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.
