Sesquiterpene lactones from Michelia Rajaniana stem bark and Grangea Maderaspatana

Abstract

Examination of the stem bark of Michelia rajaniana Craib. (Magnoliaceae) revealed the presence of five epoxy germacranolides, parthenolide, bisparthenolidine, paramicholide, N-acetylparthenolidine and N-acetyl-8α-hydroxy-parthenolidine. The latter three components were found to be unusual germacranolides which have not been reported previously while the former two were demonstrated to possess antitumor activity. In addition, the sixth component was oxoaporphinoid alkaloid liriodenine. The present investigation was also undertaken to further study of sesquiterpene lactones from Grangea maderaspatana Poir. (Compositae) . Three eudesmanolides were isolated and their structures were determined. The first component was allergenic lactone named frullanolide whilst the other two were unusual 7-hydroxy eudesmanolide named 7α-hydroxy-frullanolide and 3α, 7α-dihydroxydihydrofrullanolide Structural elucidations have been established through high field 1H-NMR 13C-NMR spectroscopy and 2D-COSY experiment. A detailed discussion on the elucidation of chemical structures is included.