Discovery of Ethyl Ketone-Based Highly Selective HDACs 1, 2, 3 Inhibitors for HIV Latency Reactivation with Minimum Cellular Potency Serum Shift and Reduced hERG Activity.

We describe the discovery of histone deacetylase (HDACs) 1, 2, and 3 inhibitors with ethyl ketone as the zinc-binding group. These HDACs 1, 2, and 3 inhibitors have good enzymatic and cellular activity. Their serum shift in cellular potency has been minimized, and selectivity against hERG has been improved. They are also highly selective over HDACs 6 and 8. These inhibitors contain a variety of substituted heterocycles on the imidazole or oxazole scaffold. Compounds 31 and 48 stand out due to their good potency, high selectivity over HDACs 6 and 8, reduced hERG activity, optimized serum shift in cellular potency, and good rat and dog PK profiles.

Development of a selective HDAC inhibitor aimed at reactivating the HIV latent reservoir.

The synthesis and SAR development of a trisubstituted imidazole HDAC inhibitor is described. The compounds were synthesized with high diastereocontrol by leveraging Ellman sulfinyl imine chemistry. Structural elucidation provided insight into binding mode and supported design rational. Pharmacokinetic properties of lead compounds were determined.

Selective Class I HDAC Inhibitors Based on Aryl Ketone Zinc Binding Induce HIV-1 Protein for Clearance.

HIV persistence in latently infected, resting CD4+ T cells is broadly considered a barrier to eradicate HIV. Activation of the provirus using latency-reversing agents (LRAs) followed by immune-mediated clearance to purge reservoirs has been touted as a promising therapeutic approach. Histone deacetylases (HDACs) and histone acetyltransferases (HATs) control the acetylation level of lysine residues in histones to regulate the gene transcription. Several clinical HDAC inhibitors had been examined as LRAs, which induced HIV activation in vitro and in vivo. Here we report the discovery of a series of selective and potent class I HDAC inhibitors based on aryl ketones as a zinc binding group, which reversed HIV latency using a Jurkat model of HIV latency in 2C4 cells. The SAR led to the discovery of a highly selective class I HDAC inhibitor 10 with excellent potency. HDACi 10 induces the HIV gag P24 protein in patient latent CD4+ T cells.

Discovery of ethyl ketone-based HDACs 1, 2, and 3 selective inhibitors for HIV latency reactivation.

A novel series of ethyl ketone based HDACs 1, 2, and 3 selective inhibitors have been identified with good enzymatic and cellular activity and high selectivity over HDACs 6 and 8. These inhibitors contain a spirobicyclic group in the amide region. Compound 13 stands out as a lead due to its good potency, high selectivity, and reasonable rat and dog PK. Compounds 33 and 34 show good potency and rat PK profiles as well.

Accelerating the discovery of DGAT1 inhibitors through the application of parallel medicinal chemistry (PMC).

The parallel medicinal chemistry (PMC) was effectively applied to accelerate the optimization of diacylglycerol O-acyltransferase I (DGAT-1) inhibitors. Through a highly collaborative and iterative library design, synthesis and testing, a benzimidazole lead was rapidly and systematically advanced to a highly potent, selective and bioavailable DGAT1 inhibitor with the potential for further development.

Benzimidazole-based DGAT1 inhibitors with a [3.1.0] bicyclohexane carboxylic acid moiety.

Previously disclosed benzimidazole-based DGAT1 inhibitors containing a cyclohexane carboxylic acid moiety suffer from isomerization at the alpha position of the carboxylic acid group, generating active metabolites which exhibit DGAT1 inhibition comparable to the corresponding parent compounds. In this report, we describe the design, synthesis and profiling of benzimidazole-based DGAT1 inhibitors with a [3.1.0] bicyclohexane carboxylic acid moiety. Our results show that single isomer 3A maintains in vitro and in vivo inhibition against DGAT1. In contrast to previous lead compounds, 3A does not undergo isomerization during in vitro hepatocyte incubation study or in vivo mouse study.

Discovery of a Potent and Selective DGAT1 Inhibitor with a Piperidinyl-oxy-cyclohexanecarboxylic Acid Moiety.

We report the discovery of a novel series of DGAT1 inhibitors in the benzimidazole class with a piperdinyl-oxy-cyclohexanecarboxylic acid moiety. This novel series possesses significantly improved selectivity against the A2A receptor, no ACAT1 off-target activity at 10 µM, and higher aqueous solubility and free fraction in plasma as compared to the previously reported pyridyl-oxy-cyclohexanecarboxylic acid series. In particular, 5B was shown to possess an excellent selectivity profile by screening it against a panel of more than 100 biological targets. Compound 5B significantly reduces lipid excursion in LTT in mouse and rat, demonstrates DGAT1 mediated reduction of food intake and body weight in mice, is negative in a 3-strain Ames test, and appears to distribute preferentially in the liver and the intestine in mice. We believe this lead series possesses significant potential to identify optimized compounds for clinical development.

Potent DGAT1 Inhibitors in the Benzimidazole Class with a Pyridyl-oxy-cyclohexanecarboxylic Acid Moiety.

We report the design and synthesis of a series of novel DGAT1 inhibitors in the benzimidazole class with a pyridyl-oxy-cyclohexanecarboxylic acid moiety. In particular, compound 11A is a potent DGAT1 inhibitor with excellent selectivity against ACAT1. Compound 11A significantly reduces triglyceride excursion in lipid tolerance tests (LTT) in both mice and dogs at low plasma exposure. An in vivo study in mice with des-fluoro analogue 10A indicates that this series of compounds appears to distribute in intestine preferentially over plasma. The propensity to target intestine over plasma could be advantageous in reducing potential side effects since lower circulating levels of drug are required for efficacy. However, in the preclinical species, compound 11A undergoes cis/trans epimerization in vivo, which could complicate further development due to the presence of an active metabolite.

Antidiabetic and antisteatotic effects of the selective fatty acid synthase (FAS) inhibitor platensimycin in mouse models of diabetes.

Platensimycin (PTM) is a recently discovered broad-spectrum antibiotic produced by Streptomyces platensis. It acts by selectively inhibiting the elongation-condensing enzyme FabF of the fatty acid biosynthesis pathway in bacteria. We report here that PTM is also a potent and highly selective inhibitor of mammalian fatty acid synthase. In contrast to two agents, C75 and cerulenin, that are widely used as inhibitors of mammalian fatty acid synthase, platensimycin specifically inhibits fatty acid synthesis but not sterol synthesis in rat primary hepatocytes. PTM preferentially concentrates in liver when administered orally to mice and potently inhibits hepatic de novo lipogenesis, reduces fatty acid oxidation, and increases glucose oxidation. Chronic administration of platensimycin led to a net reduction in liver triglyceride levels and improved insulin sensitivity in db/+ mice fed a high-fructose diet. PTM also reduced ambient glucose levels in db/db mice. These results provide pharmacological proof of concept of inhibiting fatty acid synthase for the treatment of diabetes and related metabolic disorders in animal models.

Discovery and optimization of novel 4-[(aminocarbonyl)amino]-N-[4-(2-aminoethyl)phenyl]benzenesulfonamide ghrelin receptor antagonists.

This Letter describes optimization of ghrelin receptor antagonists and inverse agonists starting from a screening hit.

A fluorescence-based thiol quantification assay for ultra-high-throughput screening for inhibitors of coenzyme A production.

Here we report the development and miniaturization of a cell-free enzyme assay for ultra-high-throughput screening (uHTS) for inhibitors of two potential drug targets for obesity and cancer: fatty acid synthase (FAS) and acetyl-coenzyme A (CoA) carboxylase (ACC) 2. This assay detects CoA, a product of the FAS-catalyzed condensation of malonyl-CoA and acetyl-CoA. The free thiol of CoA can react with 7-diethylamino-3-(4'-maleimidylphenyl)-4-methylcoumarin (CPM), a profluorescent coumarin maleimide derivative that becomes fluorescent upon reaction with thiols. FAS produces long-chain fatty acid and CoA from the condensation of malonyl-CoA and acetyl-CoA. In our FAS assay, CoA released in the FAS reaction forms a fluorescence adduct with CPM that emits at 530 nm when excited at 405 nm. Using this detection method for CoA, we measured the activity of sequential enzymes in the fatty acid synthesis pathway to develop an ACC2/FAS-coupled assay where ACC2 produces malonyl-CoA from acetyl-CoA. We miniaturized the FAS and ACC2/FAS assays to 3,456- and 1,536-well plate format, respectively, and completed uHTSs for small molecule inhibitors of this enzyme system. This report shows the results of assay development, miniaturization, and inhibitor screening for these potential drug targets.

3-Aryl-4-hydroxyquinolin-2(1H)-one derivatives as type I fatty acid synthase inhibitors.

A series of 3-aryl-4-hydroxyquinolin-2(1H)-ones with fatty acid synthase inhibitory activity was prepared. Starting from a derivative with an IC(50) = 1.4 microM, SAR studies led to compounds with more than 70-fold increase in potency (IC(50) < 20 nM).

Expression, refolding, and purification of recombinant human phosphodiesterase 3B: definition of the N-terminus of the catalytic core.

We have developed an expression, refolding, and purification protocol for the catalytic domain of human Phosphodiesterase 3B (PDE3B). High level expression in Escherichia coli has been achieved with yields of up to 20mg/L. The catalytic domain of the enzyme was purified by affinity chromatography utilizing a novel affinity ligand. PDE3B, purified by affinity chromatography, with no single impurity #10878;1% as determined by SDS-PAGE, has a specific activity of 2210+/-442nmol/min/mg and a KM for cAMP of 44+/-4.5nM. Reducing the size of the expressed catalytic domain from residues 387-1112 to residues 654-1086 greatly reduced the aggregation phenomena observed with the affinity purified PDE3B. The definition of the N-terminus of the catalytic core was examined through the generation of several truncation mutants spanning amino acid residues 636-674. Constructs starting at E665 and M674 were fully active and devoid of activity, respectively. A construct starting at D668 had a Vmax reduced by approximately 10-fold relative to the longer constructs, yet the KM was not affected. This indicates the minimal N-terminus of the catalytic core lies between E665 and Y667. Refolding and affinity purification of the 654-1073 catalytic core of PDE3B has been employed to produce large quantities of highly pure enzyme for structural studies.

Benzyl vinylogous amide substituted aryldihydropyridazinones and aryldimethylpyrazolones as potent and selective PDE3B inhibitors.

Aryldihydropyridazinones and aryldimethylpyrazolones with 2-benzyl vinylogous amide substituents have been identified as potent PDE3B subtype selective inhibitors. Dihydropyridazinone 8a (PDE3B IC(50)=0.19 nM, 3A IC(50)=1.3 nM) was selected for in vivo evaluation of lipolysis induction, metabolic rate increase, and cardiovascular effects.