HUMULENE SESQUITERPENE LACTONES FROM Asteriscus schimperi

Asteriscus schimperi is a rarely distributed species, belongs to the family Composite. This species has not been previously investigated for natural products. In this article we report the isolation and structure elucidation of two bisabolone sesquiterpenes and four humulene sesquiterpene lactones. The bisabolone derivatives are bisabola-2, 10-dien-1-one 1 and 6-hydroxybisabola-2, 10-dien-1-one 2, while the humulene derivatives are 9-oxohumula-4-en-6, 15-olide 3, 9-oxohumula-4, 7 (E)-dien-6,15-olide 4, 9-oxohumula-1 (10) (Z), 4, 7 (E)-trien-6, 15-olide 5, and 9-oxohumula-1 (10) (E), 4, 7 (E)-trien-6, 15-olide 6. The humulene sesquiterpene lactone 4 is a new one since it has not been previously isolated from any natural source. The structure elucidation of the isolated compounds is based on spectral analysis.