Application Study On Antioxidants Based On The Active Oxygen Species From The Process Of Fructose Autoxidation

The development and progression of diseases related to free radicals have been gotlots of attention from researchers with the development of free radicals medicine andbiology. Accordingly, the prevention and treatment of antioxidants on those diseases hasbecome a hot topic. There are several deficiencies in the evaluation of antioxidantsactivity by traditional methods, which didn，t evaluate the comprehensive antioxiantsactivity because there is only a single type of free radical. In addition, researches on theantioxiants are devoted to the prevention and treatment of diseases related to freeradicals and the generation of reaction oxygen species (ROS) is a complex and dynamicprocess in organism, currently methods established evaluating antioxidants activity aresingle and static system, so it is very siginificant to develop a dynamic and complexmethod which is similar to the generation and transition of ROS in organism.It is suggested that fructose has a faster autoxidation rate and the ability to triggerprotein glycosylation compared with other sugars, such as glucose, gatactose and so on.There are a variety of active oxygen species (O2-·、HO2-·、·OH) generated from theprocess of fructose autoxidation under the catalysis of metal ions, and those ROSchange into·OH after a series of changes. In this thesis, a novel method of screeningand evaluating antioxidants activity based on the ROS from the process of fructoseautoxidation has been established because the generation and transition of ROS infructose autoxidation is similar to the orgamism. Based on the principle that·OHproduced in the fructose autoxidation is able to oxidize benzoic acid to hydroxybenzoicacid, which has a strong fluorescence intensity, and the ROS could be eliminated by theantioxidants, which can decrease the fluorescence intensity quantitatively, the screeningration and antioxidants acivity were obtained. This method was applied to severalantioxidant standards substances and different solvent extracts of Radix Ophiopogonis.The main research work and results are as follows:①A novel methodbased on the fructose autoxidation for screening and evaluatingantioxidant activity has established. Several important factors have been investigated bysingle factor experiment firstly, and then the orthogonal experiment was conducted onthe basis of single facor experiment, optimum experimental conditions have obtained.②The established method was applied to several antioxidant standard substances.Under optimum conditions, the antioxidant activity of chlorogenic acid, caffeic acid, protocatechuic acid, catechcins, erucic acid, vanillic acid,4-coumaric acid against ROSgenerated in fructose autoxidation were evaluated, the IC50was introduced to measurethe antioxidant activy of compounds. The relationship between antioxidant activity andits structure was discussed preliminarily. The results indicated that the antioxidantactivity investigated in this experiment related to the the number of phenonic hydroxyl,the kinds and properties of substituents, and whether the phenonic hydroxyl could formthe intramolecular hydrogen bond with impurity atoms.③The canonical method including Fenton and pyrogallot autoxidation wereapplied to several antioxidant standard substances. The antioxidant activity ofchlorogenic acid, caffeic acid, protocatechuic acid, catechcins, erucic acid, vanillic acid,4-coumaric acid against tow type of free radica system including·OH and s O2-· wereevaluated respectively, the IC50was introduced to measure the antioxidant activity ofcompounds. The result was compared with fructose autoxidation system. The resultssuggested that the antioxidant activity evaluated by fructose autoxidation method ismore precise than Fenton and pyrogallot autoxidation method only from the relationshipbetween antioxidant activity and its structure.④The novel estabished method, Fentonsystem, eliminating DPPH· and FRAPmethod were applied to different solvent extracts of Radix Ophiopogonis. The resultsindicated that different solvent extracts of Radix Ophiopogonis have good antioxidantactivity and it can be a reference to the development and utilization of RadixOphiopogonis as natural antioxidants.