Identification of New Hsp90 Inhibitors: Structure Based Virtual Screening, Molecular Dynamic Simulation, Synthesis and Biological Evaluation.

BACKGROUND: Heat shock protein90 (Hsp90) is overexpressed in tumor cells, thus the inhibition of the Hsp90 ATPase activity would be a meaningfully effective strategy in cancer therapy. OBJECTIVE: The present work was aimed at four steps: designing new Hsp90 inhibitors as anti-cancer by a virtual screening study; synthesize designed compounds; biological evaluation of them and finally molecular dynamic (MD) simulations of best compounds. METHODS: A virtual screening study was performed on a library (100 compounds) of the ZINC database with benzimidazole scaffold; then an extracted compound and two derivatives were synthesized. The anti-proliferative and ATPase inhibitory activities of these compounds were evaluated by MTT and ATPase inhibition assays, respectively. The western blot analysis was performed to the evaluation of the expression level of Hsp70 and Her2 proteins. Finally, 200 ns molecular dynamic simulation was carried out to confirm the stability of the strongest synthesized compound in Hsp90 active site. RESULTS: ZINC00173501 compound with an aminobenzimidazole scaffold was chosen by the virtual screening study. ZINC00173501 compound and two of its derivatives were synthesized. ATPase inhibitory activity of three synthesized compounds shown that ZINC00173501 compound was the most potent inhibitor (IC50= 8.6 µM) with the anti-proliferative activity 14.41 µM, 19.07 µM and more than 100 µM against MCF-7, HeLa and HUVEC cell lines, respectively. The high level of Hsp70 expression and low level of Her2 expression confirmed ZINC00173501 as an Hsp90 inhibitor. Finally, molecular dynamics simulation showed that ZINC00173501 was stable in Hsp90 active site during 200 ns simulation. CONCLUSION: The biological evaluation results show that 2-aminobenzimidazole scaffold could be suggested as a lead for inhibition of Hsp90.

In vitro H(+) -K(+) ATPase inhibitory potential of methanolic extract of Cissus quadrangularis Linn.

OBJECTIVE: This study was undertaken to study in vitro H(+) -K(+) ATPase inhibitory potential of methanolic extract of Cissus quadrangularis Linn. MATERIALS AND MATHODS: Total phenolic and flavonoid contents from extract was quantified and H(+) -K(+) ATPase inhibition assay was performed in presence of different concentrations of standard (omeprazole) and methanol extract. RESULTS: Extract showed significant (*P < 0.05) proton pump inhibitory activity in the goat gastric mucosal homogenate which was comparable to standard. CONCLUSIONS: These findings showed that methanolic extract of C. quadrangularis Linn. is potent inhibitor of proton pump.