Triterpene Glycosides from the Underground Parts of Alternanthera philoxeroides Designated as an Invasive Alien Species and Their Cytotoxicity

Abstract

A phytochemical investigation was conducted on the underground parts of Alternanthera philoxeroides, designated by Japan as an invasive alien species, to find new candidates for anti-cancer drugs. As a result, nine oleanane-type triterpene glycosides (1－9), including two new ones (1 and 2), and five noroleanane-type triterpene glycosides (10－14) were collected. The structures of 1 and 2 were determined by analysis of their NMR spectral data and enzymatic hydrolysis. Compounds 1－14 were evaluated for their cytotoxicity toward 　SBC-3 human small-cell lung cancer cells using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Compounds 1, 4, 7, and 11 exerted cytotoxicity against SBC-3 cells with IC₅₀ values ranging from 1.2 M to 16 M. This study implies that invasive alien species could be potential resources for new pharmaceutical seeds.