2,2-diphenyl-1 -picrylhydrazyl

The reduction of the stable 1,1 -diphenyl-2-picrylhydrazyl radical (DPPH) has been used to assess the efficiency of antioxidants in beverages (Larrauri et al, 1999 Porto et al, 2000), vegetable oils (Espin et al, 2000) and of pure phenolic compounds (Madsen et al, 2000), reaction [16.17] ... 

Another nitrogen radical, of considerable importance, is 1,1-diphenyl-2-picrylhydrazyl (10) obtained by PbOz oxidation of the triaryl-... 

The hetero radicals that have already been referred to—(9, p. 301), (10, p. 302), (14, p. 302) and (15, p. 302)—owe their relative stability [with respect to their dimers—apart from 1,1 -diphenyl-2-picrylhydrazyl (10)] to a variety of factors (a) the relative weakness of N—N, S—S and 0—0 bonds, (b) the delocalisation through the agency of aromatic nuclei, and (c) steric inhibition of access to the atom with the unpaired electron, or to an aryl p-position, cf. (50). The latter factor bulks large (in addition to the weakness of O—O bonds) in the great stability of (15, c/ p. 302) and all three factors operate to stabilise (51), which is wholly dissociated in solution ... 

Popular EPR-based assays of antioxidant activity include the DPPH assay, in which the ability of compounds to quench (by H-atom transfer) the 1,1-diphenyl-2-picrylhydrazyl radical is used to rank their antioxidant activity. This method has been applied widely to the analysis of dietary antioxidants and extracts from medicinal plants.213 219 Extensive use has also been made of assays based on the competition between spin traps and test compounds for reaction with enzymatically-generated 02 and, in the presence of a metal catalyst, the OH rad-... 

Superoxide dismutase Polyunsaturated fatty acid 1,1 -Diphenyl-2-picrylhydrazyl Low density lipoprotein Phorbol-12-mysri state-13-acetate 12-0-Tetradecanoylphorbol-13-acetate Di-O-caffeoylquinic acids Di-O-caffeoylquinic acid Herpes simplex virus type 1 Human immunodeficiency virus Acquired immunodeficiency syndrome Human immunodeficiency virus type-1 CafFeoylquinic acid derivatives 3-fer/-Butyl-4-hydroxyanisole... 

Different model systems and different methods are used to evaluate the antioxidant properties of flavonoids. The stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), which changes color after being reduced by an antiradical compound, was employed to study the antioxidant properties of isoflavones genistein (42) and daidzein (40), flavones apigenin (23) and lute-... 

DNAP, DNA-dependent DNA polymerase DNAS, DNA synthesis DPPH, 1,1 -diphenyl-2-picrylhydrazyl radical... 

Several studies described the interaction of flavonoids with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical [76, 79, 107-108] (Fig. (3)). DPPH is a stable free radical and is frequently used in ESR studies [109]. The DPPH assay provides information on the reactivity of flavonoids with a stable free radical [79]. Because of its odd electron, DPPH gives a strong absorption band in ethanol at 517 nm. As this... 

Radical scavenging effects of tannins and related polyphenols were also evidenced by ESR studies for the effects on the superoxide anion radical generated in the hypoxanthine-xanthine oxidase system and on the 1,1-diphenyl-2-picrylhydrazyl radical which is often used as a model of free radicals in lipid peroxidation [100]. Investigation of structure-activity... 

Electron spin resonance (ESR) spectrometry measures the presence of unpaired electrons and is a widely accepted method for investigating antioxidant-radical reactions. A few ESR studies have been conducted to investigate the CLA reactions with 1,1-diphenyl-2-picrylhydrazyl (DPPH ) free radical in toluene (7,8). DPPH is... 

Sawai, Y. and Sakata, K. 1998. NMR analytical approach to clarify the antioxidative molecular mechanism of catechins using 1,1- diphenyl-2-picrylhydrazyl , /. Agric. Food. Chem., 46 111-114. 

The cathodic solution exerted a radical scavenging effect on aqueous 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (4), so that the antioxidant effect of the cathodic solution on AAPH-induced oxidation would be in part due to the trapping of aqueous AAPH radicals by the cathodic solution. The radical scavenging effect of the cathodic solution may be derived from the reduction in activity caused by dissolved hydrogen formed just after preparation. The cathodic solution also had an inhibitory effect on AMVN-induced oxidation, although this effect was weaker than that on AAPH-induced oxidation Figure 4). AMVN is a fat-soluble radical initiator and induces the oxidation of lipids in emulsion from the lipid droplet interior, but it was reported that AMVN also induced oxidation from the interface of water and the lipid phase (P). Therefore, the antioxidant action of tiie cathodic solution on AMVN-induced oxidation would be derived from its scavenging effect on the AMVN radical at the interface. 

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