Anti-inflammatory, Anti-aging, Antioxidant, and Anti-melanogenesis Effects of Extracts from Toona sinensis Leaf

Background: Many researchers have developed cosmetic and medicinal ingredients using natural plant extracts to regulate and improve the skin health. We investigated Toona sinensis leaf (TSL) extract as a potential functional cosmetic ingredient by testing its pharmacological effects on skin cells. Methods and Results: The anti-inflammatory and anti-aging effects of TSL were evaluated in tumor necrosis factor (TNF)-α-stimulated human epidermal keratinocytes (HaCaT) and human dermal fibroblasts (HS68) by quantitative reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay. Notably, TSL antioxidant effects were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. Its anti-melanogenic activity of TSL was determined by quantifying extracellular and intracellular melanin content in α-melanocyte stimulating hormone (α-MSH)-stimulated B16F10 melanoma cells. Furthemore, its inhibitory effects on mushroom tyrosinase activity was investigated. Western blotting was performed to identify the anti-melanogenesis mechanism. Notably, TSL decreased interleukin (IL)-6, IL-8, and matrix metalloproteinase (MMP)-1 expression in TNF-α-stimulated HaCaT and HS68 cells. Furthermore, TSL inhibited DPPH radical activity in a concentration-dependent manner, significantly reduced α- MSH-induced intra/extracellular melanin production in B16F10 cells, and inhibited mushroom tyrosinase activity. Additionally, TSL treatment decreased protein levels of melanogenic enzymes.<br/>Conclusion: Notably, TSL demonstrated anti-inflammatory, anti-aging, antioxidant, and anti-melanogenetic effects on skin cells, confirming its protective effects on skin physiology and suggesting its potential as a functional cosmetic ingredient.