Reversal of P-glycoprotein-mediated multidrug resistance in MCF-7/Adr cancer cells by sesquiterpene coumarins.

In the present study, fifteen sesquiterpene coumarins were isolated and purified from different Ferula species, and were tested for their MDR reversal properties. Enhancement of doxorubicin cytotoxicity in MCF-7/Adr cells (doxorubicin resistant derivatives of MCF-7 cells overexpressing P-gp), when combined with very non-toxic concentrations of the sesquiterpene coumarins (50 μM) including umbelliprenin, farnesiferol B, farnesiferol C and lehmferin, proved significant MDR reversal activity of these coumarins. Flow cytometric efflux assay confirmed that the intracellular accumulation of Rho123 was significantly increased in MCF-7/Adr cells when treated with sesquiterpene coumarins. A deeper insight into the structure-activity relationship of sesquiterpene coumarins revealed that ring-opened drimane-type sesquiterpene coumarins including farnesiferol B, farnesiferol C and lehmferin possessed the best inhibitory effects on P-gp pump efflux and they could be considered as lead scaffolds for further structure modifications.