Components of ether-insoluble resin glycoside (rhamnoconvolvulin) from rhizoma jalapae braziliensis.

Alkaline hydrolysis of the ether-insoluble resin glycoside (convolvulin) fraction of the roots of Ipomoea operculata (GOMES) MART. (Convolvulaceae) afforded a glycosidic acid named operculinic acid H along with isovaleric, tiglic, and exogonic (3,6:6,9-diepoxydecanoic) acids. Operculinic acid H was characterized to be 3S,12S-dihydroxyhexadecanoic acid 12-O-beta-D-glucopyranosyl-(1-->3)-O-alpha-L-rhamnopyranosyl-(1-->2)-[O-beta-D-glucopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->2)-[O-alpha-L-rhamnopyranosyl-(1-->6)]-O-beta-D-glucopyranoside on the basis of spectroscopic data and chemical evidence. The absolute configuration of exogonic acid determined from the alpha-methoxy-alpha-trifluoromethylphenylacetic acid esters of the hydrogenolysis products revealed that exogonic acid exists as a mixture (ca. 1 : 1) of two epimers, (3S,6S,9R)- and (3S,6R,9R)-diepoxydecanoic acids.