Abstract:

The method of H₂O₂ oxidation was used for decolorization of the commercial raw tea saponin. By optimizing the H₂O₂ dosage, pH value and decolorization temperature/time, the decolorization rate of the tea saponin solution could reach up to 91%. Moreover, the decolorized tea saponin showed improved foaming property and significantly reduced cytotoxicity. Subsequently, the human immortalized sebaceous gland cell （SZ95） model was used to study the sebum control effects of decolorized tea saponin. The results showed that the lipid synthesis of SZ95 cells incubated under conventional conditions was inhibited by 24.87% in the presence of tea saponin （4 μg/mL）. For the SZ95 cells incubated under oleic acid/linoleic acid stimulation conditions, the lipid synthesis was inhibited by 14.96% and the expression of IL-8 inflammatory factors in SZ95 was also reduced by 29.01%. Therefore, tea saponin can not only significantly inhibit the lipid synthesis of SZ95 cells under normal and stimulating conditions, but also reduce the cellular inflammatory response induced by sebum imbalance, thus possibly benefiting the metabolic balance of sebaceous gland. Finally, the efficacy evaluation of a cosmetic product containing 2.5% tea saponin was carried out based on volunteers. The results showed that within 6 hours after using the product, the skin moisture content and transdermal water loss of volunteers were not significantly changed, while the sebum secretion was significantly reduced, suggesting that effective sebum control can be achieved by tea saponin-containing products without affecting the skin's moisture content and barrier function. The present research may not only promote the practical application of tea saponin in cosmetic products, but also reveal the sebum control effect of tea saponin.

Key words: tea saponin, non-ionic surfactant, H₂O₂ decolorization, anti-inflammatory