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

Abstract

Kinetics and stoichiometric measurements based on the reactions of stable free radicals are among the most employed procedures in the evaluation of antioxidant activities of pure compounds and complex mixtures. In the present work it is shown that initial rates of diphenyl-picryl hydrazyl (DPPH) consumption elicited by cinnamic acid derivatives are closely related to their reactivity towards peroxyl radicals. This implies that kinetic data regarding DPPH bleaching can be useful on the evaluation of antioxidant reactivities. On the other hand, data obtained at a single (long) reaction time are unrelated to the reactivity of the antioxidants and mostly reflect the number of phenol groups present in the tested sample

Metal chelation, radical scavenging and inhibition of Aβ42 fibrillation by food constituents in relation to Alzheimer’s disease

“…The following procedure was adapted from the method of Campos, Duran, Lopez- & Lissi (2012). Solutions of DPPH (67.5 µM) were prepared in methanol (for normal kinetic studies), or in methanol containing 11.25, 112.5, 1125 mM acetic acid (for kinetic studies at lower pH to supress phenoxide formation (Litwinienko & Ingold, 2007)).…”

Effects of Aging on the Antioxidant Capacity of Red Wines

“…In this sense, good correlations are expected, and generally found ( Simonetti et al, 1997;Poblete et al, 2009;Bernardi et al, 2008;Kondrashov et al, 2009;Alarcón et al, 2008) between AOA indexes, measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS), electron paramagnetic resonance (EPR) and oxygen radical absorbance capacity (ORAC) using fluorescein (ORAC-Fl) methods, and total phenol content (measured by Folin's assay). Furthermore, relative ratios such as ORAC using pyrogallol red (ORAC-PGR)/ORAC-Fl (López- Alarcón et al, 2011), total antioxidant reactivity (TAR)/total reactive antioxidant potential (TRAP), DPPH initial rate/DPPH total bleaching (Campos et al, 2012), can be considered as a measure of the average reactivity of the antioxidants present in the tested sample. A similar intent to introduce indexes that measure the average 'quantity' and 'quality' of the antioxidants present in a complex sample is based on measurement of the amount Simonetti et al, (1997), Campos and Lissi (1996) DPPH radical Consumption at a fixed time Amount of antioxidants Campos et al (2012) Consumption initial rate Antioxidants amount and reactivity Campos et al (2012) Time and concentration to afford 50% of protection Antioxidants amount and reactivity Larrauri et al (1999) Luminol CL induced by AAPH Induction time (TRAP) Amount of antioxidants Perez et al (2000) Instantaneous decrease after wine addition Antioxidants amount and reactivity Campos et al (1997) ORAC Fluorescein protection Amounts of AO Dávalos et al (2004) PGR protection Antioxidants amount and reactivity.…”

“…Furthermore, relative ratios such as ORAC using pyrogallol red (ORAC-PGR)/ORAC-Fl (López- Alarcón et al, 2011), total antioxidant reactivity (TAR)/total reactive antioxidant potential (TRAP), DPPH initial rate/DPPH total bleaching (Campos et al, 2012), can be considered as a measure of the average reactivity of the antioxidants present in the tested sample. A similar intent to introduce indexes that measure the average 'quantity' and 'quality' of the antioxidants present in a complex sample is based on measurement of the amount Simonetti et al, (1997), Campos and Lissi (1996) DPPH radical Consumption at a fixed time Amount of antioxidants Campos et al (2012) Consumption initial rate Antioxidants amount and reactivity Campos et al (2012) Time and concentration to afford 50% of protection Antioxidants amount and reactivity Larrauri et al (1999) Luminol CL induced by AAPH Induction time (TRAP) Amount of antioxidants Perez et al (2000) Instantaneous decrease after wine addition Antioxidants amount and reactivity Campos et al (1997) ORAC Fluorescein protection Amounts of AO Dávalos et al (2004) PGR protection Antioxidants amount and reactivity. Roginsky et al (2006) AAPH, 2,2'-azobis(2-amidino-propane) dihydrochloride; ABTS, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid; AO, antioxidant; CL, chemiluminescence; DPPH, 1,1-diphenyl-2-picrylhydrazyl; EPR, electron paramagnetic resonance; FRAP, ferric reducing antioxidant power; LDL, low-density lipoprotein; MDA, malondialdehyde; ORAC, oxygen radical absorbance capacity; PGR, pyrogallol red; TRAP, total reactive antioxidant potential.…”

Redox Capacity of an Extracellular Matrix Protein Associated with Adhesion in Mytilus californianus

“…This was necessary, as DPPH extinction coefficients are pH-dependent, and thus, the control absorbance of 100 µM DPPH had different maxima. 13 Bleaching rate V b and percentage of remaining DPPH radical at infinite time F i were calculated according to the method described in ref 15. Experimentally determined reduction of DPPH radical as a function of the number of moles of Mfp-6 per mole of DPPH radical was also determined at defined time points.…”