Studies on the biosynthesis of arteannuin Ⅰ.The biosynthesis of arteannuinic acid in Artemisia annua L.

Arteannuin(Qinghaosu)(1)is a very potent natural antimalarial isolated from theChinese medicinal herb,Artemisia annua L.(Qinghao).Its chemical structure elucidation andtotal synthesis have already been achieved.In view of its unusual sesquiterpene structureof an endoperoxide ketal-acetal lactone and its specific biological activity,the authours havebeen studying the problem of the biosynthesis of 1 since 1984.From the consideration of thegeneral isoprene principle in the biogenesis of the sesquiterpene and the finding of all the iso-