A novel endoperoxide and related sesquiterpenes from Artemisia annua which are possibly derived from allylic hydroperoxides

Seven novel cadinane sesquiterpenes, including the seven-membered endoperoxide lactone arteannuin H (1), two six-membered lactones arteannuins 1(4) and J (5), three five-membered lactones arteannuins K-M (6-8) and a keto acid arteannuin N (9) have been isolated from the dried leaves of Artemisia annua in addition to the known compounds dihydroartemisinic acid (27), dihydroarteannuin B (24) and dihydro-epi-deoxyarteannuin B (22). It is proposed that these novel sesquiterpenes are biogenetically related to dihydroartemisinic acid via intermediate secondary and tertiary allylic hydroperoxides. (C) 1998 Elsevier Science Ltd. All rights reserved.