含邻苯二酚结构的植物多酚对脂肪氧合酶的抑制作用

Inhibitory Effects of Plant polyphenol with a Catechol Structure on the Lipoxygenase

采用亚油酸-脂肪氧合酶(LOX)体系,研究了4种含邻苯二酚结构的植物多酚(咖啡酸、绿原酸、儿茶素和槲皮素)对LOX的抑制作用。基于Linweaver-Burk作图法及荧光光谱法明晰其作用机制。结果表明:4种多酚对LOX的抑制活性从强到弱依次为:槲皮素>儿茶素>咖啡酸>绿原酸。咖啡酸与绿原酸是LOX的以非竞争性抑制为主导的竞争-非竞争性混合型抑制剂,槲皮素与儿茶素是LOX的非竞争性抑制剂。槲皮素、儿茶素对LOX的动态猝灭常数、结合常数以及结合位点数大于咖啡酸、绿原酸,更易与LOX结合。4种多酚与LOX有多个结合位点。绿原酸和咖啡酸与LOX的结合位点更接近于酪氨酸残基,儿茶素与LOX的结合位点与酪氨酸、色氨酸残基距离相差不大,槲皮素与LOX的结合位点更接近于色氨酸残基。槲皮素与儿茶素在低浓度时存在协同增效作用,通过高效调控LOX活性来干预大豆蛋白氧化。

The inhibitory effects of four kinds of plant polyphenol containing a catechol structure(caffeic acid,chlorogenic acid,catechin and quercetin)on the activity of lipoxygenase(LOX)were studied using the linoleic acid-LOX system.The underlying mechanisms were studied by Linweaver-Burk plot analysis and fluorescence spectrometry.The LOX inhibitory activities of four kinds of plant polyphenol were in the order of quercetin>catechin>caffeic acid>chlorogenic acid.Caffeic acid and chlorogenic acid were mixed noncompetitive inhibitors of LOX.However,quercetin and catechin were noncompetitive inhibitors of LOX.The quenching constant,binding constant and number of binding sites of the interaction between quercetin/catechin and LOX were greater than those of the interaction between caffeic acid/chlorogenic acid and LOX,indicating that quercetin/catechin may have higher binding affinity towards LOX.LOX had multiple binding sites for four kinds of plant polyphenol.The binding sites of LOX for chlorogenic acid or caffeic acid were located close to tyrosine residues.The binding sites of LOX for catechin had similar average distance towards the tyrosine and tryptophan residues.The binding quercetin was closer to tryptophan than tyrosine residues.Quercetin had synergistic effect with catechin at low concentration,which could effectively inhibit soy protein oxidation through inhibition of LOX.