CYTOTOXIC SAPONINS FROM NEW-ZEALAND MYRSINE SPECIES

The observed biological activity in two New Zealand Myrsine species has been shown to be due to the presence of triterpene saponins. From Myrsine australis a series of eight oleanane-type saponins was obtained, with compounds 1-4 and 7 and 8 being novel. Also isolated were ardisiacrispin A [5] and ardisiacrispin B [6]. The structures of the new compounds were determined by chemical and spectroscopic techniques. Extracts of Myrsine salicina yielded only one saponin, 5. Saponins 1-8 were shown to be combinations of four oleanane triterpenes bonded to beta-D-xylp(1-->2)-beta-D-glcp(1-->4)-[beta-D-glcp(1-->2)]-alpha-L-arap (compounds 1, 3, 5, 7) and this same tetrasaccharide with alpha-L-rhap replacing the beta-D-xylp unit (compounds 2, 4, 6, 8).