An Optimized Workflow for the Discovery of New Antimicrobial Compounds Targeting Bacterial RNA Polymerase Complex Formation

Bacterial resistance represents a major health problem worldwide and there is an urgent need to develop first-in-class compounds directed against new therapeutic targets. We previously developed a drug-discovery platform to identify new antimicrobials able to disrupt the protein-protein interaction between the beta' subunit and the sigma(70) initiation factor of bacterial RNA polymerase, which is essential for transcription. As a follow-up to such work, we have improved the discovery strategy to make it less time-consuming and more cost-effective. This involves three sequential assays, easily scalable to a high-throughput format, and a subsequent in-depth characterization only limited to hits that passed the three tests. This optimized workflow, applied to the screening of 5360 small molecules from three synthetic and natural compound libraries, led to the identification of six compounds interfering with the beta'-sigma(70) interaction, and thus was capable of inhibiting promoter-specific RNA transcription and bacterial growth. Upon supplementation with a permeability adjuvant, the two most potent transcription-inhibiting compounds displayed a strong antibacterial activity against Escherichia coli with minimum inhibitory concentration (MIC) values among the lowest (0.87-1.56 mu M) thus far reported for beta'-sigma PPI inhibitors. The newly identified hit compounds share structural feature similarities with those of a pharmacophore model previously developed from known inhibitors

Discovery of Diverse Small Molecule Chemotypes with Cell-Based PKD1 Inhibitory Activity

Protein kinase D (PKD) is a novel family of serine/threonine kinases regulated by diacylglycerol, which is involved in multiple cellular processes and various pathological conditions. The limited number of cell-active, selective inhibitors has historically restricted biochemical and pharmacological studies of PKD. We now markedly expand the PKD1 inhibitory chemotype inventory with eleven additional novel small molecule PKD1 inhibitors derived from our high throughput screening campaigns. The in vitro IC50s for these eleven compounds ranged in potency from 0.4 to 6.1 µM with all of the evaluated compounds being competitive with ATP. Three of the inhibitors (CID 1893668, (1Z)-1-(3-ethyl-5-methoxy-1,3-benzothiazol-2-ylidene)propan-2-one; CID 2011756, 5-(3-chlorophenyl)-N-[4-(morpholin-4-ylmethyl)phenyl]furan-2-carboxamide; CID 5389142, (6Z)-6-[4-(3-aminopropylamino)-6-methyl-1H-pyrimidin-2-ylidene]cyclohexa-2,4-dien-1-one) inhibited phorbol ester-induced endogenous PKD1 activation in LNCaP prostate cancer cells in a concentration-dependent manner. The specificity of these compounds for PKD1 inhibitory activity was supported by kinase assay counter screens as well as by bioinformatics searches. Moreover, computational analyses of these novel cell-active PKD1 inhibitors indicated that they were structurally distinct from the previously described cell-active PKD1 inhibitors while computational docking of the new cell-active compounds in a highly conserved ATP-binding cleft suggests opportunities for structural modification. In summary, we have discovered novel PKD1 inhibitors with in vitro and cell-based inhibitory activity, thus successfully expanding the structural diversity of small molecule inhibitors available for this important pharmacological target

Synthesis of the spiroketal fragment of bistramide A via an exocyclic enol ether

International audienceAn efficient synthesis of the spirocyclic fragment 1 of bistramides is reported. An olefination reaction of lactone 4 with sulfone 5 gave the enol ether 3, which upon cyclization in acidic media provided the spiroketal ring system. This compound was then converted into the C19-C36 fragment of the bistramides via successive Julia-Kocienski and Horner-Emmons olefinations. (C) 2010 Elsevier Ltd. All rights reserved

Epoxidation of glycals with oxone-acetone-tetrabutylammonium hydrogen sulfate: a convenient access to simple beta-D-glycosides and to alpha-D-mannosamine and D-talosamine donors

International audienceThe addition of a phase transfer catalyst during the epoxidation of perbenzylated glycals with oxone-acetone under biphasic conditions allows their complete epoxidation. The epoxides were readily transformed into methyl 1,2-trans-beta-D-glycosides or 1,2-trans-beta-D-glycopyranosyl azides (D-gluco and-D-galacto configurations) bearing a free hydroxyl group at the 2-position. These glycosyl azides were converted to alkyl 1,2-trans-2-acetamido-2-deoxy-alpha-D-pyranosides or alkyl 2-allyloxycarbonylamino-2deoxy-alpha-D-pyranosides (D-manno and D-talo configurations) by a Staudinger reaction and a double inversion of configuration at C-1 and C-2. (C) 2011 Elsevier Ltd. All rights reserved

Chemoselective functionalization of α-carbolines at 2-, 3-, 4- and 6-positions by Suzuki-Miyaura reaction

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Functionnalization of α-carbolines at the C-6 position

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Chemoselective functionalization of α-carbolines at 2-, 3-, 4- and 6-positions by Suzuki-Miyaura reaction

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Functionnalization of α-carbolines at the C-6 position

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