Background: Reactive oxygen species (ROS) generated by mitochondrial dysfunction damage cellular organelles and contribute to skin aging. Therefore, strategies to reduce mitochondrial ROS production are considered important for alleviating skin aging, but no effective methods have been identified. Methods: In this study, we evaluated substances utilized as cosmetic ingredients and discovered Camellia sinensis (C. sinensis) as a substance that reduces mitochondrial ROS levels. Results: C. sinensis extracts were found to act as senolytics that selectively kill senescent fibroblasts containing dysfunctional mitochondria. In addition, C. sinensis extracts facilitated efficient electron transport in the mitochondrial electron transport chain (ETC) by increasing the efficiency of oxidative phosphorylation (OXPHOS), thereby reducing mitochondrial ROS production, a byproduct of the inefficient ETC. This novel mechanism of C. sinensis extracts led to the restoration of skin aging and the skin barrier. Furthermore, epigallocatechin gallate (EGCG) was identified as an active ingredient that plays a key role in C. sinensis extract-mediated skin aging recovery. Indeed, similar to C. sinensis extracts, EGCG reduced ROS and improved skin aging in an artificial skin model. Conclusions: Our data uncovered a novel mechanism by which C. sinensis extract reverses skin aging by reducing mitochondrial ROS production via selective senescent cell death/increased OXPHOS efficiency. Our results suggest that C. sinensis extract or EGCG may be used as a therapeutic agent to reverse skin aging in clinical and cosmetic applications.

Oxidative stress induced by reactive oxygen species (ROS) is a major contributor to senescence. Although strategies to mitigate ROS are considered crucial for reversing this process, effective interventions remain limited. Extracts from Polygonum cuspidatum (P. cuspidatum) have shown protective effects against senescence by suppressing mitochondrial ROS production; however, the specific bioactive compound responsible for these effects has not yet been identified. This study aimed to identify the active compound in P. cuspidatum responsible for reducing mitochondrial ROS and to elucidate its mechanism of action in rejuvenating senescence. Bioactive components of P. cuspidatum extract were screened for their ability to decrease mitochondrial ROS production. The most potent compound, 2-methoxystypandrone (2-MS), was further examined for its effects on oxidative phosphorylation (OXPHOS) efficiency, mitochondrial ROS generation, and senescence-associated phenotypes in a skin cell-based model. 2-MS was identified as the most effective compound for reducing mitochondrial ROS. Mechanistically, 2-MS enhanced OXPHOS efficiency, thereby minimizing ROS production resulting from inefficient respiration. Reduction in mitochondrial ROS by 2-MS restored senescence-associated phenotypes and rejuvenated senescence by suppressing ROS-driven melanogenesis and inflammatory responses in skin cells. This study identifies 2-MS as a key active ingredient of P. cuspidatum that exerts anti-aging effects through the reduction in mitochondrial ROS generation. These findings highlight 2-MS as a promising therapeutic and cosmetic candidate for rejuvenating senescence.