模拟超氧化物歧化酶抗逆剂研究

Abstract: We have designed, synthesized and characterized five series of model compounds containing copper (II), manganese (III), iron (III) and nickel (II) with benzoimidazolyl and benzotriazolyl ligands based on the structure of the active site of natural superoxide dismutases (SOD). These mimetic SODs (MSOD) have a broad spectrum of enzymatic activities although their SOD - like specificity is not better than that of natural SODs (dismutation constant at room temperature and pH=7.8, kSOD = 109 - 108 L mol-1 s-1, kMSOD = 108 - 105 L mol-1 s-1). Moreover, the MSOD compounds containing copper (II) and iron (II, III) have multifunctional activities of superoxide dismutases, catalases (CAT), lipoxygenases (LO), polyphenol oxidases (PPO) and phospholipases (PL) etc. They have been found to be able to scavenge superoxide ions ( ) and hydrogen peroxide (H2O2) simultaneously in lower concentrations (c ≤ 10-5 mol L-1) so as to prevent from the accumulation of and H2O2 result in highly toxic hydroxyl radicals (oOH) via Fenton and Haber - Wiss reaction. However, these model compounds at high concentration (c ≥ 10-4 mol L-1) can induce defense mechanism of plants in the presence of O2 or H2O2 because of the generation of active oxygen (see Fig 1), which induce lipid peroxidation resulting in the formation of cyclo - and epo - oxides of unsaturated fatty acids as well as w - oxo acids and volatile C3 -, C6 -, C9 - aldehydes and - alcohols (Fig 2), and eventuate in apoptosis or programmed death of cells as with the plants under bio- and abio-stresses. Therefore, these MSODs can increase resistances against environmental stresses including drought, high moisture, high - and low - temperature and salinity, especially drought stress as well as earlier failure of cultivating growths, so that the output of wheat production can be increase 5.1-14.3%. Agricultural, physiological and biochemical studies show that there is a common mechanism of anti-stresses relating with active oxygen and cross- adaptations toward environmental stresses and pathogen infections. These studies have important theoretical and practical significances in the chemistry of mimic metalloenzymes and free radicals and agriculture

超氧化物歧化酶是植物防卫系统酶。根据其活性部位设计、合成的模拟酶含植物必需的微量金属元素；低浓度时可以清除O2和H2O2；高浓度时产生杀灭病原微生物活性最强的羟自由基（-OH）。试验已表明这些模拟酶能增强作物抗寒、抗旱、抗涝和抗早衰能力，是创制药、屎弦坏呐浜衔镄屡┮┑男鹿顾肌⑿峦揪叮苑⒄垢咝躺┮稻哂兄匾睦砺酆褪导室庖濉