Eight C_(19)-diterpenoid alkaloids( 1-8) were isolated from the ethyl acetate soluble fraction of 95% ethanol extract of the ground roots of Aconitum austroyunnanense through various column chromatographies on silica gel,ODS,Sephadex LH-20 and MCI gel.Their structures were elucidated as 14α-benzoyloxy-13β,15α-dihydroxy-1α,6α,8β,16β,18-pentamethoxy-19-oxoaconitan( 1),N-deethylaconitine( 2),spicatine B( 3),leucanthumsine A( 4),acofamine B( 5),macrorhynine B( 6),aconitilearine( 7),and ambiguine( 8) based on their chemical and physicochemical properties and spectroscopic data. Compound 1 was a new compound and alkaloids 2-8 were isolated from this plant for the first time. Some isolated alkaloids were tested in vitro for cytotoxic potential by employing the MTT method. As a result,alkaloid 1 exhibited weak cytotoxic activity against three tested tumor cell lines( A-549,He La,and Hep G2) with IC_(50) values less than 20 μmol·L~(-1).
Keywords: Aconitum austroyunnanense; Ranunculaceae; chemical constitutent; cytotoxicity; diterpenoid alkaloids.