茶多酚复合体及L-EGCG清除超氧阴离子自由基特性的研究

Study on properties of scavenging superoxide anion free radical with tea polyphenols (TP) compounds and L-EGCG.

用自旋捕集电子顺磁共振技术(ESR)和化学发光法,研究了茶多酚复合体和L-EGCG对超氧阴离子自由基的清除特性.结果表明,茶多酚复合体和L-EGCG对超氧阴离子自由基有强的清除作用.在6.0×10^(-3)mg/mL时清除率达最大(>97％),低于6.0×10^(-3)mg/mL时,具量效关系,高于6.0×10^(-3)mg/mL时清除率下降.清除超氧阴离子自由基时,化学发光强度随时间增加平稳下降,表明清除超氧阴离子自由基后无新的自由基存在.高浓度下茶多酚复合体和L-EGCG的助氧化作用是清除率低的原因,助氧化作用的产生是由药物在空气O_2和碱的作用下产生自由基造成的,pH10.1时产生超氧阴离子自由基,pH12.0时L-EGCG产生L-EGCG自由基.清除速率常数TPⅠ为3.82×10~9,TPⅡ为2.91×10~9,L-EGCG为3.35×10~9mg/mL·s,相同浓度下TPⅠ的清除速率为最大.此外,儿茶素类清除超氧阴离子自由基的反应中心是不同的,没食子儿茶素通常发生在连苯三酚结构上.

Study of the properties of TP compounds (TPI ,TP II ) and L-EGCG Scavenging superoxide an-ion free radical was made with the ESR spin trapping methods and chemiluminence. The results showed sTP I , TP II and L-EGCG remarkably scavenged superoxide anion free radical and the percentages of scavenging at the concentration of 0. 006 mg/mL were the best (more than 97 % ). At the concentration of less than 0. 006 mg/mL there were relations of quantity-effect ,at more than 0. 006 mg/mL .the scavenging effect was weakened. When TP I ,TP II and L-EGCG scavenged superoxide anion free radical,the relative intensity of chemiluminence was decreased with the increase of time. Under the condition of pH 10.1 ,TP I ,TP II and L-EGCG were able to produce superoxide anion free radical. At pH 12. 0,L-EGCG could form L-EGCG radical. The quenching constants (ks) of superoxide anion free radical generated from Xanthine-Xanthine Oxidase system were 3. 82 × 109(TP I ), 2. 91 × 109(TP II ) and 3. 53× 109(L-EGCG) mg/mL . s at room temperature. The constant of L-EGCG was the largest at the same concentration.