Hepatoprotective Effect of Myricetin following Lipopolysaccharide/DGalactosamine: Involvement of Autophagy and Sirtuin 1.

Background: Acute liver injury (ALI) is a critical and fatal disorder associated with excessive oxidative stress and inflammation, ultimately leading to the death of hepatocytes. Myricetin is a bioflavonoid in some berries, including blueberries and strawberries, with anti-inflammatory, antioxidant and anti-apoptotic properties.

Objective: In the current research, the hepatoprotective potential of myricetin was studied in the LPS/D-GalN model of ALI in C57BL/6 mice.

Methods: For inducing liver injury, D-GalN (400 mg/kg) and LPS (50 µg/kg) were injected via intraperitoneal route and myricetin was orally administered (25 or 100 mg/kg/day) for two days before inducing injury. Functional indices of liver dysfunction along with hepatic apoptotic, autophagic, oxidative stress and inflammatory factors were measured.

Results: Myricetin (100 mg/kg) reduced the fatality rate of animals and pathological liver changes and suitably lowered serum levels of total bilirubin, 8-OH-dG, ALT, AST and ALP in addition to decreasing apoptotic, oxidative and inflammatory factors, NOX, NLRP3, caspase 3, MPO and enhancing some antioxidants. Besides, myricetin improved the hepatic level and activity of sirtuin 1 and reversed inappropriate alterations of autophagic parameters, including LC3 II, Beclin 1, and P62. The beneficial effects of myricetin were attenuated after co-treatment with the autophagy inhibitor 3- methyladenine.

Conclusion: This study indicates the hepatoprotective potential of myricetin that can be ascribed to its down-regulation of oxidative, apoptotic, and inflammatory factors and upregulation of antioxidants besides its partial regulation of sirtuin 1 and autophagic pathway.