Carbohydrates from Cynanchum otophyllum.

Four new carbohydrates were isolated from the acidic hydrolysis part of the ethyl acetate extract of Cynanchum otophyllum Schneid (Asclepiadaceae). Their structures were determined as methyl 2,6-dideoxy-3-O-methyl-beta-D-arabino-hexopyranosyl-(1-->4)-6-deoxy-3-O-methyl-beta-D-ribo-hexopyranosyl-(1-->4)-6-deoxy-3-O-methyl-alpha-L-ribo-hexopyranoside (1), methyl 6-deoxy-1,3-di-O-methyl-beta-D-ribo-hexosyl-(1-->4)-2,6-dideoxy-3-O-methyl-alpha-D-arabino-hexopyranoside (2), methyl 2,6-dideoxy-3-O-methyl-beta-D-arabino-hexopyranosyl-(1-->4)-6-deoxy-3-O-methyl-alpha-L-ribo-hexopyranoside (3), and 2,6-dideoxy-3-O-methyl-beta-D-arabino-hexopyranosyl-(1-->4)-2,6-dideoxy-3-O-methyl-alpha-D-arabino-hexopyranosyl-(1-->4)-2,6-dideoxy-3-O-methyl-beta-D-lyxo-hexopyranose (4), respectively, by spectral methods.