Moini H, Guo Q, Packer L
Department of Molecular and Cell Biology, 251 Life Sciences Addition, University of California at Berkeley, Berkeley, California 94720-3200, USA.
J Agric Food Chem. 2000 Nov;48(11):5630-9. doi: 10.1021/jf000618s.
Pycnogenol, an extract from French maritime pine bark (PBE), is a complex mixture of bioflavonoids with reported protective effects against disease. PBE is an effective scavenger of reactive oxygen species, and its main constituents are procyanidins of various chain lengths. To find out the biochemical basis of action of PBE on enzyme activity, involvement of its redox activity and direct binding to the enzyme in its subsequent action on enzyme activity have been investigated. PBE dose-dependently inhibited the activities of xanthine oxidase, xanthine dehydrogenase, horseradish peroxidase, and lipoxygenase, but it did not affect the activities of glucose oxidase, ascorbate oxidase, or elastase. To characterize the mechanism of PBE action, studies were focused on xanthine oxidase and glucose oxidase. Under non-denaturing conditions, PBE changed the electrophoretic mobility of xanthine oxidase but not of glucose oxidase. Gel filtration chromatography confirmed higher molecular weight complexes of xanthine oxidase and xanthine dehydrogenase in the presence of PBE. It was found that hydrophobic bonding might be the dominant mode of interaction between PBE and xanthine oxidase. The importance of the binding in the effect of PBE on enzyme activity was supported by the observation that PBE binds to and inhibits catalase, but not superoxide dismutase. However, no correlation was found between superoxide/hydroxyl radical scavenging activity and the inhibitory effect on xanthine oxidase activity of PBE, various purified flavonoids, or other complex mixtures of bioflavonoids. The results indicate that PBE selectively inhibits xanthine oxidase through binding to the enzyme rather than by the redox activity.
碧萝芷是一种从法国滨海松树皮中提取的提取物（PBE），是一种生物类黄酮的复杂混合物，据报道对疾病具有保护作用。PBE是活性氧的有效清除剂，其主要成分是各种链长的原花青素。为了找出PBE对酶活性作用的生化基础，研究了其氧化还原活性的参与以及在随后对酶活性的作用中与酶的直接结合。PBE剂量依赖性地抑制黄嘌呤氧化酶、黄嘌呤脱氢酶、辣根过氧化物酶和脂氧合酶的活性，但不影响葡萄糖氧化酶、抗坏血酸氧化酶或弹性蛋白酶的活性。为了表征PBE的作用机制，研究集中在黄嘌呤氧化酶和葡萄糖氧化酶上。在非变性条件下，PBE改变了黄嘌呤氧化酶的电泳迁移率，但没有改变葡萄糖氧化酶的电泳迁移率。凝胶过滤色谱法证实，在PBE存在下，黄嘌呤氧化酶和黄嘌呤脱氢酶形成了更高分子量的复合物。发现疏水键可能是PBE与黄嘌呤氧化酶之间相互作用的主要方式。PBE与过氧化氢酶结合并抑制其活性，但不抑制超氧化物歧化酶，这一观察结果支持了这种结合在PBE对酶活性影响中的重要性。然而，在超氧化物/羟基自由基清除活性与PBE、各种纯化的类黄酮或其他生物类黄酮复杂混合物对黄嘌呤氧化酶活性的抑制作用之间未发现相关性。结果表明，PBE通过与酶结合而不是通过氧化还原活性选择性地抑制黄嘌呤氧化酶。
