Vitiligo is a cutaneous depigmentation disorder caused by melanocyte injury or aberrant functioning. Oxidative stress (OS) is considered to be a major cause of the onset and progression of vitiligo. Ginsenoside Rk1 (RK1), a major compound isolated from ginseng, has antioxidant activity. However, whether RK1 can protect melanocytes against oxidative injury remains unknown. The aim of the present study was to investigate the potential protective effect of RK1 against OS in the human PIG1 melanocyte cell line induced with hydrogen peroxide (H₂O₂), and to explore its underlying mechanism. PIG1 cells were pretreated with RK1 (0, 0.1, 0.2 and 0.4 mM) for 2 h followed by exposure to 1.0 mM H₂O₂ for 24 h. Cell viability and apoptosis were determined with Cell Counting Kit‑8 and flow cytometry assays, respectively. The activity levels of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH‑Px) were analyzed using ELISA kits. Protein expression levels, including Bax, caspase‑3, Bcl‑2, phosphorylated‑AKT, AKT, nuclear factor erythroid 2‑related factor 2 (Nrf2), heme oxygenase‑1 (HO‑1), cytosolic Nrf2 and nuclear Nrf2, were analyzed using western blot analysis. In addition, the expression and localization of Nrf2 were detected by immunofluorescence. RK1 treatment significantly improved cell viability, reduced the apoptotic rate and increased the activity levels of SOD, CAT and GSH‑Px in the PIG1 cell line exposed to H₂O₂. In addition, RK1 treatment notably induced Nrf2 nuclear translocation, increased the protein expression levels of Nrf2 and HO‑1, and the ratio of phosphorylated‑AKT to AKT in the PIG1 cells exposed to H₂O₂. Furthermore, LY294002 could reverse the protective effect of RK1 in melanocytes against oxidative injury. These data demonstrated that RK1 protected melanocytes from H₂O₂‑induced OS by regulating Nrf2/HO‑1 protein expression, which may provide evidence for the application of RK1 for the treatment of vitiligo.

中文翻译：

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人参皂甙 Rk1 通过调节 PI3K/AKT/Nrf2/HO-1 通路保护人类黑色素细胞免受 H2O2 诱导的氧化损伤。

白癜风是一种由黑色素细胞损伤或功能异常引起的皮肤色素脱失性疾病。氧化应激（OS）被认为是白癜风发病和进展的主要原因。Ginsenoside Rk1 (RK1) 是一种从人参中分离出来的主要化合物，具有抗氧化活性。然而，RK1 是否可以保护黑色素细胞免受氧化损伤仍然未知。本研究旨在探讨RK1对过氧化氢(H ₂ O ₂ )诱导的人PIG1黑素细胞系OS的潜在保护作用，并探讨其潜在机制。PIG1 细胞用 RK1（0、0.1、0.2 和 0.4 mM）预处理 2 小时，然后暴露于 1.0 mM H ₂ O ₂24 小时。细胞活力和细胞凋亡分别用 Cell Counting Kit-8 和流式细胞术测定。使用ELISA试剂盒分析超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和谷胱甘肽过氧化物酶（GSH-Px）的活性水平。蛋白质表达水平，包括 Bax、caspase-3、Bcl-2、磷酸化-AKT、AKT、核因子红细胞 2 相关因子 2 (Nrf2)、血红素加氧酶-1 (HO-1)、细胞溶质 Nrf2 和核 Nrf2，使用蛋白质印迹分析进行分析。此外，通过免疫荧光检测Nrf2的表达和定位。_{在暴露于 H 2} O ₂的 PIG1 细胞系中，RK1 处理显着提高了细胞活力，降低了细胞凋亡率并增加了 SOD、CAT 和 GSH-Px 的活性水平. 此外，RK1 处理显着诱导 Nrf2 核转位，增加了暴露于 H ₂ O ₂的 PIG1 细胞中 Nrf2 和 HO-1 的蛋白质表达水平，以及磷酸化 AKT 与 AKT 的比率。此外，LY294002 可以逆转 RK1 在黑素细胞中对氧化损伤的保护作用。这些数据表明，RK1通过调节Nrf2/HO-1蛋白表达保护黑素细胞免受H ₂ O ₂诱导的OS，这可能为RK1在白癜风治疗中的应用提供证据。