A Novel Whey Protein Isolate-Proanthocyanidins Complex Alleviates Muscle Atrophy by Modulating Oxidative Stress

The study fabricated a whey protein isolate-proanthocyanidins (WPI-PC) non-covalent complex, and evaluated its anti-muscle atrophy effects based on the D-galactose-induced C2C12 senescent cell model and the sarcopenia mouse model. Results showed the complex's optimal preparation conditions: reaction time 1 h, pH 6.5, and WPI:PC = 1:1. Under the above conditions, at sample concentrations of 5 mg/mL and 1 mg/mL, the protein digestibility and DPPH radical scavenging rate reached 86.67 ± 0.97% and 60.74 ± 0.45%, respectively. The antioxidant capacity of the WPI-PC complex was significantly increased compared with WPI, while the protein digestibility of the WPI-PC complex was decreased. 4 mg/mL WPI-PC complex significantly increased the proliferation rate of C2C12 cells induced by 0.32 M and 0.16 M D-galactose by 33.50% and 30.45%, respectively. The sarcopenia mouse model results showed that gavage of the WPI-PC complex significantly increased superoxide dismutase (SOD), while malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) contents were markedly lower relative to model group (P < 0.05). Gavaged of WPI-PC-L (250 mg/kg/d.bw) significantly increased the levels of skeletal muscle mass index (SMI) relative to the model group (P < 0.05). The WPI-PC complex significantly elevated muscle cross-sectional area and type II muscle fibers proportion (P < 0.05). In conclusion, the WPI-PC complex could alleviate oxidative stress, thereby improving skeletal muscle atrophy. This study demonstrated great application potential of natural active ingredients and proteins in alleviating age-related diseases through non-covalent complexation.