在不影响细胞活力的情况下,表没食子儿茶素没食子酸酯(EGCG),gallocatechin没食子酸酯(GCG),茶黄素-3,3'-二甲酸盐(TFDG),已发现或theasinensinA(TSA)可有效降低细胞内黑色素含量和酪氨酸酶(TYR)活性。然而,对上述样品的抗黑色素生成机制的研究仍然薄弱,和这些样品在分子水平上调节黑素生成的活性缺乏比较。以α-黑素细胞刺激素(α-MSH)刺激和无α-MSH刺激的B16F10细胞为模型,EGCG的作用,GCG,TFDG,或TSA对细胞表型和黑素生成相关关键靶标的表达进行了研究。结果显示,在添加或不添加四个样品的情况下,α-MSH总是促进黑素生成。同时,四个样品的抗黑色素生成活性不受是否在培养基中添加α-MSH和α-MSH添加时间的影响。在此基础上,100微克/毫升EGCG,GCG,TFDG,或TSA不影响TYR催化活性,但部分通过下调黑皮质素1受体(MC1R)抑制黑色素形成,小眼症相关转录因子(MITF),还有TYR家族.儿茶素对TYR家族和MITF表达的下调能力在转录和翻译水平上均强于二聚体。而二聚体下调MC1R表达的能力在转录和翻译水平上都强于儿茶素。分子对接结果表明,这四个样品均能稳定结合MC1R蛋白。一起来看,这项研究提供了EGCG抗黑色素生成活性的分子机制,GCG,TFDG,和TSA,作为对抗紫外线诱导的鞣制反应的潜在有效成分,并确定了关键靶标(MC1R)。
Without affecting cell viability, epigallocatechin gallate (EGCG), gallocatechin gallate (GCG), theaflavine-3,3\'-digallate (TFDG), or theasinensin A (TSA) have been found to effectively reduce intracellular melanin content and tyrosinase (
TYR) activity. However, studies on the anti-melanogenic mechanism of the above samples remain weak, and the activities of these samples in regulating melanogenesis at the molecular level lack comparison. Using B16F10 cells with the α-melanocyte-stimulating hormone (α-MSH) stimulation and without the α-MSH stimulation as models, the effects of EGCG, GCG, TFDG, or TSA on cell phenotypes and expression of key targets related to melanogenesis were studied. The results showed that α-MSH always promoted melanogenesis with or without adding the four samples. Meanwhile, the anti-melanogenic activities of the four samples were not affected by whether the α-MSH was added in the medium or not and the added time of the α-MSH. On this basis, the 100 µg/mL EGCG, GCG, TFDG, or TSA did not affect the
TYR catalytic activity but inhibited melanin formation partly through downregulating the melanocortin 1 receptor (MC1R), microphthalmia-associated transcription factor (MITF), and the
TYR family. The downregulation abilities of catechins on the
TYR family and MITF expression were stronger than those of dimers at both the transcription and translation levels, while the ability of dimers to downregulate the MC1R expression was stronger than that of catechins at both the transcription and translation levels to some extent. The results of molecular docking showed that these four samples could stably bind to MC1R protein. Taken together, this study offered molecular mechanisms for the anti-melanogenic activity of the EGCG, GCG, TFDG, and TSA, as potential effective components against the UV-induced tanning reactions, and a key target (MC1R) was identified.