Component Analysis of <i>Saxifraga stolonifera</i> Extract and Its Mechanism of Melanin Inhibition

Emerging focus on cosmetic safety has propelled exploration of plant-derived whitening agents. Saxifraga stolonifera, a traditional Chinese herb, was investigated for its whitening potential through its ethanol extract (S. stolonifera extract [SSE]). The main components were determined by high performance liquid chromatography (HPLC)-Q-TOF-MS/MS. In vitro analyses, antioxidant activity and tyrosinase (TYR) inhibition of SSE were revealed. Anti-melanogenic efficacy was systematically validated using three models: B16F10 cells, zebrafish embryos, and 3D reconstructed pigmented skin model. Mechanistic studies demonstrated SSE modulates melanogenesis by targeting the mTOR complex 1 (mTORC1)-TYR axis, downregulating TYR expression at mRNA/protein levels. Molecular docking revealed the binding affinities of SSE with mTOR domain, similar to arbutin's mechanism. Consequently, these findings suggest that SSE may function as a promising natural ingredient for cosmetic formulations, offering potent skin-whitening properties through melanogenesis inhibition.