C19-Diterpenoid alkaloid arabinosides from an aqueous extract of the lateral root of Aconitum carmichaelii and their analgesic activities

Abstract

Eight new C19-diterpenoid alkaloid arabinosides, named aconicarmichosides E–L (1–8), were isolated from an aqueous extract of the lateral roots of Aconitum carmichaelii (Fu Zi). Their structures were determined by spectroscopic and chemical methods including 2D NMR experiments and acid hydrolysis. Compounds 1–8, together with the previously reported four neoline 14-O-arabinosides from the same plant, represent the only examples of glycosidic diterpenoid alkaloids so far. At a dose of 1.0 mg/kg (i.p.), as compared with the black control, compounds 1, 2, and 4–6 exhibited analgesic effects with >65.6% inhibitions against acetic acid-induced writhing of mice. Structure–activity relationship was also discussed. KEY WORDS: Ranunculaceae, Aconitum carmichaelii, C19-diterpenoid alkaloid, Arabinoside, Aconicarmichosides E−L, Analgesic effect, Structure–activity relationship