Bifendate-chalcone hybrids: a new class of potential dual inhibitors of P-glycoprotein and breast cancer resistance protein.

We previously described bifendate-chalcone hybrids as potent P-glycoprotein inhibitors. In the present work, we determine whether these compounds could reverse breast cancer resistance protein (BCRP, ABCG2)-mediated multidrug resistance using HEK293/BCRP cells which was BCRP-transfected stable HEK293 cells. Results indicated that compounds 8d, 8f, 8g and 8h could significantly enhance mitoxantrone accumulation in HEK293/BCRP cells via inhibiting BCRP drug efflux function. The most active compound 8g exhibited little intrinsic cytotoxicity (IC₅₀>100 μM), and could reverse BCRP-mediated drug resistance independent of decreasing BCRP expression level. Notably, 8g had little inhibitory effect on multidrug resistance-associated protein 1 (MRP1, ABCC1), another drug efflux transporter. The present findings, together with the previous results, suggest that 8g might be act as dual inhibitors of P-gp and BCRP.