Department of Physical Therapy, Hungkuang University, Taichung, Taiwan.
School of Medicine, College of Medicine, China Medical University, Taichung, 40402, Taiwan.
Nutr Metab Cardiovasc Dis. 2020 Jun 9;30(6):1032-1043. doi: 10.1016/j.numecd.2020.02.014. Epub 2020 Mar 9.
Luteolin is a common flavonoid that is abundantly present in various edible plants, it is known to exhibit beneficial effects on cardiovascular system. However, the mechanisms which underlie the protective effects of luteolin on endothelial cell damage caused by oxidative stress remains unclear. The purpose of this study is to test the hypothesis which states that luteolin protects against HO-induced oxidative stress via modulating ROS-mediated P38 MAPK/NF-κB and calcium-evoked mitochondrial apoptotic signalling pathways.
Human umbilical vein endothelial cells (HUVECs) were pretreated with luteolin prior to being stimulated by 600 μM HO for another 24 h. The expression of native and phosphorylated-P38, IκB, NF-κB, native eNOS, phosphorylated-eNOS, iNOS and several apoptosis-related proteins were analyzed by Western blot. In addition, intracellular calcium was determined by fura-2 AM and mitochondrial membrane potential was examined by using JC1. Using the data gathered, we found indications that HO induced P38 MAPK/NF-κB activation. HO downregulated the expression of eNOS and upregulated iNOS, which in turn contribute to an elevated NO generation and protein nitrosylation. However, pretreatment with luteolin markedly reversed all of these alterations dose-dependently. Additionally, an intracellular calcium rise and subsequent mitochondrial membrane potential collapse, P53 phosphorylation, reduced BcL-2/Bax ratio in the mitochondrial membrane, release cytochrome c from mitochondria, leading to the subsequent activation of caspase 3 activation by HO were all markedly suppressed in the presence of luteolin.
Results from this study may provide the possible molecular mechanisms underlying cardiovascular protective effects of luteolin.
木犀草素是一种常见的黄酮类化合物，广泛存在于各种可食用植物中，已知对心血管系统有有益作用。然而，木犀草素对氧化应激引起的内皮细胞损伤的保护作用的机制尚不清楚。本研究旨在验证以下假说，即木犀草素通过调节 ROS 介导的 P38 MAPK/NF-κB 和钙诱发的线粒体凋亡信号通路来保护 HO 诱导的氧化应激。
人脐静脉内皮细胞（HUVEC）用木犀草素预处理后，再用 600μM HO 刺激 24 小时。通过 Western blot 分析天然和磷酸化的 P38、IκB、NF-κB、天然 eNOS、磷酸化 eNOS、iNOS 和几种凋亡相关蛋白的表达。此外，通过 fura-2 AM 测定细胞内钙，通过 JC1 检测线粒体膜电位。根据收集到的数据，我们发现 HO 诱导 P38 MAPK/NF-κB 激活的迹象。HO 下调 eNOS 的表达，上调 iNOS，从而导致 NO 生成和蛋白质硝化增加。然而，木犀草素预处理可显著地剂量依赖性地逆转所有这些改变。此外，HO 还引起细胞内钙升高和随后的线粒体膜电位崩溃、P53 磷酸化、线粒体膜上 BcL-2/Bax 比值降低、细胞色素 c 从线粒体释放，导致 caspase 3 激活。
本研究的结果可能为木犀草素的心血管保护作用提供了潜在的分子机制。
