Design, synthesis, and bioactivity evaluation of novel indole-selenide derivatives as P-glycoprotein inhibitors against multi-drug resistance in MCF-7/ADR cell

The inhibition of P-glycoprotein (P-gp) has emerged as an intriguing strategy for circumventing multidrug resistance (MDR) in anticancer chemotherapy. In this study, we have designed and synthesized 30 indoleselenides as a new class of P-gp inhibitors based on the scaffold hopping strategy. Among them, the preferred compound H27 showed slightly stronger reversal activity (reversal fold: 271.7 vs 261.6) but weaker cytotoxicity (inhibition ratio: 33.7% vs 45.1%) than the third-generation P-gp inhibitor tariquidar on the tested MCF-7/ADR cells. Rh123 accumulation experiments and Western blot analysis demonstrated that H27 displayed excellent MDR reversal activity by dose-dependently inhibiting the efflux function of P-gp rather than its expression. Besides, UIC-2 reactivity shift assay revealed that H27 could bind to P-gp directly and induced a conformation change of P-gp. Moreover, docking study revealed that H27 matched well in the active pockets of P-gp by forming some key H-bonding interactions, arene-H interactions and hydrophobic contacts. These results suggested that H27 is worth to be a starting point for the development of novel Se-containing P-gp inhibitors for clinic use.