Hepatoprotective and antioxidant effects of porcine plasma protein hydrolysates on carbon tetrachloride-induced liver damage in rats

Porcine plasma protein hydrolysate (PPH) prepared by alcalase for 5 h was fractioned by ultrafiltration. Four fractions, H₁ (MW > 10k), H₂ (MW 6-10k), H₃ (MW 3-6k) and H₄ (MW < 3k), were obtained. H₄ possessed the highest antioxidant activity as indicated by thiobarbituric acid-reactive substance values and hydroxyl radical scavenging activity (P < 0.01). Male rats were pretreated with H₄ at dose of 50, 100, and 200 mg/kg of body weight orally once daily for 12 days, then they were treated intraperitoneally with a single dose of CCl₄ (2 mL/kg of body weight). The results showed that oral feeding of H₄ could significantly lower (P < 0.01) the serum levels of hepatic enzyme markers (aspartate transaminase and alanine transaminase). Compared with the CCl₄-only treatment group, levels of hepatic superoxide dismutase, glutathione peroxidase, catalase and total antioxidant capacity were significantly increased, and the malondialdehyde levels were sharply decreased (P < 0.01) in rats treated by all doses of PPH fraction H₄. A histological examination of the liver showed that lesions, including necrosis, lymphocyte infiltration and fatty degeneration, were partially healed by treatment with H₄ fractions. These data suggest that in rats, PPH can protect the liver against CCl₄-induced oxidative damage.