Carboxymethyl chitosan oligosaccharide enzymatic hydroxylates with reactive oxygen species scavenging and anti-inflammatory activity for topical treatment of skin photodamage

Skin photodamage caused by ultraviolet (UV) radiation is a major public health concern. UVB rays penetrate the epidermis, inducing oxidative stress and compromising essential cellular components. The demand for natural ingredients with properties such as moisturization, anti-inflammatory effects, antioxidant protection, and compatibility is increasing to combat the impact of photodamage on the skin. Herein, the carboxymethyl chitosan oligosaccharide (CM-COS) enzymatic hydroxylates were used on the topical application of skin photodamage for the first time. CM-COS, the degradation product of carboxymethyl chitosan, has high water solubility and multiple biological activities. Results showed that CM-COS promoted human epidermal cell (HaCaT) migration without causing cytotoxicity. In photodamaged HaCaT cells, CM-COS maintained cell viability and cytoskeletal integrity while inhibiting reactive oxygen species accumulation, apoptosis, and cell cycle arrest. CM-COS regulates gene expression related to cell cycle, oxidative stress, and inflammation in UVB-radiated HaCaT based on transcriptomic and qPCR data. In UVB-exposed mice, topical treatment of CM-COS significantly alleviated redness and scab formation and increased the moisture content of photodamaged skin. Histological analyses revealed reduced epidermal thickness and increased collagen I and collagen III deposition in photodamaged skin following CM-COS treatment. Additionally, gene expression related to the cell cycle, extracellular matrix, and inflammation were significantly activated by CM-COS based on transcriptomic and qPCR data. CM-COS modulated the levels of collagen and inflammation-related proteins. Collectively, the data confirm the therapeutic effect of CM-COS against skin photodamage and highlight the potential of natural marine oligosaccharides for treating skin diseases such as aging, wounds, and burns.