pH和缓冲体系对植物多酚抑制脂氧合酶活性的影响

The effect of pH and buffer systems on the inhibition of lipoxygenase activity by plant polyphenols

为优化紫外分光光度法测定多酚抑制脂氧合酶(LOX)活性的方法,探究缓冲体系及pH的选取对LOX酶活力的影响和多酚自氧化作用,研究了不同缓冲溶液体系及pH条件下,LOX酶活力的变化及没食子酸、槲皮素、儿茶素、3,4-二羟基苯乙酸的自氧化情况。结果发现,LOX在碱性条件下活性较强,4种多酚在硼酸盐体系中自氧化最弱,在Tris-HCl体系中自氧化最强;且各体系中pH越高4种多酚自氧化作用越强,紫外光谱中反映的自氧化中间产物和终产物越多。最终确定pH 7.5的硼酸盐缓冲液作为检测缓冲体系。分析4种多酚对LOX酶活性的影响,发现随着多酚浓度的增大,LOX酶活性呈先下降后上升的趋势,4种多酚对LOX酶活的抑制效果依次为:槲皮素>儿茶素>没食子酸>3,4-二羟基苯乙酸。

In order to optimize the Ultraviolet(UV)spectrophotometric method for determination of polyphenols inhibiting LOX activity,and to explore the influences of the buffer systems and pH on LOX enzyme activity and polyphenol auto-oxidation,this paper studied the changes of LOX enzyme activity and the autooxidation of gallic acid,quercetin,catechin and 3,4-dihydroxyphenylacetic acid under different buffer systems and pH conditions.The results showed that the activity of LOX was stronger under alkaline conditions,and the 4 polyphenols had the weakest self-oxidation in the borate system and the strongest selfoxidation in the Tris-HCl system.The higher the pH in each system,the stronger the self-oxidation of the 4 polyphenols,and the more intermediate and final products of auto-oxidation reflected in the UV spectrum.Finally,the pH 7.5 borate buffer was determined as the detection buffer system.It was found that LOX enzyme activity decreased first and then rised with the increase of 4 kinds of polyphenol concentration.The inhibitory effect of 4 kinds of polyphenols on LOX enzyme activity was in order:quercetin>catechin>gallic acid>3,4-Dihydroxyphenylacetic acid.