Biotransformation of Cycloastragenol by Cunninghamella blakesleeana NRRL 1369 Resulting in a Novel Framework

The microbial transformation of cycloastragenol by the fungus Cunninghamella blakesleeana NRRL 1369 was investigated. Unlike the original compound, the metabolite was found to possess an interesting triterpenic skeleton derived via an exceptional transformation involving ring cleavage and methyl group migration. The structure of the new metabolite was elucidated by 1-D (H-1, C-13) and 2-D NMR (COSY, HMBC, HMQC, NOESY) techniques and MS analyses.