Unusual 28, 29-nor-9, 19 cycloartane triterpenoids from Chinese medical plant Streptocaulon griffithii Hook

Abstract

Phytochemical investigation of the root of Streptocaulon griffithii Hook (Asclepiadaceae) led to the isolation of three unusual novel triterpenoids, 28, 29-nor-3β, 4β-dihydroxyl-9, 19-cycloartan-26-acid (1), 28, 29-nor-3β, 4β-dihydroxyl-9, 19-cycloartan- 26-acid methylester (2), a 30-nor-lupeol derivative 30-nor-3β-acetoxy-lupan-20-one (3) and five known compounds 4–8. Their structures were established on the basis of physical and spectroscopic analysis, including 1D and 2D NMR (1H, 13C, COSY, HSQC, and HMBC), ESI mass spectrometry, and by comparison with the NMR data published in the literature. The cytotoxicities of the isolated compounds against a panel of cultured tumor cell lines (Hela, PC3, SMMC7721, CNE) were evaluated. The new compounds 1 and 2 showed moderate activities with IC50 values of 11.76∼26.52μg/mL, respectively. The result showed that triterpenoids are typical compounds of Streptocaulon genus, which could be useful as characteristic markers in chemotaxonomic research and might helpful for explaining the use of S. griffithii in traditional medicine.