Gaye Öngen

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 ((1)H, (13)C) and 2-D NMR (COSY, HMBC, HMQC, NOESY) techniques and MS analyses.

Microbial transformation of cycloastragenol.

The microbial transformation of cycloastragenol by the fungi Cunninghamella blakesleeana NRRL 1369 and Glomerella fusarioides ATCC 9552, and the bacterium Mycobacterium sp. NRRL 3805 were investigated. Both fungi mainly provided hydroxylated metabolites together with products formed by cyclization, dehydrogenation and Baeyer-Villiger oxidation resulting in a ring cleavage. The bacteria yielded only a single oxidation product, namely, 3-oxo-cycloastragenol. Structures of the metabolites were elucidated by 1-D ((1)H,(13)C), 2-D NMR (COSY, HMBC, HMQC) and HRMS analyses.