Non-reductive Scavenging of 1,1-Diphenyl-2-picrylhydrazyl (DPPH) by Peroxyradical: A Useful Method for Quantitative Analysis of Peroxyradical

Abstract

For quantitative investigations of hydrogen-radical donation, stable radicals have the advantage that their concentrations are readily and directly measurable. Among them a stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) 1) was investigated as a reactive hydrogen acceptor 2) and further found to be useful for the antioxidant determination.3) Since then DPPH has been mainly used to examine radical scavenging activity of antioxidative vitamins and polyhydroxy aromatic compounds 4,5) based on the reactions in Fig. 1. Besides DPPH-scavenging by reductive hydrogen transfer between various donors and DPPH, non-reductive DPPH-decomposing and -scavenging were found to be induced by reacting with tertiary hydroperoxides 6) and by radical-binding at the para position in the phenyl rings of DPPH, 7) respectively.However, nowadays non-reductive DPPH-scavenging has hardly applied for biochemical and physicochemical purposes. It has been reported that peroxyradicals are unique among reactive oxygen species implicated in the production of DNA damage because they possess an extremely long half-life (order of seconds) and are predicted to have a relatively greater chemical selectivity in its reactions as compared with other radical intermediates. A stable radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) has long been used as a convenient method for the antioxidant assay of biological materials such as cysteine, glutathione, ascorbic acid, tocopherol and polyhydroxy aromatic compounds (hydroquinone, pyrogallol, etc). In this study, non-reductive scavenging of DPPH was investigated by electron spin resonance (ESR) analyses for the purpose of developing a useful method for quantitative determination of peroxyradical. Since DPPH was degraded in the presence of peroxyradical derived from UV-irradiated benzoylperoxide and the peroxyradical-induced degradation of DPPH was inhibited by the addition of a spin trapping agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), it is concluded that DPPH is non-reductively scavenged by peroxyradical. Therefore, it is suggested that DPPH could be a useful agent for the quantitative measurement of peroxyradical.Key words 1,1-diphenyl-2-picrylhydrazyl (DPPH); non-reductive scavenging; peroxyradical; electron spin resonance (ESR) Fig. 1. The Reaction Scheme between DPPH and the Conjugated Group of Ascorbic Acid (a) or Hydroquinone (b)

Protective Effect of Emblica officinalis Against Alcohol-Induced Hepatic Injury by Ameliorating Oxidative Stress in Rats

“…(cation radical) free radical. A wide variety of in vitro methods used to assess radical scavenging ability of certain agents from natural and synthetic source [30]. It can be observed that the content of flavonoids and tannoid compounds of EFE could be responsible for the radical scavenging activity.…”

Presence of Peroxyradicals in Cigarette Smoke and the Scavenging Effect of Shikonin, a Naphthoquinone Pigment

“…Recently, we have found that a stable radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) is a useful agent for the quantitative measurement of peroxyradicals. 7) In brief, as shown in Fig. 1, non-reductive DPPHscavenging by peroxyradical is quantitatively determined by ESR analysis.…”

“…In this study, we report that peroxyradical(s) was proved to be present in the gas-phase cigarette smoke using the method described in our previous study. 7) Several studies have been conducted to inactivate free radicals from cigarette smoke by using antioxidants. [8][9][10][11] As indicated in the previous study, 10) antioxidants used should necessarily be effective against broad range of free radical species, be heat resistant, nonvolatile and display high affinity to the filter.…”

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“…a free radical scavenging antioxidant, the absorption strength is decreased and the resulting decolorization is stoichiometric with respect to the number of electrons captured. It has been found that DPPH * can oxidize cysteine, glutathione, ascorbic acid, tocopherol and polyhydroxy aromatic compounds [56]. ABTS*+produce more powerful free radicals than DPPH * radicals and the reactions with ABTS *+ radicals involve a single electron transfer process [57].…”