Five new anthraquinones from the seed of Cassia obtusifolia.

A phytochemical investigation on the seeds of Cassia obtusifolia led to the isolation of five new anthraquinones, including one aglycon and four glycosides. The structures were elucidated by analysis of extensive spectroscopic data and the results of acid hydrolysis. All these isolates were evaluated for their inhibitory effects against α-glucosidase, and 1 showed potent activity with IC50 value of 185 ± 15 µM.