High Fischer ratio oligopeptides from hard-shelled mussel: Preparation and hepatoprotective effect against acetaminophen-induced liver injury in mice

High Fischer ratio oligopeptides (HFOPs) have a variety of physiological activities, but there are few literatures reporting the hepatoprotective effects of HFOPs against acetaminophen (APAP)-induced liver injury. The objectives of this study were to establish the preparation process of HFOPs from hard-shelled mussel (Mytilus coruscus) (HFOPs-HM) and investigate the hepatoprotective effects and potential mechanisms of HFOPs-HM against APAP-induced liver injury in mice. Therefore, trypsin and papain were selected as the endo and exogenous proteases for preparing HFOPs-HM according to the degree of hydrolysis (DH) of hard-shelled mussel hydrolysates, and activated carbon of XHJ-200 displayed the best effect to remove aromatic amino acids according to the Fischer ratio (OD220/OD280) and its parameters were optimized as adsorption time of 3.0 h and solid-liquid ratio of 1:10. The HFOPs-HM's Fischer ratio and average molecular weight were 26.03 (>20) and 878.54 Da, respectively. Furthermore, a mice model of liver injury induced by APAP was established. HFOPs-HM could significantly improve liver index and histopathological features, decrease the serum alanine aminotransferase (ALT) and aspartate transaminase (AST) activities, increase the glutathione content and superoxide dismutase (SOD) and catalase (CAT) activities. Further research demonstrated that HFOPs-HM could alleviate liver oxidative stress in liver tissue via activating the Nrf2 pathway to initiate the intracellular antioxidant enzyme system. In addition, HFOPs-HM also suppressed liver inflammation by downregulating the secretion of TNF-α, IL-1β, and IL-6. Thus, HFOPs-HM could serve as an auxiliary functional dietary molecule applied in function products to alleviate drug-induced liver injury.