Reversal of multidrug resistance by purgin ii in human breast cancer cells

Reversal of multidrug resistance (MDR) by purgin II, a new resin glycoside isolated from Ipomoea purga, was evaluated in vinblastine-resistant human breast carcinoma cells (MCF-7/Vin). The effects on the cytotoxicity and P-glycoprotein (P-gp)-mediated MDR were estimated with the sulforhodamine B colorimetric assay. Purgin II enhanced vinblastine activity >1906-fold when incorporated at 25µg/mL and increased the intracellular accumulation of rhodamine 123 based on flow cytometry. Incubation of MCF-7/Vin cells with tested compound notably lowered the efflux rate of rhodamine 123.