Microbial transformation of Astragalus sapogenins using Cunninghamella blakesleeana NRRL 1369 and Glomerella fusarioides ATCC 9552

• Microbial transformations of Astragalus saponins were investigated.
• Two fungi were used as whole cell systems.
• Each organism led to characteristic transformations with different substrates.
• Eight molecules are introduced to the literature for the first time.

The microbial transformation of Astragalus sp. derived sapogenins, namely cycloastragenol, astragenol and cyclocanthogenol, by Cunninghamella blakesleeana NRRL 1369 and Glomerella fusarioides ATCC 9552 were investigated. The unique enzyme system of both fungi resulted hydroxylation, cyclization, dehydrogenation and oxidation reactions. Structures of the new metabolites were elucidated by 1-D (1H, 13C, NOESY), 2-D NMR (DQF-COSY, HMBC, HMQC, NOESY) and HR-MS analyses.

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