Acylated oleanane-type saponins from Ganophyllum giganteum

Five oleanane-type saponins, 3-O-β-D-glucuronopyranosylzanhic acid 28-O-β-D-xylopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-(4-O-acetyl)-β-D-fucopyranosyl ester (1), 3-O-β-D-glucopyranosylzanhic acid 28-O-β-D-xylopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-(4-O-acetyl)-β-D-fucopyranosyl ester (2), zanhic acid 28-O-β-D-xylopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-(4-O-acetyl)-β-D-fucopyranosyl ester (3), zanhic acid 28-O-α-L-rhamnopyranosyl-(1→2)-4-O-[(3'-hydroxy-2'-methyl-butyroyloxy)-3-hydroxy-2-methyl-butyroyloxy]-β-D-fucopyranosyl ester (4), medicagenic acid 28-O-α-L-rhamnopyranosyl-(1→2)-4-O-[(3'-hydroxy-2'-methyl-butyroyloxy)-3-hydroxy-2-methyl-butyroyloxy]-β-D-fucopyranosyl ester (5), were isolated from the root barks of Ganophyllum giganteum. Compounds 4 and 5 possessed an unusual substitution of the C-4 position of the β-D-fucopyranosyl moiety by a C10 ester group formed by two symmetrical C5 nilic acid. From a chemotaxonomic point of view, their structures are in accordance with the previous saponins isolated from the Doratoxyleae tribe of the Sapindaceae family. Their cytotoxicity and anti-inflammatory activity were also evaluated.