Lapenna Domenico, Ciofani Giuliano, Pierdomenico Sante Donato, Neri Matteo, Cuccurullo Chiara, Giamberardino Maria Adele, Cuccurullo Franco
Dipartimento di Medicina e Scienze dell'Invecchiamento, and Centro di Scienze dell'Invecchiamento-Fondazione Università G. d'Annunzio, Facoltà di Medicina e Chirurgia, 66100 Chieti, Italy.
Biochim Biophys Acta. 2009 Jan 1;1790(1):25-30. doi: 10.1016/j.bbagen.2008.09.007. Epub 2008 Oct 7.
Since iron is essential for lipoxygenase activity and salicylic acid (SA) can interact with the metal, possible lipoxygenase inhibition by SA was investigated.
Kinetic spectrophotometric evaluation of enzymatic lipid peroxidation catalyzed by soybean lipoxygenase (SLO), rabbit reticulocyte 15-lipoxygenase (RR15-LOX), porcine leukocyte 12-lipoxygenase (PL12-LOX) and human recombinant 5-lipoxygenase (HR5-LOX) with and without SA.
SA inhibited linoleic, arachidonic and docosahexaenoic acid or human lipoprotein peroxidation catalyzed by SLO with IC50 of, respectively, 107, 153, 47 and 108 microM. Using the same substrates, SA inhibited RR15-LOX with IC50 of, respectively, 49, 63, 27 and 51 microM. Further, arachidonic acid peroxidation catalyzed by PL12-LOX and HR5-LOX was inhibited by SA with IC50 of 101 and 168 microM, respectively. Enzymatic inhibition was complete, reversible and non-competitive. Conceivably due to its lower hydrophobicity, aspirin was less effective, indicating acetylation-independent enzyme inhibition. SA and aspirin were ineffective peroxyl radical scavengers but readily reduced Fe3+, i.e. FeCl3, to Fe2+, suggesting their capacity to reduce Fe3+ at the enzyme active site. Indeed, similar to the catecholic redox inhibitor nordihydroguaiaretic acid, SA inhibited with the same efficiency both ferric and the native ferrous SLO form, indicating that these compounds reduce the active ferric enzyme leading to its inactivation.
SA can inhibit lipoxygenase-catalyzed lipid peroxidation at therapeutic concentrations, suggesting its possible inhibitory activity against enzymatic lipid peroxidation in the clinical setting.
由于铁对于脂氧合酶活性至关重要，且水杨酸（SA）可与该金属相互作用，因此对SA可能抑制脂氧合酶的情况进行了研究。
采用动力学分光光度法评估大豆脂氧合酶（SLO）、兔网织红细胞15-脂氧合酶（RR15-LOX）、猪白细胞12-脂氧合酶（PL12-LOX）和人重组5-脂氧合酶（HR5-LOX）在有和没有SA存在时催化的酶促脂质过氧化反应。
SA抑制SLO催化的亚油酸、花生四烯酸和二十二碳六烯酸或人脂蛋白过氧化反应，其IC50分别为107、153、47和108微摩尔。使用相同底物时，SA抑制RR15-LOX的IC50分别为49、63、27和51微摩尔。此外，SA抑制PL12-LOX和HR5-LOX催化的花生四烯酸过氧化反应，IC50分别为101和168微摩尔。酶抑制作用是完全的、可逆的且非竞争性的。可以想象，由于阿司匹林疏水性较低，其效果较差，表明存在不依赖乙酰化的酶抑制作用。SA和阿司匹林不是有效的过氧自由基清除剂，但能轻易地将Fe3+（即FeCl3）还原为Fe2+，表明它们有能力在酶活性位点还原Fe3+。实际上，与儿茶酚类氧化还原抑制剂去甲二氢愈创木酸类似，SA对三价铁形式和天然二价铁形式的SLO具有相同的抑制效率，表明这些化合物可还原活性三价铁酶导致其失活。
SA在治疗浓度下可抑制脂氧合酶催化的脂质过氧化反应，提示其在临床环境中可能对酶促脂质过氧化反应具有抑制活性。
