Comparative Study of Polyphenol Scavenging Activities Assessed by Different Methods

Abstract

The effect of procyanidin solutions on superoxide anion radicals was studied with an enzymatic method and their EC(50) values were determined. A comparative study of the results suggested that the free radical scavenger potential of these phenolic compounds closely depends on their chemical and stereochemical structures. Oligomeric procyanidins were isolated in different fractions from grapes and wines by low- and high-pressure liquid chromatography. These compounds were found to be efficient free radical scavengers even for the weak concentrations in wines. Their activity in grapes or wines was much stronger than that of other commercially available natural antioxidants (such as ascorbic acid and gallic acid). The effect of tannins isolated from grapes on different radicals was analyzed according to three distinct methods: an enzymatic method for superoxide anion radicals (O(2)(*)(-)), a chemical method for the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(*)), and an immunochemical method to study the scavenging activity of seed procyanidins on DNA lesions induced by the radical HO(*).

Antioxidant Capacity, Anthocyanin Content Profile in ‘Bluecrop’ Blueberry Fruit

“…The soluble solids content was determined refractometrically, according to the Polish standard PN-EN 12143 (2000) in the juice squeezed out from 20 berries. In 2003 also the antioxidant activity was determined according to the method by Saint Criq de Gaulejac et al (1999) with the help of the synthetic radical DPPH (1,1-diphenyl-2-picrylhydrazine, Sigma). The antioxidant activity was calculated on the basis of absorbance measurements for the proper sample (fruit extract + DPPH + ) performed after 20 min at λ=517 nm in relation to the control sample (H 2 O + DPPH + ).…”

Kinetic and Stoichiometric Evaluation of Free Radicals Scavengers Activities Based on Diphenyl-Picryl Hydrazyyl (Dpph) Consumption

“…Frequently the antioxidant capacity of complex samples is estimated from evaluations of DPPH consumption at a fixed time (10 or 15 minutes), measured at a very long time, at the end of the initial fast reaction 24 , at the plateau or at the steady state 13,17,25,32 , or extrapolated to "infinite" time. We have chosen this last procedure in order to avoid the uncertainty associated to a visual estimation of the steady state conditions.…”

“…In the present work we discuss the validity of the proposed methodologies, with particular emphasis on the information that can be derived from kinetic evaluations of the rate of DPPH bleaching and the stoichiometry of the process. This is a conflicting subject and even there are not consensus regarding how to estimate the "final" DPPH concentration: 5 minutes 18 24 or reaching a plateau 25 or a steady state condition 26,27 .…”

Minocycline exerts a neuroprotective action against 6-OHDA-induced neurotoxicity: in vivo and in vitro studies

“…This assay provides an easy and rapid way to evaluate antioxidants by spectrophotometry. Minocycline and alpha-tocopherol (as reference) were evaluated by the DPPH assay [27]. Briefly, an aliquot (0.1 mL) of Mino (1 to 50 µg/ mL) or alpha-tocopherol (5 or 50 mg/mL) was mixed with 3.9 mL DPPH solution (0.3 mM).…”