Water‐soluble intracellular extract of Desmodesmus sp. YT enhanced the antioxidant capacity of human skin fibroblast to protect the skin from UV damage

Abstract Background The oxidative stress induced by ultraviolet (UV) radiation is a pivotal factor in skin aging and can even contribute to the development of skin cancer. Aim This study explored the antioxidant effect and mechanism of water‐soluble intracellular extract (WIE) of Desmodesmus sp.YT (YT), aiming to develop a natural antioxidant suitable for incorporation into cosmetics. Methods The study evaluated the scavenging capacity of YT‐WIE against free radicals and assessed its impact on human skin fibroblasts (HSF) cell viability and UV resistance using Cell Counting Kit‐8 (CCK‐8). Transcriptome sequencing was employed to elucidate the mechanism of action, while RT‐qPCR and western blot were used to validate the expression of key genes. Results YT‐WIE displayed robust antioxidant activity, demonstrating potent scavenging abilities against 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH; IC50 = 0.55 mg mL −1 ), 2,2′‐Azino‐bis (3 ethylbenzothiazoline‐6‐sulfonic acid; ABTS; IC50 = 3.11 mg mL −1 ), Hydroxyl (·OH; IC50 = 2.21 mg mL −1 ), and Superoxide anion (O 2 •− ; IC50 = 0.98 mg mL −1 ). Furthermore, compared to the control group, the YT‐WIE group exhibited an 89.30% enhancement in HSF viability and a 44.63% increase in survival rate post‐UV irradiation. Significant upregulation of antioxidant genes ( GCLC , GCLM , TXNRD1 , HMOX1 , NQO1 ) was observed with YT‐WIE treatment at 400 μg mL −1 , with fold increases ranging from 1.13 to 5.85 times. Conclusion YT‐WIE demonstrated considerable potential as an antioxidant, shielding human cells from undue oxidative stress triggered by external stimuli such as UV radiation. This suggests its promising application in cosmetics antioxidants.