Functional Characterization of Naematelia aurantialba Basidiospore Polysaccharides in L929 Cells: Photoprotective, Antioxidant, and Anti-Inflammatory Effects Against UVB-Induced Damage.

Ultraviolet (UV) radiation is a primary driver of skin photoaging, characterized by oxidative stress, persistent inflammatory responses, and excessive degradation of the extracellular matrix (ECM). Naematelia aurantialba is a traditional medicinal and edible fungus recognized for its diverse pharmacological activities. In this study, N. aurantialba polysaccharides (NAPS-A)-high-value bioactive compounds obtained through liquid fermentation-were subjected to detailed functional characterization to evaluate their restorative potential against UVB-induced damage. The results demonstrated that NAPS-A treatment effectively mitigated UVB-induced cytotoxicity. Furthermore, NAPS-A significantly suppressed the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), while robustly revitalizing the endogenous antioxidant defense system by restoring superoxide dismutase (SOD) and catalase (CAT) activities. Moreover, NAPS-A exerted potent anti-inflammatory effects by inhibiting the secretion of nitric oxide (NO) and pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α. NAPS-A maintained ECM homeostasis by counteracting collagen depletion, exhibiting inhibitory activity against collagenase and elastase, and modulating the mRNA expression of Col1a1 and Col3a1. These findings suggested that NAPS-A protects fibroblasts from UVB-induced damage through a synergistic mechanism involving radical scavenging, the enhancement of cellular redox homeostasis, and the modulation of ECM metabolism. Overall, NAPS-A represents a promising, sustainably produced, food-derived bioactive ingredient with significant potential for the development of functional foods and nutricosmetics aimed at mitigating UVB-induced skin damage.