Centre R&D Pierre Fabre, Applied Research Department, Pierre Fabre Dermo-cosmétique, Toulouse, France.
Brazilian Innovation Center, Pierre Fabre Dermo-cosmétique, Barra da Tijuca - Rio de Janeiro, Brasil.
Int J Cosmet Sci. 2021 Dec;43(6):691-702. doi: 10.1111/ics.12745. Epub 2021 Nov 9.
Deleterious effects of pollutants and ultraviolet radiation on the skin can be attenuated using formulations containing antioxidants. However, these have disadvantages, including chemical instability, photodegradation, poor bioavailability or biological activity. Here, two commercial formulations were evaluated: one optimized to stabilize and deliver ascorbic acid (AA) at 15% and the other containing a glucoside form of AA, namely ascorbic acid 2-glucoside (AA2G), at 1.8% and at a physiological pH. We compared the skin delivery, antioxidative effects and chemical stability of AA2G with AA in their respective formulations.
Skin delivery was measured using fresh viable human skin explants, and oxidative stress was measured using a human reconstructed epidermal (RHE) model according to levels of malondialdehyde (MDA), superoxide dismutase (SOD) and catalase.
Ascorbic acid 2-glucoside was completely metabolized to AA by the skin before entering the receptor compartment. The skin contained parent and AA, indicating a reserve of AA2G was present for further metabolism. For AA2G and AA, maximum flux of AA-equivalents was at 12 h, with continued absorption over 24 h. The absolute amount in µg was higher in the skin after application of AA than after application of AA2G. This may suggest a greater antioxidative effect; however, according to all three measurements of oxidative stress, the protective effect of AA and AA2G was similar. Unlike AA, AA2G was chemically stable under storage conditions.
A lower concentration of AA2G is as effective as the active metabolite, AA, in terms of antioxidant effects. AA2G was chemically stable and can be applied at a lower concentration than AA, thus avoiding the need for an acidic formulation with a pH below 3.5.
使用含有抗氧化剂的制剂可以减轻污染物和紫外线辐射对皮肤的有害影响。然而，这些制剂也有缺点，包括化学不稳定性、光降解、生物利用度或生物活性差。在这里，我们评估了两种商业制剂：一种是优化的制剂，可稳定并输送 15%的抗坏血酸（AA）；另一种含有 AA 的糖苷形式，即抗坏血酸 2-糖苷（AA2G），浓度为 1.8%，且处于生理 pH 值。我们比较了 AA2G 和 AA 在各自制剂中的皮肤输送、抗氧化作用和化学稳定性。
使用新鲜的活体人皮肤外植体测量 AA2G 和 AA 的皮肤输送，根据丙二醛（MDA）、超氧化物歧化酶（SOD）和过氧化氢酶的水平，用人重建的表皮（RHE）模型测量氧化应激。
AA2G 在进入受体室之前被皮肤完全代谢为 AA。皮肤中含有母体和 AA，表明存在 AA2G 的储备以进行进一步代谢。对于 AA2G 和 AA，AA-等价物的最大通量在 12 小时，24 小时内持续吸收。AA 应用后皮肤中 AA 的绝对量高于 AA2G。这可能表明 AA 具有更大的抗氧化作用；然而，根据三种氧化应激测量方法，AA 和 AA2G 的保护作用相似。与 AA 不同，AA2G 在储存条件下化学稳定。
AA2G 的浓度低于 AA 时，在抗氧化作用方面与活性代谢物 AA 一样有效。AA2G 化学稳定，可以以低于 AA 的浓度应用，从而避免需要 pH 值低于 3.5 的酸性制剂。
