Microbial transformation of sesquiterpene lactones by the fungi Cunninghamella echinulata and Rhizopus oryzae

Article abstract of DOI:10.1021/np980520w

Incubations of the fungi Cunninghamella echinulata and Rhizopus oryzae with the sesquiterpene lactones (+)-costunolide (1), (+)-cnicin (2), (+)- salonitenolide (3), (-)-dehydrocostuslactone (4), (-)-lychnopholide (5), and (-)-eremantholide C (6) were performed. Incubation of 1 with C. echinulata afforded Δ(11(13))-dihydrogenation and Δ(1(10))-epoxidation products (7- 10). C. echinulata also hydrolyzed the side chain of 2, and transformed 4 into (+)-11α,13-dihydrodehydrocostuslactone (12), a new natural product. R. oryzae converted 4 into both Δ(11(13))-dihydrogenation and Δ(10(14))- epoxidation products (16 and 17). Both fungi transformed 5 into (-)-16-(1- methyl-1-propenyl)eremantholanolide (13), providing experimental evidence for the biosynthesis of the eremantholide hemiketal unit. Compounds 3 and 6 were not metabolized by either fungus under the test conditions.