Standardized Methods for the Determination of Antioxidant Capacity and Phenolics in Foods and Dietary Supplements
26 Apr 2005-Journal of Agricultural and Food Chemistry (American Chemical Society)-Vol. 53, Iss: 10, pp 4290-4302
TL;DR: Methods available for the measurement of antioxidant capacity are reviewed, presenting the general chemistry underlying the assays, the types of molecules detected, and the most important advantages and shortcomings of each method.
Abstract: Methods available for the measurement of antioxidant capacity are reviewed, presenting the general chemistry underlying the assays, the types of molecules detected, and the most important advantages and shortcomings of each method. This overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceutical, and dietary supplement industries. From evaluation of data presented at the First International Congress on Antioxidant Methods in 2004 and in the literature, as well as consideration of potential end uses of antioxidants, it is proposed that procedures and applications for three assays be considered for standardization: the oxygen radical absorbance capacity (ORAC) assay, the Folin-Ciocalteu method, and possibly the Trolox equivalent antioxidant capacity (TEAC) assay. ORAC represent a hydrogen atom transfer (HAT) reaction mechanism, which is most relevant to human biology. The Folin-Ciocalteu method is an electron transfer (ET) based assay and gives reducing capacity, which has normally been expressed as phenolic contents. The TEAC assay represents a second ET-based method. Other assays may need to be considered in the future as more is learned about some of the other radical sources and their importance to human biology.
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TL;DR: The anticancer effects of phenolics in-vitro and in- vivo animal models are viewed, including recent human intervention studies, and possible mechanisms of action involving antioxidant and pro-oxidant activity as well as interference with cellular functions are discussed.
Abstract: Phenolics are broadly distributed in the plant kingdom and are the most abundant secondary metabolites of plants. Plant polyphenols have drawn increasing attention due to their potent antioxidant properties and their marked effects in the prevention of various oxidative stress associated diseases such as cancer. In the last few years, the identification and development of phenolic compounds or extracts from different plants has become a major area of health- and medical-related research. This review provides an updated and comprehensive overview on phenolic extraction, purification, analysis and quantification as well as their antioxidant properties. Furthermore, the anticancer effects of phenolics in-vitro and in-vivo animal models are viewed, including recent human intervention studies. Finally, possible mechanisms of action involving antioxidant and pro-oxidant activity as well as interference with cellular functions are discussed.
3,213 citations
Cites background from "Standardized Methods for the Determ..."
...be considered for standardization at the First International Congress on Antioxidant Methods held in Orlando, FL, in June 2004 [157]....
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...For example, the total antioxidant capacity has to be able to reflect both lipophilic and hydrophilic capacity, and to reflect and distinguish hydrogen atom transfer, electron transfer, as well as transition metal chelation [157]....
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...evaluating effectiveness of antioxidant compounds against various ROS/RNS such as O2·, HO·, and ONOO to fully elucidate a full profile of antioxidant capacity [157]....
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TL;DR: A microplate-adapted colorimetric total phenolics assay that utilizes Folin–Ciocalteu (F–C) reagent is described that eliminates approximately 85% of ascorbic acid and other potentially interfering compounds.
Abstract: Non-structural phenolic compounds perform a variety of functions in plants, including acting as antioxidants. We describe a microplate-adapted colorimetric total phenolics assay that utilizes Folin-Ciocalteu (F-C) reagent. The F-C assay relies on the transfer of electrons in alkaline medium from phenolic compounds to phosphomolybdic/phosphotungstic acid complexes, which are determined spectroscopically at 765 nm. Although the electron transfer reaction is not specific for phenolic compounds, the extraction procedure eliminates approximately 85% of ascorbic acid and other potentially interfering compounds. This assay is performed in microcentrifuge tubes and assessed in a 96-well plate reader. At least 64 samples can be processed in 1 d.
2,047 citations
Cites methods from "Standardized Methods for the Determ..."
...and has been proposed as a standardized method for use in the routine quality control and measurement of antioxidant capacity of food products and dietary supplement...
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TL;DR: A review of phenolic and polyphenolic compounds can be found in this article, which summarizes both the synthetic and natural phenolic antioxidants, emphasizing their mode of action, health effects, degradation products and toxicology.
1,800 citations
TL;DR: The chemistry and biochemistry of polyphenols as related to classification, extraction, separation and analytical methods, their occurrence and biosynthesis in plants, and the biological activities and implications in human health are reviewed.
Abstract: Polyphenols are the biggest group of phytochemicals, and many of them have been found in plant-based foods. Polyphenol-rich diets have been linked to many health benefits. This paper is intended to review the chemistry and biochemistry of polyphenols as related to classification, extraction, separation and analytical methods, their occurrence and biosynthesis in plants, and the biological activities and implications in human health. The discussions are focused on important and most recent advances in the above aspects, and challenges are identified for future research.
1,674 citations
TL;DR: A critical review on various developments to the DPPH method is presented, which has undergone various modifications to suit the requirements, even though the basic approach remains same in all of them.
Abstract: α, α-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging method offers the first approach for evaluating the antioxidant potential of a compound, an extract or other biological sources. This is the simplest method, wherein the prospective compound or extract is mixed with DPPH solution and absorbance is recorded after a defined period. However, with the advancement and sophistication in instrumental techniques, the method has undergone various modifications to suit the requirements, even though the basic approach remains same in all of them. This article presents a critical review on various developments to the DPPH method.
1,290 citations
Cites methods from "Standardized Methods for the Determ..."
...DPPH method may be utilized in aqueous and nonpolar organic solvents and can be used to examine both hydrophilic and lipophilic antioxidants (Prior et al. 2005)....
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References
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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
Journal Article•
TL;DR: In this paper, the use of Folin-Ciocalteu reagent rather than the FolinDenis reagent, gallic acid as a reference standard, and a more reproducible time-temperature color development period was investigated.
Abstract: Several details of the assay of total phenolic substances have been investigated and an improved procedure developed. The improvements include the use of Folin-Ciocalteu reagent rather than the Folin-Denis reagent, gallic acid as a reference standard, and a more reproducible time-temperature color development period. The values obtained are less subject to variation and interference from several nonphenols, yet are directly comparable to the "tannin" values obtained by the previously standard method.
18,629 citations
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
TL;DR: The FRAP assay offers a putative index of antioxidant, or reducing, potential of biological fluids within the technological reach of every laboratory and researcher interested in oxidative stress and its effects.
17,394 citations
TL;DR: In this article, the antioxidant activity and total phenolics of 28 plant products, including sunflower seeds, flaxseeds, wheat germ, buckwheat, and several fruits, vegetables, and medicinal plants were determined.
Abstract: The antioxidant activities and total phenolics of 28 plant products, including sunflower seeds, flaxseeds, wheat germ, buckwheat, and several fruits, vegetables, and medicinal plants were determined. The total phenolic content, determined according to the Folin−Ciocalteu method, varied from 169 to 10548 mg/100 g of dry product. Antioxidant activity of methanolic extract evaluated according to the β-carotene bleaching method expressed as AOX (Δ log A470/min), AA (percent inhibition relative to control), ORR (oxidation rate ratio), and AAC (antioxidant activity coefficient) ranged from 0.05, 53.7, 0.009, and 51.7 to 0.26, 99.1, 0.46, and 969.3, respectively. The correlation coefficient between total phenolics and antioxidative activities was statistically significant. Keywords: Antioxidant activity; phenolics; medicinal plants; oilseeds; buckwheat; vegetables; fruits; wheat products
3,633 citations