53 research outputs found
Identification and synthesis of a unique thiocarbazate cathepsin L inhibitor
Library samples containing 2,5-disubstituted oxadiazoles were identified as potent hits in a high throughput screen (HTS) of the NIH Molecular Libraries Small Molecule Repository (MLSMR) directed at discovering inhibitors of cathepsin L. However, when synthesized in pure form, the putative actives were found to be devoid of biological activity. Analyses by LC–MS of original library samples indicated the presence of a number of impurities, in addition to the oxadiazoles. Synthesis and bioassay of the probable impurities led to the identification of a thiocarbazate that likely originated via ring opening of the oxadiazole. Previously unknown, thiocarbazates (-)-11 and (-)-12 were independently synthesized as single enantiomers and found to inhibit cathepsin 20 L in the low nanomolar range
Identification and characterization of 3-substituted pyrazolyl esters as alternate substrates for cathepsin B: The confounding effects of DTT and cysteine in biological assays
Substituted pyrazole esters were identified as hits in a high throughput screen (HTS) of the NIH Molecular Libraries Small Molecule Repository (MLSMR) to identify inhibitors of the enzyme cathepsin B. Members of this class, along with functional group analogs, were synthesized in an effort to define the structural requirements for activity. Analog characterization was hampered by the need to include a reducing agent such as dithiothreitol (DTT) or cysteine in the assay, highlighting the caution required in interpreting biological data gathered in the presence of such nucleophiles. Despite the confounding effects of DTT and cysteine, our studies demonstrate that the pyrazole 1 acts as alternate substrate for cathepsin B, rather than as an inhibitor
Select pyrimidinones inhibit the propagation of the malarial parasite, Plasmodium falciparum
Plasmodium falciparum, the Apicomplexan parasite that is responsible for the most lethal forms of human malaria, is exposed to radically different environments and stress factors during its complex lifecycle. In any organism, Hsp70 chaperones are typically associated with tolerance to stress. We therefore reasoned that inhibition of P. falciparum Hsp70 chaperones would adversely affect parasite homeostasis. To test this hypothesis, we measured whether pyrimidinone-amides, a new class of Hsp70 modulators, could inhibit the replication of the pathogenic P. falciparum stages in human red blood cells. Nine compounds with IC50 values from 30 nM to 1.6 μM were identified. Each compound also altered the ATPase activity of purified P. falciparum Hsp70 in single-turnover assays, although higher concentrations of agents were required than was necessary to inhibit P. falciparum replication. Varying effects of these compounds on Hsp70s from other organisms were also observed. Together, our data indicate that pyrimidinone-amides constitute a novel class of anti-malarial agents. © 2009 Elsevier Ltd. All rights reserved
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2.3 Ã… resolution cryo-EM structure of human p97 and mechanism of allosteric inhibition
p97 is a hexameric AAA ATPase that is an attractive target for cancer drug development. Here, we report cryo-EM structures for ADP-bound, full-length, hexameric wild-type p97 in the presence and absence of an allosteric inhibitor at resolutions of 2.3 Å and 2.4 Å, respectively. We also report cryo-EM structures at ~ 3.3 Å, 3.2 Å and 3.3 Å resolutions respectively, for three distinct, co-existing functional states of p97 with occupancies of 0, 1 or 2 molecules of ATPγS per protomer. A large corkscrew-like change in molecular architecture coupled with upward displacement of the N-domain is observed only when ATPγS is bound to both D1 and D2 domains. These cryo-EM structures establish the sequence of nucleotide-driven structural changes in p97 at atomic resolution. They also enable elucidation of the binding mode of an allosteric small molecule inhibitor to p97 and illustrate how inhibitor binding at the interface between D1 and D2 domains prevents propagation of the conformational changes necessary for p97 function
Allosteric Indole Amide Inhibitors of p97: Identification of a Novel Probe of the Ubiquitin Pathway
A high-throughput screen to discover inhibitors of p97 ATPase activity identified an indole amide that bound to an allosteric site of the protein. Medicinal chemistry optimization led to improvements in potency and solubility. Indole amide 3 represents a novel uncompetitive inhibitor with excellent physical and pharmaceutical properties that can be used as a starting point for drug discovery efforts
Identification and characterization of 3-substituted pyrazolyl esters as alternate substrates for cathepsin B: The confounding effects of DTT and cysteine in biological assays
Identification of Novel Inhibitors of Dietary Lipid Absorption Using Zebrafish
Pharmacological inhibition of dietary lipid absorption induces favorable changes in serum lipoprotein levels in patients that are at risk for cardiovascular disease and is considered an adjuvant or alternative treatment with HMG-CoA reductase inhibitors (statins). Here we demonstrate the feasibility of identifying novel inhibitors of intestinal lipid absorption using the zebrafish system. A pilot screen of an unbiased chemical library identified novel compounds that inhibited processing of fluorescent lipid analogues in live zebrafish larvae. Secondary assays identified those compounds suitable for testing in mammals and provided insight into mechanism of action, which for several compounds could be distinguished from ezetimibe, a drug used to inhibit cholesterol absorption in humans that broadly inhibited lipid absorption in zebrafish larvae. These findings support the utility of zebrafish screening assays to identify novel compounds that target complex physiological processes
Medicinal Chemistry: Where Are All the Women?
A review of multiple parameters including membership in professional organizations, corresponding authorship of medicinal chemistry journal articles, and representation in professional and leadership positions reveals that the percentage of women who participate in professional medicinal chemistry activities is less than 20%. These surrogate demographics are consistent across organizations, regions in the world and the various parameters evaluated, and parallel statistics compiled on the broader participation of women in all STEM fields. As in other STEM fields, a leaky pipeline is also evident. Suggestions for how to encourage and support women in medicinal chemistry in order to provide a more balanced representation are provided
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