Cytotoxic Saponins from the Seeds of Pittosporum angustifolium

Abstract

Three new acylated R1-barrigenol triterpene glycosides, 1 - 3, were isolated from the seeds of Pittosporum angustifolium Lodd. together with four known glycosides, 4 - 7, containing R1- and A1-barrigenol backbones. On the basis of spectroscopic, spectrometric, and chemical analyses the novel compounds were named pittangretosides N- P and established as 21ß-acetoxy- 22α-angeloyloxy- (1), 21ß-acetoxy-22α-(2-acetoxy-2-methylbutyroyloxy)- (2), and 21ß-(2-methylbutyroyloxy)- 22α-acetoxy-3ß-[b-D-glucopyranosyl- (1→2)]-[α-L-arabinopyranosyl-(1→3)]-[α- L-arabinofuranosyl-(1!4)]-ß-D-glucuronopyranosyloxyolean-12-ene-15α,16α,28-triol (3). Evaluation of the in vitro cytotoxicity against three tumour cell lines and one non-tumourigenic cell line revealed antiproliferative effects with IC50 values in a range of 1:74 - 34:1 μM