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Journal ArticleDOI

Structure-antioxidant activity relationships of flavonoids and phenolic acids

01 Jan 1996-Free Radical Biology and Medicine (FREE RADICAL BIOLOGY AND MEDICINE)-Vol. 20, Iss: 7, pp 933-956
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.
About: This article is published in Free Radical Biology and Medicine.The article was published on 1996-01-01. It has received 8513 citations till now. The article focuses on the topics: Health effects of natural phenols and polyphenols.
Citations
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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.

18,580 citations


Additional excerpts

  • ...Generation of the ABTS [2,29-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)] radical cation [18] forms the basis of one of the spectrophotometric methods that have been applied to the measurement of the total antioxidant activity of solutions of pure substances [12,19,20], aqueous mixtures and beverages [7,8]....

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Journal ArticleDOI
TL;DR: This review examines the evidence for involvement of the oxidative stress in the carcinogenesis process and the role of enzymatic and non-enzymatic antioxidants in the process of carcinogenesis as well as the antioxidant interactions with various regulatory factors.

5,937 citations

Journal ArticleDOI
02 Jun 2006-Science
TL;DR: Using metabolic function analyses of identified genes, the human genome is compared with the average content of previously sequenced microbial genomes and humans are superorganisms whose metabolism represents an amalgamation of microbial and human attributes.
Abstract: The human intestinal microbiota is composed of 10(13) to 10(14) microorganisms whose collective genome ("microbiome") contains at least 100 times as many genes as our own genome. We analyzed approximately 78 million base pairs of unique DNA sequence and 2062 polymerase chain reaction-amplified 16S ribosomal DNA sequences obtained from the fecal DNAs of two healthy adults. Using metabolic function analyses of identified genes, we compared our human genome with the average content of previously sequenced microbial genomes. Our microbiome has significantly enriched metabolism of glycans, amino acids, and xenobiotics; methanogenesis; and 2-methyl-d-erythritol 4-phosphate pathway-mediated biosynthesis of vitamins and isoprenoids. Thus, humans are superorganisms whose metabolism represents an amalgamation of microbial and human attributes.

4,111 citations

Journal ArticleDOI
TL;DR: It is now possible to establish the antioxidant activities of plant-derived flavonoids in the aqueous and lipophilic phases, and to assess the extent to which the total antioxidant potentials of wine and tea can be accounted for by the activities of individual polyphenols.

4,076 citations

Journal ArticleDOI
TL;DR: The diversity and multiple mechanisms of flavonoid action, together with the numerous methods of initiation, detection and measurement of oxidative processes in vitro and in vivo offer plausible explanations for existing discrepancies in structure-activity relationships.
Abstract: Flavonoids are a class of secondary plant phenolics with significant antioxidant and chelating properties. In the human diet, they are most concentrated in fruits, vegetables, wines, teas and cocoa. Their cardioprotective effects stem from the ability to inhibit lipid peroxidation, chelate redox-active metals, and attenuate other processes involving reactive oxygen species. Flavonoids occur in foods primarily as glycosides and polymers that are degraded to variable extents in the digestive tract. Although metabolism of these compounds remains elusive, enteric absorption occurs sufficiently to reduce plasma indices of oxidant status. The propensity of a flavonoid to inhibit free-radical mediated events is governed by its chemical structure. Since these compounds are based on the flavan nucleus, the number, positions, and types of substitutions influence radical scavenging and chelating activity. The diversity and multiple mechanisms of flavonoid action, together with the numerous methods of initiation, detection and measurement of oxidative processes in vitro and in vivo offer plausible explanations for existing discrepancies in structure-activity relationships. Despite some inconsistent lines of evidence, several structure-activity relationships are well established in vitro. Multiple hydroxyl groups confer upon the molecule substantial antioxidant, chelating and prooxidant activity. Methoxy groups introduce unfavorable steric effects and increase lipophilicity and membrane partitioning. A double bond and carbonyl function in the heterocycle or polymerization of the nuclear structure increases activity by affording a more stable flavonoid radical through conjugation and electron delocalization. Further investigation of the metabolism of these phytochemicals is justified to extend structure-activity relationships (SAR) to preventive and therapeutic nutritional strategies.

3,567 citations

References
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Journal ArticleDOI
TL;DR: Flavonoids in regularly consumed foods may reduce the risk of death from coronary heart disease in elderly men and showed an inverse relation with incidence of myocardial infarction.

4,440 citations

Journal ArticleDOI
TL;DR: Data from Caerphilly, Wales, show that platelet aggregation, which is related to CHD, is inhibited significantly by alcohol at levels of intake associated with reduced risk of CHD.

3,489 citations

Journal ArticleDOI
TL;DR: The method has been applied to investigate the total plasma antioxidant capacity of neonates and how this may be compromised in prematurity, and an antioxidant ranking was established based on their reactivity relative to a 1.0 mmol/l Trolox standard.
Abstract: 1. A new method has been developed for measuring the total antioxidant capacity of body fluids and drug solutions, based on the absorbance of the ABTS.+ radical cation. 2. An automated method for use on a centrifugal analyser, as well as a manual method, is described. 3. The procedure has been applied to physiological antioxidant compounds and radical-scavenging drugs, and an antioxidant ranking was established based on their reactivity relative to a 1.0 mmol/l Trolox standard. 4. The Trolox equivalent antioxidant capacity of plasma from an adult reference population has been measured, and the method optimized and validated. 5. The method has been applied to investigate the total plasma antioxidant capacity of neonates and how this may be compromised in prematurity.

2,844 citations

Journal ArticleDOI
TL;DR: A comprehensive survey on the compositional properties of LDL relevant for its susceptibility to oxidation, on the mechanism and kinetics of LDL oxidation, and on the chemical and physico-chemical properties of HDL oxidized by exposure to copper ions is provided.

2,289 citations