Study on the Protective Effect and Underlying Mechanisms of <i>Sarcandra glabra</i> Extract Against UVB-Induced Photodamage in Zebrafish

Objective: Ultraviolet B (UVB) irradiation primarily causes skin photoaging by disrupting redox homeostasis, triggering inflammatory responses, and accelerating collagen loss. Sarcandra glabra extract (SGE) is a traditional Chinese herbal extract rich in bioactive compounds and exhibits potential anti-inflammatory and antioxidant activities. Methods: This study used a zebrafish model to investigate the protective effect and molecular mechanism of SGE against UVB-induced photodamage. Results: High-performance liquid chromatography (HPLC) analysis identified rosmarinic acid as the main bioactive component in SGE, with a mass fraction of 4.67%, while safety evaluations showed that it showed no significant toxicity toward zebrafish at concentrations of 10 μg/mL or lower. After establishing the UVB zebrafish photodamage model, different SGE concentrations were administered, which alleviated UVB-induced mortality, repaired caudal fin damage, reduced the apoptosis rate, and decreased the intracellular reactive oxygen species levels in zebrafish in a dose-dependent manner. Further, SGE significantly enhanced the superoxide dismutase, catalase, and glutathione peroxidase activity, while decreasing the malondialdehyde content in the UVB-irradiated zebrafish, effectively mitigating oxidative stress injury. At the molecular level, SGE significantly inhibited the abnormal upregulation of the cox-2 and IL-1β inflammation-related genes induced by UVB. It also promoted the transcriptional expression of the col1a1a and col1a1b type I collagen-encoding genes, breaking the detrimental oxidative stress-inflammation-collagen loss cycle. Conclusions: The findings of this study indicate that SGE possesses excellent anti-inflammatory, antioxidant, and anti-UVB photodamage properties and can be used as a natural bioactive ingredient in skincare products.