Fermentation of Premna microphylla Turcz. by Eurotium cristatum Enhanced Its Nutrients and Antidiabetic Activity

This study developed a probiotic Eurotium cristatum-fermented Premna microphylla Turcz. (EFPT) and systematically evaluated its nutritional profile and antidiabetic effects in a type 2 diabetes mellitus (TIIDM) mouse model. After 8 days of fermentation, the contents of pectin (9.001% vs. 4.222%) and water-soluble polysaccharides (13.339% vs. 4.826%) increased significantly (p < 0.05), whereas the levels of polyphenols (12.12% vs. 15.917%) and soluble proteins (3.829% vs. 5.797%) decreased (p < 0.05). Notable alterations were also observed in short-chain fatty acids (SCFAs), monosaccharide composition, and amino acid profiles. Specifically, the levels of propionic acid, histidine, threonine, serine, glycine, lysine, glutamic acid, and methionine decreased significantly (p < 0.05), while those of butyric acid, valeric acid, galactose, valine, alanine, and proline increased (p < 0.05). Furthermore, EFPT exhibited dose-dependent antidiabetic effects and showed greater efficacy than non-fermented Premna microphylla Turcz. powder in high-fat diet combined with streptozotocin-induced TIIDM mice (p < 0.05). These effects were primarily associated with enhanced SCFAs production and the amelioration of liver and kidney damage. Overall, these findings suggest that Eurotium cristatum fermentation enhances the bioactive properties of Premna microphylla Turcz., contributing to its improved nutritional quality and potent antidiabetic activity.