Research on the Metabolites and Biological Activities of the Endophytic Fungus Ilyonectria cyclaminicola From Epimedium koreanum Nakai

ABSTRACT This study aims to optimize the growth conditions of the endophytic fungus Ilyonectria cyclaminicola from the Korean Epimedium Nakai ( EK ), investigate whether I. cyclaminicola possesses the same anti‐osteoporotic effects and kidney‐injury effects as its host plant, identify the structure of its monomeric compounds and evaluate their antibacterial and antioxidant effects. The fermentation process was optimized through single‐factor experiments, and the biological activity of the strain was assessed using a zebrafish model. Nuclear magnetic resonance was used to determine the structure of the monomeric compounds, and their antibacterial and antioxidant activities were evaluated using the paper disc diffusion method and DPPH free radical scavenging assay. The results showed that the optimal solid‐state culture conditions for I. cyclaminicola were as follows: α‐lactose as the carbon source, glycine as the nitrogen source, a temperature of 25°C, 12 h of natural light, and a pH of 6. Using wheat bran as the fermentation substrate, the total flavonoid content reached 28.431 mg/g after 60 days. I. cyclaminicola exhibits significant anti‐osteoporotic and kidney‐injury effects, and the nine isolated compounds all show varying degrees of DPPH radical scavenging and antibacterial activities. Among them, compound ( 2 ) 5‐methylfurfural achieved a DPPH scavenging rate of 23.71% at 1.0 mg/mL.