Triterpenoid Saponins from the Seeds of Pharbitis nil

From the seeds of Pharbitis nil (Convolvulaceae), two new oleanene-type triterpene glycosides, pharbitosides A (1) and B (2), together with β-sitosterol, β-sitosterol glucoside (daucosterol), caffeic acid, and methyl caffeate were isolated. The structure of pharbitoside A (1) was elucidated to be queretaroic acid 3-O-α-L-rhamnopyranosyl-(1→2)-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside (1). Pharbitoside B (2) is a 21α-hydroxyoleanolic acid saponin carrying the same sugar moiety as that of pharbitoside A (1).