Lo Ai-Hsiang, Liang Yu-Chih, Lin-Shiau Shoei-Yn, Ho Chi-Tang, Lin Jen-Kun
Institute of Biochemistry, College of Medicine, National Taiwan University, No. 1, Section 1, Jen-Ai Road, Taipei, Taiwan.
Carcinogenesis. 2002 Jun;23(6):983-91. doi: 10.1093/carcin/23.6.983.
Carnosol is a naturally occurring phytopolyphenol found in rosemary. Carnosol functions as antioxidant and anticarcinogen. In the present study, we compared the antioxidant activity of carnosol and other compounds extracted from rosemary. Carnosol showed potent antioxidative activity in alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) free radicals scavenge and DNA protection from Fenton reaction. High concentrations of nitric oxide (NO) are produced by inducible NO synthase (iNOS) in inflammation and multiple stages of carcinogenesis. Treatment of mouse macrophage RAW 264.7 cell line with carnosol markly reduced lipopolysaccharide (LPS)-stimulated NO production in a concentration-related manner with an IC50 of 9.4 microM; but other tested compounds had slight effects. Western blot, reverse transcription-polymerase chain reaction, and northern blot analyses demonstrated that carnosol decreased LPS-induced iNOS mRNA and protein expression. Carnosol treatment showed reduction of nuclear factor-kappaB (NF-kappaB) subunits translocation and NF-kappaB DNA binding activity in activated macrophages. Carnosol also showed inhibition of iNOS and NF-kappaB promoter activity in transient transfection assay. These activities were referred to down-regulation of inhibitor kappaB (IkappaB) kinase (IKK) activity by carnosol (5 microM), thus inhibited LPS-induced phosphorylation as well as degradation of IkappaBalpha. Carnosol also inhibited LPS-induced p38 and p44/42 mitogen-activated protein kinase (MAPK) activation at a higher concentration (20 microM). These results suggest that carnosol suppresses the NO production and iNOS gene expression by inhibiting NF-kappaB activation, and provide possible mechanisms for its anti-inflammatory and chemopreventive action.
鼠尾草酸是一种天然存在于迷迭香中的植物多酚。鼠尾草酸具有抗氧化剂和抗癌剂的功能。在本研究中，我们比较了鼠尾草酸与从迷迭香中提取的其他化合物的抗氧化活性。鼠尾草酸在α,α-二苯基-β-苦基肼（DPPH）自由基清除和铁离子诱导反应对DNA的保护方面表现出强大的抗氧化活性。在炎症和癌症发生的多个阶段，诱导型一氧化氮合酶（iNOS）会产生高浓度的一氧化氮（NO）。用鼠尾草酸处理小鼠巨噬细胞RAW 264.7细胞系，能显著降低脂多糖（LPS）刺激的NO生成，且呈浓度依赖性，半数抑制浓度（IC50）为9.4微摩尔；但其他测试化合物的影响较小。蛋白质免疫印迹法、逆转录-聚合酶链反应和Northern印迹分析表明，鼠尾草酸可降低LPS诱导的iNOS mRNA和蛋白质表达。鼠尾草酸处理显示，活化巨噬细胞中核因子-κB（NF-κB）亚基的易位和NF-κB DNA结合活性降低。在瞬时转染试验中，鼠尾草酸还显示出对iNOS和NF-κB启动子活性的抑制作用。这些活性归因于鼠尾草酸（5微摩尔）对抑制蛋白κB（IkappaB）激酶（IKK）活性的下调，从而抑制LPS诱导的IkappaBα磷酸化以及降解。在较高浓度（20微摩尔）下，鼠尾草酸还抑制LPS诱导的p38和p44/42丝裂原活化蛋白激酶（MAPK）激活。这些结果表明，鼠尾草酸通过抑制NF-κB激活来抑制NO生成和iNOS基因表达，并为其抗炎和化学预防作用提供了可能的机制。
