Drug Design, Synthesis and In Vitro Evaluation of Substituted Benzofurans as Hsp90 Inhibitors

Heat shock protein 90 is a molecular chaperone required for the stability and function of several client proteins that promote cancer cell growth and/or survival. Discovery of Hsp90 inhibitors has emerged as an attractive target of research in cancer therapeutics. Natural products like geldanamycin and radicicol are established Hsp90 inhibitors, but face limitations with toxicity and inactivity, by in vivo studies respectively. However, they lay the logical starting point for the design of novel synthetic or semi-synthetic congeners as Hsp90 inhibitors.

In this article, the structure based drug design of substituted 2-aryl/heteroarylidene-6- hydroxybenzofuran-3(2H)-one analogues to optimize and mimic the pharmacophoric interactions of the valid Hsp90 inhibitor radicicolis focused.

In silico docking study was performed by Surflex dock-Geom (SYBYL- X 1.2 drug discovery suite) and the designed ligands were chemically synthesized by conventional method using resorcinol and chlororesorcinol as starting materials. Two dimensional chemical similarity search was carried out to identify the chemical space of 'SY' series in comparison with reported Hsp90 inhibitors. The in vitro cell proliferation assay (resazurin reduction method) and proteomic investigation (DARTS) was carried out on whole cell lysate to evaluate anticancer activity.

The chemical structures of all the synthesized compounds were confirmed by IR, 1H-NMR and Mass spectral analysis. The results of chemical similarity search show that SY series fit it in the chemical space defined by existing Hsp90 inhibitors. In vitro cell proliferation assay, against human melanoma and breast cancer cell lines, identified 'SY3' as the promising anticancer agent amongst the series.

Docking studies, 2D chemical similarity search, resazurin reduction assay and qualitative proteomic analysis identify 'SY3'as a promising Hsp90 inhibitor amongst the series.