Biodiversity conservation and drug discovery in Madagascar. Part 1. A new triterpene saponin from Pittosporum viridiflorum from the Madagascar rainforest

A novel triterpenoid saponin, pittoviridoside (1), which possesses an unusual 2,3,4-trisubstituted glycosidic linkage, has been isolated from Pittosporum viridiflorum using the engineered yeast strains 1138, 1140, 1353, and Sc-7 for bioactivity-guided fractionation. The structure of this compound was determined to be 3-O-[beta-D-glueopyranosyl(1-->2)]-[alpha-D-arabinopyranosyl(1-->3)],[alpha-1-arabinofuranosyl(1-->4)-beta-D-glucuronopyranosyl-21-angeloyl-22-senecioylolean-12-en-3beta,15alpha,16alpha,21beta,22alpha,28-hexol by spectral, chemical, and GC analyses. This compound showed weak cytotoxicity against the A2780 human ovarian cancer cell line.