茶黄素与EGCG抑制体内外β-淀粉样蛋白1-42水平及其诱导的神经细胞氧化损伤

摘要

In this study, amyloid β-protein Aβ42 was incubated with EGCG, TF, TF-3-G, TF-3'-G, TF-DG at the ratio of 1:1 and 1:5 under simulated physiological condition. The contents ofβ-sheets after incubation were tested by thioflavin T fluorometric assay. It was found that EGCG and theaflavins could suppress the formation ofβ-sheet structure, thereby inhibiting aggregations of Aβ42. In addition, an SH-SY5Y cell damage model was established and MTT assay was used to examine cell viabilities when 20 μmol·L-1 Aβ42 was incubated with different concentrations of EGCG and theaflavins (10, 50, 100μmol·L-1). Intracellular reactive oxygen species (ROS) levels, antioxidant enzyme activities (GSH-Px) and MDA levels were also measured. The results showed EGCG and theaflavins treatments could alleviate the Aβ42 induced oxidative damage to neural cells by reducing ROS and increasing the activity of GSH-Px. To study the in vivo protective effects of EGCG and theaflavins, SAMP8 mice were treated with 10 mg·kg-1·d-1 EGCG or theaflavins respectively by gavage for 10 weeks, and the contents of Aβ42 and AGEs in mouse serum were determined. The results showed that EGCG and theaflavins significantly decreased the content s of Aβ42 and AGEs in SAMP8 serum. In summary, EGCG and theaflavins could inhibit the aggregations of Aβ42 and reduce oxidative injury induced by Aβ42 in neural cells, thereby exerting protective effects on AD.%通过模拟生理条件体外实验，将β-淀粉样蛋白1-42（Aβ42）与EGCG和4种茶黄素单体分别按照1︰1和1︰5比例进行孵育，采用硫黄素 T 荧光检测β-折叠结构的生成量，结果表明，EGCG 与茶黄素均能明显降低β-折叠结构生成，从而抑制Aβ42聚集；此外，通过建立20μmol·L-1 Aβ42诱导人神经母细胞瘤SH-SY5Y细胞损伤模型，将不同浓度的 EGCG 或茶黄素（10、50、100μmol·L-1）处理后，MTT 法检测细胞存活率，同时，检测细胞内活性氧（ROS）、谷胱甘肽过氧化物酶（GSH-Px）及丙二醛（MDA）等抗氧化指标，结果表明， EGCG 与茶黄素可抑制因 Aβ42诱导 SH-SY5Y 细胞活力下降及氧化损伤。体内实验中，通过10 mg·kg-1·d-1的 EGCG 或茶黄素处理快速老化模型小鼠（SAMP8），10周后检测小鼠血清 Aβ42及晚期糖基化终末产物（AGEs）含量，结果表明，EGCG和茶黄素可显著降低SAMP8小鼠血清中 Aβ42及 AGEs含量。本研究表明了茶黄素和 EGCG 可抑制 Aβ42聚集纤维化及 Aβ42导致的神经氧化损伤，从而对阿尔茨海默病具有一定保护作用。