柑橘類黃酮屬於一種植物多酚類且具有抗氧化的性質，是很有潛力使用於營養補充品及 化妝品中。本研究利用偵測皮膚角質層蛋白質羰基暴露的方法，在有曝曬陽光的條件下評估 三種柑橘類黃酮(橙皮素、柚皮素及槲皮素)對人類角質層蛋白質羰基化的影響，以做為研製抗 氧化化妝品的重要參考。結果顯示含0.5% (w/w) 的柚皮素並沒有顯著的抗光氧化效力，而使 用相同濃度的橙皮素及槲皮素則顯現有輕微的抗光氧化效力，但二者之間的差異性並不大。 我們推論這三種柑橘類黃酮在皮膚角質層中與主要的抗氧化劑-Vit E 之間所能產生的抗氧 化協同效應是微弱的，我們建議使用這三種柑橘類黃酮運用於抗光老化的化妝保養品的開 發，尚需要再添加其他具有確效性的抗氧化劑，以提升產品配方總體的抗光氧化效能。

Citrus flavonoids possess the polyphenol’s chemical structure feature and antioxidant properties. They are great potential for use in nutritional supplements and cosmetics. In this study, we detected the changes in the exposed protein carbonyl group level in the most outer layer of the human stratum corneum under natural sunlight exposure in the presence of flavonoid and compared this to the level without flavonoid. Three citrus flavonoids (hesperetin, naringenin, and quercetin) were examined by this in vivo test platform. The results indicated that 0.5% (w/w) of naringenin represented an insignificant antioxidative capability. The hesperetin and quercetin had a slight antioxidative capability using the same concentration. We suggested that the anti-oxidative synergistic effect of the individual flavonoid and -Vit E is weak in the human stratum corneum. Thus, we recommend that the three citrus flavonoids used in anti-photoaging cosmetic products, still need to add validity of other antioxidants to enhance overall product formulations against photo-oxidation performance.