Mohamed Riyaz, Tarannum Shaista, Yariswamy Manjunath, Vivek Hamse K, Siddesha Jalahalli M, Angaswamy Nataraju, Vishwanath Bannikuppe S
Department of Studies in Biochemistry, University of Mysore, Mysore, India.
J Pharm Pharmacol. 2014 Jun;66(6):769-78. doi: 10.1111/jphp.12200. Epub 2013 Dec 22.
Lipoxygenases (LOX) are the key enzymes involved in the biosynthesis of leukotrienes and reactive oxygen species, which are implicated in pathophysiology of inflammatory disorders. This study was conducted to evaluate the inhibitory effect of water-soluble antioxidant ascorbic acid and its lipophilic derivative, ascorbic acid 6-palmitate (Vcpal) on polymorphonuclear lymphocyte 5-LOX and soybean 15-LOX (sLOX) in vitro.
LOX activity was determined by measuring the end products, 5-hydroperoxy eicosatetraenoic acid (5-HETE) and lipid hydroperoxides, by spectrophotometric and high performance liquid chromatography methods. The substrate-dependent enzyme kinetics and docking studies were carried out to understand the nature of inhibition.
Vcpal potently inhibited 5-LOX when compared with its inhibitory effect on sLOX (IC50; 2.5 and 10.3 μm respectively, P = 0.003). Further, Vcpal inhibited 5-LOX more strongly than the known synthetic drugs: phenidone and nordihydroguaiaretic acid (P = 0.0007). Enzyme kinetic studies demonstrated Vcpal as a non-competitive reversible inhibitor of 5-LOX. In-silico molecular docking revealed high MolDock and Rerank score for Vcpal than ascorbic acid, complementing in-vitro results.
Both in-vitro and docking studies demonstrated Vcpal but not ascorbic acid as a non-competitive inhibitor of 5-LOX- and sLOX-induced lipid peroxidation, suggesting a key role for lipophilic nature in bringing about inhibition.
脂氧合酶（LOX）是参与白三烯和活性氧生物合成的关键酶，与炎症性疾病的病理生理学有关。本研究旨在评估水溶性抗氧化剂抗坏血酸及其亲脂性衍生物抗坏血酸6 - 棕榈酸酯（Vcpal）对多形核淋巴细胞5 - LOX和大豆15 - LOX（sLOX）的体外抑制作用。
通过分光光度法和高效液相色谱法测量终产物5 - 氢过氧化二十碳四烯酸（5 - HETE）和脂质氢过氧化物来测定LOX活性。进行底物依赖性酶动力学和对接研究以了解抑制的性质。
与对sLOX的抑制作用相比，Vcpal对5 - LOX具有更强的抑制作用（IC50分别为2.5和10.3μm，P = 0.003）。此外，Vcpal对5 - LOX的抑制作用比已知的合成药物非那吡啶和去甲二氢愈创木酸更强（P = 0.0007）。酶动力学研究表明Vcpal是5 - LOX的非竞争性可逆抑制剂。计算机模拟分子对接显示Vcpal的MolDock和重排分数高于抗坏血酸，这与体外实验结果相补充。
体外实验和对接研究均表明Vcpal而非抗坏血酸是5 - LOX和sLOX诱导的脂质过氧化的非竞争性抑制剂，表明亲脂性在发挥抑制作用中起关键作用。
