Microbial transformation of dehydrocostuslactone and costunolide by Mucor polymorphosporus and Aspergillus candidus

Twenty strains of filamentous fungi (from nine genera) and four species of bacteria were screened for their capabilities to transform dehydrocostuslactone (1) and costunolide (10). Stereo- and region-specific hydroxylation, epoxidation and hydrogenation reactions of the substrates by Mucor polymorphosporus AS 3.3443 and Aspergillus candidus CICC 2360 were reported. Twelve transformed products were obtained and their structures were identified on the basis of their spectral data. Among them, 10α,14β-epoxy-11α,13-dihydrodehydrocostuslactone and 10α,14-dihydroxy-11α,13-dihydrodehydrocostuslactone are new compounds. The biotransformation kinetics were also investigated.