Determination And Application Of The Antioxidant Activities Of Natural Antioxidants

ROS( reactive oxygen species) are continuously formed via environmental influence and aerobic metabolism. In healthy subject, there is a tightly controlled balance between the generation of ROS and the capacity of the antioxidant protective system, whereas, excessive ROS play an important role in aging and pathogenesis. It is necessary to supply antioxidants in vitro, thus, development of safe, cheap and highly efficient antioxidants has attracted many scientists' attention.The development of antioxidants in recent years has been reviewed, besides the classification of antioxidants, some systems and methods used in determining the antioxidant activity and speculating the mechanism have been introduced.Based on this, the purpose of this paper is to determine the radical scavenging activities of natural antioxidants (a,γ-magonstin, genistein, neohesperidin dihydrochalcone, ellagic acid, 5-hydroxytryptophan, kojic acid and Vitamin C) toward different reactive oxygen species (ROS), including superoxide anion(O₂^·|-), hydroxyl radical(^·OH),hydrogen peroxide (H₂O₂) and singlet oxygen (¹O₂), using a spectrophotometry and chemiluminescence. Meanwhile, the inhibitory effect on the lipid peroxidation is measured with fluorophotometry. O₂^·|-, ^·OH, H₂O₂, and ¹O₂ are generated from a pyrogallol autoxidation system, Fenton reaction system, H₂O₂-luminol system and Na₂MoO₄-H₂O₂ system, respectively. The results show that six products have stronger antioxidant activities than Vc except kojic acid. In order to study the relationship between the antioxidant activity and molecular structure, electrochemical properties have been investigated through voltammetry preliminarily. The results show that all products can be oxidized on glass-carbon electrode except kojic acid, the antioxidant activitiy of flavonoid is negative correlation to the oxidized peak potential.