Two pregnane derivatives and a quinolone alkaloid from Helicteres angustifolia

Phytochemical investigation of the ethanol extract from roots of Helicteres angustifolia led to the isolation of two new pregnane derivatives, heligenin A-B (1-2), and a new quinolone alkaloid, helicterone A (3), along with thirteen known compounds (4-16). The structures of new compounds were established by analysis of extensive spectroscopic data. The absolute configuration of 1 was determined by application of the modified Mosher's method. All of the isolates were evaluated for their anti-proliferative activities against HT-29 human colon cancer cells and OVCA 429 ovarian cancer cells by MTT assay.