Abstract

Prolonged exposure to ultraviolet (UV) radiation in sunlight is a major extrinsic factor that impairs skin function and accelerates photoaging. In this study, a murine model of ultraviolet B (UVB)-induced photoaging exhibited characteristic symptoms, including skin roughness, erythema, hyperpigmentation, and increased wrinkle formation. Epicatechin gallate (ECG), a natural flavonoid, has demonstrated potential skin-protective properties. However, its specific effects and mechanisms against UVB-induced photoaging are not fully understood. Here, we investigated the protective role and underlying mechanism of ECG against UVB-induced damage in human epidermal keratinocytes (HaCaT cells). Using network pharmacology, p38 mitogen-activated protein kinase (p38 MAPK), specifically the p38α isoform, was identified as a key potential target of ECG. Our experimental results confirmed that ECG significantly attenuated UVB-induced photoaging. Mechanistically, ECG treatment effectively suppressed UVB-triggered phosphorylation of p38α, promoted autophagic flux (as evidenced by increased LC3B conversion and decreased p62 levels), and substantially reduced intracellular reactive oxygen species (ROS) accumulation. Consequently, ECG mitigated mitochondrial dysfunction, restored normal cell cycle progression, and decreased the expression of senescence-associated markers (p53, p16, p21) and inflammatory cytokines (IL6, TNF-α). In summary, our findings demonstrate that ECG protects against UVB-induced photoaging primarily by inhibiting p38α activation, thereby enhancing autophagy and alleviating oxidative stress. This study positions ECG as a promising therapeutic candidate for preventing and treating skin photoaging.