Determination Of Hydroxyl Radical And Reactive Oxygen Free Radicals In The Sensitizing Effect Of The Polarographic Wave,

The hydroxyl radical,one of the strongest oxidant known,is thought to play an important role in a number of biological phenomena such as aging,radiation damage,inflammation and other pathological conditions. Here,we present three new simple and rapid methods for the determination of hydroxyl radical. Hydroxyl radical,generated by Fenton reaction,attacks dimethyl sulfoxide to form formaldehyde,which then separately reacts with 2,4-pentanedione,1,3-cyclohexanedione and hydrazine hydrochloride. Based on the electrochemical and fluorescent characters of the products,hydroxyl radical can be determined inderectly.Hydroxyl radicals,generated by Fenton reaction,attacks dimethyl sulfoxide to form formaldehyde,which reacts with ammonia and 2,4-pentanedione and forms 3,5-diacetyl-l,4-dihydropyridine at pH of -6.2.The product shows a second-order derivative reduction wave with the peak potential of -1.20 (vs SCE) by oscillopolarograghy and produce its characteristic fluorescence with its excitation and emission wavelength at 419.4 nm and 505.5 run. The quantitative analysis of hydroxyl radical can be done through the determination of the peak current and the fluorescence intensity.Hydroxyl radical,generated by Fenton reaction,attacks dimethyl sulfoxide to form formaldehyde,which reacts with ammonia and 1,3-cyclohexanedione at pH of -4.5. The product shows a second-order derivative reduction wave with the peak potential of-1.21 by single sweep oscillopolarograghy and produces its characteristic fluorescence with its excitation and emission wavelength at 400.5 nm and 450.5 nm. The quantitative analysis of hydroxyl radical can be done through the determination of the peak current and the fluorescence intensity.Hydroxyl radical,generated by Fenton reaction,attacks dimethyl sulfoxide to form formaldehyde,which reacts with hydrazine hydrochloride at pH 6.2. The product showed a second-order derivative cathodic wave with the peak potential of-1.08V( vs SCE) by single sweep oscilloplarography. The quantitative analysis of hydroxyl radical can be done through the determination of the peak current.The three methods above have been applied into the research of scavenging activity of someamino acids (Tyr,His,Pro,Tip,Arg,Cys,Arg,Lys) and some flavonoids (quercetin,morin,rutin,hesperidin,naringin,baicalin). The contribution of the structural features of the amino acids and the flavonoids is discussed.