Oleanane and taraxerane glycosides from the roots of Gomphrena macrocephala

Phytochemical screening of the roots of Gomphrena macrocephala, with particular attention to its triterpene glycoside constituents, has resulted in the isolation of two new oleanane glycosides (1 and 2) and a new taraxerane glycoside (3). The structures of 1-3 were determined as 11alpha,12alpha-epoxy-3beta-[(O-beta-D-glucuronopyranosyl)oxy]olean-28,13-olide (1), 11alpha,12alpha-epoxy-3beta-[(O-beta-D-galactopyranosyl-(1-->3)-O-[beta-D-glucopyranosyl-(1-->2)]-beta-D-glucuronopyranosyl)-oxy]olean-28,13-olide (2), and 11alpha,12alpha-epoxy-3beta-[(O-beta-D-glucuronopyranosyl)oxy]taraxer-14-en-28-oic acid beta-D-glucopyranosyl ester (3), respectively, on the basis of their spectroscopic data and the results of hydrolysis. The aglycones (1a and 3a) of 1-3 with an epoxy group showed cytotoxic activity against HSC-2 human oral squamous carcinoma cells.