Microbial transformation of cycloastragenol by Penicillium spinulosum AS3.149.

Two new metabolites, 29-demethyl-3-ene-cycloastragenol (2) and 1α,12α-dihydroxy-cycloastragenone (3), along with six known compounds (4-9) were obtained from the microbial transformation of cycloastragenol (1) by Penicillium spinulosum AS3.149. The structures of these metabolites were determined by extensive spectroscopic (IR, UV, HRESIMS, 1D and 2D NMR) data analyses. Compound 2 features a 29-nor-triterpenic skeleton, possibly formed through sequential oxidation, decarboxylation, and dehydration reactions. Biological assays revealed that compound 6 exhibited significant cytotoxic activity against the K562 cell line with an IC50 value of 1.0 μM.