Takeshima Mika, Murata Maiko, Urasoe Natsuho, Murakami Shinki, Miyazaki Ikuko, Asanuma Masato, Kita Taizo
School of Food and Nutrition Science, Kyushu Nutrition Welfare University, Fukuoka, Japan.
Neurol Res. 2011 Dec;33(10):1050-6. doi: 10.1179/1743132811Y.0000000032.
Baicalein, a flavonoid derived from the root of Scutelaria baicalensis Georgi, possesses anti-oxidative properties including reactive oxygen species scavenging and lipid peroxidation inhibiting activities. The present study was undertaken to investigate the neuroprotective effect of baicalein against dopamine (DA) neurotoxicity induced by exposure to a synthetic DA precursor, L-3,4-dihydroxyphenylalanine (L-DOPA), in cultured dopaminergic CATH.a cells.
Exposure to L-DOPA for 24 hours reduced the number of viable cells and enhanced protein-bound quinone (quinoprotein) formation in the cell. Both effects were prevented by simultaneous treatment with baicalein. In addition, baicalein prevented the formation of DA semiquinone radicals from DA in an in vitro cell-free system. Long-term baicalein treatment for 96 hours also protected against excess L-DOPA-induced cell death, and also increased glutathione (GSH) levels in CATH.a cells.
Our results indicate that baicalein has neuroprotective properties against excess L-DOPA-induced DA neurotoxicity through the suppression of DA quinone formation. Furthermore, the long-term treatment of baicalein upregulates intracellular GSH contents, which may also exert neuroprotective effects against oxidative stress-induced neuronal damage.
黄芩素是从黄芩根中提取的一种黄酮类化合物，具有抗氧化特性，包括清除活性氧和抑制脂质过氧化活性。本研究旨在探讨黄芩素对培养的多巴胺能CATH.a细胞中因暴露于合成多巴胺前体L-3,4-二羟基苯丙氨酸（L-DOPA）而诱导的多巴胺（DA）神经毒性的神经保护作用。
暴露于L-DOPA 24小时可减少活细胞数量，并增强细胞中蛋白结合醌（醌蛋白）的形成。同时用黄芩素处理可预防这两种效应。此外，黄芩素在体外无细胞系统中可阻止DA形成DA半醌自由基。黄芩素长期处理96小时也可保护细胞免受过量L-DOPA诱导的细胞死亡，并且还可提高CATH.a细胞中的谷胱甘肽（GSH）水平。
我们的结果表明，黄芩素通过抑制DA醌的形成对过量L-DOPA诱导的DA神经毒性具有神经保护作用。此外，黄芩素的长期处理可上调细胞内GSH含量，这也可能对氧化应激诱导的神经元损伤发挥神经保护作用。
