The dynamic analysis of non-targeted metabolomics and antioxidant activity of Dendrobium officinale Kimura et Migo by the synergistic fermentation of bacteria and enzymes

The fermentation metabolites of Dendrobium officinale Kimura et Migo (D. officinale) exists a crucial influence on its antioxidant activity which further affects the comprehensive utilization of D. officinale fermentation products. In this research, multiple proteases were selected for the synergistic fermentation of D. officinale with Lactobacillus plantarum and Saccharomyces cerevisiae. GC-MS-based untargeted metabolomics was employed to analyze the metabolite characteristics and predict the metabolic pathways of fermented D. officinale liquid (FDL). In vitro chemical assay and cellular oxidative stress model were employed to evaluate the antioxidant activity of FDL. The contents of phenols, flavonoids and B vitamins were significantly increased during the synergistic fermentation of bacteria and enzymes. A total of 45 key differential metabolites were identified, consisting primarily of 16 sugars, 15 organic acids and 5 polyols. Furthermore, the changes in their types and contents were shaped by 6 critical differential metabolic pathways. As fermentation progressed, the scavenging capability of FDL on free radicals was notably augmented, and it had the ability to enhance the activity of intracellular antioxidant enzymes by suppressing the generation of intracellular ROS and MDA. The synergistic fermentation of bacteria and enzymes was beneficial for D. officinale exhibited efficient antioxidant activity.