To investigate the effect of Lactobacillus plantarum L 3 fermentation on the antioxidant activity of Auricularia auricula liquor, the antioxidant capacity of the fermentation broth was assessed both in vitro and in vivo. Additionally, the changes in the main components of A. auricula liquor before and 48 h after fermentation were analyzed using HPLC–MS/MS non-targeted metabolomics. The results indicated that the free radical scavenging capacity of the A. auricula fermentation broth was significantly enhanced after 48 h of fermentation. The fermentation broth effectively repaired oxidative damage in RAW264.7 cells, enhanced the activities of antioxidant enzymes, and reduced MDA content in Drosophila melanogaster . Metabolomic analysis identified 98 metabolites in A. auricula liquor, with significant differences observed before and after fermentation. The upregulation of organic acids (2-aminobenzoic acid, aminocaproic acid, guanidinoacetic acid, etc.), phenolic acids (4-hydroxycinnamic acid, quinic acid), and amino acids (L-lysine, L-phenylalanine, citrulline, etc.) was positively correlated with antioxidant activity. Amino acids with antioxidant activity interconvert in the metabolic pathway dominated by amino acid biosynthesis and interact with organic acids and alkaloids possessing antioxidant activity to form a metabolic cross-network, which collectively enhances antioxidant activity. These findings elucidated the mechanism underlying the increased antioxidant activity of the A. auricula fermentation broth.
Yu et al. (Sat,) studied this question.