Design, synthesis and biological evaluation of novel indole-benzimidazole hybrids targeting estrogen receptor alpha (ER-α)

In the course of efforts to develop novel selective estrogen receptor modulators (SERMs), indole-benzimidazole hybrids were designed and synthesised by fusing the indole nucleus with benzimidazole. All the compounds were first inspected for anti-proliferative activity using ER-α responsive T47D breast cancer cell lines and ER-α binding assay. From this study, two representative bromo substituted compounds 5f and 8f were found to be most active and thus were escalated for gene expression studies for targeting ER-α. Cell imaging experiment clearly suggest that compounds were able to cross cell membrane and accumulate thus causing cytotoxicity. RT-PCR and Western blotting experiments further supported that both compounds altered the expression of mRNA and receptor protein of ER-α, thereby preventing the further transactivation and signalling pathway in T47D cells lines. Structural investigation from induced fit simulation study suggest that compound 5f and 8f bind in antagonistic conformation similar to bazedoxifene by extensive hydrogen bonding and Van der Waals forces. All these results strongly indicate that compound 5f and 8f represents a novel potent ER-α antagonist properties and will proved promising in the discovery of SERM for the management of breast cancer.