Improved Antioxidant Capacity of Akebia trifoliata Fruit Inoculated Fermentation by Plantilactobacillus plantarum, Mechanism of Anti-Oxidative Stress through Network Pharmacology, Molecular Docking and Experiment Validation by HepG2 Cells

In this work, spontaneously fermented and inoculation-fermented Akebia trifoliata fruit Jiaosu (SFAJ/IFAJ) were compared. The key metabolites and antioxidant activities of SFAJ and IFAJ were tracked and tested during fermentation. The antioxidant effect of fermented Akebia trifoliata fruit and the underlying mechanisms were explored using network pharmacology for the prediction and verification of the molecular targets and pathways of the Akebia trifoliata fruit's action against oxidative stress. Furthermore, the results were verified by molecular docking and then investigated, based on a HepG2 cell model. The results of correlation analysis and principal component analysis (PCA) showed that there were significant positive correlations between the phenols, flavonoids, and terpenoids in SFAJ and IFAJ and their antioxidant activities. Network pharmacology and molecular docking analysis disclosed the antioxidation mechanism at the molecular level. In addition, both SFAJ and IFAJ were effective at alleviating oxidative stress in HepG2 cells. In particular, IFAJ performed better than SFAJ in protecting cells with an intracellular reactive oxygen species (ROS) level of 99.96 +/- 4.07 U/mg prot, superoxide dismutase (SOD) activity of 41.56 +/- 0.06 U/mg prot, catalase (CAT) activity of 91.78 +/- 3.85 U/mg prot, and glutathione peroxidase (GSH-Px) activity of 39.32 +/- 2.75 mU/mg prot in the IFAJ group. Collectively, this study revealed the changes in bioactive metabolite contents and the in vitro antioxidant activity during fermentation and investigated the protectiveness of SFAJ and IFAJ against oxidative stress within HepG2 cells, promoting the study of the antioxidant efficacy of IFAJ, thereby providing valuable reference data for the optimization of its preparation and the development of relevant products with health benefits.