Dhiman Surajdevprakash B, Kamat Jayashree P, Naik Devidas B
Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
Chem Biol Interact. 2009 Dec 10;182(2-3):119-27. doi: 10.1016/j.cbi.2009.07.025. Epub 2009 Aug 7.
Comparative studies on free radical scavenging by isomers of hydroxybenzyl alcohols (HBAs) were carried out to understand the molecular mechanisms involved in the antioxidant action. Using rat liver mitochondria as model systems, we have examined the radioprotective and antioxidant effects of hydroxybenzyl alcohols. Apart from their ability to scavenge free radicals and ferric reducing power, HBAs have shown good protection against radiation and oxidative stress. Using peroxyl radicals as initiator of reactive oxygen species (ROS), studies were carried out to evaluate antioxidant properties of HBAs against rat liver mitochondrial membrane components such as lipid and protein. Our results show that HBAs are potent inhibitor of lipid peroxidation and protein oxidation thus suggesting their role as free radical scavengers. In the presence of HBAs, restoration of depleted activity of Mn-SOD has also been investigated. In the presence of 2-hydroxybenzyl alcohol (2-HBA) complete restoration in the activity of Mn-SOD was observed on exposure to 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH). Free radical scavenging ability of HBAs were found to be comparable to alpha tocopherol. Pulse radiolysis technique has been used to study the reactions of HBAs with various biologically relevant reactive species such as hydroxyl radical (OH) and trichloromethyl peroxyl radical (CCl3O2). HBAs could scavenge OH radical giving initially OH-adducts which in turn decays to phenoxyl radicals. Reactions of phenoxyl radicals of HBAs with ascorbic acid have been also studied. Redox potential of HBAs has been evaluated with cyclic voltammetry. Studies clearly suggest a structural reactivity correlation between radical scavenging and antioxidant properties of these isomers of HBA. Among the 3 isomers of HBAs, 4-HBA and 2-HBA are found to have better radical scavenging and antioxidant properties than 3-HBA.
为了解抗氧化作用所涉及的分子机制，对羟基苄醇（HBA）异构体的自由基清除作用进行了比较研究。以大鼠肝线粒体为模型系统，我们研究了羟基苄醇的辐射防护和抗氧化作用。除了具有清除自由基的能力和铁还原能力外，HBA还对辐射和氧化应激表现出良好的保护作用。以过氧自由基作为活性氧（ROS）的引发剂，开展研究以评估HBA对大鼠肝线粒体膜成分（如脂质和蛋白质）的抗氧化性能。我们的结果表明，HBA是脂质过氧化和蛋白质氧化的有效抑制剂，因此表明它们作为自由基清除剂的作用。在存在HBA的情况下，还研究了锰超氧化物歧化酶（Mn-SOD）耗尽活性的恢复情况。在存在2-羟基苄醇（2-HBA）的情况下，在暴露于2,2'-偶氮二异丁脒二盐酸盐（AAPH）时观察到Mn-SOD活性完全恢复。发现HBA的自由基清除能力与α-生育酚相当。脉冲辐解技术已用于研究HBA与各种生物相关活性物种（如羟基自由基（OH）和三氯甲基过氧自由基（CCl3O2））的反应。HBA可以清除OH自由基，最初生成OH加合物，然后这些加合物又会衰变为苯氧基自由基。还研究了HBA的苯氧基自由基与抗坏血酸的反应。用循环伏安法评估了HBA的氧化还原电位。研究清楚地表明了这些HBA异构体的自由基清除和抗氧化性能之间的结构-反应性相关性。在HBA的3种异构体中，发现4-HBA和2-HBA比3-HBA具有更好的自由基清除和抗氧化性能。
