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Paramichelia baillonii has been used by the natives of Northern Thailand for medicinal purposes. Four components have been isolated from the bark of this plant and their structures determined by spectroscopic means. Three of the components had been reported previously: the germacranolide epoxides (--)-dihydroparthenolide [1] and (--)-parthenolide [2] and the oxoaporphinoid alkaloid liriodenine [4]. The fourth component is an unusual new germacranolide alkaloid which has been named (--)-bisparthenolidine [3] because it was presumably formed in the plant from ammonia and two molecules of parthenolide. Parthenolide was reported previously to possess anti-tumor activity, and in the present study we report on the significant activity of the new alkaloid 3 in the KB cell culture assay.

Six components have been isolated from the bark of Michelia rajaniana, and their structures have been determined by spectroscopic analysis. Four of the components have been reported previously: The germacranolide (-)-parthenolide and the oxoaporphinoid alkaloid liriodenine have been observed as constituents of several species, and (-)-bisparthenolidine and (+)-paramicholide have been reported recently by us as constituents of Paramichelia baillonii. The two new components 3 and 4, which are novel derivatives of parthenolide and contain an unusual N-acetyl substituent at C-13, have been given the names (+)-N-acetylparthenolidine and (+)-N-acetyl-8 alpha-hydroxyparthenolidine, respectively. The crude CHCl3 extract of the bark of M. rajaniana exhibited strong cytotoxicity in the KB cell culture assay.