Echinocystic acid 3,16-O-bisglycosides from Albizia procera

Three echinocystic acid 3,16-O-bisglycosides were isolated from the bark of Albizia procera. Their structures were elucidated by 1D and 2D NMR experiments, FABMS as well as chemical means. In contrast to other cytotoxic echinocystic acid glycosides with N-acetyl glucosamine unit, the glycosides were found inactive when assayed by MTT method for their cytotoxicities against the human tumor cell lines HEPG2, A549, HT29 and MCF7. The results showed that the free hydroxyl group at C-16 of echinocystic acid, is important for exhibiting cytotoxic properties.