Microwave-assisted natural deep eutectic solvents extraction of saponins from the fibrous roots of American ginseng: process optimization, antioxidant activity, and metabolomics analysis

This study established an efficient method for the microwave-assisted natural deep eutectic solvent (NADES) extraction of saponins from the fibrous roots of American ginseng (SFRAG). The proposed method achieved a saponin yield of 18.68% within only 15 minutes. Notably, the obtained extract exhibited superior in vitro antioxidant activity compared to that of the traditional method, with DPPH IC 50 values of 0.49 mg/mL vs. 1.92 mg/mL ABTS IC 50 values of 1.29 mg/mL vs. 2.72 mg/mL, and FRAP values of 88.96 vs. 36.69 μmol TE/g, respectively. Comprehensive analyses using widely targeted metabolomic analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and correlation analysis indicated that the microwave-assisted NADES extract was enriched with rare saponins (e.g., ginsenoside Rg 3 , showing approximately a 2.0-fold increase based on relative peak area). Furthermore, the total content of saponins was higher than that obtained via the traditional extraction method. Upregulated metabolites in the microwave-assisted NADES extracts included ginsenoside Rg 3 , oleanolic acid, and dihydrophaseic acid, which are involved in the biosynthesis of various plant secondary metabolites, general metabolic pathways, and carotenoid biosynthesis. These upregulated metabolites exhibited a significant positive correlation with antioxidant activity. In conclusion, microwave-assisted NADES represents an efficient method for extraction of SFRAG.