Abstract: For high-value utilization of wheat germ, the effects of wheat germ-derived peptide ADWGGPLPH on the viability of osteoblast (OB) and osteoclast (OC) in an H2O2-induced oxidative stress model were investigated in OB-OC co-culture system. Flow cytometry, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and Annexin V-fluorescein isothiocyanate/propidium iodide (FITC/PI) double staining were used to clarify the effects of wheat germ-derived peptide on OB proliferation and apoptosis in oxidative stress environment. The effects of wheat germ-derived peptide on the differentiation of OB and OC in the co-culture system under oxidative stress were determined by using alkaline phosphatase (ALP) activity assay, enzyme-linked immunosorbent assay (ELISA) and tartrate resistant acid phosphatase (TRAP) staining. The results showed that wheat germ-derived peptide effectively prevented the increase of reactive oxygen species (ROS) in OB, and enhanced the ability of OB to protect against and scavenge free radicals by suppressing malondialdehyde (MDA) generation and increasing the activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). Wheat germ-derived peptide significantly inhibited the apoptosis of OB and improved its proliferation. Annexin V-FITC/PI double staining showed that the apoptosis rate was decreased from 12.4% to 5.3%, and the viability was increased from 60.4% to 92.8% (P < 0.01). In addition, wheat germ-derived peptide prevented the decrease of ALP activity, protein type I collagen (COL-I) and osteocalcin (OCN) expression, and increased OB mineralization from 21.3% to 84.3% (P < 0.01), thus maintaining OB differentiation and ensuring normal bone mineralization. Moreover, TRAP staining results showed that wheat germ-derived peptide effectively inhibited the over-differentiation of OC under oxidative stress condition, decreasing the relative positive area of OC from 376.4% to 128.1% (P < 0.01). In conclusion, this wheat germ-derived peptide has protective effects against H2O2-induced cellular oxidative damage in OB-OC co-culture system, thereby maintaining cellular homeostasis. This finding provides a certain theoretical basis for the development and utilization of wheat germ protein.

Key words: wheat germ-derived peptide; cellular oxidative damage; osteoblast-osteoclast co-culture system; cellular homeostasis