. Norwood, and Jennifer Collins
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0301 basic medicine ,Stereochemistry ,Plasmodium falciparum ,030106 microbiology ,Drug Resistance ,Chemical biology ,Ring (chemistry) ,Cleavage (embryo) ,Article ,Indole Alkaloids ,Antimalarials ,Structure-Activity Relationship ,03 medical and health sciences ,Parasitic Sensitivity Tests ,Drug Discovery ,Humans ,Trophozoites ,Ideal (ring theory) ,Indole test ,Biological Products ,Molecular Structure ,Indole alkaloid ,Drug discovery ,Chemistry ,Yohimbine ,Chloroquine ,Biological activity ,Hep G2 Cells ,Malaria ,030104 developmental biology ,Infectious Diseases - Abstract
Select natural products are ideal starting points for ring distortion, or the dramatic altering of inherently complex molecules through short synthetic pathways, to generate an array of novel compounds with diverse skeletal architectures. A major goal of our ring distortion approach is to re-engineer the biological activity of indole alkaloids to identify new compounds with diverse biological activities in areas of significance to human health and medicine. In this study, we re-engineered the biological activity of the indole alkaloid yohimbine through ring rearrangement and ring cleavage synthesis pathways to discover new series of antiplasmodial agents. One new compound, Y7j, was found to demonstrate good potency against chloroquine-resistant Plasmodium falciparum Dd2 cells (EC(50) = 0.33 μM) without eliciting cytotoxicity against HepG2 cells (EC(50) > 40 μM). Y7j demonstrated stage-specific action against parasites at the late ring/trophozoite stage. A series of analogues was synthesized to gain structure—activity relationship insights, and we learned that both benzyl groups of Y7j are required for activity and fine-tuning of antiplasmodial activities could be accomplished by changing substitution patterns on the benzyl moieties. This study demonstrates the potential for ring distortion to drive new discoveries and change paradigms in chemical biology and drug discovery.
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- 2020
14. Modular Synthetic Routes to Fluorine-Containing Halogenated Phenazine and Acridine Agents That Induce Rapid Iron Starvation in Methicillin-Resistant Staphylococcus aureus Biofilms
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Ke Liu, Massimiliano Brivio, Tao Xiao, Verrill M. Norwood, Young S. Kim, Shouguang Jin, Antonio Papagni, Luca Vaghi, Robert W. Huigens, Liu, K, Brivio, M, Xiao, T, Norwood, V, Kim, Y, Jin, S, Papagni, A, Vaghi, L, and Huigens, R
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Methicillin-Resistant Staphylococcus aureus ,chemical synthesi ,antibacterial agent ,Iron ,Fluorine ,Article ,iron starvation ,Anti-Bacterial Agents ,halogenated phenazine ,Infectious Diseases ,Biofilms ,biofilm-eradicating agent ,CHIM/06 - CHIMICA ORGANICA ,Acridines ,Phenazines ,halogenated acridine - Abstract
During infection, bacteria use an arsenal of resistance mechanisms to negate antibiotic therapies. In addition, pathogenic bacteria form surface-attached biofilms bearing enriched populations of metabolically dormant persister cells. Bacteria develop resistance in response to antibiotic insults; however, nonreplicating biofilms are innately tolerant to all classes of antibiotics. As such, molecules that can eradicate antibiotic-resistant and antibiotic-tolerant bacteria are of importance. Here, we report modular synthetic routes to fluorine-containing halogenated phenazine (HP) and halogenated acridine (HA) agents with potent antibacterial and biofilm-killing activities. Nine fluorinated phenazines were rapidly accessed through a synthetic strategy involving (1) oxidation of fluorinated anilines to azobenzene intermediates, (2) S(N)Ar with 2-methoxyaniline, and (3) cyclization to phenazines upon treatment with trifluoroacetic acid. Five structurally related acridine heterocycles were synthesized using S(N)Ar and Buchwald–Hartwig approaches. From this focused collection, phenazines 5g, 5h, 5i, and acridine 9c demonstrated potent antibacterial activities against Gram-positive pathogens (MIC = 0.04–0.78 μM). Additionally, 5g and 9c eradicated Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis biofilms with excellent potency (5g, MBEC = 4.69–6.25 μM; 9c, MBEC = 4.69–50 μM). Using real-time quantitative polymerase chain reaction (RT-qPCR), 5g, 5h, 5i, and 9c rapidly induce the transcription of iron uptake biomarkers isdB and sbnC in methicillin-resistant S. aureus (MRSA) biofilms, and we conclude that these agents operate through iron starvation. Overall, fluorinated phenazine and acridine agents could lead to ground-breaking advances in the treatment of challenging bacterial infections.
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- 2022
15. Pyrazines and Their Benzo Derivatives
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Srinivasarao Tenneti, Aaron T. Garrison, Tao Xiao, and Robert W. Huigens
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Chemistry ,Organic chemistry - Published
- 2022
16. Instructive Advances in Chemical Microbiology Inspired by Nature’s Diverse Inventory of Molecules
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Robert W. Huigens and Ke Liu
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0301 basic medicine ,Biological Products ,Natural product ,Bacteria ,Chemistry, Pharmaceutical ,030106 microbiology ,Bacterial Infections ,Biology ,Article ,Anti-Bacterial Agents ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,Infectious Diseases ,chemistry ,Drug Discovery ,Humans ,Biochemical engineering - Abstract
Natural product antibiotics have played an essential role in the treatment of bacterial infection in addition to serving as useful tools to explore the intricate biology of bacteria. Our current arsenal of antibiotics operate through the inhibition of well-defined bacterial targets critical for replication and growth. Pathogenic bacteria effectively utilize a diversity of mechanisms that lead to acquired resistance and/or innate tolerance toward antibiotic therapies, which can result in devastating consequences to human life. Several research groups have established innovative programs that work at the chemistry-biology interface to develop new molecules that aim to define and address concerns related to antibiotic resistance and tolerance. In this Review, we present recent progress by select research groups that highlight a diversity of integrated chemical biology and medicinal chemistry approaches aimed at the development and utilization of chemical tools that have led to promising new microbiological insights that may lead to significant clinical advances regarding the treatment of pathogenic bacteria.
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- 2019
17. Pyrazine and Phenazine Heterocycles: Platforms for Total Synthesis and Drug Discovery
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Robert W. Huigens, Beau R. Brummel, Srinivasarao Tenneti, Aaron T. Garrison, and Tao Xiao
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phenazine ,Chemistry, Pharmaceutical ,Organic Chemistry ,Pharmaceutical Science ,heterocyclic chemistry ,Analytical Chemistry ,QD241-441 ,Chemistry (miscellaneous) ,Heterocyclic Compounds ,medicinal chemistry ,Pyrazines ,Drug Discovery ,pyrazine ,Molecular Medicine ,Humans ,Phenazines ,Physical and Theoretical Chemistry ,total synthesis - Abstract
There are numerous pyrazine and phenazine compounds that demonstrate biological activities relevant to the treatment of disease. In this review, we discuss pyrazine and phenazine agents that have shown potential therapeutic value, including several clinically used agents. In addition, we cover some basic science related to pyrazine and phenazine heterocycles, which possess interesting reactivity profiles that have been on display in numerous cases of innovative total synthesis approaches, synthetic methodologies, drug discovery efforts, and medicinal chemistry programs. The majority of this review is focused on presenting instructive total synthesis and medicinal chemistry efforts of select pyrazine and phenazine compounds, and we believe these incredible heterocycles offer promise in medicine.
- Published
- 2021
18. An ether-linked halogenated phenazine-quinone prodrug model for antibacterial applications
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Hongfen Yang, Ke Liu, Young Soon Kim, Shouguang Jin, and Robert W. Huigens
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Methicillin-Resistant Staphylococcus aureus ,0303 health sciences ,010405 organic chemistry ,Organic Chemistry ,Phenazine ,Biofilm ,Ether ,Pathogenic bacteria ,Prodrug ,medicine.disease_cause ,01 natural sciences ,Biochemistry ,Chemical synthesis ,Combinatorial chemistry ,Article ,0104 chemical sciences ,Quinone ,03 medical and health sciences ,chemistry.chemical_compound ,chemistry ,Staphylococcus aureus ,medicine ,Physical and Theoretical Chemistry ,030304 developmental biology - Abstract
Antibiotic-resistant infections present significant challenges to patients. As a result, there is considerable need for new antibacterial therapies that eradicate pathogenic bacteria through non-conventional mechanisms. Our group has identified a series of halogenated phenazine (HP) agents that induce rapid iron starvation that leads to potent killing of methicillin-resistant Staphylococcus aureus biofilms. Here, we report the design, chemical synthesis and microbiological assessment of a HP-quinone ether prodrug model aimed to (1) eliminate general (off-target) iron chelation, and (2) release an active HP agent through the bioreduction of a quinone trigger. Here, we demonstrate prodrug analogue HP-29-Q to have a stable ether linkage that enables HP release and moderate to good antibacterial activities against lab strains and multi-drug resistant clinical isolates.
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- 2021
19. Combination Treatment of Erythromycin and Furamidine Provides Additive and Synergistic Rescue of Mis-splicing in Myotonic Dystrophy Type 1 Models
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Masayuki Nakamori, Hongfen Yang, Robert W. Huigens, J. Andrew Berglund, and Jana R. Jenquin
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musculoskeletal diseases ,Pharmacology ,Untranslated region ,congenital, hereditary, and neonatal diseases and abnormalities ,RNA ,Biology ,medicine.disease ,Myotonia ,Myotonic dystrophy ,Phenotype ,Article ,RNA splicing ,Gene expression ,medicine ,Pharmacology (medical) ,Gene - Abstract
Myotonic dystrophy type 1 (DM1) is a multi-systemic disease that presents with clinical symptoms including myotonia, cardiac dysfunction and cognitive impairment. DM1 is caused by a CTG expansion in the 3’ UTR of the DMPK gene. The transcribed expanded CUG repeat RNA sequester the muscleblind-like (MBNL) and up-regulate the CUG-BP Elav-like (CELF) families of RNA-binding proteins leading to global mis-regulation of RNA processing and altered gene expression. Currently, there are no disease-targeting treatments for DM1. Given the multi-step pathogenic mechanism, combination therapies targeting different aspects of the disease mechanism may be a viable therapeutic approach. Here, as proof-of-concept, we studied a combination of two previously characterized small molecules, erythromycin and furamidine, in two DM1 models. In DM1 patient-derived myotubes, rescue of mis-splicing was observed with little to no cell toxicity. In a DM1 mouse model, a combination of erythromycin and the prodrug of furamidine (pafuramidine), administered orally, displayed both additive and synergistic mis-splicing rescue. Gene expression was only modestly affected and over 40 % of the genes showing significant expression changes were rescued back toward WT expression levels. Further, the combination treatment partially rescued the myotonia phenotype in the DM1 mouse. This combination treatment showed a high degree of mis-splicing rescue coupled with low off-target gene expression changes. These results indicate that combination therapies are a promising therapeutic approach for DM1.
- Published
- 2019
20. Microwave-enhanced, stereospecific ring-closure of medium-ring cyanamide ethers to yohimbine
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Verrill M. Norwood, Nicholas G. Paciaroni, Robert W. Huigens, and Daniel E. Garcia
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Indole alkaloid ,010405 organic chemistry ,Organic Chemistry ,Ether ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Medicinal chemistry ,0104 chemical sciences ,chemistry.chemical_compound ,Stereospecificity ,chemistry ,Nucleophile ,Drug Discovery ,Electrophile ,Moiety ,Cyanamide ,Reactivity (chemistry) - Abstract
A highly efficient acid-promoted, stereospecific, transannular ring-closure of medium-ring ether compounds to the indole alkaloid yohimbine is described. Microwave-enhanced acetic acid degradation of cyanamide compounds involves loss of (R)- or (S)-ethers, followed by a stereospecific, nucleophilic ring-closure from the cyanamide to afford yohimbine in up to 74% yield in as little as one minute. This nucleophilic reactivity of the amino moiety of the cyanamide highlights an alternative reactivity profile from its traditional electrophilic properties. Additionally, this reaction pathway highlights a rare case of an SN1 pathway that proceeds with complete stereospecificity.
- Published
- 2019
21. Rapid kill assessment of anN-arylated NH125 analogue against drug-resistant microorganisms
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Yasmeen Abouelhassan, Robert W. Huigens, Peilan Zhang, and Yousong Ding
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Pharmacology ,Multidrug tolerance ,010405 organic chemistry ,Microorganism ,Disinfectant ,Organic Chemistry ,Biofilm ,Pharmaceutical Science ,macromolecular substances ,Drug resistance ,Fungal pathogen ,Biology ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Microbiology ,010404 medicinal & biomolecular chemistry ,Antibiotic resistance ,Drug Discovery ,Healthcare settings ,Molecular Medicine - Abstract
While a number of disinfection techniques are employed in healthcare units, the eradication of drug-resistant microorganisms remains a challenge. We recently reported N-arylated NH125 analogue 1, which demonstrated potent biofilm eradication and antibacterial activities against a panel of drug-resistant pathogens. The broad-spectrum activities observed for 1 along with its rapid eradication of MRSA persister cells suggested that this agent, and related analogues, can serve as disinfectants for antibiotic resistant pathogens in healthcare settings. Here, we report the rapid bactericidal activities of 1 against a panel of exponentially-growing, drug-resistant pathogens. Against MRSA, MRSE, VRE and MDR A. baumannii, 1 eradicated bacterial cells after five minutes when tested at 50 μM (3- to 6-log reduction of CFU per mL). We highlighted the rapid killing activities by demonstrating that 1 eradicates 99.99% of viable MRSA 1707 cells in one minute (50 μM, 4-log reduction of CFU per mL). In addition, 1 rapidly eradicated fungal pathogen C. neoformans in kill kinetic experiments. A solution of 1 demonstrated similar shelf stability to known disinfectant BAC-16 when tested up to 111 days after being stored. Collectively, our data highlights the potential of 1 to be used as a disinfecting agent to prevent healthcare-associated, drug-resistant infections.
- Published
- 2019
22. Abstract 4055: First in class multifunctional non classical antifolates inhibits thymidylate synthase and extends survival in pancreatic cancer model
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Maria V. Guijarro, Patrick C. Kellish, Peter E. Dib, Nicholas G. Paciaroni, Akbar Nawab, Jacob Andring, Lidia Kulemina, Nicholas V. Borrero, Carlos Modenutti, Richard L. Bennett, Daniil Shabashvili, Jonathan D. Licht, Robert McKenna, Adrian Roitberg, Robert W. Huigens, Frederic J. Kaye, and Maria Zajac-Kaye
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Cancer Research ,Oncology - Abstract
Thymidylate synthase (TS) inhibitors are an integral component of chemotherapy regimens for difficult to treat cancer subtypes. Despite initial therapeutic benefit, current inhibitors induce TS overexpression or alter folate transport metabolism feedback pathways that tumor cells exploit for drug resistance. Here we report a small molecule TS inhibitor that exhibits i) enhanced antitumor activity as compared to current fluoropyrimidines and antifolates without inducing TS overexpression, ii) is structurally distinct from classical antifolates, iii) extends survival in a pancreatic tumor mouse model, iv) and is well tolerated with equal efficacy using either intraperitoneal or oral administration. Mechanistically, we confirm the compound is a multifunctional non classical antifolate and through a series of analogues identify structural features allowing direct TS inhibition while also maintaining the ability to inhibit dihydrofolate reductase (DHFR). Collectively, this work identifies new non classical antifolate inhibitors that optimize inhibition of thymidylate biosynthesis with a favorable safety profile highlighting potential for enhanced cancer therapy. Citation Format: Maria V. Guijarro, Patrick C. Kellish, Peter E. Dib, Nicholas G. Paciaroni, Akbar Nawab, Jacob Andring, Lidia Kulemina, Nicholas V. Borrero, Carlos Modenutti, Richard L. Bennett, Daniil Shabashvili, Jonathan D. Licht, Robert McKenna, Adrian Roitberg, Robert W. Huigens, Frederic J. Kaye, Maria Zajac-Kaye. First in class multifunctional non classical antifolates inhibits thymidylate synthase and extends survival in pancreatic cancer model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4055.
- Published
- 2022
23. Transcript Profiling of MRSA Biofilms Treated with a Halogenated Phenazine Eradicating Agent: A Platform for Defining Cellular Targets and Pathways Critical to Biofilm Survival
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Shouguang Jin, Yasmeen Abouelhassan, Robert W. Huigens, and Yanping Zhang
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Methicillin-Resistant Staphylococcus aureus ,0301 basic medicine ,Proteases ,Halogenation ,Iron ,ATP-binding cassette transporter ,01 natural sciences ,Article ,Catalysis ,Microbiology ,03 medical and health sciences ,Gene expression ,Humans ,KEGG ,Gene ,Arginine deiminase ,biology ,010405 organic chemistry ,Chemistry ,Biofilm ,General Medicine ,General Chemistry ,Staphylococcal Infections ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Anti-Bacterial Agents ,0104 chemical sciences ,030104 developmental biology ,Biofilms ,Phenazines ,Transcriptome ,Bacteria ,Signal Transduction - Abstract
Bacterial biofilms are surface-attached communities of non-replicating bacteria innately tolerant to antibiotics. Biofilms display differential gene expression profiles and physiologies as compared to their planktonic counterparts; however, their biology remains largely unknown. In this study, we used a halogenated phenazine (HP) biofilm eradicator in transcript profiling experiments (RNA-seq) to define cellular targets and pathways critical to biofilm viability. WoPPER analysis with time–course validation (RT-qPCR) revealed that HP-14 induces rapid iron starvation in MRSA biofilms, as evident by the activation of iron-acquisition gene clusters in 1 hour. Serine proteases and oligopeptide transporters were also found to be up-regulated, whereas glycolysis, arginine deiminase, and urease gene clusters were down-regulated. KEGG analysis revealed that HP-14 impacts metabolic and ABC transporter functional pathways. These findings suggest that MRSA biofilm viability relies on iron homeostasis.
- Published
- 2018
24. A Modular Synthetic Route Involving
- Author
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Hongfen, Yang, Shivani, Kundra, Michaelle, Chojnacki, Ke, Liu, Marisa A, Fuse, Yasmeen, Abouelhassan, Dimitris, Kallifidas, Peilan, Zhang, Guangtao, Huang, Shouguang, Jin, Yousong, Ding, Hendrik, Luesch, Kyle H, Rohde, Paul M, Dunman, José A, Lemos, and Robert W, Huigens
- Subjects
Methicillin-Resistant Staphylococcus aureus ,Mice, Inbred BALB C ,Wound Healing ,Aniline Compounds ,Halogenation ,Cell Survival ,Iron ,Iron Deficiencies ,Mycobacterium tuberculosis ,Staphylococcal Infections ,Article ,Anti-Bacterial Agents ,Cell Line ,Disease Models, Animal ,Mice ,Structure-Activity Relationship ,Biofilms ,Drug Design ,Animals ,Humans ,Phenazines ,Female - Abstract
Pathogenic bacteria demonstrate incredible abilities to evade conventional antibiotics through the development of resistance and formation of dormant, surface-attached biofilms. Therefore, agents that target and eradicate planktonic and biofilm bacteria are of significant interest. We explored a new series of halogenated phenazines (HP) through the use of N-aryl-2-nitrosoaniline synthetic intermediates that enabled functionalization of the 3-position of this scaffold. Several HPs demonstrated potent antibacterial and biofilm-killing activities (e.g., HP 29, against methicillin-resistant Staphylococcus aureus: MIC = 0.075 μM; MBEC = 2.35 μM), and transcriptional analysis revealed that HPs 3, 28, and 29 induce rapid iron starvation in MRSA biofilms. Several HPs demonstrated excellent activities against Mycobacterium tuberculosis (HP 34, MIC = 0.80 μM against CDC1551). This work established new SAR insights, and HP 29 demonstrated efficacy in dorsal wound infection models in mice. Encouraged by these findings, we believe that HPs could lead to significant advances in the treatment of challenging infections.
- Published
- 2021
25. Molecular characterization of myotonic dystrophy fibroblast cell lines for use in small molecule screening
- Author
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Jana R. Jenquin, Alana P. O’Brien, Kiril Poukalov, Yidan Lu, Jesus A. Frias, Hannah K. Shorrock, Jared I. Richardson, Hormoz Mazdiyasni, Hongfen Yang, Robert W. Huigens, David Boykin, Laura P.W. Ranum, John Douglas Cleary, Eric T. Wang, and J. Andrew Berglund
- Subjects
Multidisciplinary - Abstract
Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are common forms of adult onset muscular dystrophy. Pathogenesis in both diseases is largely driven by production of toxic-expanded repeat RNAs that sequester MBNL RNA-binding proteins, causing mis-splicing. Given this shared pathogenesis, we hypothesized that diamidines, small molecules that rescue mis-splicing in DM1 models, could also rescue mis-splicing in DM2 models. While several DM1 cell models exist, few are available for DM2 limiting research and therapeutic development. Here, we characterize DM1 and DM2 patient-derived fibroblasts for use in small molecule screens and therapeutic studies. We identify mis-splicing events unique to DM2 fibroblasts and common events shared with DM1 fibroblasts. We show that diamidines can partially rescue molecular phenotypes in both DM1 and DM2 fibroblasts. This study demonstrates the potential of fibroblasts as models for DM1 and DM2, which will help meet an important need for well-characterized DM2 cell models.
- Published
- 2021
26. Evolution of Resistance to Phenazine Antibiotics in
- Author
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Tongtong, Fu, Zhao, Cai, Zhuo, Yue, Hongfen, Yang, Bo, Fang, Xinwen, Zhang, Zheng, Fan, Xiaolei, Pan, Fan, Yang, Yongxin, Jin, Zhihui, Cheng, Wuihui, Wu, Baolin, Sun, Robert W, Huigens, Liang, Yang, and Fang, Bai
- Subjects
Staphylococcus aureus ,Coinfection ,Tandem Mass Spectrometry ,Pseudomonas aeruginosa ,Humans ,Phenazines ,Gene Expression Regulation, Bacterial ,Anti-Bacterial Agents ,Chromatography, Liquid - Abstract
In the niches that
- Published
- 2021
27. Design, synthesis and biological evaluation of a halogenated phenazine-erythromycin conjugate prodrug for antibacterial applications
- Author
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Shouguang Jin, Ke Liu, Robert W. Huigens, and Hongfen Yang
- Subjects
inorganic chemicals ,Staphylococcus aureus ,medicine.drug_class ,Antibiotics ,Enterococcus faecium ,Erythromycin ,Microbial Sensitivity Tests ,medicine.disease_cause ,01 natural sciences ,Biochemistry ,Article ,Microbiology ,03 medical and health sciences ,Staphylococcus epidermidis ,medicine ,Prodrugs ,Physical and Theoretical Chemistry ,030304 developmental biology ,0303 health sciences ,biology ,Molecular Structure ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Biofilm ,Pathogenic bacteria ,Prodrug ,biology.organism_classification ,0104 chemical sciences ,Anti-Bacterial Agents ,Phenazines ,medicine.drug - Abstract
There is a significant need for new antibacterial agents as pathogenic bacteria continue to threaten human health through the acquisition of resistance and tolerance towards existing antibiotics. Over the last several years, our group has been developing a novel series of halogenated phenazines that demonstrate potent antibacterial and biofilm eradication activities against critical Gram-positive pathogens, including: Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecium. Here, we report the design, chemical synthesis and initial biological assessment of a halogenated phenazine-erythromycin conjugate prodrug 5 aimed at enhancing the translational potential for halogenated phenazines as a treatment of bacterial infections.
- Published
- 2021
28. Yohimbine as a Starting Point to Access Diverse Natural Product-Like Agents with Re-programmed Activities against Cancer-Relevant GPCR Targets
- Author
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Ranjala Ratnayake, Nicholas G. Paciaroni, Verrill M. Norwood, Robert W. Huigens, and Hendrik Luesch
- Subjects
Clinical Biochemistry ,Pharmaceutical Science ,Antineoplastic Agents ,Computational biology ,01 natural sciences ,Biochemistry ,Article ,Receptors, G-Protein-Coupled ,chemistry.chemical_compound ,Structure-Activity Relationship ,Neoplasms ,Drug Discovery ,medicine ,Humans ,Molecular Targeted Therapy ,Receptor ,Molecular Biology ,G protein-coupled receptor ,Biological Products ,Natural product ,Dose-Response Relationship, Drug ,Molecular Structure ,010405 organic chemistry ,Drug discovery ,Organic Chemistry ,Yohimbine ,Biological activity ,Protein superfamily ,Small molecule ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,chemistry ,Molecular Medicine ,medicine.drug - Abstract
G protein-coupled receptors (GPCRs) constitute the largest protein superfamily in the human genome. GPCRs play key roles in mediating a wide variety of physiological events including proliferation and cancer metastasis. Given the major roles that GPCRs play in mediating cancer growth, they present promising targets for small molecule therapeutics. One of the principal goals of our lab is to identify complex natural products (NPs) suitable for ring distortion, or the dramatic altering of the inherently complex architectures of NPs, to rapidly generate an array of compounds with diverse molecular skeletal systems. The overarching goal of our ring distortion approach is to re-program the biological activity of select natural products and identify new compounds of importance to the treatment of disease, such as cancer. Described herein are the results from biological screens of diverse small molecules derived from the indole alkaloid yohimbine against a panel of GPCRs involved in various diseases. Several analogues displayed highly differential antagonistic activities across the GPCRs tested. We highlight the re-programmed profile of one analogue, Y7g, which exhibited selective antagonistic activities against AVPR2 (IC50 = 459 nM) and OXTR (IC50 = 1.16 µM). The activity profile of Y7g could correlate its HIF-dependent anti-cancer activity to its GPCR antagonism since these receptors are known to be upregulated in hypoxic cellular environments. Our findings demonstrate that the ring distortion of yohimbine can lead to the identification of new compounds capable of interacting with distinct cancer-relevant targets.
- Published
- 2020
29. Efficacy data of halogenated phenazine and quinoline agents and an NH125 analogue to veterinary mycoplasmas
- Author
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Katherine V. Cisneros, Mary Bomberger Brown, Margaret O. James, Marissa A. Valentine-King, and Robert W. Huigens
- Subjects
Mycoplasma gallisepticum ,Veterinary medicine ,medicine.drug_class ,Antibiotics ,Quinoline ,Microbial Sensitivity Tests ,medicine.disease_cause ,Nitroxoline ,Agar dilution ,03 medical and health sciences ,chemistry.chemical_compound ,Antibiotic resistance ,Mycoplasma ,medicine ,Phenazine ,030304 developmental biology ,0303 health sciences ,lcsh:Veterinary medicine ,Minimum bactericidal concentration ,General Veterinary ,biology ,030306 microbiology ,Imidazoles ,Drug evaluation ,General Medicine ,biology.organism_classification ,Triclosan ,Anti-Bacterial Agents ,chemistry ,Veterinary mycoplasmas ,Quinolines ,NH125 analogue ,lcsh:SF600-1100 ,Phenazines ,Research Article - Abstract
BackgroundMycoplasmas primarily cause respiratory or urogenital tract infections impacting avian, bovine, canine, caprine, murine, and reptilian hosts. In animal husbandry, mycoplasmas cause reduced feed-conversion, decreased egg production, arthritis, hypogalactia or agalactia, increased condemnations, culling, and mortality in some cases. Antibiotics reduce transmission and mitigate clinical signs; however, concerning levels of antibiotic resistance inMycoplasma gallisepticumandM. capricolumisolates exist. To address these issues, we evaluated the minimum inhibitory concentrations (MICs) of halogenated phenazine and quinoline compounds, anN-arylated NH125 analogue, and triclosan against six representative veterinary mycoplasmas via microbroth or agar dilution methods. Thereafter, we evaluated the minimum bactericidal concentration (MBC) of efficacious drugs.ResultsWe identified several compounds with MICs ≤25 μM againstM. pulmonis(n = 5),M. capricolum(n = 4),M. gallisepticum(n = 3),M. alligatoris(n = 3),M. agassizii(n = 2), andM. canis(n = 1). AnN-arylated NH125 analogue, compound 21, served as the most efficacious, having a MIC ≤25 μM against all mycoplasmas tested, followed by two quinolines, nitroxoline (compound 12) and compound 20, which were effective against four and three mycoplasma type strains, respectively. Nitroxoline exhibited bactericidal activity among all susceptible mycoplasmas, and compound 21 exhibited bactericidal activity when the MBC was able to be determined.ConclusionsThese findings highlight a number of promising agents from novel drug classes with potential applications to treat veterinary mycoplasma infections and present the opportunity to evaluate preliminary pharmacokinetic indices usingM. pulmonisin rodents as an animal model of human infection.
- Published
- 2019
30. Halogenated quinolines bearing polar functionality at the 2-position: Identification of new antibacterial agents with enhanced activity against Staphylococcus epidermidis
- Author
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Verrill M. Norwood, Shouguang Jin, Robert W. Huigens, Akash Basak, Young Soon Kim, and Yasmeen Abouelhassan
- Subjects
0301 basic medicine ,Pharmacology ,biology ,Drug discovery ,Chemistry ,030106 microbiology ,Organic Chemistry ,Biofilm ,Human pathogen ,General Medicine ,biology.organism_classification ,Small molecule ,Microbiology ,HeLa ,03 medical and health sciences ,030104 developmental biology ,Staphylococcus epidermidis ,Drug Discovery ,Cytotoxicity ,Bacteria - Abstract
Antibiotic-resistant bacteria and surface-attached biofilms continue to play a significant role in human health and disease. Innovative strategies are needed to identify new therapeutic leads to tackle infections of drug-resistant and tolerant bacteria. We synthesized a focused library of 14 new halogenated quinolines to investigate the impact of ClogP values on antibacterial and biofilm-eradication activities. During these investigations, we found select polar appendages at the 2-position of the HQ scaffold were more well-tolerated than others. We were delighted to see multiple compounds display enhanced activities against the major human pathogen S. epidermidis. In particular, HQ 2 (ClogP = 3.44) demonstrated enhanced activities against MRSE 35984 planktonic cells (MIC = 0.59 μM) compared to MRSA and VRE strains in addition to potent MRSE biofilm eradication activities (MBEC = 2.35 μM). Several of the halogenated quinolines identified here reported low cytotoxicity against HeLa cells with minimal hemolytic activity against red blood cells. We believe that halogenated quinoline small molecules could play an important role in the development of next-generation antibacterial therapeutics capable of targeting and eradicating biofilm-associated infections.
- Published
- 2018
31. Identification of Nitroxoline and Halogenated Quinoline Analogues with Antibacterial Activities against Plant Pathogens
- Author
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Hussain Yousaf, Aaron T. Garrison, Robert W. Huigens, Akash Basak, Jeffrey B. Jones, and Yasmeen Abouelhassan
- Subjects
food and beverages ,Human pathogen ,Burkholderia andropogonis ,Pathogenic bacteria ,General Chemistry ,Biology ,biology.organism_classification ,medicine.disease_cause ,Xanthomonas citri ,Microbiology ,chemistry.chemical_compound ,Nitroxoline ,chemistry ,Xanthomonas ,Citrus canker ,medicine ,Antibacterial activity - Abstract
Bacterial pathogens that infect and kill plants are responsible for major crop damage (e.g. citrus canker). As is the case with human pathogens, bacterial species which are invasive to plants acquire resistance to common crop-bactericidal agents. Herein we report the identification of nitroxoline and simple halogenated quinoline (HQ) antibacterial agents that demonstrate antibacterial activities against a panel of plant pathogens, including Xanthomonas citri and Burkholderia andropogonis. A subset of active analogues was identified from an in-house library of 36 nitrogen-containing heterocycles which our group previously evaluated against multiple human pathogenic bacteria (e.g., Staphylococcus aureus). In this report, we also demonstrate that the phytochemical gallic acid (GA) potentiates the antibacterial activity of select halogenated quinolines against multiple Xanthomonas strains, including Xcc 306. We also show that nitroxoline and HQ 1 alone and in combination with GA inhibit Xcc 306 infection in a plant model, demonstrating the potential these compounds have as crop-bactericidal agents.
- Published
- 2017
32. A Tryptoline Ring-Distortion Strategy Leads to Complex and Diverse Biologically Active Molecules from the Indole Alkaloid Yohimbine
- Author
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Nicholas G. Paciaroni, Robert W. Huigens, Ranjala Ratnayake, Long H. Dang, Hendrik Luesch, James H. Matthews, Verrill M. Norwood, and Austin C. Arnold
- Subjects
Cell Survival ,Molecular Conformation ,010402 general chemistry ,01 natural sciences ,Article ,Catalysis ,Indole Alkaloids ,Stereocenter ,Small Molecule Libraries ,Mice ,chemistry.chemical_compound ,Animals ,Humans ,Transcription factor ,Biological Products ,Reporter gene ,Indole alkaloid ,010405 organic chemistry ,Organic Chemistry ,Yohimbine ,Stereoisomerism ,Biological activity ,General Chemistry ,HCT116 Cells ,Combinatorial chemistry ,Small molecule ,Chemical space ,0104 chemical sciences ,RAW 264.7 Cells ,chemistry ,Tryptoline ,Carbolines - Abstract
High-throughput screening (HTS) is the primary driver to current drug-discovery efforts. New therapeutic agents that enter the market are a direct reflection of the structurally simple compounds that make up screening libraries. Unlike medically relevant natural products (e.g., morphine), small molecules currently being screened have a low fraction of sp3 character and few, if any, stereogenic centers. Although simple compounds have been useful in drugging certain biological targets (e.g., protein kinases), more sophisticated targets (e.g., transcription factors) have largely evaded the discovery of new clinical agents from screening collections. Herein, a tryptoline ring-distortion strategy is described that enables the rapid synthesis of 70 complex and diverse compounds from yohimbine (1); an indole alkaloid. The compounds that were synthesized had architecturally complex and unique scaffolds, unlike 1 and other scaffolds. These compounds were subjected to phenotypic screens and reporter gene assays, leading to the identification of new compounds that possessed various biological activities, including antiproliferative activities against cancer cells with functional hypoxia-inducible factors, nitric oxide inhibition, and inhibition and activation of the antioxidant response element. This tryptoline ring-distortion strategy can begin to address diversity problems in screening libraries, while occupying biologically relevant chemical space in areas critical to human health.
- Published
- 2017
33. Nitroxoline: a broad-spectrum biofilm-eradicating agent against pathogenic bacteria
- Author
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Hussain Yousaf, Minh Thu Nguyen, Qingping Yang, Gregory S. Schultz, Yasmeen Abouelhassan, Melanie Rolfe, and Robert W. Huigens
- Subjects
Acinetobacter baumannii ,0301 basic medicine ,Microbiology (medical) ,Multidrug tolerance ,Staphylococcus ,030106 microbiology ,Anti-Infective Agents, Urinary ,macromolecular substances ,Biology ,medicine.disease_cause ,Vancomycin-Resistant Enterococci ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,medicine ,Humans ,Pharmacology (medical) ,Antibacterial agent ,Antiinfective agent ,Biofilm ,Nitroquinolines ,Pathogenic bacteria ,General Medicine ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Infectious Diseases ,Nitroxoline ,chemistry ,Biofilms ,Vancomycin ,medicine.drug - Abstract
Bacterial biofilms are surface-attached communities of slow-growing or non-replicating bacteria tolerant to conventional antibiotic therapies. Although biofilms are known to occur in ca. 80% of all bacterial infections, no therapeutic agent has been developed to eradicate bacteria housed within biofilms. We have discovered that nitroxoline, an antibacterial agent used to treat urinary tract infections, displays broad-spectrum biofilm-eradicating activities against major human pathogens, including drug-resistant Staphylococcus aureus and Acinetobacter baumannii strains. In this study, the effectiveness of nitroxoline to eradicate biofilms was determined using an in vitro [minimum biofilm eradication concentration (MBEC) = 46.9 µM against A. baumannii] and ex vivo porcine skin model (2-3 log reduction in viable biofilm cells). Nitroxoline was also found to eradicate methicillin-resistant S. aureus (MRSA) persister cells in non-biofilm (stationary) cultures, whereas vancomycin and daptomycin were found to be inactive. These findings could lead to effective, nitroxoline-based therapies for biofilm-associated infections.
- Published
- 2017
34. Identification of N-Arylated NH125 Analogues as Rapid Eradicating Agents against MRSA Persister Cells and Potent Biofilm Killers of Gram-Positive Pathogens
- Author
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Robert W. Huigens, Akash Basak, Yasmeen Abouelhassan, and Hussain Yousaf
- Subjects
Methicillin-Resistant Staphylococcus aureus ,0301 basic medicine ,Erythrocytes ,Multidrug tolerance ,Pyridines ,medicine.drug_class ,030106 microbiology ,Antibiotics ,Microbial Sensitivity Tests ,macromolecular substances ,Gram-Positive Bacteria ,medicine.disease_cause ,Biochemistry ,Microbiology ,03 medical and health sciences ,Antibiotic resistance ,Staphylococcus epidermidis ,Acetamides ,medicine ,Humans ,Molecular Biology ,Molecular Structure ,biology ,Organic Chemistry ,Imidazoles ,Biofilm ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Anti-Bacterial Agents ,030104 developmental biology ,Staphylococcus aureus ,Biofilms ,Molecular Medicine ,Enterococcus faecium - Abstract
Bacterial biofilms housing dormant persister cells are innately tolerant to antibiotics and disinfectants, yet several membrane-active agents are known to eradicate tolerant bacterial cells. NH125, a membrane-active persister killer and starting point for development, led to the identification of two N-arylated analogues (1 and 2) that displayed improved biofilm eradication potencies compared to the parent compound and rapid persister-cell-killing activities in stationary cultures of methicillin-resistant Staphylococcus aureus (MRSA). We found 1 and 2 to be superior to other membrane-active agents in biofilm eradication assays, with 1 demonstrating minimum biofilm eradication concentrations (MBEC) of 23.5, 11.7, and 2.35 μm against MRSA, methicillin-resistant Staphylococcus epidermidis (MRSE), and vancomycin-resistant Enterococcus faecium (VRE) biofilms, respectively. We tested our panel of membrane-active agents against MRSA stationary cultures and found 1 to rapidly eradicate MRSA stationary cells by 4 log units (99.99 %) in 30 min. The potent biofilm eradication and rapid persister-cell-killing activities exhibited by N-arylated NH125 analogues could have significant impact in addressing biofilm-associated problems.
- Published
- 2017
35. Microwave-enhanced Friedländer synthesis for the rapid assembly of halogenated quinolines with antibacterial and biofilm eradication activities against drug resistant and tolerant bacteria
- Author
-
Robert W. Huigens, Aaron T. Garrison, Hongfen Yang, Hussain Yousaf, Tho J. Nguyen, and Yasmeen Abouelhassan
- Subjects
Pharmacology ,Lysis ,biology ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Biofilm ,Pharmaceutical Science ,Treatment options ,macromolecular substances ,Drug resistance ,biochemical phenomena, metabolism, and nutrition ,010402 general chemistry ,biology.organism_classification ,01 natural sciences ,Biochemistry ,Small molecule ,Combinatorial chemistry ,Friedländer synthesis ,0104 chemical sciences ,Membrane ,Drug Discovery ,Molecular Medicine ,Bacteria - Abstract
Herein, we disclose the development of a catalyst- and protecting-group-free microwave-enhanced Friedländer synthesis which permits the single-step, convergent assembly of diverse 8-hydroxyquinolines with greatly improved reaction yields over traditional oil bath heating (increased from 34% to 72%). This rapid synthesis permitted the discovery of novel biofilm-eradicating halogenated quinolines (MBECs = 1.0-23.5 μM) active against MRSA, MRSE, and VRE. These small molecules exhibit activity through mechanisms independent of membrane lysis, further demonstrating their potential as a clinically useful treatment option against persistent biofilm-associated infections.
- Published
- 2017
36. Phenazine Antibiotic Inspired Discovery of Bacterial Biofilm-Eradicating Agents
- Author
-
Yasmeen Abouelhassan, Hongfen Yang, and Robert W. Huigens
- Subjects
Multidrug tolerance ,medicine.drug_class ,Phenazine ,Antibiotics ,Microbial Sensitivity Tests ,Biology ,010402 general chemistry ,medicine.disease_cause ,Bacterial Physiological Phenomena ,01 natural sciences ,Biochemistry ,Cystic fibrosis ,Article ,Microbiology ,chemistry.chemical_compound ,Mice ,Drug Discovery ,medicine ,Animals ,Humans ,Molecular Biology ,010405 organic chemistry ,Pseudomonas aeruginosa ,Organic Chemistry ,Biofilm ,medicine.disease ,0104 chemical sciences ,Anti-Bacterial Agents ,Competition strategy ,chemistry ,Biofilms ,Molecular Medicine ,Phenazines ,Staphylococcus aureus infections ,HeLa Cells - Abstract
Bacterial biofilms are surface-attached communities of slow-growing and non-replicating persister cells that demonstrate high levels of antibiotic tolerance. Biofilms occur in nearly 80 % of infections and present unique challenges to our current arsenal of antibiotic therapies, all of which were initially discovered for their abilities to target rapidly dividing, free-floating planktonic bacteria. Bacterial biofilms are credited as the underlying cause of chronic and recurring bacterial infections. Innovative approaches are required to identify new small molecules that operate through bacterial growth-independent mechanisms to effectively eradicate biofilms. One source of inspiration comes from within the lungs of young cystic fibrosis (CF) patients, who often endure persistent Staphylococcus aureus infections. As these CF patients age, Pseudomonas aeruginosa co-infects the lungs and utilizes phenazine antibiotics to eradicate the established S. aureus infection. Our group has taken a special interest in this microbial competition strategy and we are investigating the potential of phenazine antibiotic-inspired compounds and synthetic analogues thereof to eradicate persistent bacterial biofilms. To discover new biofilm-eradicating agents, we have established an interdisciplinary research program involving synthetic medicinal chemistry, microbiology and molecular biology. From these efforts, we have identified a series of halogenated phenazines (HPs) that potently eradicate bacterial biofilms, and future work aims to translate these preliminary findings into ground-breaking clinical advances for the treatment of persistent biofilm infections.
- Published
- 2019
37. Recent Progress in Natural-Product-Inspired Programs Aimed To Address Antibiotic Resistance and Tolerance
- Author
-
Aaron T. Garrison, Yasmeen Abouelhassan, Alejandra Chávez-Riveros, Robert W. Huigens, Hongfen Yang, and Gena M. Burch
- Subjects
medicine.drug_class ,Antibiotics ,Drug resistance ,Computational biology ,Microbial Sensitivity Tests ,01 natural sciences ,Article ,03 medical and health sciences ,chemistry.chemical_compound ,Antibiotic resistance ,Drug Discovery ,medicine ,Humans ,030304 developmental biology ,0303 health sciences ,Biological Products ,Natural product ,biology ,Bacteria ,Molecular Structure ,Drug Resistance, Microbial ,Drug Tolerance ,biology.organism_classification ,0104 chemical sciences ,Anti-Bacterial Agents ,010404 medicinal & biomolecular chemistry ,chemistry ,Drug development ,Molecular Medicine - Abstract
Bacteria utilize multiple mechanisms that enable them to gain or acquire resistance to antibiotic therapies during the treatment of infections. In addition, bacteria form biofilms which are surface-attached communities of enriched populations containing persister cells encased within a protective extracellular matrix of biomolecules, leading to chronic and recurring antibiotic-tolerant infections. Antibiotic resistance and tolerance are major global problems that require innovative therapeutic strategies to address the challenges associated with pathogenic bacteria. Historically, natural products have played a critical role in bringing new therapies to the clinic to treat life-threatening bacterial infections. This Perspective provides an overview of antibiotic resistance and tolerance and highlights recent advances (chemistry, biology, drug discovery, and development) from various research programs involved in the discovery of new antibacterial agents inspired by a diverse series of natural product antibiotics.
- Published
- 2019
38. Turning the Tide against Antibiotic Resistance by Evaluating Novel, Halogenated Phenazine, Quinoline, and NH125 Compounds against Ureaplasma Species Clinical Isolates and Mycoplasma Type Strains
- Author
-
Katherine V. Cisneros, Marissa A. Valentine-King, Mary Bomberger Brown, Margaret O. James, and Robert W. Huigens
- Subjects
Mycoplasma pneumoniae ,medicine.drug_class ,Antibiotics ,urologic and male genital diseases ,medicine.disease_cause ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,Ureaplasma ,0302 clinical medicine ,medicine ,Pharmacology (medical) ,030212 general & internal medicine ,Pharmacology ,0303 health sciences ,biology ,030306 microbiology ,Broth microdilution ,Mycoplasma ,bacterial infections and mycoses ,biology.organism_classification ,female genital diseases and pregnancy complications ,3. Good health ,Infectious Diseases ,Nitroxoline ,chemistry ,Mycoplasma genitalium ,Ureaplasma urealyticum - Abstract
Escalating levels of antibiotic resistance in mycoplasmas, particularly macrolide resistance in Mycoplasma pneumoniae and M. genitalium, have narrowed our antibiotic arsenal. Further, mycoplasmas lack a cell wall and do not synthesize folic acid, rendering common antibiotics, such as beta-lactams, vancomycin, sulfonamides, and trimethoprim, of no value. To address this shortage, we screened nitroxoline, triclosan, and a library of 20 novel, halogenated phenazine, quinoline, and NH125 analogues against Ureaplasma species and M. hominis clinical isolates from urine. We tested a subset of these compounds (n = 9) against four mycoplasma type strains (M. pneumoniae, M. genitalium, M. hominis, and Ureaplasma urealyticum) using a validated broth microdilution or agar dilution method. Among 72 Ureaplasma species clinical isolates, nitroxoline proved most effective (MIC90, 6.25 µM), followed by an N-arylated NH125 analogue (MIC90, 12.5 µM). NH125 and its analogue had significantly higher MICs against U. urealyticum isolates than against U. parvum isolates, whereas nitroxoline did not. Nitroxoline exhibited bactericidal activity against U. parvum isolates but bacteriostatic activity against the majority of U. urealyticum isolates. Among the type strains, the compounds had the greatest activity against M. pneumoniae and M. genitalium, with 8 (80%) and 5 (71.4%) isolates demonstrating MICs of ≤12.5 µM, respectively. Triclosan also exhibited lower MICs against M. pneumoniae and M. genitalium Overall, we identified a promising range of quinoline, halogenated phenazine, and NH125 compounds that showed effectiveness against M. pneumoniae and M. genitalium and found that nitroxoline, approved for use outside the United States for the treatment of urinary tract infections, and an N-arylated NH125 analogue demonstrated low MICs against Ureaplasma species isolates.
- Published
- 2019
39. Foliar-Applied Small Molecule that Suppresses Biofilm Formation and Enhances Control of Copper-Resistant Xanthomonas euvesicatoria on Pepper
- Author
-
Steven A. Rogers, Roberta J. Worthington, Robert W. Huigens, Christian Melander, and D. F. Ritchie
- Subjects
Natural product ,Strain (chemistry) ,Biofilm ,food and beverages ,chemistry.chemical_element ,Plant Science ,Biology ,Copper ,Small molecule ,Microbiology ,chemistry.chemical_compound ,chemistry ,Xanthomonas euvesicatoria ,Pepper ,Food science ,Cultivar ,Agronomy and Crop Science - Abstract
We report a small molecule additive, a member of the 2-aminoimidazole (2AI) group that is an analogue of the marine sponge natural product oroidin that suppresses resistance of Xanthomonas euvesicatoria to copper and decreases biofilm formation in an in vitro system. In laboratory experiments, 2AI combined with copper reduced both bacterial multiplication in broth and bacterial recovery on pepper leaf discs of a copper-resistant strain of X. euvesicatoria to a level close to that of a copper-sensitive strain. Compound 2AI used alone exhibited minimal bactericidal activity. In 3 years of field experiments, when combined with a copper-containing material, copper hydroxide (Kocide 3000), and other antibacterial materials, these spray mixtures resulted in decreased bacterial spot foliar disease and increased fruit yields using hybrid bell pepper (Capsicum annuum) cultivars and copper-resistant strains of X. euvesicatoria. This study demonstrates the concept for using small molecules as additives to antibacterial compounds at nonbactericidal concentrations under field conditions that, in the laboratory, were demonstrated to suppress bacterial biofilms and copper-resistant strains.
- Published
- 2019
40. Rapid kill assessment of an
- Author
-
Yasmeen, Abouelhassan, Peilan, Zhang, Yousong, Ding, and Robert W, Huigens Iii
- Subjects
Chemistry ,macromolecular substances - Abstract
While a number of disinfection techniques are employed in healthcare units, the eradication of drug-resistant microorganisms remains a challenge. We recently reported N-arylated NH125 analogue 1, which demonstrated potent biofilm eradication and antibacterial activities against a panel of drug-resistant pathogens. The broad-spectrum activities observed for 1 along with its rapid eradication of MRSA persister cells suggested that this agent, and related analogues, can serve as disinfectants for antibiotic resistant pathogens in healthcare settings. Here, we report the rapid bactericidal activities of 1 against a panel of exponentially-growing, drug-resistant pathogens. Against MRSA, MRSE, VRE and MDR A. baumannii, 1 eradicated bacterial cells after five minutes when tested at 50 μM (3- to 6-log reduction of CFU per mL). We highlighted the rapid killing activities by demonstrating that 1 eradicates 99.99% of viable MRSA 1707 cells in one minute (50 μM, 4-log reduction of CFU per mL). In addition, 1 rapidly eradicated fungal pathogen C. neoformans in kill kinetic experiments. A solution of 1 demonstrated similar shelf stability to known disinfectant BAC-16 when tested up to 111 days after being stored. Collectively, our data highlights the potential of 1 to be used as a disinfecting agent to prevent healthcare-associated, drug-resistant infections.
- Published
- 2018
41. Harnessing the Chemistry of the Indole Heterocycle to Drive Discoveries in Biology and Medicine
- Author
-
Robert W. Huigens and Verrill M. Norwood
- Subjects
Indole test ,Molecular interactions ,Research groups ,Indoles ,Cycloaddition Reaction ,010405 organic chemistry ,Drug discovery ,Chemistry ,Organic Chemistry ,Chemical biology ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Combinatorial chemistry ,Small molecule ,Chemical space ,0104 chemical sciences ,Indole Alkaloids ,Drug Discovery ,Molecular Medicine ,Humans ,Molecular Biology - Abstract
Indole-containing compounds demonstrate an array of biological activities relevant to numerous human diseases. The biological activities of diverse indole-based agents are driven by molecular interactions between indole agent and critical therapeutic target. The chemical inventory of medicinally useful or promising indole compounds spans the entire structural spectrum, from simple synthetic indoles to highly complex indole alkaloids. In an analogous fashion, the chemistry behind the indole heterocycle is unique and provides rich opportunities for extensive synthetic chemistry, enabling the construction and development of novel indole compounds to explore chemical space. This review will present heterocyclic chemistry of the indole nucleus, indole compounds of clinical use, complex indole alkaloids and indole-inspired discovery efforts by multiple research groups interested in using novel indole-containing small molecules to drive discoveries in human biology and medicine.
- Published
- 2018
42. Progress towards a stable cephalosporin-halogenated phenazine conjugate for antibacterial prodrug applications
- Author
-
Robert W. Huigens, Tao Xiao, and Ke Liu
- Subjects
Staphylococcus aureus ,Halogenation ,Clinical Biochemistry ,Phenazine ,Pharmaceutical Science ,Ether ,Microbial Sensitivity Tests ,01 natural sciences ,Biochemistry ,Article ,Structure-Activity Relationship ,chemistry.chemical_compound ,Drug Discovery ,Moiety ,Prodrugs ,Molecular Biology ,Dose-Response Relationship, Drug ,Molecular Structure ,010405 organic chemistry ,Chemistry ,Drug discovery ,Organic Chemistry ,Prodrug ,Combinatorial chemistry ,Anti-Bacterial Agents ,Cephalosporins ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,Phenazines ,Molecular Medicine ,Antibacterial activity ,Linker ,Conjugate - Abstract
Resistant bacteria successfully evade the action of conventional antibiotic therapies during infection, often leading to significant illness and death. Our lab has discovered halogenated phenazine (HP) analogues which demonstrate potent antibacterial activities through a unique iron-starving mechanism. Herein, we describe synthetic efforts towards a stable cephalosporin-HP conjugate prodrug with the aim of translating HPs into useful clinical agents. Cephalosporin-antibiotic conjugates offer multiple advantages for antibacterial design, including the release of active agents through the targeting of intracellular cephalosporinase following selective ring-opening of the beta-lactam warhead. During these studies, carbonate-linked cephalosporin-HP conjugate 16 was synthesized; however, we were unable to successfully remove the ester group required for cephalosporinase processing. Cephalosporin-HP 16 was then utilized as a probe to investigate the stability of the carbonate linker in antibacterial assays and, as predicted, this compound proved to be inactive against Staphylococcus aureus (MIC > 100 µM). The lack of 16’s antibacterial activity can be attributed to the carbonate linker remaining intact throughout the MIC assay, thus not liberating the active HP moiety. These efforts have led to a more stable cephalosporin-HP conjugate joined through a carbonate linker compared to a highly unstable ether linked analogue we previously reported.
- Published
- 2020
43. In vitro antifungal and antibiofilm activities of halogenated quinoline analogues against Candida albicans and Cryptococcus neoformans
- Author
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Ran Zuo, Peilan Zhang, Robert W. Huigens, Yousong Ding, Akash Basak, and Aaron T. Garrison
- Subjects
0301 basic medicine ,Microbiology (medical) ,Antifungal Agents ,Halogenation ,030106 microbiology ,Microbial Sensitivity Tests ,Drug resistance ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,Minimum inhibitory concentration ,Candida albicans ,Humans ,Pharmacology (medical) ,Mode of action ,Cryptococcus neoformans ,biology ,Quinoline ,Biofilm ,General Medicine ,biology.organism_classification ,In vitro ,030104 developmental biology ,Infectious Diseases ,chemistry ,Biofilms ,Quinolines - Abstract
With the increasing prevalence of fungal infections coupled with emerging drug resistance, there is an urgent need for new and effective antifungal agents. Here we report the antifungal activities of 19 diverse halogenated quinoline (HQ) small molecules against Candida albicans and Cryptococcus neoformans. Four HQ analogues inhibited C. albicans growth with a minimum inhibitory concentration (MIC) of 100 nM, whilst 16 analogues effectively inhibited C. neoformans at MICs of 50–780 nM. Remarkably, two HQ analogues eradicated mature C. albicans and C. neoformans biofilms [minimum biofilm eradication concentration (MBEC) = 6.25–62.5 µM]. Several active HQs were found to penetrate into fungal cells, whilst one inactive analogue was unable to, suggesting that HQs elicit their antifungal activities through an intracellular mode of action. HQs are a promising class of small molecules that may be useful in future antifungal treatments.
- Published
- 2016
44. Synthetically Tuning the 2-Position of Halogenated Quinolines: Optimizing Antibacterial and Biofilm Eradication Activities via Alkylation and Reductive Amination Pathways
- Author
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Shouguang Jin, Yasmeen Abouelhassan, Robert W. Huigens, Verrill M. Norwood, Fang Bai, Minh Thu Nguyen, and Akash Basak
- Subjects
Methicillin-Resistant Staphylococcus aureus ,0301 basic medicine ,Erythrocytes ,Alkylation ,Halogenation ,Multidrug tolerance ,Cell Survival ,medicine.drug_class ,Staphylococcus ,Enterococcus faecium ,Antibiotics ,medicine.disease_cause ,Hemolysis ,Catalysis ,Microbiology ,Structure-Activity Relationship ,03 medical and health sciences ,Staphylococcus epidermidis ,Drug Resistance, Bacterial ,medicine ,Humans ,Organic chemistry ,Amination ,biology ,Chemistry ,Organic Chemistry ,Biofilm ,General Chemistry ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Haemolysis ,Anti-Bacterial Agents ,030104 developmental biology ,Staphylococcus aureus ,Biofilms ,Quinolines ,HeLa Cells - Abstract
Agents capable of eradicating bacterial biofilms are of great importance to human health as biofilm-associated infections are tolerant to our current antibiotic therapies. We have recently discovered that halogenated quinoline (HQ) small molecules are: 1) capable of eradicating methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE) and vancomycin-resistant Enterococcus faecium (VRE) biofilms, and 2) synthetic tuning of the 2-position of the HQ scaffold has a significant impact on antibacterial and antibiofilm activities. Here, we report the chemical synthesis and biological evaluation of 39 HQ analogues that have a high degree of structural diversity at the 2-position. We identified diverse analogues that are alkylated and aminated at the 2-position of the HQ scaffold and demonstrate potent antibacterial (MIC≤0.39 μm) and biofilm eradication (MBEC 1.0-93.8 μm) activities against drug-resistant Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecium strains while demonstrating
- Published
- 2016
45. Structure–Activity Relationships of a Diverse Class of Halogenated Phenazines That Targets Persistent, Antibiotic-Tolerant Bacterial Biofilms and Mycobacterium tuberculosis
- Author
-
Dimitris Kallifidas, Fang Bai, Robert W. Huigens, Minh Thu Nguyen, Yasmeen Abouelhassan, Verrill M. Norwood, Shouguang Jin, Hendrik Luesch, Gena M. Burch, Melanie Rolfe, and Aaron T. Garrison
- Subjects
0301 basic medicine ,Multidrug tolerance ,medicine.drug_class ,Proton Magnetic Resonance Spectroscopy ,Antibiotics ,Microbial Sensitivity Tests ,Bioinformatics ,01 natural sciences ,Microbiology ,Mycobacterium tuberculosis ,Structure-Activity Relationship ,03 medical and health sciences ,Halogens ,Drug Resistance, Bacterial ,Drug Discovery ,medicine ,Humans ,Carbon-13 Magnetic Resonance Spectroscopy ,biology ,010405 organic chemistry ,Chemistry ,Biofilm ,biology.organism_classification ,Antimicrobial ,0104 chemical sciences ,030104 developmental biology ,Cell killing ,Biofilms ,Phenazines ,Molecular Medicine ,Drug Screening Assays, Antitumor ,Antibacterial activity ,Bacteria ,HeLa Cells - Abstract
Persistent bacteria, including persister cells within surface-attached biofilms and slow-growing pathogens lead to chronic infections that are tolerant to antibiotics. Here, we describe the structure-activity relationships of a series of halogenated phenazines (HP) inspired by 2-bromo-1-hydroxyphenazine 1. Using multiple synthetic pathways, we probed diverse substitutions of the HP scaffold in the 2-, 4-, 7-, and 8-positions, providing critical information regarding their antibacterial and bacterial eradication profiles. Halogenated phenazine 14 proved to be the most potent biofilm-eradicating agent (≥99.9% persister cell killing) against MRSA (MBEC < 10 μM), MRSE (MBEC = 2.35 μM), and VRE (MBEC = 0.20 μM) biofilms while 11 and 12 demonstrated excellent antibacterial activity against M. tuberculosis (MIC = 3.13 μM). Unlike antimicrobial peptide mimics that eradicate biofilms through the general lysing of membranes, HPs do not lyse red blood cells. HPs are promising agents that effectively target persistent bacteria while demonstrating negligible toxicity against mammalian cells.
- Published
- 2016
46. Turning the Tide against Antibiotic Resistance by Evaluating Novel, Halogenated Phenazine, Quinoline, and NH125 Compounds against
- Author
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Marissa A, Valentine-King, Katherine, Cisneros, Margaret O, James, Robert W, Huigens, and Mary B, Brown
- Subjects
Ureaplasma Infections ,Imidazoles ,Mycoplasma genitalium ,Microbial Sensitivity Tests ,bacterial infections and mycoses ,Ureaplasma ,Anti-Bacterial Agents ,Mycoplasma pneumoniae ,Mycoplasma ,nitroxoline ,Susceptibility ,drug evaluation ,Drug Resistance, Multiple, Bacterial ,quinoline ,Quinolines ,Humans ,Phenazines ,NH125 analogues ,Mycoplasma Infections ,Ureaplasma urealyticum - Abstract
Escalating levels of antibiotic resistance in mycoplasmas, particularly macrolide resistance in Mycoplasma pneumoniae and M. genitalium, have narrowed our antibiotic arsenal. Further, mycoplasmas lack a cell wall and do not synthesize folic acid, rendering common antibiotics, such as beta-lactams, vancomycin, sulfonamides, and trimethoprim, of no value., Escalating levels of antibiotic resistance in mycoplasmas, particularly macrolide resistance in Mycoplasma pneumoniae and M. genitalium, have narrowed our antibiotic arsenal. Further, mycoplasmas lack a cell wall and do not synthesize folic acid, rendering common antibiotics, such as beta-lactams, vancomycin, sulfonamides, and trimethoprim, of no value. To address this shortage, we screened nitroxoline, triclosan, and a library of 20 novel, halogenated phenazine, quinoline, and NH125 analogues against Ureaplasma species and M. hominis clinical isolates from urine. We tested a subset of these compounds (n = 9) against four mycoplasma type strains (M. pneumoniae, M. genitalium, M. hominis, and Ureaplasma urealyticum) using a validated broth microdilution or agar dilution method. Among 72 Ureaplasma species clinical isolates, nitroxoline proved most effective (MIC90, 6.25 µM), followed by an N-arylated NH125 analogue (MIC90, 12.5 µM). NH125 and its analogue had significantly higher MICs against U. urealyticum isolates than against U. parvum isolates, whereas nitroxoline did not. Nitroxoline exhibited bactericidal activity against U. parvum isolates but bacteriostatic activity against the majority of U. urealyticum isolates. Among the type strains, the compounds had the greatest activity against M. pneumoniae and M. genitalium, with 8 (80%) and 5 (71.4%) isolates demonstrating MICs of ≤12.5 µM, respectively. Triclosan also exhibited lower MICs against M. pneumoniae and M. genitalium. Overall, we identified a promising range of quinoline, halogenated phenazine, and NH125 compounds that showed effectiveness against M. pneumoniae and M. genitalium and found that nitroxoline, approved for use outside the United States for the treatment of urinary tract infections, and an N-arylated NH125 analogue demonstrated low MICs against Ureaplasma species isolates.
- Published
- 2018
47. The Path to New Halogenated Quinolines With Enhanced Activities Against
- Author
-
Robert W Huigens
- Subjects
lcsh:QR1-502 ,lcsh:Microbiology - Abstract
Antibiotic-resistant bacteria and surface-attached bacterial biofilms play a significant role in human disease. Conventional antibiotics target actively replicating free-floating, planktonic cells. Unfortunately, biofilm communities are endowed with nonreplicating persister cells that are tolerant to antibiotics. Innovative approaches are necessary to identify new molecules able to eradicate resistant and tolerant bacterial cells. Our group has discovered that select halogenated quinolines (HQs) can eradicate drug-resistant, gram-positive bacterial pathogens and their corresponding biofilms. Interestingly, the HQ scaffold is synthetically tunable and we have discovered unique antibacterial profiles through extensive analogue synthesis and microbiologic studies. We recently reported the synthesis of 14 new HQs to investigate the impact of ClogP values on antibacterial and biofilm eradication activities. We conducted diverse synthetic modifications at the 2-position of the HQ scaffold in an attempt to enhance water solubility and found new compounds that display enhanced activities against Staphylococcus epidermidis . In particular, HQ 2 (ClogP = 3.44) demonstrated more potent antibacterial activities against methicillin-resistant S epidermidis (MRSE) 35984 planktonic cells (minimum inhibitory concentration = 0.59 µM) compared with methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus isolates while demonstrating potent MRSE biofilm eradication activities (minimum biofilm eradication concentration = 2.35 µM). We believe that HQ could play a critical role in the development of next-generation antibacterial therapeutics.
- Published
- 2018
48. An Efficient Buchwald-Hartwig/Reductive Cyclization for the Scaffold Diversification of Halogenated Phenazines: Potent Antibacterial Targeting, Biofilm Eradication, and Prodrug Exploration
- Author
-
Hendrik Luesch, Robert W. Huigens, Dimitris Kallifidas, Hao Tan, Aaron T. Garrison, Young Sik Kim, Yasmeen Abouelhassan, and Shouguang Jin
- Subjects
Methicillin-Resistant Staphylococcus aureus ,Scaffold ,Multidrug tolerance ,Halogenation ,medicine.drug_class ,Antibiotics ,Phenazine ,Microbial Sensitivity Tests ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Drug Discovery ,medicine ,Moiety ,Humans ,010405 organic chemistry ,Chemistry ,Biofilm ,Prodrug ,Combinatorial chemistry ,0104 chemical sciences ,Anti-Bacterial Agents ,Cyclization ,Biofilms ,Molecular Medicine ,Phenazines ,HeLa Cells - Abstract
Bacterial biofilms are surface-attached communities comprised of nonreplicating persister cells housed within a protective extracellular matrix. Biofilms display tolerance toward conventional antibiotics, occur in ∼80% of infections, and lead to500000 deaths annually. We recently identified halogenated phenazine (HP) analogues which demonstrate biofilm-eradicating activities against priority pathogens; however, the synthesis of phenazines presents limitations. Herein, we report a refined HP synthesis which expedited the identification of improved biofilm-eradicating agents. 1-Methoxyphenazine scaffolds were generated through a Buchwald-Hartwig cross-coupling (70% average yield) and subsequent reductive cyclization (68% average yield), expediting the discovery of potent biofilm-eradicating HPs (e.g., 61: MRSA BAA-1707 MBEC = 4.69 μM). We also developed bacterial-selective prodrugs (reductively activated quinone-alkyloxycarbonyloxymethyl moiety) to afford HP 87, which demonstrated excellent antibacterial and biofilm eradication activities against MRSA BAA-1707 (MIC = 0.15 μM, MBEC = 12.5 μM). Furthermore, active HPs herein exhibit negligible cytotoxic or hemolytic effects, highlighting their potential to target biofilms.
- Published
- 2018
49. Halogenated Phenazines that Potently Eradicate Biofilms, MRSA Persister Cells in Non‐Biofilm Cultures, and Mycobacterium tuberculosis
- Author
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Yasmeen Abouelhassan, Robert W. Huigens, Volker Mai, Dimitris Kallifidas, Hendrik Luesch, Shouguang Jin, Fang Bai, Maria Ukhanova, and Aaron T. Garrison
- Subjects
Methicillin-Resistant Staphylococcus aureus ,Multidrug tolerance ,Cell Survival ,medicine.drug_class ,Antibiotics ,Microbial Sensitivity Tests ,medicine.disease_cause ,Catalysis ,Microbiology ,Mycobacterium tuberculosis ,Structure-Activity Relationship ,medicine ,Humans ,Cells, Cultured ,Dose-Response Relationship, Drug ,Molecular Structure ,biology ,Biofilm ,General Chemistry ,General Medicine ,biochemical phenomena, metabolism, and nutrition ,bacterial infections and mycoses ,biology.organism_classification ,Methicillin-resistant Staphylococcus aureus ,Anti-Bacterial Agents ,Biofilms ,Phenazines ,Vancomycin ,Daptomycin ,Bacteria ,HeLa Cells ,medicine.drug - Abstract
Conventional antibiotics are ineffective against non-replicating bacteria (for example, bacteria within biofilms). We report a series of halogenated phenazines (HP), inspired by marine antibiotic 1, that targets persistent bacteria. HP 14 demonstrated the most potent biofilm eradication activities to date against MRSA, MRSE, and VRE biofilms (MBEC = 0.2-12.5 μM), as well as the effective killing of MRSA persister cells in non-biofilm cultures. Frontline MRSA treatments, vancomycin and daptomycin, were unable to eradicate MRSA biofilms or non-biofilm persisters alongside 14. HP 13 displayed potent antibacterial activity against slow-growing M. tuberculosis (MIC = 3.13 μM), the leading cause of death by bacterial infection around the world. HP analogues effectively target persistent bacteria through a mechanism that is non-toxic to mammalian cells and could have a significant impact on treatments for chronic bacterial infections.
- Published
- 2015
50. A Phytochemical-Halogenated Quinoline Combination Therapy Strategy for the Treatment of Pathogenic Bacteria
- Author
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Shouguang Jin, Minh Thu Nguyen, Aaron T. Garrison, Robert W. Huigens, Fang Bai, Yasmeen Abouelhassan, and Verrill M. Norwood
- Subjects
Methicillin-Resistant Staphylococcus aureus ,inorganic chemicals ,Cell Survival ,medicine.drug_class ,Phytochemicals ,Antibiotics ,Microbial Sensitivity Tests ,Biology ,Pharmacology ,medicine.disease_cause ,Biochemistry ,Microbiology ,Structure-Activity Relationship ,chemistry.chemical_compound ,Gallic Acid ,Drug Discovery ,medicine ,Humans ,Gallic acid ,General Pharmacology, Toxicology and Pharmaceutics ,Cytotoxicity ,Dose-Response Relationship, Drug ,Molecular Structure ,Organic Chemistry ,Quinoline ,Biofilm ,Pathogenic bacteria ,Anti-Bacterial Agents ,Drug Combinations ,chemistry ,Phytochemical ,Staphylococcus aureus ,Quinolines ,Molecular Medicine ,HeLa Cells - Abstract
With the continued rise of drug-resistant bacterial infections coupled with the current discouraging state of the antibiotic pipeline, the need for new antibacterial agents that operate through unique mechanisms compared with conventional antibiotics and work in synergy with other agents is at an all-time high. We have discovered that gallic acid, a plant-derived phytochemical, dramatically potentiates the antibacterial activities of several halogenated quinolines (up to 11,800-fold potentiation against Staphylococcus aureus) against pathogenic bacteria, including drug-resistant clinical isolates. S. aureus demonstrated the highest sensitivity towards gallic acid-halogenated quinoline combinations, including one halogenated quinoline that demonstrated potentiation of biofilm eradication activity against a methicillin-resistant S. aureus (MRSA) clinical isolate. During our studies, we also demonstrated that these halogenated quionlines operate through an interesting metal(II) cation-dependent mechanism and display promising mammalian cytotoxicity.
- Published
- 2015
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