Abstract: The protective effect of the pentapeptide Leu-Pro-Leu-Leu-Arg (LPLLR) from manchurian walnut (Juglans mandshurica Maxim) meal protein on PC12 cells against hydrogen peroxide (H2O2)-induced damage were investigated and the underlying mechanism was elucidated based on the NF-κB/iNOS/NO signaling pathway. The results showed that LPLLR had no cytotoxicity and significantly increased the survival rate of PC12 cells suffering from oxidative stress induced by H2O2. LPLLR could reduce the production of reactive oxygen species (ROS) and malondialdehyde (MDA), and enhance the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) and acetylcholine (ACh) level (P < 0.05, P < 0.001) in H2O2-induced PC12 cells. ELISA and Western blotting results confirmed that LPLLR could up-regulate the expression of SOD2 and down-regulate the expression of nuclear transcription factor-κB (NF-κB) p65 and inducible nitricoxide synthase (iNOS), as well as decrease the secretion of NO (P < 0.05, P < 0.001). Therefore, LPLLR can protect PC12 cells against hydrogen peroxide-induced injury.

Key words: walnut protein-derived peptides, hydrogen peroxide, PC12 cells, oxidative stress