Department of Physics and Chemistry, School of Pharmaceutical Sciences, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
J Med Food. 2013 Aug;16(8):692-700. doi: 10.1089/jmf.2012.0184. Epub 2013 Aug 1.
Increased neutrophil activation significantly contributes to the tissue damage in inflammatory illnesses; this phenomenon has motivated the search for new compounds to modulate their effector functions. Coumarins are natural products that are widely consumed in the human diet. We have evaluated the antioxidant and immunomodulator potential of five 4-methylcoumarin derivatives. We found that the 4-methylcoumarin derivatives inhibited the generation of reactive oxygen species by human neutrophils triggered by serum-opsonized zymosan or phorbol-12-myristate-13-acetate; this inhibition occurred in a concentration-dependent manner, as revealed by lucigenin- and luminol-enhanced chemiluminescence assays. Cytotoxicity did not mediate this inhibitory effect. The 7,8-dihydroxy-4-methylcoumarin suppressed the neutrophil oxidative metabolism more effectively than the 6,7- and 5,7-dihydroxy-4-methylcoumarins, but the 5,7- and 7,8-diacetoxy-4-methylcoumarins were less effective than their hydroxylated counterparts. An analysis of the biochemical pathways suggested that the 6,7- and 7,8-dihydroxy-4-methylcoumarins inhibit the protein kinase C-mediated signaling pathway, but 5,7-dihydroxy-4-methylcoumarin, as well as 5,7- and 7,8-diacetoxy-4-methylcoumarins do not significantly interfere in this pathway of the activation of the human neutrophil oxidative metabolism. The 4-methylcoumarin derivatives bearing the catechol group suppressed the elastase and myeloperoxidase activity and reduced the 1,1-diphenyl-2-picrylhydrazyl free radical the most strongly. Interestingly, the 5,7-dihydroxy-4-methylcoumarin scavenged hypochlorous acid more effectively than the o-dihydroxy-substituted 4-methylcoumarin derivatives, and the diacetoxylated 4-methylcoumarin derivatives scavenged hypochlorous acid as effectively as the 7,8-dihydroxy-4-methylcoumarin. The significant influence of small structural modifications in the inhibitory potential of 4-methylcoumarin derivatives on the effector functions of neutrophil makes them interesting candidates to develop new drugs for the treatment of inflammatory diseases mediated by increased neutrophil activation.
中性粒细胞的过度激活是炎症性疾病中组织损伤的主要原因之一，这一现象促使人们寻找新的化合物来调节其效应功能。香豆素是一种天然产物，广泛存在于人类饮食中。我们评估了五种 4-甲基香豆素衍生物的抗氧化和免疫调节潜力。我们发现，这些 4-甲基香豆素衍生物可以抑制人中性粒细胞在血清调理酵母聚糖或佛波醇 12-肉豆蔻酸 13-乙酸酯刺激下产生的活性氧物质；这一抑制作用呈浓度依赖性，通过发光素和鲁米诺增强化学发光实验可以证实。细胞毒性并没有介导这种抑制作用。7,8-二羟基-4-甲基香豆素比 6,7-和 5,7-二羟基-4-甲基香豆素更有效地抑制中性粒细胞的氧化代谢，但 5,7-和 7,8-二乙酰氧基-4-甲基香豆素的效果不如它们的羟基化对应物。对生化途径的分析表明，6,7-和 7,8-二羟基-4-甲基香豆素抑制蛋白激酶 C 介导的信号通路，但 5,7-二羟基-4-甲基香豆素以及 5,7-和 7,8-二乙酰氧基-4-甲基香豆素对人中性粒细胞氧化代谢的激活途径并没有显著的干扰作用。具有儿茶酚基团的 4-甲基香豆素衍生物能强烈抑制弹性蛋白酶和髓过氧化物酶的活性，并能显著减少 1,1-二苯基-2-苦基肼自由基。有趣的是，5,7-二羟基-4-甲基香豆素比邻二羟基取代的 4-甲基香豆素衍生物更有效地清除次氯酸，而二乙酰氧基-4-甲基香豆素衍生物与 7,8-二羟基-4-甲基香豆素一样有效地清除次氯酸。4-甲基香豆素衍生物的结构微小变化对中性粒细胞效应功能的抑制作用有显著影响，这使它们成为开发用于治疗由中性粒细胞过度激活引起的炎症性疾病的新药的有前途的候选物。
