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DPPH

About: DPPH is a(n) research topic. Over the lifetime, 30196 publication(s) have been published within this topic receiving 759916 citation(s). The topic is also known as: 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazin-1-yl.


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Journal ArticleDOI
TL;DR: A method for the screening of antioxidant activity is reported as a decolorization assay applicable to both lipophilic and hydrophilic antioxidants, including flavonoids, hydroxycinnamates, carotenoids, and plasma antioxidants.
Abstract: A method for the screening of antioxidant activity is reported as a decolorization assay applicable to both lipophilic and hydrophilic antioxidants, including flavonoids, hydroxycinnamates, carotenoids, and plasma antioxidants. The pre-formed radical monocation of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS*+) is generated by oxidation of ABTS with potassium persulfate and is reduced in the presence of such hydrogen-donating antioxidants. The influences of both the concentration of antioxidant and duration of reaction on the inhibition of the radical cation absorption are taken into account when determining the antioxidant activity. This assay clearly improves the original TEAC assay (the ferryl myoglobin/ABTS assay) for the determination of antioxidant activity in a number of ways. First, the chemistry involves the direct generation of the ABTS radical monocation with no involvement of an intermediary radical. Second, it is a decolorization assay; thus the radical cation is pre-formed prior to addition of antioxidant test systems, rather than the generation of the radical taking place continually in the presence of the antioxidant. Hence the results obtained with the improved system may not always be directly comparable with those obtained using the original TEAC assay. Third, it is applicable to both aqueous and lipophilic systems.

16,566 citations

Journal ArticleDOI
Abstract: The antiradical activities of various antioxidants were determined using the free radical, 2,2-Diphenyl-1-picrylhydrazyl (DPPH*). In its radical form. DPPH* has an absorption band at 515 nm which dissappears upon reduction by an antiradical compound. Twenty compounds were reacted with the DPPH* and shown to follow one of three possible reaction kinetic types. Ascorbic acid, isoascorbic acid and isoeugenol reacted quickly with the DPPH* reaching a steady state immediately. Rosmarinic acid and δ-tocopherol reacted a little slower and reached a steady state within 30 min. The remaining compounds reacted more progressively with the DPPH* reaching a steady state from 1 to 6 h. Caffeic acid, gentisic acid and gallic acid showed the highest antiradical activities with a stoichiometry of 4 to 6 reduced DPPH* molecules per molecule of antioxidant. Vanillin, phenol, γ-resorcylic acid and vanillic acid were found to be poor antiradical compounds. The stoichiometry for the other 13 phenolic compounds varied from one to three reduced DPPH* molecules per molecule of antioxidant. Possible mechanisms are proposed to explain the experimental results.

16,150 citations

Journal ArticleDOI
TL;DR: 5-Aminosalicylate reacts promptly with DPPH, suggesting a potent radical scavenger activity and was found to be the most active in inhibiting Fe2+/ascorbate-induced lipid peroxidation, suggesting an antioxidant activity of chain-breaking type.
Abstract: The action of the phenolic compounds acetaminophen, salicylate, and 5-aminosalicylate (5-ASA) as inhibitors of lipid peroxidation was studied under conditions suitable for establishing their antioxidant potencies. These phenolic compounds react differently with diphenylpicrylhydrazyl (DPPH) and protect differently sarcoplasmic reticulum membranes against lipid peroxidation induced by Fe2+/ascorbate, as evaluated by the formation of thiobarbituric acid-reactive substances (TBARS) and by the loss of the polyunsaturated fatty acyl chains. 5-Aminosalicylate reacts promptly with DPPH, suggesting a potent radical scavenger activity and was found to be the most active in inhibiting Fe2+/ascorbate-induced lipid peroxidation. These compounds also exhibit peroxyl radical scavenging activity generated by the water-soluble 2,2'-azobis-(2-amidinopropane hydrochloride) azoinitiator of peroxyl radicals, as evidenced by the inhibition of cis-parinaric acid fluorescence decay or oxygen consumption. 5-ASA rapidly scavenges peroxyl radicals in the aqueous phase, producing a concentration-dependent inhibition period similar to Trolox or cysteine, suggesting an antioxidant activity of chain-breaking type. By comparison, the reactivities of acetaminophen and salicylate are significantly weaker, acting essentially as oxidation retardants. Although closely related in structure, the antioxidant efficiencies of the three phenolic compounds are significantly different. The higher antioxidant activity of 5-ASA is putatively related with the p-amine relative to the hydroxyl group, potentially increasing the stability of the phenoxyl radical. Such a stabilization is not possible with salicylate and is decreased in acetaminophen by an electron withdrawing effect of the p-acetyl.

2,279 citations

Journal ArticleDOI
Abstract: Guava fruit extracts were analyzed for antioxidant activity measured in methanol extract (AOAM), antioxidant activity measured in dichloromethane extract (AOAD), ascorbic acid, total phenolics, and total carotenoids contents. The ABTS, DPPH, and FRAP assays were used for determining both AOAM and AOAD, whereas the ORAC was used for determining only AOAM. Averaged AOAM [mM Trolox equivalent (TE)/g fresh mass (FM)] were 31.1, 25.2, 26.1, and 21.3 as determined by the ABTS, DPPH, FRAP, and ORAC assays, respectively. Averaged AOAD (mM TE/g FM) were 0.44, 0.27, and 0.16 as determined by the ABTS, DPPH, and FRAP assays, respectively. AOAM determined by all assays were well correlated with ascorbic acid (0.61prp0.92) and total phenolics (0.81prp0.97) and also among themselves (0.68prp0.97) but had negative correlation with total carotenoids (� 0.67prp� 0.81).

2,264 citations

Journal Article
TL;DR: The use of the stable free radical diphenylpicrylhydrazyl (DPPH) for estimating antioxidant activity and its application in antioxidant research is described.
Abstract: Molyneux, P. The use of the stable free radical diphenylpicrylhydrazyl (DPPH) for estimating antioxidant activity

2,225 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202254
20212,148
20202,332
20192,072
20182,158
20172,189