褐藻硫酸多糖清除活性氧自由基作用及动力学的ESR研究

利用ＥＳＲ和自旋捕集技术，首次观察了不同方法提取的两种褐藻硫酸多糖（ＳＰ）对Ｆｅｎｔｏｎ反应和光照Ｈ２Ｏ２两个体系产生的·ＯＨ清除作用，及对次黄嘌呤／黄嘌呤氧化酶和光照核黄素两个体系产生的Ｏ－．２（ＨＯ·２）清除作用，并且对其清除·ＯＨ和Ｏ－．２的动力学进行了研究。结果表明，热提取物（ＳＰｈ）和冷提取物（ＳＰｃ）均有明显清除ＯＨ和Ｏ－．２作用，且呈量效关系。对Ｏ－．２的清除率高于对·ＯＨ的清除率（８４．７％ｖｓ６９．２％）。ＳＰｈ对两种自由基的清除效果比ＳＰｃ好。在光照核黄素体系中ＳＰｈ３０ｇ／Ｌ几乎完全清除Ｏ－．２，ＳＰｃ可清除６８．９％，而在次黄嘌呤／黄嘌呤氧化酶体系中只需３ｇ／ＬＳＰｈ便可完全清除Ｏ－．２。１５ｇ／ＬＳＰｈ和３０ｇ／ＬＳＰｃ对Ｆｅｎｔｏｎ反应产生的·ＯＨ的清除率分别为７７．７％和６８．７％。动力学研究表明，ＳＰｈ与·ＯＨ和Ｏ－．２反应的表观速率常数分别为７．１×１０９ｍｏｌ－１·ｓ－１和３２３０．５ｍｏｌ－１·ｓ－１。实验提示ＳＰ可作为一种预防性的抗氧化剂。确证ＳＰ清除自由基为研究其抗ＨＩＶ及肿瘤的机理提供了一条新途径。

AN IN VITRO ESR STUDY OF THE FREE RADICAL SCAVENGING EFFECTS OF THE SULFATED POLYSACCHARIDES FROM BROWN SEAWEED AND THEIR KINETICS

The purpose of this study is to investigate the scavenging effects of the sulfated polysaccharides (SP) from brown seaweed Laminaria Japonica(hot water extract SPh and cold water extract SPc)on superoxide radical (O . 2 or HO · 2) and hydroxyl radical ( ·OH) and their spin trapping kinetics by electron spin resonance (ESR) in vitro.The results showed that both SPh and SPc had significant effects of scavenging ·OH and O . 2 with dose effect relationships.The scavenging effects of SPh were better than those of SPc.In the light riboflavin system,30g/L SPh almost completely scavenged O . 2(or HO · 2) and only 3g/L SPh were needed in the xanthine oxidase system.30g/L SPc scavenged 68.9% O . 2.The scavenging effects of 15g/L SPh and 30g/L SPc on ·OH were 77.7% and 68.7%,respectively.The rate constants of SPh for ·OH and O . 2 were 7.1×10 9mol -1 ·s -1 and 3230.5mol -1 ·s -1 respectively.These suggested that SP might be a preventive antioxidant beneficial in treatment for some diseases associated with oxidative stress,including cancer and HIV infections.