| With the development of free radical biology and medicine, the relationship betweenfree radicals and pathological changes have got more and more attention of people. So,the research to combat free radicals which can cause disease has been caused theattention of people increasingly. Many systems of screening and evaluation to theability of antioxidants have been established by researchers. However, previousevaluation of antioxidant was based on a single type of free radicals such as·OH fromFenton reaction, O-2·from the antoxidation of pyrogallol, stable free radicals such asDPPH· and ABTS+. The above system or the free radicals such as DPPH· and ABTS+.do not exist in the body, so that the evaluation of the antioxidant is not comprehensiveenough and no physiological basis and pathological significance.In this paper, we screen antioxidants on the basis of free radicals which generatedfrom fructose autoxidation. it is demonstrated that fructose promotes the formation ofadvanced glycation end products （AGEs）, the rate of fluorescent substance produced byfructose was faster than other monosaccharide which in vivo, and various reactiveoxygen species such as O2-·, H2O2, and·OH were produced in this autoxidation process.So it can comprehensively evaluate the ability of antioxidants and have pathologicalbasis. This article main research content is as follows.①Investigate the influence factors of fructose autoxidation, such as theconcentration of fructose and catalyst. The effect of temperature and pH on the fructoseautoxidation. At the same time, we also have studied the ability of sodium benzoate tocapture free radicals extremely. Apply this evaluation system to examine antioxidantability of berberine hydrochloride and ferulic acid.②Fluorescence method was used as detection means to evaluate nine kinds ofantioxidants based on fructose autoxidation system, IC50（half inhibitory concentration）was choosed as standerd to evaluate the antioxidant ability. The experimental resultsshow that the antioxidation ability of polyphenols is related to the number of phenolhydroxyl and ketone. The larger number of phenolic hydroxyl and ketone the strongerability of antioxidation. Influence of alkaloid antioxidant activity is the structure, the"naked" nitrogen atom is conducive to close to the reactive oxygen species and thereaction.③High performance liquid chromatography （HPLC） was used as a detection means based on fructose autoxidation to evaluate the antioxidant capacity of nine kinds ofantioxidants, IC50（half inhibitory of formaldehyde which generated from fructose） waschoosed as standerd to evaluate the antioxidant ability. The experimental resultsdemonstrate that the antioxidation ability of polyphenols is related to the number ofphenol hydroxyl and ketone. This results is same as fluorescence method.④Ultraviolet spectrophotometer was used as a detection means according to fructoseautoxidation conditions, the classic DPPH system was used to evaluate the antioxidantcapacity of nine kinds of antioxidants. Antioxidant capacity IC50（half inhibitoryconcentration） still was choosed as standerd to evaluate the antioxidant ability. Thisresults were same as fluorescence and HPLC method.⑤We found that Trolox shows abnormal antioxidational phenomenon in fructoseautoxidation system, Trolox not only showed no antioxidation to the fructoseautoxidation but also improve the autoxidation of fructose. We guessed that Trolox maybe have the phenomenon of autoxidation. So, NBT was used as ultra oxygen anionscavenger, which yields specific ultraviolet absorption substance. Sodium benzoate wasused as the hydroxyl free radical scavenger which yields salicylate that has specificfluorescence signal. We have studied the autoxidation phenomenon of Trolox（water-soluble vitamin E）. The effect of oxygen, tempreture and pH on the Troloxautoxidation have been studied. Experiments show that under the condition of hightemperature and acid, Trolox is vulnerable to autoxidation. |
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