Synthesis, in silico studies and in vitro evaluation of benzimidazole and benzotriazole derivatives as efflux pump inhibitors

Abstract

Multidrug resistance (MDR), primarily mediated by overexpression of ATP-binding cassette (ABC) transporters such as breast cancer resistance protein (BCRP) and P-glycoprotein (P-gp), pose a significant barrier to effective cancer chemotherapy. In this study, a series of benzimidazole (3a-3j) and benzotriazole (4a-4j) derivatives were rationally designed, synthesized, and characterised, aiming to develop efflux pump inhibitors with minimal intrinsic cytotoxicity. In silico docking studies against BCRP and P-gp revealed favourable binding profiles, with several compounds displaying key interactions with transporter residues. AutoQSAR-based predictive modelling further supported their potential, with disubstituted analogues emerging as promising candidates due to their superior predicted activity. Selected compounds were evaluated in vitro using MTT cytotoxicity assays and efflux inhibition studies in differentiated Caco-2 cells. Compounds 3c and 4c preferentially inhibited P-gp, while 3g showed higher BCRP inhibition, with compound 3c exhibiting dual activity and a favourable safety profile. Collectively, these findings suggest that the benzimidazole and benzotriazole scaffolds offer a viable strategy for the development of selective efflux pump modulators to combat MDR in cancer.