A novel dipeptide derived from porcine liver hydrolysate induces recovery from physical fatigue in a mouse model

The present study was conducted to identify anti-fatigue peptides in porcine liver hydrolysate (LH) and to evaluate their effects. Peptides in LH were fractionated into hydrophilic and hydrophobic fractions and further into peptides with amino groups (Pep-NH2) and pyroglutamyl peptide fractions (pE). Low dose of hydrophobic Pep-NH2 fraction reversed the decrease in locomotor activity after forced walking in a mouse model upon intraperitoneal (i.p.) administration. The anti-fatigue effects of i.p. injection of Asp-Val, Asp-Leu, and Asp-Phe with α and β peptide bonds and D- and L- asparatyl residue, which appeared in blood after oral administration of LH, were examined. In particular, Asp-Leu (Lβ), Asp-Phe (Dα), and Asp-Phe (Lα) exerted anti-fatigue effects at a low concentration (0.03 mg/kg). We found that Asp-Phe (Lα), but not other dipeptides, activated adenosine monophosphate-activated protein kinase (AMPK) in the liver, indicating that Asp-Phe (Lα) could induce recovery from fatigue via AMPK activation.