Polypeptides extracted from Eupolyphaga sinensis walker via enzymic digestion alleviate UV radiation-induced skin photoaging

The traditional medicine-Eupolyphaga sinensis walker is a rich source of functional proteins and peptides. In this study, Eupolyphaga sinensis walker were identified to include fifteen amino acids, of which hydrophobic amino acids accounted for 46.7%. Eupolyphaga sinensis walker polypeptides (EPs) were extracted by sequentially hydrolyzing with pepsin and trypsin. EPs could effectively scavenge 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·), superoxide anion radical (O2−·), and hydroxyl radical (OH-·), and reduce ferric solution in vitro. EPs also enhanced the activities of Ssuperoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPH-Px), increased the contents of hydroxyproline (HYP), and reduced the content of Malondialdehyde (MDA) in photoaged mice skin. Histological study confirmed that EPs improved UV irradiation-induced damage of skin texture and morphology. Therefore, the extracted EPs are effective antioxidants and can serve as powerful treatment for skin photoaging.