Microbial transformation of the antimalarial sesquiterpene endoperoxide dihydroartemisinin

Dihydroartemisinin (DHA, 1), a sesquiterpene endoperoxide derived from artemisinin, has shown potent antimalarial and anticancer activities. Microbial transformation of DHA by Absidia coerulea and Penicillium chrysogenum yielded one new (3) and four known metabolites (2, 4-6). The chemical structures of these compounds were identified as deoxydihydroartemisinin (2), 8α-hydroxydeoxyartemisinin (3), deoxyartemisinin (4), 9α-hydroxyartemethin-I (5) and 3α-hydroxydeoxydihydroartemisinin (6) using spectroscopic analyses. Among them, compounds 3 and 4 are artemisinin analogues, which were achieved by unusual oxidation at C-12 position. Biotransformation of DHA by microorganisms was an effective approach to obtain new derivatives of DHA.