Abstract: Abstract Three C18-diterpenoid alkaloids were isolated from Aconitum forre-stii Stapf collected in Lijiang area, Yunnan province, at the altitute of 3200 m, two known alkaloids, aconosine( 1 ), dolaconitine( 2 ), and one new alkaloid, lico-nosine A ( 3 ) , whose structures were determined based on spectroscopic evidence. It is interesting to note that liconosine A (3) , whose structure feature is dealkyled and with N=C double bond, appears to be unique in the C18-diterpenoid alkaloids. More than interesting is that the chemical components of this plant is different according to its growing altitute. The once studied Aconitum forrestii Stapf collected in Lijiang area, Yunnan province, at the altitute of 3500 m, con-tained thirteen C19-diterpenoid alkaloids, which indicates that difference in plant growing altitute leads to different chemical types. Since C19-diterpenoid alkaloids are more evolved than G19-type, the above result will possibly be significant for chemical ecology.

Key words: Aconitum

摘要： 从丽江乌头根中分离、鉴定了三个二萜生物碱成分，其中碱1、碱II分别为已知成分阿克诺辛(aconosine)和嘟拉碱(dolaconine);碱III为一新的C18-型二萜生物碱，从MS、IR、1H NMR、13C NMR等光谱数据推定了其结构，并命名为丽日碱甲(liconosine A)。

关键词: 乌头属, 丽江乌头, 二萜生物碱, 丽日碱甲