Enzymatic pretreatment of Panax notoginseng leaves alleviates obesity and modulates the gut microbiota in high-fat diet-fed mice

The root of Panax notoginseng (Burk.) F.H. is one of the most famous natural medicines and functional foods for numerous diseases. The saponin constituents present in Panax notoginseng leaves (PNGL) demonstrate an elevated level of glycosylation in comparison to those in the roots, resulting in a significantly diminished bioavailability. In this study, we systematically screened nine recombinant thermostable glycosidases and identified a synergistic combination, namely Tpexy3 and Tpebgl3, to catalyze PNGL. At 70 °C, 2000 U of both glycosidases were added before and after 1 g of PNGL, yielding 650 mg of new fractions, of which ginsenosides Rg3, F2, CK, and PPD were identified as the major products. The enzymatic PNGL demonstrated a lipid droplet-lowering effect on the 3 T3-L1 lipid deposition model. Furthermore, the enzymatic PNGL exhibited significant inhibitory effects on weight gain, hyperlipidemia, hyperglycemia, and inflammation in high-fat diet (HFD) mice. Importantly, the enzymatic PNGL restored the HFD-induced increase in the Firmicutes/Bacteroidetes (F/B) ratio and promoted the growth of beneficial gut microbes with anti-inflammatory properties, improved lipid metabolism, and short-chain fatty acid production. These results strongly indicate that enzyme-catalyzed pretreatment of PNGL can effectively enhance its bioavailability and anti-obesity effects. Biological enzyme catalysis not only provides technical support for the development of specific functional products but also promotes the efficient and high-value utilization of natural product resources.