Haemolytic acylated triterpenoid saponins from Harpullia austro-caledonica

Eight new acylated triterpenoid saponins were isolated from the stem bark of Harpullia austro-caledonica along with the known harpuloside (9). Their structures were established using 1D and 2D NMR and mass spectrometry as 3O-beta-D-galactopyranosyl-(1 -> 2)-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylbarringtogenol C (1), 3-O-alpha-L-rhamnopyranosyl-(1 -> 3)-[beta-D-galactopyranosyranoysl-(1 -> 2)]-beta-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylbarringtogenol C (2), 3-O-alpha-L-arabinofuranosyl-(1 -> 3)-[beta-D-galactopyranosyl-(1 -> 2)]-beta-D-glueuronopyranosyl-21 beta, 22 alpha-di-O-angeloylbarringtogenol C (3), 3-O-alpha-L-arabinofuranosyl-(1 -> 2)]-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylprotoaescigenin (4), 3-O-alpha-L-arabinofuranosyl-(1 -> 3)-[alpha-L-arabinofuranosyl-(1 -> 2)]-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylprotoaescigenin (5), 3-O-alpha-L-arabinofuranosyl-(1 -> 3)-[beta-D-xylopyranosyl-(1 -> 2)]-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylprotoaescigenin (6), 3-O-alpha-L-arabinofuranosyl-(1 -> 3)-[beta-D-glucopyranosyl-(1 -> 2)]-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylprotoaescigenin (7), 3-O-beta-D-xylopyranosyl-(1 -> 2)-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylprotoaeseigenin (8). The EtOH extract of the stem bark showed in vitro cytotoxic activity against KB cells (90% at 10 mu g/ml). At a concentration of 5 mu g/ml, the saponin mixture showed haemolytic activity and caused 100% haemolysis of a 10% suspension of sheep erythrocytes. (c) 2005 Elsevier Ltd. All rights reserved.