Kinmoonosides A-C, three new cytotoxic saponins from the fruits of Acacia concinna, a medicinal plant collected in Myanmar

Three genuine saponins, named kinmoonosides A-C (1-3), have been isolated, together with a new monoterpenoid (4), from a methanolic extract of the fruits of Acacia concinna. The structures of kinmoonosides A-C were elucidated on the basis of spectral analysis as 3-O-{alpha -L-arabinopyranosyl(1-->6)[beta -D-glucopyranosyl(1-->2)]-beta -D-glucopyranosyl)-21-O-{(6R,2E)-2-hydroxymethyl-6-methyl-6-O-[4-O-(2'E)-6'-hydroxyl-2'-hydroxymethyl-6'-methyl-2', 7'-octadienoyl-beta -D-quinovopyranosyl]-2,7-octadienoyl} acacic acid 28-O-alpha -L-arabinofuranosyl(1-->4)-[beta -D-glucopyranosyl(1-->3)]-alpha -L-rhamnopyranosyl(1-->2)]-beta -D-glucopyranosyl ester (1); 3-O-(alpha -L-arabinopyranosyl(1-->6)-[beta -D-glucopyranosyl(1-->2)]-beta -D-glucopyranosyl}-21-O-{(6S,2E)-2-hydroxymethyl-6-methyl-6-O-[4-O-(2'E)-6'-hydroxyl-2'-hydroxymethyl-6'-methyl-2',7'-octadienoyl-beta -D-quinobopyranosyl]-2,7-octadienoyl}acacic acid 28-O-alpha -L-arabinofuranosyl(1-->4)-[beta -D-glucopyranosyl(1-->3)]-alpha -L-rhamnopyranosyl(1-->2)-beta -D-glucopyranosyl ester (2); and 3-O-{alpha -L-arabinopyranosyl(1-->6)-[beta -D-glucopyranosyl(1-->2)]-beta -D-glucopyranosyl}-21-O-[(2E)-6-hydroxyl-2-hydroxymethyl-6-methyl-2,7- octadienoyl]acacic acid 28-O-alpha -L-arabinofuranosyl(1-->4)-[beta -D-glucopyranosyl(1-->3)]-alpha -L-rhamnopyranosyl-(1-->2)-beta -D-glucopyranosyl ester (3), respectively. The new monoterpenoid 4 was determined as 4-O-[(2E)-6-hydroxyl-2-hydroxymethyl-6-methyl-2,7-octadienoyl] -D-quinovopyranose. Compounds 1-3 showed significant cytotoxicity against human HT-1080 fibrosarcoma cells.