Constituents of Michelia Rajaniana. Two new germacranolide amides

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.