Resveratrol oligomers are potent MRP1 transport inhibitors.

BACKGROUND Knowledge of the structure-activity relationships of multidrug resistance protein 1 (MRP1, ABCC1) inhibitors may aid in developing potent inhibitors that can be used to circumvent MRP1-mediated multidrug resistance. MATERIALS AND METHODS Six stilbenes were examined for their ability to inhibit MRP1-mediated transport of 2',7'-bis-(carboxypropyl)-5(6)-carboxyfluorescein (BCPCF) from human erythrocytes and into inside-out erythrocyte membrane vesicles (IOVs). The concentrations of stilbenes decreasing BCPCF transport by 50% during 60 min of incubation at 37 degrees C (IC50) were determined from dose-response curves. RESULTS Stilbenes inhibited BCPCF transport in cells in the rank order (+)-alpha-viniferin (IC50 = 0.8 microM) > sophorastilbene A (IC50 = 3.1 microM) > (-)-epsilon-viniferin (IC50 = 8.9 microM) > piceatannol (IC50 = 57 microM). Resveratrol and rhaponticin were ineffective. (+)-alpha-Viniferin (IC50 = 0.8 microM), sophorastilbene A (IC50 = 3.7 microM) and (-)-epsilon-viniferin (IC50 = 3.5 microM) were also efficient BCPCF transport inhibitors in IOVs. CONCLUSION Stilbenes may efficiently inhibit MRP1-mediated organic anion transport. This inhibitory potency of stilbenes increases with oligomerisation. The membrane is not a strong barrier for the inhibitory activity of the trimeric stilbenes.