New alkaloids from a Popowia species (Annonaceae)

Abstract

A bisbenzylisoquinoline and three noraporphine alkaloids have been isolated from the bark of a Popowia species (Popowia cf. cyanocarpa Laut. 85 K. Schum.) of the family Annonaceae. The major alkaloid is 1-hydroxy-2,9,10-trimethoxynoraporphine (1), and comparison with the known alkaloid wilsonirine, to which the same structure had been assigned, indicates that the Popowia base is the (+)-form, while wilsonirine is largely racemic. Another alkaloid, 2-hydroxy-1-methoxynoraporphine (3), is identical with the known alkaloid asimilobine, while the third noraporphine, 1-hydroxy-2,10,11-trimethoxynoraporphine (4), has not previously been reported. The bisbenzylisoquinoline alkaloid, dauricine O-methyl ether (6), has not previously been isolated as an alkaloid but it has been prepared as a derivative of dauricine.