Hepatoprotective Effects of Fermented <i>Laminaria japonica</i> in Oleic Acid–Induced HepG2 Cells and in a High‐Fat Diet–Induced NAFLD Mice Model via Activating the SIRT1 Signaling Pathway

Laminaria japonica is a kind of brown algal with good nutritional and medicinal value. Our previous studies demonstrated that the phytochemical components and bioactivities of Laminaria japonica were markedly enhanced by fermentation. However, the specific activity and underlying mechanism of fermented Laminaria japonica (FLJ) against NAFLD remain poorly understood. For this study, Laminaria japonica was fermented using S. cerevisiae and Lactiplantibacillus . In vitro assays were employed to evaluate the efficacy of FLJ in regulating cholesterol reduction and fat binding. In addition, the hepatoprotective effects and underlying mechanisms of FLJ in the treatment of NAFLD were evaluated using oleic acid (OA)–induced HepG2 cells and NAFLD mice. Our data revealed that FLJ significantly promoted fat‐binding and cholesterol‐reducing activity in vitro . Moreover, FLJ alleviated hepatic lipid accumulation, oxidative stress, and the inflammatory response in high‐fat diet (HFD)–induced NAFLD mice and in OA–induced HepG2 cells. The underlying protective mechanisms of FLJ against NAFLD may be attributed to the activation of the SIRT1 signaling pathway. These observations suggested that FLJ could be developed as a functional food supplement for the prevention or improvement of NAFLD.