Unraveling the time-dependent mechanism of quercetin glycosides from natural green silk in ameliorating UV-induced photoaging

Abstract

Skin photoaging, driven by chronic ultraviolet (UV) exposure, represents a growing global health concern, with epidemiological studies linking cumulative UV exposure to increased skin cancer risk and accelerated aging phenotypes. Quercetin glycosides, such as rutin and isoquercitrin, exhibit superior antioxidant and UV-protective properties. Different quercetin glycosides possess distinct physicochemical properties and biological functions. This study aimed to investigate the protective and reparative effects of quercetin glycosides (QGT), natural antioxidants derived from green silk, against skin photoaging and to elucidate their time-dependent efficacy. Human keratinocytes and fibroblasts were exposed to UVB irradiation (50 mJ cm⁻²) and treated with 40 µM QGT at multiple time points (24, 48, and 72 h) either prior to or following UV exposure. Cell viability, collagen metabolism, DNA damage, and reactive oxygen species (ROS) scavenging were evaluated. Our findings reveal that pre- and post-treatment are equally effective within 24 h, whereas post-treatment becomes superior beyond 48 h. During short-term action, QGT primarily functions via direct antioxidant capacity to neutralize the acute ROS burst, with both pre- and post-treatment effectively mitigating initial damage. Critically, during prolonged intervention (48–72 h), pre-treatment efficacy diminishes due to QGT depletion, whereas post-treatment demonstrates superior advantage through sustained ROS clearance, suppression of MMP-1 expression, activation of the TGF-β collagen synthesis pathway, preservation of DNA integrity, and synergistic engagement of endogenous repair systems. In conclusion, QGT functions as a multi-target photoprotective agent by disrupting the injury cascade and empowering cellular self-repair. The advantage of post-treatment lies in the fact that its delayed protection function precisely targets the ultraviolet-induced delayed and cumulative damage. This work provides a solid scientific foundation for considering natural green silk as a functional wear-and-care skincare material.