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Gonzalez P.M.,University of Santiago de Chile | Lagos C.F.,University of Santiago de Chile | Ward W.C.,Scynexis, Inc. | Polli J.E.,University of Maryland, Baltimore
Molecular Pharmaceutics | Year: 2014

Bile acids (BAs) are the end products of cholesterol metabolism. One of the critical steps in their biosynthesis involves the isomerization of the 3β-hydroxyl (-OH) group on the cholestane ring to the common 3α-configuration on BAs. BAs are actively recaptured from the small intestine by the human Apical Sodium-dependent Bile Acid Transporter (hASBT) with high affinity and capacity. Previous studies have suggested that no particular hydroxyl group on BAs is critical for binding or transport by hASBT, even though 3β-hydroxylated BAs were not examined. The aim of this study was to elucidate the role of the 3α-OH group on BAs binding and translocation by hASBT. Ten 3β-hydroxylated BAs (Iso-bile acids, iBAs) were synthesized, characterized, and subjected to hASBT inhibition and uptake studies. hASBT inhibition and uptake kinetics of iBAs were compared to that of native 3α-OH BAs. Glycine conjugates of native and isomeric BAs were subjected to molecular dynamics simulations to identify topological descriptors related to binding and translocation by hASBT. Iso-BAs bound to hASBT with lower affinity and exhibited reduced translocation than their respective 3α-epimers. Kinetic data suggests that, in contrast to native BAs where hASBT binding is the rate-limiting step, iBAs transport was rate-limited by translocation and not binding. Remarkably, 7-dehydroxylated iBAs were not hASBT substrates, highlighting the critical role of 7-OH group on BA translocation by hASBT, especially for iBAs. Conformational analysis of gly-iBAs and native BAs identified topological features for optimal binding as: concave steroidal nucleus, 3-OH "on-" or below-steroidal plane, 7-OH below-plane, and 12-OH moiety toward-plane. Our results emphasize the relevance of the 3α-OH group on BAs for proper hASBT binding and transport and revealed the critical role of 7-OH group on BA translocation, particularly in the absence of a 3α-OH group. Results have implications for BA prodrug design. © 2013 American Chemical Society.

Lavocat F.,French Institute of Health and Medical Research | Deny P.,French Institute of Health and Medical Research | Deny P.,University of Paris 13 | Pichoud C.,French Institute of Health and Medical Research | And 6 more authors.
Journal of Hepatology | Year: 2013

Background & Aims Adefovir (ADV) resistance mutations induce low-level cross-resistance to tenofovir in vitro. Our aim was to compare viral kinetics, nucleos(t)ide analog resistance mutations, and quasispecies (QS) evolution during therapy with tenofovir disoproxil fumarate (TDF) or emtricitabine + TDF (FTC/TDF) in selected patients with incomplete ADV responses. Methods Patients with chronic hepatitis B and incomplete response to ADV were randomized in a double-blind trial of TDF vs. FTC/TDF. Extensive analysis of QS evolution was performed in 17 patients through 48 weeks of treatment. Results At week 24, 48% of patients (9/17) achieved HBV DNA undetectability (<69 IU/ml) with no difference between treatment groups. ADV and/or LAM resistance mutations were detected in all 17 patients at baseline and in 5/6 analyzable patients at week 48. A total of 1224 reverse transcriptase clones were analyzed. Clonal analysis revealed no significant difference at baseline in QS complexity or diversity between treatment groups. There was a trend in both treatment groups for an increase in QS complexity at week 12, followed by a decrease in complexity and diversity by week 48. Analysis of individual patients showed no consistent selection/accumulation of specific viral resistance patterns during treatment, but at week 48, mutations at rtA181 persisted in 4 patients. Conclusions TDF or FTC/TDF demonstrated strong viral suppression in patients with an incomplete response to ADV and no significant selective pressure on pre-existing ADV or LAM resistant strains. TDF monotherapy and FTC/TDF combination therapy had a comparable impact on QS evolution. © 2013 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

Heasley B.,Scynexis, Inc.
European Journal of Organic Chemistry | Year: 2011

Limonoid natural products are a large family of oxygenated terpenoid compounds that are best known as secondary metabolites found in citrus fruit. The diverse array of significant bioactivities associated with limonoids has stimulated targeted synthetic investigations that are often confounded by complex three-dimensional landscapes and dense functionalization within a compact molecular framework. This Microreview aims to delineate the various structural subcategories of the limonoid aglycon class as well as provide an overview of synthetic efforts invested toward the laboratory preparation of these fascinating molecules. Limonoid natural products are a large family of oxygenated terpenoid compounds that are best known as secondary metabolites found in citrus fruit. This Microreview provides a synopsis of the organic chemistry that has been applied over the last three decades to the synthesis of limonoid tetranortriterpenoids. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spangenberg T.,Medicines for Malaria Venture MMV | Burrows J.N.,Medicines for Malaria Venture MMV | Kowalczyk P.,Scynexis, Inc. | McDonald S.,Medicines for Malaria Venture MMV | And 2 more authors.
PLoS ONE | Year: 2013

Historically, one of the key problems in neglected disease drug discovery has been identifying new and interesting chemotypes. Phenotypic screening of the malaria parasite, Plasmodium falciparum has yielded almost 30,000 submicromolar hits in recent years. To make this collection more accessible, a collection of 400 chemotypes has been assembled, termed the Malaria Box. Half of these compounds were selected based on their drug-like properties and the others as molecular probes. These can now be requested as a pharmacological test set by malaria biologists, but importantly by groups working on related parasites, as part of a program to make both data and compounds readily available. In this paper, the analysis and selection methodology and characteristics of the compounds are described. © 2013 Spangenberg et al.

Methods of predicting the response in a patient infected with hepatitis C virus (HCV) to a treatment regime involving the use of a cyclophilin-binding compound are described which provide for improvements in treatments, pharmaceutical compositions, dosing regimen, assays, kits, and other aspects of the art.

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