Glucuronide triterpene saponins from Bersama engleriana

Five 3-O-glucuronide triterpene saponins (1-5) were isolated from the stem bark of Bersama engleriana Gurke along with two known saponins, polyscias saponin C and aralia saponin 15, and one major C-glycoside xanthone, mangiferin. The structures of the saponins were established mainly by means of spectroscopic methods (one- and two-dimensional NMR spectroscopy as well as FAB-, HRESI-mass spectrometry) as 3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucuronopyranosyl]-28-O-[beta-D-glucopyranosyl]-betulinic acid (1), 3-O-[beta-D-glucopyranosyl-(1-->2)-[beta-D-galactopyranosyl-(1-->3)]-beta-D-glucuronopyranosyl]-oleanolic acid (2), 3-O-[beta-D-glucopyranosyl-(1-->3)-beta-D-glucuronopyranosyl]-28-O-[beta-D-xylopyranosyl-(1-->6)-beta-d-glucopyranosyl]-oleanolic acid (3), 3-O-[beta-D-galactopyranosyl-(1-->3)-beta-D-glucuronopyranosyl]-28-O-[beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl]-oleanolic acid (4), and 3-O-[beta-d-glucopyranosyl-(1-->3)-beta-D-galactopyranosyl-(1-->3)-beta-D-glucuronopyranosyl]-28-O-[beta-d-xylopyranosyl-(1-->6)-beta-D-glucopyranosyl]-oleanolic acid (5).