Antimitotic activity and reversal of breast cancer resistance protein-mediated drug resistance by stilbenoids from Bletilla striata

Eight stilbenoids 1-8 have been isolated by the guidance of inhibitory effect of tubulin polymerization from the tubers of Bletilla striata (Orchidaceae). Among them, both of bisbenzyls 4 and 5 inhibited the polymerization of tubulin at IC50 of 10 μM, while bisbenzyl 4 potentiated the cytotoxicity of SN-38 in BCRP-transduced K562 (K562/BCRP) cells.