A New Sesquiterpene Ester from Celastrus orbiculatus Reversing Multidrug Resistance in Cancer Cells

Abstract
In a search for revertants of multidrug-resistance in cancer cells, a novel (1) and two known (2, 3) sesquiterpene esters were isolated from the root of Celastrus orbiculatus. The structure of 1 was elucidated as 1β,2β-diacetoxy-6α,9α-bis(benzoyloxy)dihydro-β-agarofuran. Compounds 1 − 3 partially or completely reversed resistance to adriamycin, vinblastine, and paclitaxel of multidrug-resistant KB-V1 and MCF7/ADR cells.