Preliminary study on resistance of oyster and its enzymatic hydrolysis products to skin photoaging

To explore the protective effects of Hong Kong oyster (Crassostrea hongkongensis) meat (OM) and its enzymatic hydrolysis (OH) products on UV-induced photoaging of mouse (Mus musculus) skin. Ultraviolet rays (UVA+UVB) were irradiated every day to build a mouse skin photoaging model. The mice were given OM and OH daily and divided into low, medium and high dose groups (30, 90, 180 mg·kg⁻¹) for eight weeks. The results show that OM and OH can reduce mice skin wrinkles, improve skin elasticity, reduce subcutaneous blood vessel atrophy, and prevent increase in vascular permeability. The results of skin HE staining show that medium and high doses of OM and OH can slow down hyperkeratosis and epidermis thickening significantly (P<0.05). Masson staining and aldehyde fuchsin staining results show that OM and OH can reduce the curling and degradation of collagen fibers, avoid abnormal proliferation of elastic fibers, and restore the arrangement of the dermal extracellular matrix network. Compared with the model group, OM and OH can increase the enzyme activity of superoxide dismutase (SOD) and glutathione catalase (GSH-Px) in skin, while malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHDG) concentration decreased significantly (P<0.05). OM and OH can inhibit the expression of matrix metalloproteinases (MMP-3, MMP-9), and reduce the degradation of hydroxyproline (Hyp) in the dermis significantly. In addition, high doses of OH can reduce the expression of inflammatory factors, interleukin 6 (IL-6) and tumor necrosis factor (TNF-α) in the skin significantly, and increase the skin's anti-inflammatory ability by increasing transforming growth factor (TGF-β).