Antioxidant and anti-inflammatory peptide fraction from salmon byproduct protein hydrolysates by peptic hydrolysis

Salmon byproduct protein was hydrolyzed with six proteases, and antioxidant activities of salmon byproduct protein hydrolysates (SPHs) were evaluated. The peptic hydrolysates from SPHs showed the highest antioxidant activity compared to that of the other protease hydrolysates, and were further fractionated into four fractions by size-exclusion chromatography. The SPH fractions (SPHFs) showed 2,2-diphenyl-1-picrylhydrazyl and hydrogen peroxide scavenging activity, and SPHF1 exhibited the highest antioxidant activity. SPHF1 contained 1000-2000 Da molecular weight peptides and antioxidant amino acids such as Tyr, Phe, Pro, Ala, His, and Leu, which accounted for 28.62% of the total amino acids. SPHF1 showed no cytotoxic effects on Chang liver or RAW264.7 macrophage cells, and it significantly inhibited intracellular reactive oxygen species generation, lipid peroxidation, and enhanced the level of glutathione in Chang liver cells. Additionally, SPHF1 showed anti-inflammatory activity by inhibiting nitric oxide production and proinflammatory cytokines including tumor necrosis factor-α, interleukin-6 and -1β in RAW264.7 macrophage cells.

► Salmon byproduct protein hydrolysates (SPHs) possessed strong antioxidant activity. ► The SPHF with high antioxidant activity was obtained by size-exclusion chromatography. ► The SPHF with 1-2 kDa peptides showed the highest antioxidant activity in Chang liver cells. ► The SPHF exhibited anti-inflammatory in LPS-induced RAW264.7 macrophage cells.