Effects of solid-state fermentation using R. oligosporus on the phytochemical composition of wild-simulated ginseng leaf and its biological properties

Wild-simulated ginseng (WSG) grown in the mountains without specific facilities is widely used as functional foods in Asian countries due to its bioactive compounds, such as ginsenosides. However, long-time cultivation, lower survival rate, and small size of WSG limit its use in the food industry. In this study, WSG leaves, which can be harvested annually, were fermented using R. oligosporus for 0–10 days. The phytochemical compounds of fermented WSG leaves, including squalene, phenols, saponins, and most ginsenosides (except for Rb1), were increased. L-carnitine was newly synthesized in WSG leaves, with a content of 165.1 μg/g measured after 10 days of fermentation. Moreover, the minor ginsenosides Rg2, Rg3, Rh1, F1, F2, and CK increased by 1.32-, 1.58-, 1.42-, 1.91-, 1.49-, and 4.43-fold compared to non-fermented WSG leaves. The highest antioxidant activities, as measured by FRAP and ORAC assays of WSG leaves, were obtained after 3 days of fermentation. Furthermore, the suppression of NO release in LPS-stimulated RAW264.7 cells and lipid accumulation in mouse 3T3-L1 cells of fermented WSG leaves was greater than in WSG leaves. From these results, fermented WSG leaves have potential applications as functional materials in the food industry.