Triterpenoid saponins and acylated prosapogenins from Harpullia austro-caledonica

Three new triterpenoid saponins have been isolated from the stem bark of Harpullia austro-caledonica and identified as 24-O-alpha-L-rhamnopyranosyl-(1->2)-beta-D-glucopyranosyl]-28-O-beta-D-glucopyranosyl-(1->2)-beta-D-glucopyranosyl]-protoaescigenin, 24-O-alpha-L-rhamnopyranosyl-(1->2)-beta-D-glucopyranosyl]-28-O-beta-D-glucopyranosyl-(1->2)-beta-D-glucopyranosyl]-16-desoxyprotoaescigenin, 24-O-alpha-L-rhamnopyranosyl-(1->2)-beta-D-glucopyranosyl]-28-O-beta-D-glucopyranosyl-(1->2)-beta-D-glucopyranosyl]-24-oxo-camelliagenin D. The 21,22-di-O-angeloate esters of protoaescigenin and barringtogenol C were isolated in the acid hydrolysate of the saponin extract together with a new prosapogenin identified as 21beta,22alpha-di-O-angeloyl camelliagenin D. The structures were established using one- and two- dimensional NMR and mass spectrometry.