67 results on '"Erhardt PW"'
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2. Synthesis and Evaluation of PPARδ Agonists That Promote Osteogenesis in a Human Mesenchymal Stem Cell Culture and in a Mouse Model of Human Osteoporosis.
- Author
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Kress BJ, Kim DH, Mayo JR, Farris JT, Heck B, Sarver JG, Andy D, Trendel JA, Heck BE, and Erhardt PW
- Subjects
- Animals, Disease Models, Animal, Drug Design, Female, Femur diagnostic imaging, Humans, Mesenchymal Stem Cells cytology, Mesenchymal Stem Cells drug effects, Mesenchymal Stem Cells metabolism, Mice, Mice, Inbred C57BL, Osteoporosis drug therapy, PPAR delta metabolism, Structure-Activity Relationship, Thiazoles metabolism, Thiazoles pharmacology, Thiazoles therapeutic use, X-Ray Microtomography, Cell Differentiation drug effects, Osteogenesis drug effects, PPAR delta agonists, Thiazoles chemistry
- Abstract
We synthesized a directed library of compounds to explore the structure-activity relationships of peroxisome proliferator-activated receptor δ (PPARδ) activation relative to mesenchymal stem cell (MSC) osteogenesis. Our scaffold used para-substituted cinnamic acids as a polar headgroup, a heteroatom and heterocycle core connecting units, and substituted phenyl groups for the lipophilic tail. Compounds were screened for their ability to increase osteogenesis in MSCs, and the most promising were examined for subunit specificity using a quantitative PPAR transactivation assay. Six compounds were selected for in vivo studies in an ovariectomized mouse model of human postmenopausal osteoporosis. Four compounds improved bone density in vivo, with two ( 12d and 31a ) having activity comparable to that of GW0742, a well-studied PPARδ-selective agonist. 31a (2-methyl-4-[ N -methyl- N -[5-methylene-4-methyl-2-[4-(trifluoromethyl)phenyl]thiazole]]aminocinnamic acid) had the highest selectivity for PPARδ compared to other subtypes, its selectivity far exceeding that of GW0742. Our results confirm that PPARδ is a new drug target for possible treatment of osteoporosis via in situ manipulation of MSCs.
- Published
- 2021
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3. Investigating the Potential to Deliver and Maintain Plasma and Brain Levels of a Novel Practically Insoluble Methuosis Inducing Anticancer Agent 5-Methoxy MOMIPP Through an Injectable In Situ Forming Thermoresponsive Hydrogel Formulation.
- Author
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Oppong F, Li Z, Fakhrabadi EA, Raorane T, Giri PM, Liberatore MW, Sarver JG, Trabbic CJ, Hosier CE, Erhardt PW, Maltese WA, and Nesamony J
- Subjects
- Animals, Brain metabolism, Gels, Indoles, Poloxamer metabolism, Pyridines, Rheology, Temperature, Viscosity, Antineoplastic Agents, Hydrogels
- Abstract
A new indole based chalcone molecule MOMIPP induced methuosis mediated cell death in gliobastoma and other cancer cell lines. But the drug was insoluble in water and had a very short plasma half-life. The purpose of this work was to develop a formulation that can provide sustained levels of MOMIPP in vivo. Initial studies established drug solubility in various solvents. N-methyl pyrrolidone (NMP) was determined as an excellent solvent for the drug. Subsequently a poloxamer-407 based thermoreversible gel containing NMP was used to develop the formulation. Rheological studies were performed via oscillatory temperature mode, continuous shear analysis, and oscillatory frequency mode experiments. The mechanical properties of the formulations were tested using a texture profile analyzer. The gelation temperature and time of formulations increased with increasing amounts of NMP. However, the viscosity at 20 °C and storage modulus decreased as the amount of NMP increased. Characterization studies helped to identify the gel formulation that was used to administer the drug orally, sub-cutaneously, and intra-peritoneally. When the gel was given intraperitoneally the target plasma and brain levels of over 5 μM was maintained for about 8 h. Thus, a thermoreversible gel formulation that can deliver MOMIPP in animal studies was successfully developed., (Copyright © 2020 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)
- Published
- 2020
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4. Bilirubin remodels murine white adipose tissue by reshaping mitochondrial activity and the coregulator profile of peroxisome proliferator-activated receptor α.
- Author
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Gordon DM, Neifer KL, Hamoud AA, Hawk CF, Nestor-Kalinoski AL, Miruzzi SA, Morran MP, Adeosun SO, Sarver JG, Erhardt PW, McCullumsmith RE, Stec DE, and Hinds TD Jr
- Subjects
- Animals, Bilirubin metabolism, Mice, Receptors, Adrenergic, beta-3 biosynthesis, Uncoupling Protein 1 biosynthesis, Adipose Tissue, White metabolism, Bilirubin pharmacology, Gene Expression Regulation drug effects, Mitochondria metabolism, PPAR alpha metabolism
- Abstract
Activation of lipid-burning pathways in the fat-storing white adipose tissue (WAT) is a promising strategy to improve metabolic health and reduce obesity, insulin resistance, and type II diabetes. For unknown reasons, bilirubin levels are negatively associated with obesity and diabetes. Here, using mice and an array of approaches, including MRI to assess body composition, biochemical assays to measure bilirubin and fatty acids, MitoTracker-based mitochondrial analysis, immunofluorescence, and high-throughput coregulator analysis, we show that bilirubin functions as a molecular switch for the nuclear receptor transcription factor peroxisome proliferator-activated receptor α (PPARα). Bilirubin exerted its effects by recruiting and dissociating specific coregulators in WAT, driving the expression of PPARα target genes such as uncoupling protein 1 ( Ucp1 ) and adrenoreceptor β 3 ( Adrb3 ). We also found that bilirubin is a selective ligand for PPARα and does not affect the activities of the related proteins PPARγ and PPARδ. We further found that diet-induced obese mice with mild hyperbilirubinemia have reduced WAT size and an increased number of mitochondria, associated with a restructuring of PPARα-binding coregulators. We conclude that bilirubin strongly affects organismal body weight by reshaping the PPARα coregulator profile, remodeling WAT to improve metabolic function, and reducing fat accumulation., Competing Interests: Conflict of interest—Terry Hinds and David Stec have submitted patents on bilirubin and obesity-related disorders., (© 2020 Gordon et al.)
- Published
- 2020
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5. 6-MOMIPP, a novel brain-penetrant anti-mitotic indolyl-chalcone, inhibits glioblastoma growth and viability.
- Author
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Du S, Sarver JG, Trabbic CJ, Erhardt PW, Schroering A, and Maltese WA
- Subjects
- Animals, Brain Neoplasms metabolism, Brain Neoplasms pathology, Cell Cycle drug effects, Female, Glioblastoma metabolism, Glioblastoma pathology, Humans, Indoles pharmacokinetics, Mice, Mice, Nude, Pyridines pharmacokinetics, Tissue Distribution, Tumor Cells, Cultured, Xenograft Model Antitumor Assays, Apoptosis drug effects, Brain Neoplasms drug therapy, Cell Proliferation drug effects, Glioblastoma drug therapy, Indoles pharmacology, Mitosis, Pyridines pharmacology
- Abstract
Purpose: 3-(6-Methoxy-2-methyl-1H-indol-3-yl)-1-(4-pyridinyl)-2-propene-1-one (6-MOMIPP) is a novel indole-based chalcone that disrupts microtubules. The present study aims to define the mechanism through which 6-MOMIPP induces cell death and to evaluate the efficacy of the compound in penetrating the blood-brain barrier and inhibiting growth of glioblastoma xenografts., Methods: The effects of 6-MOMIPP were evaluated in cultured U251 glioblastoma cells, using viability, flow cytometry, and tubulin polymerization assays. Scintillation proximity and tubulin crosslinking methods were used to identify the binding site of 6-MOMIPP on tubulin, and western blots were performed to define the signaling pathways that contribute to cell death. LC/MS assays were used to study the pharmacokinetic behavior of 6-MOMIPP in mice. Subcutaneous and intracerebral xenograft models were utilized to assess the effects of 6-MOMIPP on growth of U251 glioblastoma in vivo., Results: The findings indicate that 6-MOMIPP targets the colchicine site on β-tubulin. At concentrations ≥ 250 nm, 6-MOMIPP induces mitotic arrest, caspase activation and loss of cell viability. Cells are protected by caspase inhibitors, pointing to an apoptotic mechanism of cell death. Loss of cell viability is preceded by activation of Cdk1(Cdc2) and phosphorylation of Bcl-2 and Bcl-xL. Inhibition of both events with a Cdk1 inhibitor prevents cell death. 6-MOMIPP has broad activity against the viability of multiple glioblastoma, melanoma and lung carcinoma cell lines. Viability of normal cells, including differentiated neurons, is not significantly affected at a drug concentration (1 µM) that reduces viability in most cancer lines. Pharmacokinetic studies in mice show that concentrations of 6-MOMIPP in the brain mirror those in the plasma, indicating that 6-MOMIPP readily penetrates the blood-brain barrier. Studies with mice bearing human U251 glioblastoma xenografts demonstrate that 6-MOMIPP is effective in suppressing growth of subcutaneous and intracerebral tumors without causing general toxicity., Conclusions: The results indicate that 6-MOMIPP is a novel microtubule disruptor that targets the colchicine binding site on β-tubulin to induce mitotic arrest and cell death. The ability of 6-MOMIPP to penetrate the blood-brain barrier and inhibit growth of glioblastoma xenografts suggests that it warrants further preclinical evaluation as potential small-molecule therapeutic that may have advantages in treating primary and metastatic brain tumors.
- Published
- 2019
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6. The JNK signaling pathway plays a key role in methuosis (non-apoptotic cell death) induced by MOMIPP in glioblastoma.
- Author
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Li Z, Mbah NE, Overmeyer JH, Sarver JG, George S, Trabbic CJ, Erhardt PW, and Maltese WA
- Subjects
- Adult, Animals, Antineoplastic Agents therapeutic use, Brain metabolism, Brain pathology, Brain Neoplasms drug therapy, Brain Neoplasms pathology, Cell Line, Tumor, Cell Survival drug effects, Female, Glioblastoma drug therapy, Glioblastoma pathology, Humans, Indoles therapeutic use, Mice, Pyridines therapeutic use, Tissue Distribution, Xenograft Model Antitumor Assays, Antineoplastic Agents pharmacology, Cell Death drug effects, Indoles pharmacology, JNK Mitogen-Activated Protein Kinases metabolism, MAP Kinase Signaling System drug effects, Pyridines pharmacology
- Abstract
Background: Synthetic indolyl- pyridinyl- propenones (IPPs) induce methuosis, a form of non-apoptotic cell death, in glioblastoma and other cancer cell lines. Methuosis is characterized by accumulation of cytoplasmic vacuoles derived from macropinosomes and late endosomes, followed by metabolic failure and rupture of the plasma membrane. However, not all IPPs that cause vacuolization are cytotoxic. The main goals of the present study were to identify key signaling pathways that contribute to methuosis induced by cytotoxic IPPs and to evaluate the anti-tumor potential of a prototype IPP in vivo., Methods: We utilized metabolic flux analysis, glucose uptake, immunoblotting, and selective pharmacological inhibitors to compare the effects of closely related cytotoxic and non-cytotoxic IPPs in cultured glioblastoma cells. To determine whether the use of methuosis-inducing IPPs might be feasible in a therapeutic context, we quantified the distribution of our lead IPP compound, MOMIPP, in mouse plasma and brain, and tested its ability to inhibit tumor growth in an intracerebral glioblastoma xenograft model., Results: The cytotoxic IPP compound, MOMIPP, causes early disruptions of glucose uptake and glycolytic metabolism. Coincident with these metabolic changes, MOMIPP selectively activates the JNK1/2 stress kinase pathway, resulting in phosphorylation of c-Jun, Bcl-2 and Bcl-xL. At the same concentration, the non-cytotoxic analog, MOPIPP, does not activate these pathways. Pharmacologic inhibition of JNK activity promotes survival, even when cells are extensively vacuolated, but suppression of c-Jun transcriptional activity offers no protection. MOMIPP readily penetrates the blood-brain barrier and is moderately effective in suppressing progression of intracerebral glioblastoma xenografts., Conclusions: The results suggest that interference with glucose uptake and induction of JNK-mediated phosphorylation of pro-survival members of the Bcl-2 family represent key events in the methuosis death process. In addition to providing new insights into the underlying molecular mechanism of methuosis, the results indicate that compounds of the cytotoxic IPP class may have potential for further development as therapeutic agents for brain tumors.
- Published
- 2019
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7. Corrigendum: Leukocyte integrin Mac-1 regulates thrombosis via interaction with platelet GPIbα.
- Author
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Wang Y, Gao H, Shi C, Erhardt PW, Pavlovsky A, Soloviev DA, Bledzka K, Ustinov V, Zhu L, Qin J, Munday AD, Lopez J, Plow E, and Simon DI
- Abstract
This corrects the article DOI: 10.1038/ncomms15559.
- Published
- 2017
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8. Leukocyte integrin Mac-1 regulates thrombosis via interaction with platelet GPIbα.
- Author
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Wang Y, Gao H, Shi C, Erhardt PW, Pavlovsky A, A Soloviev D, Bledzka K, Ustinov V, Zhu L, Qin J, Munday AD, Lopez J, Plow E, and Simon DI
- Subjects
- Animals, Binding Sites, Bleeding Time, Blood Coagulation, Blood Platelets cytology, Blood Platelets metabolism, Carotid Arteries pathology, Glucosamine chemistry, Hemostasis, Inflammation, Leukocytes cytology, Macrophages metabolism, Male, Mice, Mice, Inbred C57BL, Mice, Transgenic, Microcirculation, NIH 3T3 Cells, Partial Thromboplastin Time, Phagocytosis, Platelet Activation, Platelet Count, Protein Binding, Protein Domains, Signal Transduction, Thrombin metabolism, Blood Platelets immunology, Leukocytes metabolism, Macrophage-1 Antigen genetics, Platelet Glycoprotein GPIb-IX Complex metabolism, Thrombosis immunology
- Abstract
Inflammation and thrombosis occur together in many diseases. The leukocyte integrin Mac-1 (also known as integrin α
M β2 , or CD11b/CD18) is crucial for leukocyte recruitment to the endothelium, and Mac-1 engagement of platelet GPIbα is required for injury responses in diverse disease models. However, the role of Mac-1 in thrombosis is undefined. Here we report that mice with Mac-1 deficiency (Mac-1-/- ) or mutation of the Mac-1-binding site for GPIbα have delayed thrombosis after carotid artery and cremaster microvascular injury without affecting parameters of haemostasis. Adoptive wild-type leukocyte transfer rescues the thrombosis defect in Mac-1-/- mice, and Mac-1-dependent regulation of the transcription factor Foxp1 contributes to thrombosis as evidenced by delayed thrombosis in mice with monocyte-/macrophage-specific overexpression of Foxp1. Antibody and small-molecule targeting of Mac-1:GPIbα inhibits thrombosis. Our data identify a new pathway of thrombosis involving leukocyte Mac-1 and platelet GPIbα, and suggest that targeting this interaction has anti-thrombotic therapeutic potential with reduced bleeding risk.- Published
- 2017
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9. Synthesis and biological evaluation of isomeric methoxy substitutions on anti-cancer indolyl-pyridinyl-propenones: Effects on potency and mode of activity.
- Author
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Trabbic CJ, George SM, Alexander EM, Du S, Offenbacher JM, Crissman EJ, Overmeyer JH, Maltese WA, and Erhardt PW
- Subjects
- Antineoplastic Agents chemistry, Cell Line, Tumor, Cell Proliferation drug effects, Chemistry Techniques, Synthetic, Humans, Indoles chemistry, Isomerism, Structure-Activity Relationship, Antineoplastic Agents chemical synthesis, Antineoplastic Agents pharmacology, Indoles chemical synthesis, Indoles pharmacology, Pyridines chemistry
- Abstract
Certain indolyl-pyridinyl-propenone analogues kill glioblastoma cells that have become resistant to conventional therapeutic drugs. Some of these analogues induce a novel form of non-apoptotic cell death called methuosis, while others primarily cause microtubule disruption. Ready access to 5-indole substitution has allowed characterization of this position to be important for both types of mechanisms when a simple methoxy group is present. We now report the syntheses and biological effects of isomeric methoxy substitutions on the indole ring. Additionally, analogues containing a trimethoxyphenyl group in place of the pyridinyl moiety were evaluated for anticancer activity. The results demonstrate that the location of the methoxy group can alter both the potency and the mechanism of cell death. Remarkably, changing the methoxy from the 5-position to the 6-position switched the biological activity from induction of methuosis to disruption of microtubules. The latter may represent a prototype for a new class of mitotic inhibitors with potential therapeutic utility., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)
- Published
- 2016
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10. Synthesis and biological evaluation of indolyl-pyridinyl-propenones having either methuosis or microtubule disruption activity.
- Author
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Trabbic CJ, Overmeyer JH, Alexander EM, Crissman EJ, Kvale HM, Smith MA, Erhardt PW, and Maltese WA
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- Cell Cycle drug effects, Cell Proliferation drug effects, Glioblastoma pathology, Humans, Indoles pharmacology, Microscopy, Fluorescence, Pyridines pharmacology, Structure-Activity Relationship, Tubulin metabolism, Tumor Cells, Cultured, Alkenes chemistry, Antineoplastic Agents chemical synthesis, Antineoplastic Agents pharmacology, Cell Death drug effects, Glioblastoma drug therapy, Indoles chemistry, Microtubules drug effects, Pyridines chemistry
- Abstract
Methuosis is a form of nonapoptotic cell death characterized by an accumulation of macropinosome-derived vacuoles with eventual loss of membrane integrity. Small molecules inducing methuosis could offer significant advantages compared to more traditional anticancer drug therapies that typically rely on apoptosis. Herein we further define the effects of chemical substitutions at the 2- and 5-indolyl positions on our lead compound 3-(5-methoxy-2-methyl-1H-indol-3-yl)-1-(4-pyridinyl)-2-propene-1-one (MOMIPP). We have identified a number of compounds that induce methuosis at similar potencies, including an interesting analogue having a hydroxypropyl substituent at the 2-position. In addition, we have discovered that certain substitutions on the 2-indolyl position redirect the mode of cytotoxicity from methuosis to microtubule disruption. This switch in activity is associated with an increase in potency as large as 2 orders of magnitude. These compounds appear to represent a new class of potent microtubule-active anticancer agents.
- Published
- 2015
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11. Differential Induction of Cytoplasmic Vacuolization and Methuosis by Novel 2-Indolyl-Substituted Pyridinylpropenones.
- Author
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Trabbic CJ, Dietsch HM, Alexander EM, Nagy PI, Robinson MW, Overmeyer JH, Maltese WA, and Erhardt PW
- Abstract
Because many cancers harbor mutations that confer resistance to apoptosis, there is a need for therapeutic agents that can trigger alternative forms of cell death. Methuosis is a novel form of non-apoptotic cell death characterized by accumulation of vacuoles derived from macropinosomes and endosomes. Previous studies identified an indole-based chalcone, 3-(5-methoxy-2-methylindol-3-yl)-1-(4-pyridinyl)-2-propen-1-one (MOMIPP), that induces methuosis in human cancer cells. Herein, we describe the synthesis of related 2-indolyl substituted pyridinylpropenones and their effects on U251 glioblastoma cells. Increasing the size of the 2-indolyl substituent substantially reduces growth inhibitory activity and cytotoxicity, but does not prevent cell vacuolization. Computational models suggest that the results are not due to steric-driven conformational effects. The unexpected uncoupling of vacuolization and cell death implies that the relationship between endosomal perturbations and methuotic cell death is more complex than previously realized. The new series of compounds will be useful in further defining the molecular and cellular mechanisms underlying methuosis.
- Published
- 2014
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12. Glyceollins, soy isoflavone phytoalexins, improve oral glucose disposal by stimulating glucose uptake.
- Author
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Boué SM, Isakova IA, Burow ME, Cao H, Bhatnagar D, Sarver JG, Shinde KV, Erhardt PW, and Heiman ML
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- 3T3 Cells, Adipocytes drug effects, Adipocytes metabolism, Animals, Biological Transport, Diabetes Mellitus, Type 2 metabolism, Humans, Male, Mice, Rats, Rats, Sprague-Dawley, Phytoalexins, Diabetes Mellitus, Type 2 drug therapy, Glucose metabolism, Isoflavones administration & dosage, Plant Extracts administration & dosage, Pterocarpans administration & dosage, Sesquiterpenes administration & dosage, Glycine max chemistry
- Abstract
Soy glyceollins, induced during stress, have been shown to inhibit cancer cell growth in vitro and in vivo. In the present study, we used prediabetic rats to examine the glyceollins effect on blood glucose. During an oral glucose tolerance test (OGTT), the blood glucose excursion was significantly decreased in the rats treated with oral administration of either 30 or 90 mg/kg glyceollins. Plasma analysis demonstrated that glyceollins are absorbed after oral administration, and duration of exposure extends from 20 min to at least 4 h postadministration. Exposure of 3T3-L1 adipocytes to glyceollins significantly increased both insulin-stimulated and basal glucose uptake. Basal glucose uptake was increased 1.5-fold by exposure to 5 μM glyceollin in a dose-response manner. Coincubation with insulin significantly stimulated maximal glucose uptake above basal uptake levels and tended to increase glucose uptake beyond the levels of either stimulus alone. On a molecular level, polymerase chain reaction showed significantly increased levels of glucose transporter GLUT4 mRNA in 3T3-L1 adipocytes, especially when the cells were exposed to 5 μM glyceollins for 3 h in vitro. It correlated with elevated protein levels of GLUT4 detected in the 5 μM glyceollin-treated cells. Thus, the simulative effect of the glyceollins on adipocyte glucose uptake was attributed to up-regulation of glucose transporters. These findings indicate potential benefits of the glyceollins as an intervention in prediabetic conditions as well as a treatment for type 1 and type 2 diabetes by increasing both the insulin-mediated and the basal, insulin-independent, glucose uptake by adipocytes.
- Published
- 2012
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13. Early stage efficacy and toxicology screening for antibiotics and enzyme inhibitors.
- Author
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Sarver JG, Trendel JA, Bearss NR, Wang L, Luniwal A, Erhardt PW, and Viola RE
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- Anti-Bacterial Agents toxicity, Cell Line, Enzyme Inhibitors toxicity, Humans, Inhibitory Concentration 50, Reproducibility of Results, Anti-Bacterial Agents pharmacology, Aspartate-Semialdehyde Dehydrogenase antagonists & inhibitors, Enzyme Inhibitors pharmacology, Microbial Sensitivity Tests methods
- Abstract
The rise in organisms resistant to existing drugs has added urgency to the search for new antimicrobial agents. Aspartate β-semialdehyde dehydrogenase (ASADH) catalyzes a critical step in an essential microbial pathway that is absent in mammals. Our laboratory is using fragment library screening to identify efficient and selective ASADH inhibitors. These preliminary agents are then tested to identify compounds with desired antimicrobial properties for further refinement. Toward this end, we have established a microplate-based, dual-assay approach using a single reagent to evaluate antibiotic activity and mammalian cell toxicity during early stage development. The bacterial assay uses nonpathogenic bacteria to allow efficacy testing without a dedicated microbial laboratory. Toxicity assays are performed with a panel of mammalian cells derived from representative susceptible tissues. These assays can be adapted to target other microbial systems, such as fungi and biofilms, and additional mammalian cell lines can be added as needed. Application of this screening approach to antibiotic standards demonstrates the ability of these assays to identify bacterial selectivity and potential toxicity issues. Tests with selected agents from the ASADH inhibitor fragment library show some compounds with antibiotic activity, but as expected, most of these early agents display higher than desired mammalian cell toxicity.
- Published
- 2012
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14. On the interaction of aliphatic amines and ammonium ions with carboxylic acids in solution and in receptor pockets.
- Author
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Nagy PI and Erhardt PW
- Subjects
- Acetates chemistry, Hydrogen Bonding, Monte Carlo Method, Solutions, Solvents chemistry, Surface Properties, Thermodynamics, Water chemistry, Amines chemistry, Carboxylic Acids chemistry, Quaternary Ammonium Compounds chemistry
- Abstract
Association energies of the acetate ion with cationic amines bearing one to three methyl groups were calculated in the range of -14 to -17 kcal/mol in aqueous solution by means of the IEF-PCM method at the CCSD(T)/CBS//MP2/aug-cc-pvdz and DFT/B97D/CBS//B97D/aug-cc-pvtz levels. The main stabilization factor for the association is the possibility for the formation of an ionic intermolecular hydrogen bond between the elements of the complex. For a quaternary ammonium ion, the favorable electrostatic interaction energy is the only driving force, and the stabilization energy for the complex is reduced to -4 kcal/mol. The internal free energies of the ion-pair tautomers of the studied species are higher by 10-15 kcal/mol in water than those for the neutral, hydrogen-bonded forms. Monte Carlo free energy perturbation calculations at T = 298 K and p = 1 atm predict -11 to -16 kcal/mol relative solvation free energy in favor of the corresponding ionic form. As a result, the ion-pair tautomer is the prevailing form in aqueous solution and on the extracellular surface of a receptor. Modeling the complex of a protonated ligand interacting with an Asp/Glu carboxylate side-chain in the binding cavity of a receptor, two strongly bound water molecules were considered so as to form hydrogen-bonded water bridges between the elements of the ion-pair. Nonetheless, the low polarity environment mimicked by a chloroform solvent cannot stabilize the ionic tautomer. A proton jump was predicted, which suggests that acetylcholine, an inherent cation by structure, might have evolved as the natural agonist for muscarinic receptors because a quaternary ammonium system assures the maintenance of the ion-pair form with a carboxylate side-chain in a protein cavity, the latter perhaps then being needed for receptor activation.
- Published
- 2012
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15. Molecular docking and enzymatic evaluation to identify selective inhibitors of aspartate semialdehyde dehydrogenase.
- Author
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Luniwal A, Wang L, Pavlovsky A, Erhardt PW, and Viola RE
- Subjects
- Aspartate-Semialdehyde Dehydrogenase metabolism, Binding Sites, Enzyme Inhibitors chemical synthesis, Kinetics, Molecular Dynamics Simulation, Protein Structure, Tertiary, Streptococcus pneumoniae enzymology, Vibrio cholerae enzymology, Aspartate-Semialdehyde Dehydrogenase antagonists & inhibitors, Enzyme Inhibitors chemistry
- Abstract
Microbes that have gained resistance against antibiotics pose a major emerging threat to human health. New targets must be identified that will guide the development of new classes of antibiotics. The selective inhibition of key microbial enzymes that are responsible for the biosynthesis of essential metabolites can be an effective way to counter this growing threat. Aspartate semialdehyde dehydrogenases (ASADHs) produce an early branch point metabolite in a microbial biosynthetic pathway for essential amino acids and for quorum sensing molecules. In this study, molecular modeling and docking studies were performed to achieve two key objectives that are important for the identification of new selective inhibitors of ASADH. First, virtual screening of a small library of compounds was used to identify new core structures that could serve as potential inhibitors of the ASADHs. Compounds have been identified from diverse chemical classes that are predicted to bind to ASADH with high affinity. Next, molecular docking studies were used to prioritize analogs within each class for synthesis and testing against representative bacterial forms of ASADH from Streptococcus pneumoniae and Vibrio cholerae. These studies have led to new micromolar inhibitors of ASADH, demonstrating the utility of this molecular modeling and docking approach for the identification of new classes of potential enzyme inhibitors., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2012
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16. Synthesis and evaluation of indole-based chalcones as inducers of methuosis, a novel type of nonapoptotic cell death.
- Author
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Robinson MW, Overmeyer JH, Young AM, Erhardt PW, and Maltese WA
- Subjects
- Antineoplastic Agents chemistry, Antineoplastic Agents pharmacology, Azides chemistry, Azides pharmacology, Cell Death drug effects, Cell Line, Tumor, Cell Survival drug effects, Chalcones chemistry, Chalcones pharmacology, Drug Resistance, Neoplasm, Drug Screening Assays, Antitumor, Humans, Indoles chemistry, Indoles pharmacology, Photoaffinity Labels chemical synthesis, Photoaffinity Labels chemistry, Pyridines chemistry, Pyridines pharmacology, Structure-Activity Relationship, Antineoplastic Agents chemical synthesis, Azides chemical synthesis, Chalcones chemical synthesis, Indoles chemical synthesis, Pyridines chemical synthesis
- Abstract
Methuosis is a novel caspase-independent form of cell death in which massive accumulation of vacuoles derived from macropinosomes ultimately causes cells to detach from the substratum and rupture. We recently described a chalcone-like compound, 3-(2-methyl-1H-indol-3-yl)-1-(4-pyridinyl)-2-propen-1-one (i.e., MIPP), which can induce methuosis in glioblastoma and other types of cancer cells. Herein, we describe the synthesis and structure-activity relationships of a directed library of related compounds, providing insights into the contributions of the two aryl ring systems and highlighting a potent derivative, 3-(5-methoxy, 2-methyl-1H-indol-3-yl)-1-(4-pyridinyl)-2-propen-1-one (i.e., MOMIPP) that can induce methuosis at low micromolar concentrations. We have also generated biologically active azide derivatives that may be useful for future studies aimed at identifying the protein targets of MOMIPP by photoaffinity labeling techniques. The potential significance of these studies is underscored by the finding that MOMIPP effectively reduces the growth and viability of Temozolomide-resistant glioblastoma and doxorubicin-resistant breast cancer cells. Thus, it may serve as a prototype for drugs that could be used to trigger death by methuosis in cancers that are resistant to conventional forms of cell death (e.g., apoptosis).
- Published
- 2012
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17. Hypoxia activated prodrugs of a 9-aza-anthrapyrazole derivative that has promising anticancer activity.
- Author
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El-Dakdouki MH, Adamski N, Foster L, Hacker MP, and Erhardt PW
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- Anthraquinones chemistry, Anthraquinones pharmacology, Antineoplastic Agents chemistry, Antineoplastic Agents pharmacology, Aza Compounds chemistry, Aza Compounds pharmacology, Cell Hypoxia, Cell Line, Tumor, Drug Screening Assays, Antitumor, Free Radicals metabolism, Humans, Prodrugs chemistry, Prodrugs pharmacology, Pyrazoles chemistry, Pyrazoles pharmacology, Structure-Activity Relationship, Anthraquinones chemical synthesis, Antineoplastic Agents chemical synthesis, Aza Compounds chemical synthesis, Prodrugs chemical synthesis, Pyrazoles chemical synthesis
- Abstract
Mono- and bis-N-oxides of a 9-aza-anthrapyrazole derivative having two 2-(dimethylamino)ethyl appendages were prepared by using a mild oxaziridine reagent. Biochemical and cell culture assays indicate that the bis-oxide is an inactive prodrug that readily converts to the active parent molecule under hypoxic conditions that are analogous to those present within certain tumors.
- Published
- 2011
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18. Syntheses of 2,3-diarylated 2H-benzo[e][1,2]thiazine 1,1-dioxides and their 3,4-dihydro derivatives, and assessment of their inhibitory activity against MCF-7 breast cancer cells.
- Author
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Shan YY, Zhang CM, Tang LQ, Liu ZP, Bearss NR, Sarver JG, Luniwal A, and Erhardt PW
- Subjects
- Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Cell Line, Tumor, Cell Proliferation drug effects, Dose-Response Relationship, Drug, Drug Screening Assays, Antitumor, Humans, Models, Molecular, Structure-Activity Relationship, Thiazines chemical synthesis, Thiazines chemistry, Antineoplastic Agents pharmacology, Breast Neoplasms pathology, Thiazines pharmacology
- Abstract
A practical synthesis of 2,3-diarylated 2H-benzo[e][1,2]thiazine 1,1-dioxides and their 3,4-dihydro derivatives was developed. ortho-Methyl lithiation of N-aryl-o-toluenesulfonamide followed by reaction with aryl aldehydes gave carbinol sulfonamides, which were either converted directly, or first oxidized to their ketones and converted, to 2,3-diarylated six-membered benzosultams via a TMSCl-NaI-MeCN mediated cyclization. A library of benzosultams was synthesized and evaluated for inhibitory activity against MCF-7 cells. Compound 3 in the 3,4-dihydro (saturated) series and compound 8 in the unsaturated series exhibited the highest potencies with growth inhibition (GI50) values of 0.8 and 18.0 μM, respectively. Molecular modeling studies suggest that these compounds can associate with the colchicine binding site on microtubules. However, experimental assessments of that and other mechanistic possibilities are still ongoing.
- Published
- 2011
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19. Biomimetic syntheses and antiproliferative activities of racemic, natural (-), and unnnatural (+) glyceollin I.
- Author
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Khupse RS, Sarver JG, Trendel JA, Bearss NR, Reese MD, Wiese TE, Boue SM, Burow ME, Cleveland TE, Bhatnagar D, and Erhardt PW
- Subjects
- Breast Neoplasms drug therapy, Cell Line, Tumor, Cell Proliferation, Chromatography, High Pressure Liquid methods, Drug Screening Assays, Antitumor methods, Female, Humans, Magnetic Resonance Spectroscopy methods, Male, Models, Chemical, Ovarian Neoplasms drug therapy, Prostatic Neoplasms drug therapy, Receptors, Estrogen metabolism, Stereoisomerism, Antineoplastic Agents pharmacology, Biomimetics, Pterocarpans chemistry
- Abstract
A 14-step biomimetic synthetic route to glyceollin I (1.5% overall yield) was developed and deployed to produce the natural enantiomeric form in soy, its unnatural stereoisomer, and a racemic mixture. Enantiomeric excess was assessed by asymmetric NMR shift reagents and chiral HPLC. Antiproliferative effects were measured in human breast, ovarian, and prostate cancer cell lines, with all three chiral forms exhibiting growth inhibition (GI) in the low to mid μM range for all cells. The natural enantiomer, and in some cases the racemate, gave significantly greater GI than the unnatural stereoisomer for estrogen receptor positive (ER(+)) versus ER(-) breast/ovarian cell lines as well as for androgen receptor positive (AR(+)) versus AR(-) prostate cancer cells. Surprisingly, differences between ER(+) and ER(-) cell lines were not altered by media estrogen conditions. These results suggest the antiproliferative mechanism of glyceollin I stereoisomers may be more complicated than strictly ER interactions.
- Published
- 2011
- Full Text
- View/download PDF
20. Theoretical studies of salt-bridge formation by amino acid side chains in low and medium polarity environments.
- Author
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Nagy PI and Erhardt PW
- Subjects
- Acetic Acid chemistry, Algorithms, Formates chemistry, Guanidine chemistry, Hydrophobic and Hydrophilic Interactions, Methylamines chemistry, Molecular Structure, Amino Acids chemistry, Models, Theoretical, Protons
- Abstract
Salt-bridge formation between Asp/Glu···Lys and Asp/Glu···Arg side chains has been studied by model systems including formic and acetic acids as proton donors and methylamine, guanidine, and methylguanidine as proton acceptors. Calculations have been performed up to the CCSD(T)(CBS)//MP2/aug-cc-pvtz level with formic acid proton donors. Complexes formed with acetic acid were studied at the CCSD(T)/aug-cc-pvdz//MP2/aug-cc-pvdz level. Protein environments of low and moderate polarity were mimicked by a continuum solvent with dielectric constants (ε) set to 5 and 15, respectively. Free energy differences, ΔG(tot), were calculated for the neutral, hydrogen-bonded form and for the tautomeric ion pair. These values predict that a salt bridge is not favored for the Asp/Glu···Lys pair, even in an environment with ε as large as 15. In contrast, the Asp/Glu···Arg salt bridge is feasible even in an environment with ε = 5. Charge transfers for the complexes were calculated on the basis of CHELPG and AIM charges.
- Published
- 2010
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21. Determination of esmolol and metabolite enantiomers within human plasma using chiral column chromatography.
- Author
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Fang L, Bykowski-Jurkiewicz C, Sarver JG, and Erhardt PW
- Subjects
- Adrenergic beta-1 Receptor Antagonists chemistry, Adrenergic beta-1 Receptor Antagonists pharmacokinetics, Humans, Linear Models, Propanolamines chemistry, Propanolamines pharmacokinetics, Reproducibility of Results, Sensitivity and Specificity, Stereoisomerism, Adrenergic beta-1 Receptor Antagonists blood, Chromatography, High Pressure Liquid methods, Propanolamines blood
- Abstract
A high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed for the simultaneous determination of each of esmolol's enantiomers at the 25-1000 ng/ml concentrations observed in human plasma upon intravenous administration of this rapidly metabolized beta-adrenergic receptor blocking agent. Alternatively, a high performance liquid chromatography (HPLC) UV detection method has been developed for the simultaneous determination of each of the enantiomers for esmolol's metabolite which, in turn, achieve 2.5-50 microg/ml concentrations in human plasma. Utilizing chiral columns, these methods do not require a precolumn asymmetric derivatization step. Linearity in all cases was >0.99. Precision and accuracy at all but the lowest concentrations were within +/-6% for the esmolol enantiomers and within +/-2.5% for the esmolol metabolite enantiomers. These values should be suitable for performing thorough pharmacokinetic studies for all of the stereoisomers of this prototypical soft drug and its corresponding metabolite., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)
- Published
- 2010
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22. Total syntheses of racemic and natural glycinol.
- Author
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Luniwal A, Khupse RS, Reese M, Fang L, and Erhardt PW
- Subjects
- Molecular Structure, Stereoisomerism, Biological Products chemical synthesis, Biological Products chemistry, Flavonols chemical synthesis, Flavonols chemistry
- Abstract
Total syntheses of racemic and (-)-glycinol (1) are described. A Wittig reaction produced the isoflav-3-ene from which a Sharpless dihydroxylation introduced either the racemic or enantiomeric 6a-hydroxy group. A 5.5% overall yield of racemic material was obtained after 12 steps. A method was devised for a one-pot switch of protecting groups masking a sensitive resorcinolic para-functionality, and conditions were optimized to prompt spontaneous closure of the pterocarpanolic dihydrofuran upon subsequent exposure of its ortho-functionality. These improvements eliminated two steps and increased the overall yield to 9.8% during production of the natural enantiomer.
- Published
- 2009
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23. Total syntheses of racemic, natural (-) and unnatural (+) glyceollin I.
- Author
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Khupse RS and Erhardt PW
- Subjects
- Biological Products chemistry, Molecular Structure, Pterocarpans chemistry, Stereoisomerism, Biological Products chemical synthesis, Pterocarpans chemical synthesis
- Abstract
The first total syntheses of racemic glyceollin I and its enantiomers are described. A Wittig approach was utilized as an entry to the appropriately substituted isoflav-3-ene so that an osmium tetroxide mediated asymmetric dihydroxylation could be deployed for stereospecific introduction of the 6a-hydroxy group. While using triphenylphosphine hydrobromide, a novel method was found for gently removing MOM from protected phenolic hydroxyl groups present within sensitive systems.
- Published
- 2008
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- View/download PDF
24. Catalytically active peptidylglycine alpha-amidating monooxygenase in the media of androgen-independent prostate cancer cell lines.
- Author
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Trendel JA, Ellis N, Sarver JG, Klis WA, Dhananjeyan M, Bykowski CA, Reese MD, and Erhardt PW
- Subjects
- Animals, Cell Line, Tumor, Disulfiram metabolism, Dopamine metabolism, Enzyme Inhibitors metabolism, Humans, Male, Culture Media chemistry, Mixed Function Oxygenases metabolism, Multienzyme Complexes metabolism, Prostatic Neoplasms enzymology
- Abstract
Peptidylglycine alpha-amidating monooxygenase (PAM) converts inactive terminal-glycine prohormones into their activated alpha-amidated forms. PAM is thought to play a role in the development of antiandrogen drug resistance in prostate cancer (CaP) through PAMactivated autocrine growth. On the basis of the previous finding that many lung cancer cell lines excrete PAM into their culture media, this study investigates PAM levels in media collected from human CaP cell line cultures. Androgen-independent DU145 and PC-3 prostate cancer cell lines exhibited readily detectable levels of PAM activity in extracts and media, whereas the androgen-dependent LNCaP cell line showed little or no activity. Because of the much larger volume of media versus cell extracts, more than 90% of the total PAM activity was located in the media for both the PC-3 and DU145 cell lines, providing a readily accessible source of CaP PAM. A simple, scalable method to obtain PAM from the culture media of androgen-independent human prostate cancer cell lines is described in this article. This approach provides a much easier means of collecting CaP-derived PAM than previously described cell fractionation procedures and should facilitate the investigations of the role and targeting of PAM in hormone-independent CaP.
- Published
- 2008
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- View/download PDF
25. Rapid and sensitive HPLC assay for simultaneous determination of procaine and para-aminobenzoic acid from human and rat liver tissue extracts.
- Author
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Dhananjeyan MR, Trendel JA, Bykowski C, Sarver JG, Ando H, and Erhardt PW
- Subjects
- Animals, Humans, Rats, Sensitivity and Specificity, 4-Aminobenzoic Acid analysis, Chromatography, High Pressure Liquid methods, Liver chemistry, Procaine analysis
- Abstract
A sensitive and rapid high-performance liquid chromatography method has been developed for simultaneous determination of procaine and its metabolite p-aminobenzoic acid (PABA) from human and rat liver tissue extracts. The method has been validated according to ICH guidelines in terms of selectivity, linearity, lower limit of detection, lower limit of quantitation, accuracy, precision and recovery from human and rat liver tissue extracts. Chromatography was carried out on a Discovery C(18) column using 10mM ammonium acetate at pH 4.0 and acetonitrile as mobile phase. Retention times for procaine and PABA were 6.6 and 5.3 min, respectively. Linearity for each calibration curve in both tissue extracts was observed across a range from 10 microM to 750 microM for procaine and PABA. The lower limit of detection for both procaine and PABA was 5 microM and the lower limit of quantitation was 10 microM in both tissue extracts. The intra- and inter-day relative standard deviations (R.S.D.) for both procaine and PABA were <6%. Recoveries of procaine and PABA from human and rat liver tissue extracts were determined by two different methods with a single-step protein precipitation technique being employed in both methods. Recoveries for both procaine and PABA were greater than 80% from both human and rat liver tissue extracts.
- Published
- 2008
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- View/download PDF
26. Ab initio study of hydrogen-bond formation between aliphatic and phenolic hydroxy groups and selected amino acid side chains.
- Author
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Nagy PI and Erhardt PW
- Subjects
- 2-Propanol chemistry, Gases chemistry, Hydrogen Bonding, Molecular Conformation, Quantum Theory, Thermodynamics, Amino Acids chemistry, Phenol chemistry
- Abstract
Hydrogen bonding was studied in 24 pairs of isopropyl alcohol and phenol as one partner, and water and amino-acid mimics (methanol, acetamide, neutral and protonated imidazole, protonated methylalamine, methyl-guanidium cation, and acetate anion) as the other partner. MP2/6-31+G* and MP2/aug-cc-pvtz calculations were conducted in the gas phase and in a model continuum dielectric environment with dielectric constant of 15.0. Structures were optimized in the gas phase with both basis sets, and zero-point energies were calculated at the MP2/6-31+G* level. At the MP2/aug-cc-pvtz level, the BSSE values from the Boys-Bernardi counterpoise calculations amount to 10-20 and 5-10% of the uncorrected binding energies of the neutral and ionic complexes, respectively. The geometry distortion energy upon hydrogen-bond formation is up to 2 kcal/mol, with the exception of the most strongly bound complexes. The BSSE-corrected MP2/aug-cc-pvtz binding energy of -27.56 kcal/mol for the gas-phase acetate...phenol system has been classified as a short and strong hydrogen bond (SSHB). The CH3NH3+...isopropyl alcohol complex with binding energy of -22.54 kcal/mol approaches this classification. The complete basis set limit (CBS) for the binding energy was calculated for twelve and six complexes on the basis of standard and counterpoise-corrected geometry optimizations, respectively. The X...Y distances of the X-H...Y bridges differ by up to 0.03 A as calculated by the two methods, whereas the corresponding CBS energy values differ by up to 0.03 kcal/mol. Uncorrected MP2/aug-cc-pvtz hydrogen-bonding energies are more negative by up to 0.35 kcal/mol than the MP2/CBS values, and overestimate the CCSD(T)/CBS binding energies generally by up to 5% for the eight studied complexes in the gas phase. The uncorrected MP2/aug-cc-pvtz binding energies decreased (in absolute value) by 11-18 kcal/mol for the ionic species and by up to 5 kcal/mol for the neutral complexes when the electrostatic effect of a polarizable model environment was considered. The DeltaECCSD(T) - DeltaEMP2 corrections still remained close to their gas-phase values for four complexes with 0, +/-1 net charges. Good correlations (R2 = 0.918-0.958) for the in-environment MP2/aug-cc-pvtz and MP2/6-31+G* hydrogen-bonding energies facilitate the high-level prediction of these energies on the basis of relatively simple MP2/6-31+G* calculations.
- Published
- 2008
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27. Practical synthesis of lespedezol A1.
- Author
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Khupse RS and Erhardt PW
- Subjects
- Benzopyrans chemistry, Heterocyclic Compounds, 4 or More Rings chemistry, Lespedeza chemistry, Molecular Structure, Plants, Medicinal chemistry, Benzopyrans chemical synthesis, Chalcones chemistry, Heterocyclic Compounds, 4 or More Rings chemical synthesis
- Abstract
A practical formal synthesis of lespedezol A 1 ( 1) was accomplished in 33% yield for four steps starting from formation of the substituted chalcone. Of particular note is a useful protocol for reduction of the 2-ene bond in the isoflavone intermediate. A significant improvement in the final ring closure when water was scavenged from the reaction is also noteworthy. The ready availability of lespedezol A 1 will provide material for further pharmacological evaluation and for exploration of the pterocarpene nucleus as a potential entry into various 6a-hydroxypterocarpans.
- Published
- 2008
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- View/download PDF
28. Total synthesis of xanthohumol.
- Author
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Khupse RS and Erhardt PW
- Subjects
- Cyclization, Flavonoids, Humulus chemistry, Molecular Structure, Plants, Medicinal chemistry, Propiophenones chemistry, Flavones chemistry, Propiophenones chemical synthesis
- Abstract
The total synthesis of xanthohumol (1) was accomplished in 10% overall yield from phloracetophenone after six steps. Insertion of a prenyl group onto the aryl ring was achieved by a para-Claisen rearrangement after using a Mitsunobu reaction to establish the key prenyl ether precursor. A Claisen-Schmidt condensation was deployed to construct the chalcone scaffold followed by removal of MOM protecting groups under acidic conditions that were optimized to prevent concomitant cyclization to the flavone.
- Published
- 2007
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- View/download PDF
29. Simultaneous determination of procaine and para-aminobenzoic acid by LC-MS/MS method.
- Author
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Dhananjeyan MR, Bykowski C, Trendel JA, Sarver JG, Ando H, and Erhardt PW
- Subjects
- 4-Aminobenzoic Acid chemistry, Molecular Structure, Procaine chemistry, Reproducibility of Results, 4-Aminobenzoic Acid analysis, Chromatography, High Pressure Liquid methods, Procaine analysis, Tandem Mass Spectrometry methods
- Abstract
A sensitive high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for simultaneous determination of procaine and its metabolite p-aminobenzoic acid (PABA). N-Acetylprocainamide (NAPA) was used as an internal standard for procaine and PABA analysis. This assay method has also been validated in terms of linearity, lower limit of detection, lower limit of quantitation, accuracy and precision as per ICH guidelines. Chromatography was carried out on an XTerra MS C(18) column and mass spectrometric analysis was performed using a Quattro Micro mass spectrometer working with electro-spray ionization (ESI) source in the positive ion mode. Enhanced selectivity was achieved using multiple reaction monitoring (MRM) functions, m/z 237-->100, m/z 138-->120, and m/z 278-->205 for procaine, PABA and NAPA, respectively. Retention times for PABA, procaine and NAPA were 4.0, 4.7 and 5.8min, respectively. Linearity for each calibration curve was observed across a range from 100nM to 5000nM for PABA, and from 10nM to 5000nM for procaine. The intra- and inter-day relative standard deviations (RSD) were <5%.
- Published
- 2007
- Full Text
- View/download PDF
30. Rapid and simultaneous determination of capecitabine and its metabolites in mouse plasma, mouse serum, and in rabbit bile by high-performance liquid chromatography.
- Author
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Dhananjeyan MR, Liu J, Bykowski C, Trendel JA, Sarver JG, Ando H, and Erhardt PW
- Subjects
- Animals, Calibration, Capecitabine, Deoxycytidine analysis, Deoxycytidine blood, Deoxycytidine metabolism, Floxuridine analysis, Floxuridine blood, Fluorouracil analysis, Fluorouracil blood, Fluorouracil metabolism, Mice, Rabbits, Reproducibility of Results, Bile chemistry, Chromatography, High Pressure Liquid methods, Deoxycytidine analogs & derivatives, Fluorouracil analogs & derivatives, Plasma chemistry, Serum chemistry
- Abstract
A rapid high-performance liquid chromatography method has been developed for simultaneous determination of capecitabine and its metabolites: 5'-deoxy-5-fluorocytidine (5'-DFCR), 5'-deoxy-5-fluorouridine (5'-DFUR) and 5-fluorouracil (5-FU). 5'-DFCR was synthesized by hydrolyzing capecitabine using commercially available carboxyl esterase (CES) and characterized by NMR, mass spectrometry and elemental analysis. Base-line separations between capecitabine, 5'-DFCR, 5'-DFUR and 5-FU were found with symmetrical peak shapes on a Discovery RP-amide C16 column using 10 mM ammonium acetate at pH 4.0 and methanol as the mobile phase. The retention times of capecitabine, 5'-DFCR, 5'-DFUR and 5-FU were 8.9, 5.0, 5.3 and 3.0 min, respectively. Linear calibration curves were obtained for each compound across a range from 1 to 500 microg ml(-1). The intra- and inter-day relative standard deviations (%RSD) were <5%. A single-step protein precipitation method was employed for separation of the analytes from bio-matrices. Greater than 85% recoveries were obtained for capecitabine, 5'-DFCR, 5'-DFUR and 5-FU from bio-fluids including mouse plasma, mouse serum and rabbit bile.
- Published
- 2007
- Full Text
- View/download PDF
31. Ab initio study of hydrogen-bond formation between cyclic ethers and selected amino acid side chains.
- Author
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Nagy PI and Erhardt PW
- Subjects
- Algorithms, Amino Acids metabolism, Ethers, Cyclic metabolism, Hydrogen Bonding, Imidazoles chemistry, Models, Molecular, Molecular Structure, Thermodynamics, Amino Acids chemistry, Ethers, Cyclic chemistry
- Abstract
Binding energies for hydrogen-bonded complexes of six cyclic ethers with five hydrogen-bond donor molecules that mimic selected amino acid side chains have been calculated at the MP2/6-31G*, MP2/6-31+G*, MP2/6-311++G**(single point), and MP2/aug-cc-pvtz levels, using geometries obtained with or without counterpoise corrections throughout the geometry optimization. The calculated basis set superposition error (BSSE) amounts to 10-20% and 5-10% of the uncorrected binding energies for the neutral and ionic species, respectively, at the MP2/aug-cc-pvtz level. The authors conclude that the O...H distances in the hydrogen bonds and binding energies for the studied systems may be determined with uncertainties of up to 0.08 A and 1-2 kcal/mol, respectively, in comparison with the MP2/aug-cc-pvtz values at a reasonable computational cost by performing standard geometry optimization at the MP2/6-31+G* level. Hydrogen-bond formation energies are more negative for cyclic ethers compared to their counterparts with a C=C double bond in the ring next to the oxygen atom. The less negative hydrogen-bonding energy and the increased O...H separation have been attributed to the reduced basicity of the ether oxygen when the lone pairs can enter conjugation with the pi-electrons of the Calpha=Cbeta double bond. The present study is the first step toward the development of an affordable computational level for estimating the binding energies of natural product, fused ring ether systems to the human estrogen receptor.
- Published
- 2006
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32. Antiestrogenic glyceollins suppress human breast and ovarian carcinoma tumorigenesis.
- Author
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Salvo VA, Boué SM, Fonseca JP, Elliott S, Corbitt C, Collins-Burow BM, Curiel TJ, Srivastav SK, Shih BY, Carter-Wientjes C, Wood CE, Erhardt PW, Beckman BS, McLachlan JA, Cleveland TE, and Burow ME
- Subjects
- Animals, Benzopyrans chemistry, Benzopyrans pharmacology, Breast Neoplasms pathology, Cell Line, Tumor, Cell Proliferation drug effects, Disease Models, Animal, Estradiol administration & dosage, Estrogen Receptor Modulators chemistry, Estrogen Receptor Modulators pharmacology, Female, Humans, Mice, Mice, Nude, Ovarian Neoplasms pathology, Predictive Value of Tests, Pterocarpans, Receptors, Progesterone biosynthesis, Receptors, Progesterone drug effects, Structure-Activity Relationship, Transplantation, Heterologous, Uterus drug effects, Uterus pathology, Xenograft Model Antitumor Assays, Benzopyrans administration & dosage, Breast Neoplasms drug therapy, Estrogen Receptor Modulators administration & dosage, Ovarian Neoplasms drug therapy
- Abstract
Purpose: We have identified the phytoalexin compounds glyceollins I, II, and III, which exhibit marked antiestrogenic effects on estrogen receptor function and estrogen-dependent tumor growth in vivo. The purpose of this study was to investigate the interactions among the induced soy phytoalexins glyceollins I, II, and III on the growth of estrogen-dependent MCF-7 breast cancer and BG-1 ovarian cancer cells implanted in ovariectomized athymic mice., Experimental Design: Four treatment groups for each cell line were used: vehicle control, 20 mg/kg/mouse/d glyceollin mixture injection, 0.72 mg estradiol (E2) implant, and E2 implant + 20 mg/kg/mouse/d glyceollin injection., Results: Treatment with glyceollin suppressed E2-stimulated tumor growth of MCF-7 cells (-53.4%) and BG-1 cells (-73.1%) in ovariectomized athymic mice. These tumor-inhibiting effects corresponded with significantly lower E2-induced progesterone receptor expression in the tumors. In contrast to tamoxifen, the glyceollins had no estrogen-agonist effects on uterine morphology and partially antagonized the uterotropic effects of estrogen., Conclusions: These findings identify glyceollins as antiestrogenic agents that may be useful in the prevention or treatment of breast and ovarian carcinoma.
- Published
- 2006
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- View/download PDF
33. Simultaneous determination of vinclozolin and detection of its degradation products in mouse plasma, serum and urine, and from rabbit bile, by high-performance liquid chromatography.
- Author
-
Dhananjeyan MR, Erhardt PW, and Corbitt C
- Subjects
- Animals, Mass Spectrometry methods, Mice, Rabbits, Reproducibility of Results, Sensitivity and Specificity, Spectrophotometry, Ultraviolet, Bile chemistry, Chromatography, High Pressure Liquid methods, Oxazoles analysis, Oxazoles metabolism
- Abstract
A specific high-performance liquid chromatography method has been developed for simultaneous detection of vinclozolin and its degradation products (M1, M2, and M3). The method has been validated according to ICH guidelines and can be extended to quantitation of vinclozolin. A base-line separation of vinclozolin and its degradation products was found with symmetrical peak shapes on an XTerra MS C18 column using 10 mM ammonium bicarbonate at pH 9.2 and acetonitrile as mobile phase. The retention times of vinclozolin, M1, M2, and M3 were 12.8, 8.1, 11.6, and 11.1 min, respectively. A linear calibration curve was obtained across a range from 5 to 200 microM for vinclozolin. The intra- and inter-day relative standard deviations (%RSD) were <1%. Greater than 90% recoveries of vinclozolin from bio-fluids including mouse plasma, serum and urine, and rabbit bile, were obtained in a single step with a single solvent.
- Published
- 2006
- Full Text
- View/download PDF
34. Monte Carlo simulations of the solution structure of simple alcohols in water-acetonitrile mixtures.
- Author
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Nagy PI and Erhardt PW
- Subjects
- Electrochemistry, Hydrogen Bonding, Molecular Structure, Solvents chemistry, Acetonitriles chemistry, Alcohols chemistry, Computer Simulation, Monte Carlo Method, Solutions chemistry, Water chemistry
- Abstract
Monte Carlo simulations have been performed to explore the solution structure of ethyl, isopropyl, isobutyl, and tertiary butyl alcohols in pure water, pure acetonitrile, and different mixtures of the two solvents. The explicit solvent studies in NpT ensembles at T = 298 K illustrate that the solute "discriminates" the solvent's components and that the composition of the first solvation shell differs from that of the bulk solution. Since the polarizable continuum dielectric method (PCM) does not presently model the solvation of molecules with both polar and apolar sites in mixed protic solvents, we suggest a direction for further program development wherein a continuum dielectric method would accept more than one solvent and the solute sites would be solvated by user-defined solvent components. The prevailing solvation model will be determined upon the lowest free energy calculated for a particular solvation pattern of the solute having a specific conformational/tautomeric state. Characterization of equilibrium hydrogen-bond formation becomes a complicated problem that depends on the chemical properties of the solute and its conformation, as well as upon the varying nature of the first solvation shell. For example, while the number of hydrogen bonds to secondary and tertiary alcohol solutes are nearly constant in pure water and in water-acetonitrile mixtures with at least 50% water content, the number of hydrogen bonds to primary alcohols gradually decreases for most of their conformations when acetonitrile content is increased. Nonetheless, the calculations indicate that O-H...O(water) hydrogen bonds are still possible in a small fraction of the arrangements for the solution models with water content of 30% or less. The isopentene solute does not form any observable hydrogen bonds, despite having an electron-rich, double-bond site.
- Published
- 2005
- Full Text
- View/download PDF
35. A human drug metabolism database: potential roles in the quantitative predictions of drug metabolism and metabolism-related drug-drug interactions.
- Author
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Erhardt PW
- Subjects
- Humans, Pharmacokinetics, Predictive Value of Tests, Structure-Activity Relationship, Xenobiotics metabolism, Databases, Factual, Drug Interactions, Pharmaceutical Preparations metabolism
- Abstract
Previous attempts to predict drug metabolism and drug-drug interaction possibilities by deploying databases that house established drug metabolism results have been only marginally successful. Consideration of some of the key issues and concerns derived from these efforts suggests that three major hurdles loom in front of using xenobiotic metabolism databases more effectively in the future. These hurdles include: the need for an improved treatment of chemical structure in three-dimensions (3D); a better quantitative accounting of competitive and complementary biotransformation pathways; and, the critical need for a comprehensive, human drug metabolism database (hDMdb) that can serve as a bio/chemoinformatic resource pertaining to drug metabolism and drug metabolism-related drug-drug interactions in general. Approaches that might be taken to traverse each of these hurdles are discussed herein where: the first involves maturation of chemical structures from simple 2D entries into more sophisticated 3D displays that can also account for interactions with relevant biological surfaces; the second involves a systematic, pair-wise comparison of various metabolic options in a statistically driven manner relative to chemical structure descriptors; and, the third involves mounting a hDMdb on the Internet in a user-friendly manner that it is available via a non-profit format.
- Published
- 2003
- Full Text
- View/download PDF
36. Microplate screening of the differential effects of test agents on Hoechst 33342, rhodamine 123, and rhodamine 6G accumulation in breast cancer cells that overexpress P-glycoprotein.
- Author
-
Sarver JG, Klis WA, Byers JP, and Erhardt PW
- Subjects
- Adenosine Triphosphate metabolism, Drug Interactions, Drug Resistance, Neoplasm, Female, Humans, Protein Binding, Substrate Specificity, Tumor Cells, Cultured, ATP Binding Cassette Transporter, Subfamily B, Member 1 biosynthesis, Antineoplastic Agents pharmacology, Benzimidazoles pharmacology, Breast Neoplasms diagnosis, Breast Neoplasms metabolism, Fluorescent Dyes pharmacology, Rhodamine 123 pharmacology, Rhodamines pharmacology
- Abstract
A microplate screening method has been developed to evaluate the effects of test agents on the accumulation of the fluorescent P-glycoprotein (Pgp) substrates Hoechst 33342, rhodamine 123, and rhodamine 6G in multidrug-resistant (MDR) breast cancer cells that overexpress Pgp. All three substrates exhibit substantially higher accumulation in MCF7 non-MDR cells versus NCI/ADR-RES MDR cells, while incubation with 50 microM reserpine significantly reduces or eliminates these differences. Rhodamine 123 shows the lowest substrate accumulation efficiency in non-MDR cells relative to the substrate incubation level. The effects of several chemosensitizing agents and a series of paclitaxel analogs on the accumulation of each fluorescent substrate suggest that there are distinct differences in the substrate interaction profiles exhibited by these different agents. The described methods may be useful in Pgp-related research in the areas of cancer MDR, oral drug absorption, the blood-brain barrier, renal/hepatic transport processes, and drug-drug interactions.
- Published
- 2002
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37. Medicinal chemistry in the development of societies. Biodiversity and natural products.
- Author
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Monge A, Chorghade M, Erhardt PW, Ganellin CR, Koga N, Lindberg P, Perun TJ, Topliss JG, Trivedi BK, and Wermuth CG
- Subjects
- Conservation of Natural Resources, Species Specificity, Biological Products, Chemistry, Pharmaceutical, Social Change
- Abstract
This document has been elaborated by the IUPAC Medicinal Chemistry section and is backed by a large number of scientists, many of whom have had direct involvement and whose names appear at the end of the article. This work discusses the role that the discovery of new medicinal agents has in the development of societies as well as in the conservation of biodiversity in terms of work carried out on natural products. Also included are several recommendations for countries which are presently in search of their own scientific and technological development in medicinal agents. The IUPAC Medicinal Chemistry section would appreciate the collaboration of the scientific societies in every country to aid in the diffusion of this document.
- Published
- 2000
- Full Text
- View/download PDF
38. Analysis of extemporaneous alprostadil formulaions.
- Author
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Sarver JG, Peng N, Lerdkanchanaporn S, Oravecz-Wilson KI, Alexander KS, and Erhardt PW
- Abstract
Twenty-two extemporaneous alprostadil (PGE1) injection solutions samples from five different suppliers and three Caverject (Pharmacia and Upjohn, Inc., Bridgewater, NJ) samples from three different lots, all intended for the clinical treatment of erectile dysfunction, were analyzed to determine PGE1 concentration, assess formation of the PGE1 aqueous breakdown product (PGA1), define pH and assess active microbial contamination. High-pressure liquid chromatography (HPLC), pH meter and cell culture techniques were used to conduct the analyses. Of the 22 extemporaneously formulated samples, six showed PGE1 concentrations 10% greater than their listed amounts and seven showed PGA1 weight fractions corresponding to at least 1.5% of the total prostaglandidn content. It should be noted that no standard has been published in the United States Pharmacopeia/National Formulary for this preparation as of this date. All samples were within the pH range 4.5 to 6.0. Four samples tested positive for active microbial contamination. In adition, nearly all the extemporaneously formulated samples contained what appeared to be benzyl alcohol, and about one half had at least two other undefined peaks within their HPLC chromatograms. In contrast, all three Caverject samples were within +/- 7.5% of their listed PGE1 concentrations while showing PGA1 prostaglandins weight fractions of less 0.6%, all were within the pH range 4.0 to 4.5 and all tested negative for active microbial contamination. Chromatograms of the Caverject samples also diplayed peaks consistent with the presence of benzyl alcohol but did not exhibit addtional undefined peaks. The results suggest that significant variations in PGE1 concentration and in PGA1 formation, accompanied by the possibility of microbial contamination, can occur as a result of the extemporaneous formulation and subsequent transfer of this type of product as a premixed solution intended for treating erectile dysfunction.
- Published
- 1999
39. Stability of Magnesium Sulfate in 0.9% Sodium Chloride and Lactated Ringers solutions.
- Author
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Sarver JG, Pryka R, Alexander KS, Weinstein L, and Erhardt PW
- Abstract
Storage stability test were peformed on two extemporaneous formulation alternatives to the commercially available magnesium sulfate injection solutions that are in 5% dextrose or in water. Preparations of the commercial water for injection formulation and two alternative formulations in lactated Ringers and in 0.9% sodium chloride were stored at room temperature in glass bottles and in polyvinyl chloride bags over a three-month period. Solutions were monitored for gross precipitation and for changes in magnesium, sulfur and calcium levels as measured by elemental analysis using atomic absorption spectroscopy and inductively coupled plasma atomic emission spectroscopy. The results demonstrate no consistent decreases in measured elemental concentrations or gross signs of precipitation for any formulation tested.
- Published
- 1998
40. Hydroxamic acids as potent inhibitors of endothelin-converting enzyme from human bronchiolar smooth muscle.
- Author
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Bihovsky R, Levinson BL, Loewi RC, Erhardt PW, and Polokoff MA
- Subjects
- Bronchi cytology, Cells, Cultured, Endothelin-Converting Enzymes, Humans, Hydroxamic Acids chemical synthesis, Hydroxamic Acids chemistry, Muscle, Smooth cytology, Aspartic Acid Endopeptidases antagonists & inhibitors, Bronchi enzymology, Hydroxamic Acids pharmacology, Metalloendopeptidases antagonists & inhibitors, Muscle, Smooth enzymology
- Abstract
Hydroxamic acids 6a-h, derived from malonyl amino acids, and 25a-d, derived from succinyl amino acids, were synthesized as inhibitors of human bronchiolar smooth muscle endothelin-converting enzyme (HBSM ECE). Several unexpected side reactions were discovered, particularly in the synthesis of hydroxamates derived from succinates. In vitro evaluation against human bronchiolar ECE revealed that in all cases hydroxamates derived from malonate were more potent than hydroxamates derived from succinate. Isopropyl and isobutyl P1' side chains were suitable; omission of the P1' side chain seriously diminished potency. In the P2' position, several amino acids gave potent malonate-derived hydroxamate inhibitors (6b, d-h, IC50 = 0.2-6.8 nM), and beta-Ala provided an extremely potent inhibitor (6c, IC50 = 0.01 nM). C-terminus carboxylates are much more potent ECE inhibitors than the corresponding amides. Most of the hydroxamates were also potent inhibitors of thermolysin and neutral endopeptidase (NEP); however, the P2' beta-Ala derivative 6c uniquely inhibited HBSM ECE much more potently than NEP.
- Published
- 1995
- Full Text
- View/download PDF
41. (Imidazolylphenyl)pyrrol-2-one inhibitors of cardiac cAMP phosphodiesterase.
- Author
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Lampe JW, Chou YL, Hanna RG, Di Meo SV, Erhardt PW, Hagedorn AA 3rd, Ingebretsen WR, and Cantor E
- Subjects
- Animals, Brain drug effects, Brain enzymology, Cardiotonic Agents pharmacology, Dogs, Heart drug effects, Hemodynamics drug effects, Imidazoles pharmacology, Myocardium enzymology, Phosphodiesterase Inhibitors pharmacology, Pyrroles pharmacology, Pyrrolidinones pharmacology, Structure-Activity Relationship, 3',5'-Cyclic-AMP Phosphodiesterases antagonists & inhibitors, Cardiotonic Agents chemical synthesis, Imidazoles chemical synthesis, Phosphodiesterase Inhibitors chemical synthesis, Pyrroles chemical synthesis, Pyrrolidinones chemical synthesis
- Abstract
Seven 3-alkyl-4-aryl-1,5-dihydro-2H-pyrrol-2-ones were prepared as potential inhibitors of cardiac cAMP phosphodiesterase (PDE). The design of these compounds made use of rolipram, a known inhibitor of the brain cAMP PDE isozyme, as a lead structure and was guided by a model which describes the features required for potent inhibition of the cardiac isozyme. Syntheses for the new compounds are described, together with the results of theoretical and crystallographic studies aimed toward ascertaining their three-dimensional structures. The activities of these compounds as inhibitors of the cardiac and brain cAMP PDE isozymes and their positive inotropic activity in ferret papillary muscle are also reported. Selected compounds were further examined in an in vivo hemodynamic model. One compound 1,5-dihydro-4-[4-(1H-imidazol-1- yl)phenyl]-3-methyl-2H-pyrrol-2-one, was identified as a potent and selective positive inotropic agent and inhibitor of cardiac cAMP PDE.
- Published
- 1993
- Full Text
- View/download PDF
42. Cardiotonic agents. 7. Prodrug derivatives of 4-ethyl-1,3-dihydro- 5-[4-(2-methyl-1H-imidazol-1-yl)benzoyl]-2H-imidazol-2-one.
- Author
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Shaw KJ, Erhardt PW, Hagedorn AA 3rd, Pease CA, Ingebretsen WR, and Wiggins JR
- Subjects
- Animals, Biological Availability, Cardiotonic Agents pharmacokinetics, Chromatography, High Pressure Liquid, Dogs, Drug Stability, Half-Life, Humans, Hydrogen-Ion Concentration, Imidazoles pharmacokinetics, Imidazoles pharmacology, Molecular Structure, Prodrugs pharmacokinetics, Structure-Activity Relationship, Cardiotonic Agents chemical synthesis, Imidazoles chemistry, Prodrugs chemical synthesis
- Abstract
The cardiotonic agent 4-ethyl-1,3-dihydro-5-4-(2-methyl-1H-imidazol-1-yl)benzoyl]-2H- imidazol-2-one (1) was found to have low bioavailability when administered orally to rats and dogs. A series of N-acyl derivatives, an underutilized prodrug of acidic NH compounds, has been synthesized and tested for their ability to improve the oral bioavailability of 1. Reaction of the monosodium salt of 1 with various anhydrides afforded the N-1 monoacylimidazolones with surprisingly high regioselectivity. In addition to the prodrugs, acylation of 1 with propionic or phenylacetic anhydride led to the novel 3H-pyrrolo[1,2-c]imidazole-3,5(2H)-diones 6. The prodrugs showed a significant increase in the partition coefficients with a minor decrease in the aqueous solubility. The benzoyl derivative 4b exhibited the highest stability in both pH 1.5 and 7.4 buffer solutions. Further evaluation of 4b showed rapid conversion to 1 in canine plasma (t1/2 = 38 min), and human plasma (t1/2 = 10 min). Oral studies indicated that the bioavailability of 4b was increased to greater than 75% (compared to less than 20% for 1), and hemodynamic studies demonstrated that the selective inotropic profile of 1 was retained.
- Published
- 1992
- Full Text
- View/download PDF
43. Novel compounds possessing potent cAMP and cGMP phosphodiesterase inhibitory activity. Synthesis and cardiovascular effects of a series of imidazo[1,2-a]quinoxalinones and imidazo[1,5-a]quinoxalinones and their aza analogues.
- Author
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Davey DD, Erhardt PW, Cantor EH, Greenberg SS, Ingebretsen WR, and Wiggins J
- Subjects
- Animals, Aza Compounds chemistry, Dogs, Heart drug effects, Imidazoles chemistry, In Vitro Techniques, Molecular Structure, Muscle Relaxation drug effects, Muscle, Smooth, Vascular drug effects, Quinoxalines chemistry, 3',5'-Cyclic-AMP Phosphodiesterases antagonists & inhibitors, 3',5'-Cyclic-GMP Phosphodiesterases antagonists & inhibitors, Aza Compounds pharmacology, Cardiotonic Agents, Imidazoles pharmacology, Quinoxalines pharmacology
- Abstract
A series of novel imidazoquinoxalinones and their aza analogues were prepared by the cyclization of o-amino(1H-imidazol-1-yl)aryls and heteroaryls with carbonyldiimidazole. The compounds were screened for inhibition of Type I and Type IV phosphodiesterases (PDE's) and evaluated for their vasorelaxant and positive inotropic activities in vitro. In general, compounds having potent PDE inhibitory activity also possessed good inotropic and vasodilator activity, although linear correlations between these activities could not be established.
- Published
- 1991
- Full Text
- View/download PDF
44. Synthesis and biological activity of angiotensin II analogues containing a Val-His replacement, Val psi[CH(CONH2)NH]His.
- Author
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Mohan R, Chou YL, Bihovsky R, Lumma WC Jr, Erhardt PW, and Shaw KJ
- Subjects
- Adrenal Glands metabolism, Amino Acid Sequence, Angiotensin I antagonists & inhibitors, Angiotensin II antagonists & inhibitors, Angiotensin II metabolism, Angiotensin Receptor Antagonists, Animals, Chemical Phenomena, Chemistry, Physical, Guinea Pigs, Ileum physiology, Molecular Sequence Data, Muscle Contraction drug effects, Oligopeptides chemistry, Oligopeptides pharmacology, Peptide Fragments chemical synthesis, Peptide Fragments pharmacology, Rabbits, Receptors, Angiotensin metabolism, Saralasin analogs & derivatives, Saralasin chemistry, Saralasin pharmacology, 1-Sarcosine-8-Isoleucine Angiotensin II analogs & derivatives, Angiotensin II analogs & derivatives, Dipeptides, Oligopeptides chemical synthesis
- Abstract
The dipeptide mimic Val psi[CH(CONH2)NH]His (4) was incorporated into angiotensin II (AII) analogues to provide an octapeptide saralasin derivative (29) as well as tetrapeptide analogue 19. Three C-terminal tetrapeptides (21, 25, and 28) were also prepared. All compounds were tested for their ability to displace 3H-AII from rabbit adrenal gland homogenate and as antagonists of AII and AI on guinea pig ileum. The octapeptide analogue 29 was 700 times less active than the parent peptide 30. All the C-terminal fragments 19, 21, 25, and 28 have no measurable AII antagonist activity. Of the four tetrapeptide fragments, only 21 showed any appreciable binding activity.
- Published
- 1991
- Full Text
- View/download PDF
45. A topographical model for the c-AMP phosphodiesterase III active site.
- Author
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Erhardt PW and Chou YL
- Subjects
- 3',5'-Cyclic-AMP Phosphodiesterases antagonists & inhibitors, 3',5'-Cyclic-AMP Phosphodiesterases pharmacology, Binding Sites, Isoenzymes antagonists & inhibitors, Isoenzymes pharmacology, Models, Chemical, Protein Conformation, 3',5'-Cyclic-AMP Phosphodiesterases chemistry, Isoenzymes chemistry
- Abstract
With this minireview, concepts about how c-AMP and various inhibitor molecules interact with the phosphodiesterases seem to have come full-circle. It will be proposed and elaborated herein that an understanding of SAR for the newest, "second generation" PDE inhibitors is best accomplished by adopting a model that supposes that these compounds are transition state inhibitors. The analysis finds an interesting parallel with early studies where it was recognized that c-AMP adopts a trigonal bipyramid transition state during hydrolysis. The dynamic interaction of ligands with the phosphodiesterase enzymes will also be made evident when simple algebraic expressions are shown to be inadequate for predicting inhibitor potencies. The latter are apparently complicated by cooperative or synergistic relationships that occur among the various binding sites within the receptor. Finally, implications that can be derived from certain topographical features of the model are discussed relative to a range of potential therapeutic indications.
- Published
- 1991
- Full Text
- View/download PDF
46. Cardiotonic agents. 6. Histamine analogues as potential cardiovascular selective H2 agonists.
- Author
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Lampe JW, Hanna RG, Piscitelli TA, Chou YL, Erhardt PW, Lumma WC Jr, Greenberg SS, Ingebretsen WR, Marshall DC, and Wiggins J
- Subjects
- Animals, Cardiotonic Agents pharmacology, Ferrets, Guinea Pigs, Heart Rate drug effects, In Vitro Techniques, Male, Muscle Contraction drug effects, Myocardial Contraction drug effects, Rats, Cardiotonic Agents chemical synthesis, Drug Design, Gastric Acid metabolism, Histamine analogs & derivatives, Receptors, Histamine H2 drug effects
- Abstract
Twenty-six alkyl and aralkyl histamine analogues were prepared as potential cardiotonic agents. Compounds were designed to allow interaction with a putative secondary aryl binding site at the H2 receptor, the presence of which was inferred from the structure of cyprohepatadine, which is known to have H2-antagonist properties. The compounds were examined for inotropic activity in ferret papillary muscle. Potent inotropic activity was generally found in N-alkyl- and N,N-dialkylimidazole-4-ethanamines, whereas N-(amidoalkyl)imidazole-4-ethanamines and N-alkylimidazole-4-propanamines were at best weakly active. Five compounds were examined in screens designed to assess hemodynamic effects and gastric acid secretion in vivo. Two of these compounds, alpha-(3-phenyl-2-transpropenyl)-1H-imidazole-4-ethanamine and N-heptyl-1H-imidazole-4-ethanamine, showed positive inotropic activity with minimal effects on heart rate and mean arterial pressure in vivo; however, both compounds were found to stimulate gastric acid secretion. These results demonstrate that selectivity between various H2-receptor-mediated activities can be obtained with substituted histamine analogues.
- Published
- 1990
- Full Text
- View/download PDF
47. Ultra-short-acting beta-adrenergic receptor blocking agents. 1. (Aryloxy)propanolamines containing esters in the nitrogen substituent.
- Author
-
Erhardt PW, Woo CM, Gorczynski RJ, and Anderson WG
- Subjects
- Animals, Blood Pressure drug effects, Chemical Phenomena, Chemistry, Dogs, Guinea Pigs, In Vitro Techniques, Muscle, Smooth drug effects, Muscle, Smooth, Vascular drug effects, Propanolamines pharmacology, Structure-Activity Relationship, Time Factors, Adrenergic beta-Antagonists chemical synthesis, Propanolamines chemical synthesis
- Abstract
In an attempt to produce short-acting beta-adrenergic receptor blocking agents, we prepared several (aryloxy)propanolamines with ester functions incorporated into the nitrogen substituent. Many of these compounds exhibited a short duration of blocking activity after their continuous intravenous infusion for 40 min. However, their durations were found to increase considerably upon longer intravenous infusion.
- Published
- 1982
- Full Text
- View/download PDF
48. Metabolism in vitro of potential apomorphine prodrugs.
- Author
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Smith RV, Erhardt PW, Neumeyer JL, and Borgmen RJ
- Subjects
- Animals, Apomorphine metabolism, Hydroxylation, In Vitro Techniques, Male, Microsomes, Liver metabolism, Rats, Apomorphine analogs & derivatives
- Published
- 1976
- Full Text
- View/download PDF
49. Thin-layer chromatography of apomorphine and its analogs.
- Author
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Erhardt PW, Smith RV, Sayther TT, and Keiser JE
- Subjects
- Gels, Indicators and Reagents, Methods, Silicon Dioxide, Solvents, Apomorphine analogs & derivatives, Apomorphine analysis, Chromatography, Thin Layer
- Published
- 1976
- Full Text
- View/download PDF
50. NMR study of amphetamines using europium shift reagents.
- Author
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Smith RV, Erhardt PW, Rusterholz DB, and Barfknecht CF
- Subjects
- Chemical Phenomena, Chemistry, Isomerism, Magnetic Resonance Spectroscopy, Methods, Molecular Conformation, Amphetamines analysis, Europium
- Abstract
Amphetamine and certain of its methoxylated derivatives show a high degree of interaction with NMR shift reagents of the type tris (1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione)europium(III). The shifts are not accompanied by appreciable line broadening, and both the aliphatic and aromatic protons can be resolved. The strong interaction between amine and shift reagent diminishes rapidly as the amine function is alkylated. For derivatives containing ortho-methoxyl groups, a weaker interaction with this functionality also becomes evident as the amine is alkylated. The stereospecificity of the shifting process was investigated by employing tris[3-(trifluoroacetyl)-d-camphorato]europium(III), a chiral shift reagent, with stereochemically pure enantiomers and known enantiomeric mixtures. Although certain (R)-enantiomers showed greater downfield C-methyl groups shifts, these shift differences from the corresponding (S)-enantiomers were small and not well resolved.
- Published
- 1976
- Full Text
- View/download PDF
Catalog
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