Inhibitory effects of ginsenosides and their hydrolyzed metabolites on daunorubicin transport in KB-C2 cells

Abstract

We studied the effects of ginsenosides and their metabolites on daunorubicin transport in multidrug-resistant P-glycoprotein (P-gp)-overexpressing KB-C2 cells. Ginsenoside Rg1, which is a protopanaxatriol-type ginseng saponin, did not have any effects on the accumulation of P-gp substrate daunorubicin. On the other hand, its metabolite M4, which has no sugar moiety, increased the accumulation 3.6-fold at 5 μM. Metabolites of protoanaxadiol-type saponin M1 and M12 also increased accumulation, but the effects were less than that of M4. The findings showed larger effects of metabolites without glucose moieties. Analysis of verapamil-stimulated ATPase activity in membrane vesicles expressing human P-gp suggested that the increased daunorubicin accumulation by M4 was at least partly due to ATPase inhibition of P-gp. © 2007 Pharmaceutical Society of Japan.