Comparison of the Antioxidative Activity of Some Acid-phenols: Structure-Activity Relationship
23 Feb 1992-Bioscience, Biotechnology, and Biochemistry (Japan Society for Bioscience Biotechnology and Agrochemistry)-Vol. 56, Iss: 2, pp 324-325
About: This article is published in Bioscience, Biotechnology, and Biochemistry.The article was published on 1992-02-23 and is currently open access. It has received 589 citations till now.
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TL;DR: The antiradical properties of various antioxidants were determined using the free radical 2,2-Diphenyl-1-picrylhydrazyl (DPPH*) in its radical form as discussed by the authors.
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.
18,907 citations
TL;DR: The factors underlying the influence of the different classes of polyphenols in enhancing their resistance to oxidation are discussed and support the contention that the partition coefficients of the flavonoids as well as their rates of reaction with the relevant radicals define the antioxidant activities in the lipophilic phase.
8,513 citations
TL;DR: The antioxidant (AO) activity of polyphenols (PPs) was determined for the first time using a modified FRAP (ferric reducing/antioxidant power) assay and polyphenol's AO efficiency seemed to depend on the extent of hydroxylation and conjugation.
Abstract: Most nonenzymatic antioxidant activity (scavenging of free radicals, inhibition of lipid peroxidation, etc.) is mediated by redox reactions. The antioxidant (AO) activity of polyphenols (PPs), as f...
1,783 citations
TL;DR: In this paper, the authors focus on the extraction of polyphenols from agricultural and industrial wastes, and summarize available data on the factors affecting their antioxidant activity and stability, and, in some cases, the reported major active compounds identified.
1,614 citations
TL;DR: Plant-derived phenolics represents good sources of natural antioxidants, however, further investigation on the molecular mechanism of action of these phytochemicals is crucial to the evaluation of their potential as prophylactic agents.
Abstract: Accumulating chemical, biochemical, clinical and epidemiological evidence supports the chemoprotective effects of phenolic antioxidants against oxidative stress-mediated disorders. The pharmacological actions of phenolic antioxidants stem mainly from their free radical scavenging and metal chelating properties as well as their effects on cell signaling pathways and on gene expression. The antioxidant capacities of phenolic compounds that are widely distributed in plant-based diets were assessed by the Trolox equivalent antioxidant capacity (TEAC), the ferric reducing antioxidant power (FRAP), the hypochlorite scavenging capacity, the deoxyribose method and the copper-phenanthroline-dependent DNA oxidation assays. Based on the TEAC, FRAP and hypochlorite scavenging data, the observed activity order was: procyanidin dimer>flavanol>flavonol>hydroxycinnamic acids>simple phenolic acids. Among the flavonol aglycones, the antioxidant propensities decrease in the order quercetin, myricetin and kaempferol. Gallic acid and rosmarinic acid were the most potent antioxidants among the simple phenolic and hydroxycinnamic acids, respectively. Ferulic acid displayed the highest inhibitory activity against deoxyribose degradation but no structure-activity relationship could be established for the activities of the phenolic compounds in the deoxyribose assay. The efficacies of the phenolic compounds differ depending on the mechanism of antioxidant action in the respective assay used, with procyanidin dimers and flavan-3-ols showing very potent activities in most of the systems tested. Compared to the physiologically active (glutathione, alpha-tocopherol, ergothioneine) and synthetic (Trolox, BHA, BHT) antioxidants, these compounds exhibited much higher efficacy. Plant-derived phenolics represents good sources of natural antioxidants, however, further investigation on the molecular mechanism of action of these phytochemicals is crucial to the evaluation of their potential as prophylactic agents.
1,293 citations
References
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01 Jan 1990
TL;DR: Caution should be employed in the use of natural compounds: except for the major commercial synthetic versions (tocopherols, ascorbic acid) they have not usually been subjected to scrutiny and scientific evaluation as have the artificial synthetic compounds (BHA, BHT).
Abstract: Reports in recent years both in the popular and scientific press have stressed the value and advantages of natural ingredients as food preservatives. There is an implied assumption of safety for compounds that occur naturally in foods and that have been consumed for many centuries. It is not the intent of the authors to debate the issue of superiority of either natural or synthetic food components as to the safety or functional properties. It is preferable, however, to use substances that do not pose problems of proof of safety. Caution should be employed in the use of natural compounds: except for the major commercial synthetic versions (tocopherols, ascorbic acid) they have not usually been subjected to scrutiny and scientific evaluation as have the artificial synthetic compounds (BHA, BHT). Their potential as mutagens, carcinogens, teratogens, or as other pathogens must be investigated.
254 citations