Walnut (Juglans regia L.) meal, being the primary by-product of walnut oil processing, is rich in high-quality proteins and of significant potential for development and utilization. The study used multi-stage gradient purification, liquid-quantity chromatography, and computerized virtual screening to isolate and characterize antioxidant peptides from walnut meal. Active sites and mechanism actions of antioxidant peptides were examined using oxidative damage model of HepG2 cells. Five novel peptides exhibiting high antioxidant activity were identified, among which YR-10 significantly increased the cell viability of HepG2 oxidatively damaged cells to 20.64 %. Meanwhile, YR-10 significantly reduced the ROS content to 42.54 % and apoptosis level to 11.80 % in HepG2 oxidatively damaged cells. In addition, YR-10 competed with Nrf2 for Keap1 binding site, inhibited Keap1 (13.83 %) expression, and promoted Nrf2 (27.15 %), HO-1 (34.59 %), and SOD1 (42.67 %) expression, which ultimately activated the Keap1/Nrf2/HO-1 pathway and alleviated oxidative damage.

中文翻译：

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有氧胁迫下核桃粕中新型抗氧化肽的筛选、鉴定及机制


核桃粉 （Juglans regia L.） 是核桃油加工的主要副产品，富含优质蛋白质，具有巨大的开发利用潜力。该研究使用多级梯度纯化、液体量色谱和计算机虚拟筛选来分离和表征核桃粕中的抗氧化肽。使用 HepG2 细胞的氧化损伤模型检查抗氧化肽的活性位点和机制作用。鉴定出 5 种表现出高抗氧化活性的新型肽，其中 YR-10 显著提高了 HepG2 氧化损伤细胞的细胞活力至 20.64 %。同时，YR-10 将 HepG2 氧化损伤细胞的 ROS 含量显著降低至 42.54 %，细胞凋亡水平降低至 11.80 %。此外，YR-10 与 Nrf2 竞争 Keap1 结合位点，抑制 Keap1 （13.83%） 表达，促进 Nrf2 （27.15%） 、HO-1 （34.59%） 和 SOD1 （42.67%） 表达，最终激活 Keap1/Nrf2/HO-1 通路并减轻氧化损伤。