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紫外线辐射除可引起皮肤急、慢性炎症反应外,也可启动皮肤内的氧化应激反应,增加活性氧水平.Nrf2-Keap1抗氧化系统具有通过调控细胞保护基因表达拮抗活性氧的作用.作为Nrf2激活剂,(-)-表没食子儿茶素-3-没食子酸酯、姜黄素和莱菔硫烷等天然抗氧化剂可通过直接清除自由基或通过间接增加内源性细胞抗氧化剂防御功能来抗氧化.其激活Nrf2的方式主要是通过不同化学结构分别与Nrf2、Keap1结合,引发构型改变,继而启动抗氧化应激反应,抵御紫外线的氧化损伤.

Ultraviolet radiation can not only induces acute and chronic inflammation in skin,but also trigger oxidative stress response tollowed by the production of reactive oxygen species (ROS).The Nrf2-Keapl system can counteract ROS via regulating the expression of protective genes in cells.As Nrf2 activators,natural antioxidants,such as (-)-epigallocatechin-3-gallate (EGCG),curcumin and sulforaphane counteract oxidative stress by directly scavenging free radicals or indirectly increasing endogenous cellular antioxidant defenses.In detail,these activators may activate Nrf2 by binding to Nrf2 or Keap1 with different chemical structures followed by alteration of configurations,which in turn initiates anti-oxidative stress response to counteract ultraviolet-induced oxidative stress.