Santanu Hati

Design, synthesis and evaluation of thiohydantoin derivatives as potent topoisomerase I (Top1) inhibitors with anticancer activity.

DNA topoisomerase I is a potential chemotherapeutic target. Here, we designed and synthesized a library comprising of hydantoin and thiohydantoin derivatives and tested them against human and Leishmania Top1. One of the thiohydantoin compounds with substituted thiophenyl as the central moiety (compound 15) exhibited potent inhibition of human Top1 (HTop1) through stabilization of Top1-DNA cleavage complexes and showed selective anticancer activity against human cervical carcinoma (HeLa) and breast carcinoma (MCF-7) cell lines. Molecular modeling studies with HTop1 rationalized the inhibitory mechanism of compound 15.

Accessing Benzimidazoles via a Ring Distortion Strategy: An Oxone Mediated Tandem Reaction of 2-Aminobenzylamines

An exceptional oxone mediated tandem transformation of 2-aminobenzylamines to 2-substituted benzimidazoles is reported. It occurs at room temperature with aromatic, heteroaromatic, and aliphatic aldehydes. In this reaction initial condensation of 2-aminobenzylamine with appropriate aldehydes afforded a tetrahydroquinazoline intermediate which underwent oxone-mediated ring distortion to afford the desired compounds in moderate to excellent yields.

Spiro[pyrrolidine-3, 3´-oxindole] as potent anti-breast cancer compounds: Their design, synthesis, biological evaluation and cellular target identification

The spiro[pyrrolidine-3, 3´-oxindole] moiety is present as a core in number of alkaloids with substantial biological activities. Here in we report design and synthesis of a library of compounds bearing spiro[pyrrolidine-3, 3´-oxindole] motifs that demonstrated exceptional inhibitory activity against the proliferation of MCF-7 breast cancer cells. The synthesis involved a one pot Pictet Spengler-Oxidative ring contraction of tryptamine to the desired scaffolds and occurred in 1:1 THF and water with catalytic trifluoroacetic acid and stoichiometric N-bromosuccinimide as an oxidant. Phenotypic profiling indicated that these molecules induce apoptotic cell death in MCF-7 cells. Target deconvolution with most potent compound 5l from the library, using chemical proteomics indicated histone deacetylase 2 (HDAC2) and prohibitin 2 as the potential cellular binding partners. Molecular docking of 5l with HDAC2 provided insights pertinent to putative binding interactions.

Diverse synthesis of natural product inspired fused and spiro-heterocyclic scaffolds via ring distortion and ring construction strategies

Several natural product inspired fused and spiro-heterocyclic scaffolds were prepared by ring distortion and ring construction strategies and evaluated for anti-breast cancer activity. A facile domino Pictet–Spengler lactamization (PSL) afforded nine natural product inspired indolo[2,3-a]quinolizidine and indolo[8,7-b]indolizidine scaffolds which are converted to seven other scaffolds by functional group transformation, ring distortion and ring construction strategies. In vitro screenings of this library of sixteen scaffolds with six distinct architectures against MCF7 cell lines afforded two compounds (10 and 21) with modest activity. Principal component analysis of this library against databases of FDA approved drugs, commercial compounds and FDA approved breast cancer compounds indicated an eclectic mix of structures among the molecules.

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

Nitrogen heteroarenes form an important class of compounds which can be found in natural products, synthetic drugs, building blocks etc. Among the diverse strategies that were developed for the synthesis of nitrogen heterocycles, oxidative dehydrogenation is extremely effective. This review discusses various oxidative dehydrogenation strategies of C–C and C–N bonds to generate nitrogen heteroarenes from their corresponding heterocyclic substrates. The strategies are categorized under stoichiometric and catalytic usage of reagents that facilitate such transformations. The application of these strategies in the synthesis of nitrogen heteroarene natural products and synthetic drug intermediates are also discussed. We hope this review will arouse sufficient interest among the scientific community to further advance the application of oxidative dehydrogenation in the synthesis of nitrogen heteroarenes.

Bioisosteric modification of known fucosidase inhibitors to discover a novel inhibitor of α-L-fucosidase

Bioisosteric modification of known fucosidase inhibitors A and B, resulted in three new types of molecules, 4b, 5c and 6a (belonging to furopyridinedione, thiohydantoin and hydantoin chemotypes) that could potentially bind to α-L-fucosidase (bovine kidney origin). Molecular docking revealed and compared the putative binding interaction between 4b, 5c and 6a with A and B against the active site of a homology model of α-L-fucosidase. Based on this initial investigation, design and synthesis of a library of small molecules based on furopyridinedione, thiohydantoin and hydantoin, followed by their in vitro screening against α-L-fucosidase (bovine kidney origin) generated a potent inhibitor (compound 4e) with IC50 of ∼0.7 μM. Compound 4e possessed no cytotoxic properties when tested against healthy mammalian COS-1 cells. Reaction kinetics study suggested it to be a mixed inhibitor. Finally compounds 4a, b, e and f, bearing the furopyridinedione motif also exhibited substantial inhibition of the proliferation of MCF 7 breast cancer cells.

A novel spiroindoline targets cell cycle and migration via modulation of microtubule cytoskeleton

Natural product-inspired libraries of molecules with diverse architectures have evolved as one of the most useful tools for discovering lead molecules for drug discovery. In comparison to conventional combinatorial libraries, these molecules have been inferred to perform better in phenotypic screening against complicated targets. Diversity-oriented synthesis (DOS) is a forward directional strategy to access such multifaceted library of molecules. From a successful DOS campaign of a natural product-inspired library, recently a small molecule with spiroindoline motif was identified as a potent anti-breast cancer compound. Herein we report the subcellular studies performed for this molecule on breast cancer cells. Our investigation revealed that it repositions microtubule cytoskeleton and displaces AKAP9 located at the microtubule organization centre. DNA ladder assay and cell cycle experiments further established the molecule as an apoptotic agent. This work further substantiated the amalgamation of DOS-phenotypic screening-sub-cellular studies as a consolidated blueprint for the discovery of potential pharmaceutical drug candidates.

Innovative techniques to discover novel antimalarials

Malaria a global pandemic has engulfed nearly 0.63 million people globally. It is high time that a cure for malaria is required to stop its ever increasing menace. Our commentary discusses the advent and contribution of genetic algorithm (GA) in the drug discovery efforts towards developing cure for malaria. GAs are computational models of Darwinian evolution, ideally capture and mimic the principles of genetic variation and natural selection to evolve good solutions through multiple iterations on the space of all possible candidate solutions, called the search space, to a given optimization problem. Herein we will discuss the applications, advantages, disadvantages and future directions of GA with respect to malaria.