Department of Fragrance and Cosmetic Science, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan.
Center for Drug Abuse and Addiction, China Medical University Hospital, Taichung, Taiwan.; China Medical University, Taichung, Taiwan.
J Ethnopharmacol. 2014;151(1):386-93. doi: 10.1016/j.jep.2013.10.054. Epub 2013 Nov 7.
In hyperpigmentation disorders marked by melanin overproduction in the skin, including melisma and freckles, melanogenesis is caused by tyrosinase overexpression. Natural medicinal resources, like Phyla nodiflora, a traditional Chinese herbal medicine, have been used for a long time to management of dermatological conditions, such as skin inflammation and melanogenesis. Eupafolin, a functional flavonoid isolated from Phyla nodiflora, is an herbal tea constituent and possesses anti-inflammatory and anticancer activities. However, molecular mechanisms of eupafolin-mediated antimelanogenesis remain unknown. We thus focused on its antimelanogenesis effects in B16F10 mouse melanoma cells.
B16F10 cells were treated with eupafolin (0.01, 0.1, 1, and 10μM) in a dose-escalation-dependent manner for the determination of melanin, tyrosinase activity and melanogenesis protein levels by ELISA or western blot analysis.
Eupafolin treatment significantly reduced cellular melanin content and tyrosinase activity in a dose-dependent manner (P<0.05), and no cytotoxic effects were observed. Eupafolin was associated with reduction in the levels of phospho-cAMP response element-binding protein and microphthalmia-associated transcription factor (MITF), and downregulation of tyrosinase synthesis and tyrosinase-related protein expression, leading to inhibit melanin production. In addition, eupafolin significantly induced the phosphorylation of ERK1/2 and p38 MAPK, whereas the decreased effect was observed in the phosphorylation of Akt. Moreover, inhibitors of these signals recovered or attenuated the inhibitory effects of eupafolin on melanogenesis.
Our results seem that inhibition of Akt and activation of phospho-ERK or p38 MAPK may lead to the suppression of melanogenesis in eupafolin-treated B16F10 mouse melanoma cells.
在以皮肤中黑色素过度生成为特征的色素沉着障碍中，包括黑斑和雀斑，黑色素生成是由于酪氨酸酶过度表达引起的。天然药用资源，如传统中药肾茶，长期以来一直用于管理皮肤炎症和黑色素生成等皮肤状况。从肾茶中分离得到的功能黄酮类化合物 eupafolin 是一种草本茶成分，具有抗炎和抗癌活性。然而，eupafolin 介导的抗黑色素生成的分子机制尚不清楚。因此，我们专注于其在 B16F10 小鼠黑色素瘤细胞中的抗黑色素生成作用。
B16F10 细胞用 eupafolin（0.01、0.1、1 和 10μM）进行剂量递增处理，通过 ELISA 或 Western blot 分析测定黑色素、酪氨酸酶活性和黑色素生成蛋白水平。
eupafolin 处理以剂量依赖性方式显著降低细胞黑色素含量和酪氨酸酶活性（P<0.05），且无细胞毒性作用。eupafolin 与磷酸化 cAMP 反应元件结合蛋白和小眼畸形相关转录因子（MITF）水平降低有关，并下调酪氨酸酶合成和酪氨酸酶相关蛋白表达，从而抑制黑色素生成。此外，eupafolin 显著诱导 ERK1/2 和 p38 MAPK 的磷酸化，而 Akt 的磷酸化则减少。此外，这些信号的抑制剂恢复或减弱了 eupafolin 对黑色素生成的抑制作用。
我们的结果表明，抑制 Akt 和激活磷酸化 ERK 或 p38 MAPK 可能导致 eupafolin 处理的 B16F10 小鼠黑色素瘤细胞中黑色素生成的抑制。
