Search

A novel method was developed to synthesize alpha-amino acid N-carboxy anhydrides (NCA), which were optically active, and their corresponding alpha-amino acid derivatives. The synthesis involved a Baeyer-Villiger rearrangement subsequent to alpha-hydroxy beta-lactam oxidation to the correlating alpha-keto beta-lactams. This reaction methodology facilitated the preparation of various NCAs from non-amino acid precursors.

The NRF2-ARE pathway is an intrinsic mechanism of defense against oxidative stress. Inhibition of the interaction between NRF2 and its main negative regulator KEAP1 is an attractive strategy toward neuroprotective agents. We report here the identification of nonacidic tetrahydroisoquinolines (THIQs) that inhibit the KEAP1/NRF2 protein-protein interaction. Peptide SAR at one residue is utilized as a tool to probe structural changes within a specific pocket of the KEAP1 binding site. We used structural information from peptide screening at the P2 pocket, noncovalent small-molecules inhibitors, and the outcome from an explorative SAR at position 5 of THIQs to identify a series of neutral THIQ analogs that bind to KEAP1 in the low micromolar range. These analogs establish new H-bond interactions at the P3 and P2 pockets allowing the replacement of the carboxylic acid functionality by a neutral primary carboxamide. X-ray crystallographic studies reveal the novel binding mode of these molecules to KEAP1., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

The application of class I HDAC inhibitors as cancer therapies is well established, but more recently their development for nononcological indications has increased. We report here on the generation of improved class I selective human HDAC inhibitors based on an ethylketone zinc binding group (ZBG) in place of the hydroxamic acid that features the majority of HDAC inhibitors. We also describe a novel set of HDAC3 isoform selective inhibitors that show stronger potency and selectivity than the most commonly used HDAC3 selective tool compound RGFP966. These compounds are again based on an alternative ZBG with respect to the ortho -anilide that is featured in HDAC3 selective compounds reported to date., Competing Interests: The authors declare no competing financial interest.

The identification of a new series of P. falciparum growth inhibitors is described. Starting from a series of known human class I HDAC inhibitors a SAR exploration based on growth inhibitory activity in parasite and human cells-based assays led to the identification of compounds with submicromolar inhibition of P. falciparum growth (EC50 < 500 nM) and good selectivity over the activity of human HDAC in cells (up to >50-fold). Inhibition of parasital HDACs as the mechanism of action of this new class of selective growth inhibitors is supported by hyperacetylation studies.

We disclose the development of a novel series of 2-phenyl-2H-indazole-7-carboxamides as poly(ADP-ribose)polymerase (PARP) 1 and 2 inhibitors. This series was optimized to improve enzyme and cellular activity, and the resulting PARP inhibitors display antiproliferation activities against BRCA-1 and BRCA-2 deficient cancer cells, with high selectivity over BRCA proficient cells. Extrahepatic oxidation by CYP450 1A1 and 1A2 was identified as a metabolic concern, and strategies to improve pharmacokinetic properties are reported. These efforts culminated in the identification of 2-{4-[(3S)-piperidin-3-yl]phenyl}-2H-indazole-7-carboxamide 56 (MK-4827), which displays good pharmacokinetic properties and is currently in phase I clinical trials. This compound displays excellent PARP 1 and 2 inhibition with IC(50) = 3.8 and 2.1 nM, respectively, and in a whole cell assay, it inhibited PARP activity with EC(50) = 4 nM and inhibited proliferation of cancer cells with mutant BRCA-1 and BRCA-2 with CC(50) in the 10-100 nM range. Compound 56 was well tolerated in vivo and demonstrated efficacy as a single agent in a xenograft model of BRCA-1 deficient cancer.

5-Aryl-2-(trifluoroacetyl)thiophenes were identified as a new series of class II HDAC inhibitors (HDACi). Further development of this new series led to compounds such as 6h, a potent inhibitor of HDAC4 and HDAC6 (HDAC4 WT IC(50) = 310 nM, HDAC6 IC(50) = 70 nM) that displays 40-fold selectivity over HDAC1 and improved stability in HCT116 cancer cells (t(1/2) = 11 h). Compounds 6h and 2 show inhibition of alpha-tubulin deacetylation in HCT116 cells at 1 microM concentration and antiproliferation effects only at concentrations where inhibition of histone H3 deacetylation is observed.

The hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase (RdRp) plays a central role in virus replication. NS5B has no functional equivalent in mammalian cells and, as a consequence, is an attractive target for inhibition. Herein, we present 1H-benzo[de]isoquinoline-1,3(2H)-diones as a new series of selective inhibitors of HCV NS5B polymerase. The HTS hit 1 shows submicromolar potency in two different HCV replicons (1b and 2b) and displays no activity on other polymerases (HIV-RT, Polio-pol, GBV-b-pol). These inhibitors act during the pre-elongation phase by binding to NS5B non-nucleoside binding site Thumb Site II as demonstrated by crystal structure of compound 1 with the DeltaC55-1b and DeltaC21-2b enzymes and by mutagenesis studies. SAR in this new series reveals inhibitors, such as 20, with low micromolar activity in the HCV replicon and with good activity/toxicity window in cells.

The design of a series of peptidomimetic inhibitors of the hepatitis C virus NS3 protease is described. These inhibitors feature an indoline-2-carboxamide as a novel heterocyclic replacement for the P3 amino acid residue and N-terminal capping group of tripeptide based inhibitors. The crystal structure of the ternary NS3/NS4A/inhibitor complex for the most active molecule in this series highlights its suitability as an N-terminal capping group of a dipeptide inhibitor of the NS3 protease.