A transition metal free tandem two-step strategy has been developed involving hydrolysis of 2-chloro-3-alkynyl quinoxalines/pyrazines followed by in situ cyclization of the corresponding 2-hydroxy-3-alkynyl intermediates in a single pot leading to fused furo N-heterocycles as potential inhibitors of sirtuins. A representative compound showed promising pharmacological properties in vitro and in vivo.

An unprecedented AlCl3-mediated method has been developed involving aromatic C-H bond addition to an alkyne and heteroarylation of an arene in a single pot leading to densely functionalized novel olefins, e.g. 2-(2,2-diarylvinyl)-3-arylquinoxalines, as potential inhibitors of sirtuins.

A new, versatile and direct Pd-mediated method involving intramolecular cyclization of N-(2-iodoaryl)-N-(1-alkyl-1H-indol-2-yl)alkane/arene/heteroarene sulfonamide has been developed leading to a diverse and unique class of indolo[2,3-b]indoles for the potential inhibition of sirtuins.

Fungi cause serious life-threatening infections in immunocompromised individuals and current treatments are now complicated by toxicity issues and the emergence of drug resistant strains. Consequently, there is a need for development of new antifungal drugs. Inosine monophosphate dehydrogenase (IMPDH), a key component of the de novo purine biosynthetic pathway, is essential for growth and virulence of fungi and is a potential drug target. In this study, a high-throughput screen of 114,000 drug-like compounds against Cryptococcus neoformans IMPDH was performed. We identified three 3-((5-substituted)-1,3,4-oxadiazol-2yl)thio benzo[b]thiophene 1,1-dioxides that inhibited Cryptococcus IMPDH and also possessed whole cell antifungal activity. Analogs were synthesized to explore the SAR of these hits. Modification of the fifth substituent on the 1,3,4-oxadiazole ring yielded compounds with nanomolar in vitro activity, but with associated cytotoxicity. In contrast, two analogs generated by substituting the 1,3,4-oxadiazole ring with imidazole and 1,2,4-triazole gave reduced IMPDH inhibition in vitro, but were not cytotoxic. During enzyme kinetic studies in the presence of DTT, nucleophilic attack of a free thiol occurred with the benzo[b]thiophene 1,1dioxide. Two representative compounds with substitution at the 5 position of the 1,3,4oxadiazole ring, showed mixed inhibition in the absence of DTT. Incubation of these compounds with Cryptococcus IMPDH followed by mass spectrometry analysis showed nonspecific and covalent binding with IMPDH at multiple cysteine residues. These results support recent reports that the benzo[b]thiophene 1,1-dioxides moiety as PAINS (pan-assay interference compounds) contributor.

A new strategy for converting antipsychotic drug olanzapine into PDE4 inhibitors is described via the design and Pd/C mediated synthesis of novel N-indolylmethyl olanzapine derivatives. One compound showed good inhibition (IC50 1.1 μM) and >10 fold selectivity towards PDE4B over D that was supported by docking studies. This compound also showed significant inhibition of TNF-α and no major toxicities in cell lines and a zebrafish embryo model except the teratogenic effects to be re-assessed in rodents.

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AMPK is considered as a potential high value target for metabolic disorders. Here, we present the molecular modeling, in vitro and in vivo characterization of Activator-3, 2-[2-(4-(trifluoromethyl)phenylamino)thiazol-4-yl]acetic acid, an AMP mimetic and a potent pan-AMPK activator. Activator-3 and AMP likely share common activation mode for AMPK activation. Activator-3 enhanced AMPK phosphorylation by upstream kinase LKB1 and protected AMPK complex against dephosphorylation by PP2C. Molecular modeling analyses followed by in vitro mutant AMPK enzyme assays demonstrate that Activator-3 interacts with R70 and R152 of the CBS1 domain on AMPK γ subunit near AMP binding site. Activator-3 and C2, a recently described AMPK mimetic, bind differently in the γ subunit of AMPK. Activator-3 unlike C2 does not show cooperativity of AMPK activity in the presence of physiological concentration of ATP (2 mM). Activator-3 displays good pharmacokinetic profile in rat blood plasma with minimal brain penetration property. Oral treatment of High Sucrose Diet (HSD) fed diabetic rats with 10 mg/kg dose of Activator-3 once in a day for 30 days significantly enhanced glucose utilization, improved lipid profiles and reduced body weight, demonstrating that Activator-3 is a potent AMPK activator that can alleviate the negative metabolic impact of high sucrose diet in rat model.

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