Kato Shinya, Saitoh Yasukazu, Miwa Nobuhiko
Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Nanatsuka 562, Shobara, Hiroshima 727-0023, Japan.
J Nanosci Nanotechnol. 2013 Jan;13(1):52-9. doi: 10.1166/jnn.2013.6848.
We investigated the anti-melanogenetic efficacy of hydrogen-occluding silica microcluster (H2-Silica), which is a silsesquioxane-based compound with hydrogen interstitially embedded in a matrix of caged silica, against melanogenesis in HMV-II human melanoma cells and L-DOPA-tyrosinase reaction [EC1.14.18.1]. HMV-II cells were subjected to oxidative stress by ultraviolet ray-A (UVA) exposure of 3-times of 0.65 J/cm2 summed up to 1.95 J/cm2. After UVA irradiation, HMV-II cells were stimulated to produce melanin by 2.72-fold more abundantly than unirradiated control. When HMV-II cells were treated with H2-Silica of 20 ppm or kojic acid of 28.4 ppm before and after UVA-irradiation, the amount of melanin was repressed to 12.2% or 14.5% as compared to that of UVA-irradiated control, respectively. That is, H2-Silica exhibited a comparable efficacy to the whitening agent kojic acid. The H2-Silica could prevent melanogenesis in HMV-II cells by low-level doses at 1-10 ppm, and cell viability and apoptosis event did not change even by high-level doses at 100-1000 ppm. On the contrary, kojic acid was cytotoxic at the concentration of 14-28 ppm or more. By microscopic observation, H2-Silica suppressed such properties indicative of melanin-rich cells as cellular hypertrophy, cell process formation, and melanogenesis around the outside of nuclei. The enzymatic assay using L-DOPA and mushroom tyrosinase demonstrated that H2-Silica restrained UVA-mediated melanin formation owing to down-regulation of tyrosinase activity, which could be attributed to scavenging of free radicals and inhibition of L-DOPA-to-dopachrome oxidation by hydrogen released from H2-Silica. Thus H2-Silica has a potential to prevent melanin production against UVA and serves as a skin-lightening ingredient for supplements or cosmetics.
我们研究了储氢二氧化硅微团簇（H2 - 二氧化硅）的抗黑素生成功效，它是一种基于倍半硅氧烷的化合物，氢间隙性地嵌入笼状二氧化硅基质中，研究其对HMV - II人黑素瘤细胞中黑素生成及L - 多巴 - 酪氨酸酶反应[EC1.14.18.1]的影响。通过3次0.65 J/cm2的紫外线A（UVA）照射，总计1.95 J/cm2，使HMV - II细胞受到氧化应激。UVA照射后，HMV - II细胞产生黑色素的量比未照射的对照细胞多2.72倍。当在UVA照射前后用20 ppm的H2 - 二氧化硅或28.4 ppm的曲酸处理HMV - II细胞时，与UVA照射的对照相比，黑色素的量分别被抑制到12.2%或14.5%。也就是说，H2 - 二氧化硅表现出与美白剂曲酸相当的功效。H2 - 二氧化硅在1 - 10 ppm的低剂量下就能防止HMV - II细胞中的黑素生成，即使在100 - 1000 ppm的高剂量下，细胞活力和凋亡事件也不会改变。相反，曲酸在14 - 28 ppm或更高浓度时具有细胞毒性。通过显微镜观察，H2 - 二氧化硅抑制了诸如细胞肥大、细胞突起形成以及细胞核周围黑素生成等富含黑色素细胞的特征。使用L - 多巴和蘑菇酪氨酸酶的酶活性测定表明，H2 - 二氧化硅由于酪氨酸酶活性的下调抑制了UVA介导的黑色素形成，这可能归因于自由基的清除以及H2 - 二氧化硅释放的氢对L - 多巴向多巴色素氧化的抑制。因此，H2 - 二氧化硅有潜力预防UVA诱导的黑色素生成，并可作为补充剂或化妆品中的美白成分。
