Cucurbitane-Type Triterpenes with Anti-proliferative Effects on U937Cells from an Egyptian Natural Medicine, Bryonia cretica: Structures ofNew Triterpene Glycosides, Bryoniaosides A. and B

摘要

The 90% aqueous ethanol extract of an Egyptian natural medicine, the roots of Bryonia cretica L., wasfound to exhibit a strong inhibitory effect on the proliferation of human leukemia U937 cells. By bioassay-guidedfractionation, we isolated two new cucurbitane-type triterpenc, glycosides, bryoniaosides A and B, were isolatedfrom the roots of Bryonia-cretica L. together with 16 known cucurbitane-type triterpenes and glycosides. Thechemical structures of bryoniaosides A and B were determined on the basis of chemical and, spectroscopic evi-dence. Effects of principal cucurbitane-type triterpenes (cucurbitacins B, B, E, and J, 23,24-dihydrocucur-bitacins B and E, and hexanorcucurbitacin D) on proliferation of the cells were examined. CucurbitacinsBand,E showed the greater cytotoxic effects with IC_(50)values of 9.2 and 16 nm after 72hand their IC_(wereequivalent to that of camptothecin. An α,β-conjugated ketone moiety at the 22-24-positions and an acetoxygroup at the 25-position are essential for the strong activity.