Silver Tip (Camellia sinensis) Extract Promotes Supersulfide Biosynthesis in Keratinocytes

"Supersulfides" is a general term for compounds containing multiple sulfur atoms within their molecules. Owing to their potent anti-oxidant and anti-inflammatory activities, these species are promising ingredients in the field of cosmetics. In this study, we elucidated the effect of silver tip (Camellia sinensis) tea on supersulfide production in epidermal keratinocytes. Silver tip extract increased the fluorescence intensity of sulfane sulfur probe 4 (SSP4) in a concentration-dependent manner and promoted supersulfide production in keratinocytes. In particular, (-)-epicatechin gallate and (-)-epigallocatechin gallate exhibited high SSP4 fluorescence intensity, indicating that these are the active components. Mechanistic analysis using quantitative polymerase chain reaction revealed that silver tip extract promotes intracellular supersulfide production by regulating supersulfide-related metabolic factors (cysteinyl-tRNA synthetase 2, cystathionine β-synthase, cystathionine γ-lyase, solute carrier family 7 member 11, and nuclear factor E2-related factor 2). Furthermore, these compounds significantly increased the supersulfide levels by reacting with sodium sulfide, a hydrogen sulfide donor, in buffer solution, thereby catalytically enhancing supersulfide production. Overall, the results of this study indicate that silver tip extract, rich in polyphenols, regulates supersulfide metabolism in keratinocytes, suggesting its potential as an anti-aging ingredient for the skin.