Four new C18-diterpenoid alkaloids with analgesic activity from Aconitum weixiense.

Abstract: Four new C18-diterpenoid alkaloids, weisaconitines A–D (1–4), were isolated from Aconitum weixiense. Based on extensive UV, IR, MS, 1D and 2D NMR analyses, their structures were elucidated as 8-O-ethyldolaconine (1), 4-demethylgenicunine B (2), 14-oxoaconosine (3), and 8-O-ethylaconosine (4). The analgesic activity of compound 4 was studied with CH3COOH-induced writhing model in mice. Compound 4 showed writhing inhibitions of 24% (50mg/kg), 26% (100mg/kg) and 34% (200mg/kg), respectively, as compared to the reference drug aspirin (63%) at a dose of 200mg/kg. [Copyright &y& Elsevier]