1.1- Diphenyl-2-picrylhydrazyl assay

In the DPPH (l,l-diphenyl-2-picrylhydrazyl) assay, garcinol exhibited potent radical scavenging activity at an extent almost 3 times higher than a-tocopherol and comparable to 85% of the activity of ascorbic acid [84],... 

Magalhaes, L. M., M. A. Segundo, S. Reis, and J. L. F. C. Lima. 2006. Automatic method for determination of total antioxidant capacity using 2,2-diphenyl-l-picrylhydrazyl assay. Analytica Chimica Acta 558(1-2) 310-318. 

Thongchai, W., B. Liawruangrath, and S. Liawruangrath. 2009. Flow injection analysis of total curcuminoids in turmeric and total antioxidant capacity using 2,20-diphenyl-l-picrylhydrazyl assay. Food Chem. 112 494-499. 

Popular EPR-based assays of antioxidant activity include the DPPH assay, in which the ability of compounds to quench (by H-atom transfer) the 1,1-diphenyl-2-picrylhydrazyl radical is used to rank their antioxidant activity. This method has been applied widely to the analysis of dietary antioxidants and extracts from medicinal plants.213 219 Extensive use has also been made of assays based on the competition between spin traps and test compounds for reaction with enzymatically-generated 02 and, in the presence of a metal catalyst, the OH rad-... 

As an assay for antioxidant activity, we examined the inhibition of lipoxygenase activity and radical scavenging activity using the a, a-diphenyl-P-picrylhydrazyl (DPPH) decolorization test. Aqueous, ethanolic and methanolic extracts of microalgae were used in the assays. 

Most stilbenoids possess antioxidant activities because they possess polyphenol functions in the molecules. Some of their beneficial effects, hepatoprotective action, cardiovascular protection, for instance, are in close relation to their antioxidant activities. Several models have been employed in the assay such as lipid peroxidation system, human low-density lipoprotein model, xanthine oxidase system and l,l-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging model, which is the most commonly used protocol. 

In addition to measuring the antioxidant effects of prenylated flavonoids from Sophora flavescens by using in vitro l,l-diphenyl-2-picrylhydrazyl (DPPH), 2,2/-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), per-oxynitrite (ONOCT), and total reactive oxygen species (ROS) assays, the examination of the inhibition of tert-butylhydroperoxide (f-BIIP)-induced intracellular ROS generation and f-BHP-induced activation of nuclear factor-kB (NF-/cB) was also added as a further examination of kuraridinol (9),... 

Several studies described the interaction of flavonoids with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical [76, 79, 107-108] (Fig. (3)). DPPH is a stable free radical and is frequently used in ESR studies [109]. The DPPH assay provides information on the reactivity of flavonoids with a stable free radical [79]. Because of its odd electron, DPPH gives a strong absorption band in ethanol at 517 nm. As this... 

Note 5 On applying the DPPH assay, the determined ICj value for arbutin ( 768 mM) represents a 176 times lower antioxidant capacity than the one determined for quercetin (4.36 mM). Although the arbutin ICj(, value correlates well with those published by other investigators applying similar DPPH-assay conditions [23], it should be pointed out that there is an experimental conflict The DPPH assay, which uses alcohols (methanol) as the l,l-diphenyl-2-picrylhydrazyl-radical dissolvent, is preferably used to investigate the antioxidant capacity of lipophilic (alcohol... 

Antioxidant activity is also a measure for substance ability to prevent free radical concentration increment, oxidative stress, and risk for development-related diseases. And for the purpose of measuring antioxidant activity, many assays are applied such as 2,2-diphenyl-l-picrylhydrazyl (DPPH) assay, 2,2 -azino-bis(3-ethylbenzthiazoline-6)-sulfonic acid (ABTS) assay, p-carotene bleaching test, ferric and cupric reducing power, and linoleic acid assay (Akrout et ah, 2011 Chabir et ah, 2011 Jia et al, 2010 Serrano et al, 2011). 

ROS scavenging ability of ERG was tested using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) solution-based chemical assay and a 2,2,7,2-dichlorodihydrofluorescein diacetate (DCFH-DA) HL-60 cell line-based assay. The cell-based fluorescent DCFH assay enables detection of antioxidant molecules which can penetrate cell membranes and inhibit ROS production in living cells. The antioxidant activity was determined by TPA-stimulated control cells with and without FRG. FRG showed strong antioxidant activity in both systems [64]. 

Various studies have inferred and quantified, through surface binding assays using radical scavengers such as l,l-diphenyl-2-picrylhydrazyl (DPPH), the presence of surface radicals that serve as initiators for graft polymerization. These studies have also reported that the surface radical number density that results from plasma treatment can be controlled and optimized by tuning the plasma treatment time and the radio frequency (rf) power of the plasma generator. 

Brisdelli et al. (2013) investigated the effects of six lichen metabolites (diffractaic acid, lobaric acid, usnic acid, vicanicin, variolaric acid, protolichesterinic acid) on reactive oxygen species (ROS) level towards three human cancer cell lines, MCF-7 (breast adenocarcinoma), HeLa (cervix adenocarcinoma) and HCT-116 (colon carcinoma). AU tested lichen compounds did not exhibit free radical scavenging activity using the l,l-diphenyl-2-picrylhydrazyl (DPPH) assay. The lichen metabolites did not significantly increase the intracellular ROS level and did not prevent oxidative injury induced by t-butyl hydroperoxide in tested cells. 

For some stictic acid derivates, Lohezic-Le Devehat et al. (2007) found moderate antiradical activity in the l,l-diphenyl-2-picrylhydrazyl (DPPH) assay and very high superoxide anion scavenging activity. 

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