Journal ArticleDOI
A procedure to measure the antiradical efficiency of polyphenols
TLDR
In this article, the kinetic behavior of polyphenols common in fruits as free radical scavengers was studied using 2,2-diphenyl-1-picrylhydrazyl (DPPH).Abstract:
The kinetic behaviour of polyphenols common in fruits as free radical scavengers was studied using 2,2-diphenyl-1-picrylhydrazyl (DPPH.). After addition of different standard concentrations to DPPH. (0.025 g litre-1), the percentage of remaining DPPH. was determined at different times from the absorbances at 515 nm. The percentage remaining DPPH. against reaction time followed a multiplicative model equation: In [DPPH.REM] = b 1n t + 1n a. The slopes of these equations may be useful parameters to define the antioxidant capacity. The steeper the slope, the lower the amount of antioxidant necessary to decrease by 50% the initial DPPH. concentration (EC50). This parameter, EC50, is widely used to measure antioxidant power, but it does not takes into account the reaction time. Time needed to reach the steady state to the concentration corresponding at EC50 (T(EC50)) was calculated, and antiradical efficiency (AE) was proposed as a new parameter to characterise the antioxidant compounds where AE = 1/EC50 T(EC50). It was shown that AE is more discriminatory than EC50. AE values are more useful because they also take into account the reaction time. The results have shown that the order of the AE (x 10(-3)) in the compounds tested was: ascorbic acid (11.44) > caffeic acid (2.75) greater than or equal to gallic acid (2.62) > tannic acid (0.57) greater than or equal to DL-alpha-tocopherol (0.52) > rutin (0.21) greater than or equal to quercetin (0.19) > ferulic acid (0.12) greater than or equal to 3-tert-butyl-4-hydroxyanisole, BHA (0.10) > resveratrol (0.05).read more
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Standardized Methods for the Determination of Antioxidant Capacity and Phenolics in Foods and Dietary Supplements
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.
Journal ArticleDOI
Polyphenols: Chemistry, Dietary Sources, Metabolism, and Nutritional Significance
TL;DR: An overview of the nutritional effects of the main groups of polyphenolic compounds, including their metabolism, effects on nutrient bioavailability, and antioxidant activity, is offered, as well as a brief description of the chemistry ofpolyphenols and their occurrence in plant foods.
Journal ArticleDOI
Antioxidant activity of dietary polyphenols as determined by a modified ferric reducing/antioxidant power assay
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.
Journal ArticleDOI
Novel total antioxidant capacity index for dietary polyphenols and vitamins C and E, using their cupric ion reducing capability in the presence of neocuproine: CUPRAC method.
TL;DR: The development of a simple, widely applicable antioxidant capacity index for dietary polyphenols and vitamins C and E is reported, utilizing the copper(II)-neocuproine [Cu(II-Nc] reagent as the chromogenic oxidizing agent.
Journal ArticleDOI
Screening of Plant Extracts for Antioxidant Activity: a Comparative Study on Three Testing Methods
TL;DR: Three methods widely employed in the evaluation of antioxidant activity, namely 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method, static headspace gas chromatography (HS-GC) and beta-carotene bleaching test (BCBT), have been compared with regard to their application in the screening of plant extracts.