Ark shell-derived oligopeptides attenuate hepatic steatosis in oleic acid induced HepG2 cell and high-fat diet induced mice.

Nonalcoholic fatty liver disease (NAFLD) is a progressive metabolic disorder with limited therapeutic options. This study investigates the hepatoprotective potential of two novel Oligopeptides, LLRLTDL (Bu1) and GYALPCDCL (Bu2), against hepatic steatosis in oleic acid (OA) induced HepG2 cells and in diet-induced obese mice. In vitro, Bu1 and Bu2 ameliorated hepatic lipid accumulation through multi-targeted mechanism; suppression of lipogenesis, attenuation of fatty acid uptake and promoting fatty acid oxidation. Both peptides downregulated key lipogenic transcription factors (PPAR-γ, SREBP-1c, C/EBPα, FAS), and moderately reduced fatty acid uptake via decreased CD36 expression. Notably, peptide treatment activated AMPK signaling, while increasing p-HSL and CPT1A expression, promoting lipolysis and fatty acid oxidation to accelerates intracellular lipid clearance. The involvement of AMPK signaling was further supported by partial attenuation of peptide effects in the presence of AMPK inhibitor Compound C. In vivo, Bu1 and Bu2 administration attenuated body weight gain, relative liver weight, hepatic lipid accumulation, and improved hepatic lipid profiles, including TG, FFA, free glycerol release, HDL, and LDL, independent of food intake. Liver histology further confirmed reversal of hepatic steatosis following peptide administration. Of note, these ameliorative effects of Bu1 and Bu2 were further substantiated at the molecular level, as evidenced by Western blot analysis. Moreover, Bu1 and Bu2 exerted anti-inflammatory effects by reducing systemic inflammatory markers and reduced hepatocellular injury, indicated by lower serum AST and ALT levels. Collectively, these findings suggest the potential of Bu1 and Bu2 as bioactive peptide-based interventions for NAFLD, offering a strong rationale for their further investigation in the treatment of metabolic liver disease.