Kim Dae Hyun, Cho Ki Ho, Moon Sang Kwan, Kim Young Suk, Kim Dong Hyun, Choi Jae Sue, Chung Hae Young
College of Pharmacy, Aging Tissue Bank, Pusan National University, Busan 609-735, Korea.
J Pharm Pharmacol. 2005 Dec;57(12):1581-90. doi: 10.1211/jpp.57.12.0008.
To evaluate the mechanism responsible for the cytoprotective effects of baicalin, an antioxidant flavonoid isolated from Scutellaria baicalensis, we investigated its effects against peroxynitrite (ONOO-)-induced endothelial cell (EC) damage. Baicalin showed efficient antioxidative actions by its ability to scavenge ONOO and inhibit ONOO(-)-mediated nitrotyrosine formation in vitro. Using an EC (YPEN-1) culture system, baicalin exhibited cytoprotective effects against cell death by ONOO- that was induced exogenously with tert-butyl hydroperoxide (t-BHP) in the YPEN-1 model. Baicalin was also found to reduce the intracellular precursors of ONOO-, NO* and O2(-) in the t-BHP-treated ECs. Evidence from Western blotting further revealed down-regulated expressions of iNOS and COX2, endogenous sources of NO* and O2(-) by baicalin treatment. In addition, pre-incubation of baicalin with EC suppressed t-BHP-induced nuclear factor kappa-B binding activity as determined by the transfection assay and Western blot analysis, further indicating baicalin's inhibition of iNOS and COX-2 expression. Based on the present data, we propose that baicalin scavenges ONOO- and protects cells against injury. Based on these data, it was concluded that baicalin is potentially a useful antioxidant against ONOO- and NO* and an inhibitor of iNOS and COX-2.
为了评估从黄芩中分离出的抗氧化黄酮类化合物黄芩苷的细胞保护作用机制，我们研究了其对过氧亚硝酸盐（ONOO⁻）诱导的内皮细胞（EC）损伤的影响。黄芩苷在体外具有清除ONOO⁻和抑制ONOO⁻介导的硝基酪氨酸形成的能力，从而表现出有效的抗氧化作用。使用EC（YPEN-1）培养系统，在YPEN-1模型中，黄芩苷对由叔丁基过氧化氢（t-BHP）外源性诱导的ONOO⁻引起的细胞死亡具有细胞保护作用。还发现黄芩苷可减少t-BHP处理的EC中ONOO⁻的细胞内前体NO˙和O₂⁻。蛋白质印迹法的证据进一步表明，黄芩苷处理可下调iNOS和COX2的表达，它们分别是NO˙和O₂⁻的内源性来源。此外，通过转染试验和蛋白质印迹分析确定，黄芩苷与EC预孵育可抑制t-BHP诱导的核因子κB结合活性，进一步表明黄芩苷对iNOS和COX-2表达的抑制作用。基于目前的数据，我们认为黄芩苷可清除ONOO⁻并保护细胞免受损伤。基于这些数据，得出结论，黄芩苷可能是一种有效的抗ONOO⁻和NO˙的抗氧化剂，也是iNOS和COX-2的抑制剂。
