Microbial transformation of oleanonic acid by Aspergillus minisclerotigenes and the -anti-neuroinflammatory properties of products.

This research explored the microbial conversion of oleanonic acid by Aspergillus minisclerotigenes CGMCC 3.86. The scaled-up biotransformation processes produced ten distinct metabolites. Structural elucidation was performed through comprehensive NMR and HR-ESI-MS spectroscopic techniques, which led to the identification of three previously undocumented derivatives (compounds 6, 7, and 9). A. minisclerotigenes exhibited catalytic versatility in mediating multiple biochemical modifications, including carboxyl reduction, site-specific hydroxylation, glycosyl transfer, and cyclic ester formation. Furthermore, the inhibitory effects of metabolites on neuroinflammatory responses were evaluated using LPS-activated murine BV-2 microglial cell models. Among the tested compounds, derivatives 7, 9, and 10 displayed significant inhibition of nitric oxide production. These findings indicate that the biotransformed derivatives of oleanonic acid have potential as effective neuroinflammatory inhibitors.