Dendrobium nobile Lindl Polysaccharides Attenuate UVB‐induced Photodamage by Regulating Oxidative Stress, Inflammation and MMPs Expression in Mice Model

Acute ultraviolet B (UVB) irradiation predominantly leads to various skin disorders caused by photodamage. The major causes of UVB‐induced photodamage include oxidative stress, inflammatory infiltration and collagen degradation. The aim of the study was to elucidate whether DNP had protective effect on the skin of KM mice when exposed to UVB irradiation. The DNP protective properties to skin appearance and histopathological alterations in KM mice were evaluated by hematoxylin–eosin staining, toluidine blue staining, Gomori staining and Masson's trichrome staining and mast cell staining. In this study, DNP pretreatment promoted the activities of antioxidant enzymes, including superoxide dismutase, catalase and glutathione peroxidase, while decreased malondialdehyde level in UVB‐irradiated skin, along with downregulation of proteins expression of matrix metalloproteinases and reduction in the level of the proinflammatory cytokines. Based on these findings, we demonstrated that DNP displayed strong ameliorative effects on UVB‐induced acute photodamage for the first time, indicating that it would be a promoting ingredient candidate that could be used in antiphotodamage.