Huang Guan-Cheng, Chow Jyh-Ming, Shen Shing-Chuan, Yang Liang-Yo, Lin Cheng-Wei, Chen Yen-Chou
Department of Internal Medicine, Chi-Mei Medical Center, Tainan, Taiwan.
Int Immunopharmacol. 2007 Aug;7(8):1054-63. doi: 10.1016/j.intimp.2007.04.001. Epub 2007 May 2.
Wogonin (Wog; 5,7-dihydroxy-8-methoxy flavone) has been shown to effectively inhibit lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) gene expression and nitric oxide production in our previous study. In the present study, we found that Nor-wogonin (N-Wog; 5,7,8-trihydroxyl flavone), a structural analogue of Wog with an OH substitution at C8, performed different effect on LPS- or lipoteichoic acid (LTA)-induced iNOS gene expression and nitric oxide (NO) production in macrophages. Wog, but not N-Wog, significantly inhibits LPS- or LTA-induced NO production through suppressing iNOS gene expression at both protein and mRNA without affecting NO donor sodium nitroprusside-induced NO production, NOS enzyme activity, and cells viability. Activation of JNKs (not ERKs) via phosphorylation induction, and an increase in c-Jun (not c-Fos) protein expression were involved in LPS- and LTA-treated RAW264.7 cells, and those events were blocked by Wog, but not N-Wog, addition. Furthermore, 5,7-diOH flavone, but not 5-OH flavone, 7-OH flavone, 5-OH-7-OCH(3) flavone, significantly inhibits LPS-induced iNOS protein expression and NO production, and 7,8-diOCH(3) flavone performs more effective inhibitory activity on LPS-induced NO production and iNOS protein expression than 7-OCH(3)-8-OH flavone. These data suggest that OHs at both C5 and C7 are essential for NO inhibition of flavonoids, and OCH(3) at C8 may contribute to this activity, and suppression of JNKs-c-Jun activation is involved.
在我们之前的研究中已表明，汉黄芩素（Wog；5,7 - 二羟基 - 8 - 甲氧基黄酮）可有效抑制脂多糖（LPS）诱导的诱导型一氧化氮合酶（iNOS）基因表达及一氧化氮生成。在本研究中，我们发现去甲汉黄芩素（N - Wog；5,7,8 - 三羟基黄酮），作为Wog的结构类似物，在C8位有一个羟基取代，对巨噬细胞中LPS或脂磷壁酸（LTA）诱导的iNOS基因表达及一氧化氮（NO）生成表现出不同的作用。Wog而非N - Wog，通过在蛋白质和mRNA水平抑制iNOS基因表达，显著抑制LPS或LTA诱导的NO生成，而不影响NO供体硝普钠诱导的NO生成、NOS酶活性及细胞活力。LPS和LTA处理的RAW264.7细胞中，通过磷酸化诱导激活JNKs（而非ERK）以及c - Jun（而非c - Fos）蛋白表达增加，这些事件可被添加的Wog而非N - Wog阻断。此外，5,7 - 二羟基黄酮而非5 - 羟基黄酮、7 - 羟基黄酮、5 - 羟基 - 7 - 甲氧基黄酮，显著抑制LPS诱导的iNOS蛋白表达及NO生成，并且7,8 - 二甲氧基黄酮对LPS诱导的NO生成及iNOS蛋白表达的抑制活性比7 - 甲氧基 - 8 - 羟基黄酮更有效。这些数据表明，C5和C7位的羟基对于黄酮类化合物抑制NO至关重要，C8位的甲氧基可能有助于此活性，并且涉及对JNKs - c - Jun激活的抑制。
