A new indole alkaloid from bulbils of Dioscorea opposite Thunb.

This study was designed to study the chemical constituents from bulbil of Dioscorea opposite Thunb.. Four compounds were isolated by silica gel column chromatography. On the basis of physic-chemical characters and spectroscopic data analysis, these compounds were identified as lyzalkaloid (3,4-dihydro-6-hydroxy-4-methyl-6H-pyrido6,5-bindol-5(1H)-one) (1), anoectochine (2), ginsenine (3), and 2-hydroxy-3-(1H-indol-3-yl) propanoic acid methyl ester (4). Compound 1 is a new indole alkaloid, named as lyzalkaloid. Compounds 2-4 were isolated from this plant for the first time. The cytotoxic activities were assessed by MTT assay. All compounds exhibited the cytotoxic activity against HepG2 and MDA-231 with IC₅₀ values of over 100 μmol·L^-1, respectively. All compounds show no significant cytotoxic activities against HepG2, MDA-231 cancer cell.