Fermentation, Identification, and Antioxidant Activity of Saponins Produced by a Wild Ginseng Endophytic Fungus Umbelopsis dimorpha Strain NSJG

Background: Endophytes from ginseng plants may produce saponins through in vitro fermentation, and some saponins possess antioxidant activity. This study aimed to enhance the total saponin yield of an endophytic fungus isolated from wild ginseng, determine saponin types, and explore whether saponin extracts from optimized fermentation protocols have antioxidant activity. Methods: Umbelopsis dimorpha strain NSJG was fermented in liquid under different conditions. The types of saponins were analyzed by Liquid Chromatography/Mass Spectrometry (LC/MS). The antioxidant activity of saponin extracts was evaluated by measuring their hemolytic inhibition rate on erythrocytes. Results: The endophytic fungus strain NSJG produced 1.236 mg/mL total saponins through liquid potato dextrose (PD) fermentation. The total saponin concentrations of optimal protocols G-ED-8 (3.107 mg/mL) and G-DP-8 (2.045 mg/mL) were three times and twice that of G-PD. Saponin extracts from G-ED-8 and G-DP-8 contained seven and eight types of ginsenosides and had higher hemolysis inhibition rates on erythrocytes than Vitamin C (VC), which were 36.05% and 46.69%. Conclusions: The research highlights the potential implications of wild ginseng endophytic fungus strain NSJG for the in vitro production of ginsenosides and the development of novel antioxidants.