Abstract:

Skin care products with carbonic acid （H₂CO₃） have gained extensive attention worldwide. However, the conversion of CO₂ to H₂CO₃ is not stable, and the mechanism of the effect of H₂CO₃ on skin care has not been clearly proved. The hydration-dissolution behaviors of CO₂ were investigated under different temperature, pH, and pressure conditions. Moreover, based on the phenomenon of CO₂ hydration transformation, the inflammatory effect of CO₂ hydrate on macrophages （RAW 264.7） was investigated. The result shows that the increase in temperature weakened the hydration of CO₂, and the increase in pH and pressure both promoted the water-phase transformation of CO₂. When pH<6, CO₂ reacts with water to generate H₂CO₃. When pH was between 6-7, the prompt solution was a mixture of H₂CO₃ and HCO₃^-. When the pH was between 7-9, they mainly generated HCO₃^-. And when pH>9, CO₂ solubility mainly converts to CO₃^2-. Besides, CO₂ can inhibit the secretion of inflammatory factors by RAW 264.7 cells by inhibiting the phosphorylation of the p38 protein. CO₂ hydrate inhibited the expression of pro-inflammatory factors IL-6, TNF-α, and up-regulated the expression of anti-inflammatory factor IL-10. Furthermore, the anti-inflammatory molecular mechanism of CO₂ hydration inhibited the MAPK signaling pathway by inhibiting the phosphorylation of p38. The hydration-dissolution behavior of CO₂ was investigated. This work revealed the anti-inflammatory bioeffect of CO₂ hydrate, providing a theoretical basis and application support for CO₂ skin care products.

Key words: CO₂, hydration transformation, anti-inflammatory effect, skin care