Abstract:The protective mechanism of gelatin against ultraviolet irradiation-induced photoaging of skin was investigated in this study. Gelatin derived from pacific-salmon skin (SG) was extracted using hot water and the molecular weight and amino acid composition analyzed. Institute of Cancer Research (ICR) mice were randomly divided into five groups, with ten mice per group: normal group (NC), model group (MC), vitamin C group (PC), low dose SG treatment group (SG-L), and high dose SG treatment group (SG-H). The activities of total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were measured in skin tissues, as were the levels of malondialdehyde (MDA) and hydroxyproline (HYP). The protective effects of SG on photoaging were evaluated by haematoxylin and eosin staining and Masson’s trichrome staining. The results indicated that the average molecular weight of SG was 81.31 Ku. Glycine accounted for approximately one-third of the total amino acids in SG, and 49.57% of amino acids were hydrophobic. Cysteine and tryptophan were not detected in SG. SG could protect collagen fibers against UV irradiation-induced photodamage. Compared with the control group, the SG-H group exhibited significantly enhanced activity of T-SOD (P < 0.05), increased levels of HYP (P < 0.01), and reduced levels of MDA（P<0.05). In addition, average activities of CAT and GSH-Px increased by 23.70% and 28.30%, respectively, in the SG-H group. This study shows that SG can effectively protect mouse skin from UV irradiation-caused photodamage.
