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Showing papers on "DPPH published in 2004"


Journal Article
TL;DR: The use of the stable free radical diphenylpicrylhydrazyl (DPPH) for estimating antioxidant activity and its application in antioxidant research is described.
Abstract: Molyneux, P. The use of the stable free radical diphenylpicrylhydrazyl (DPPH) for estimating antioxidant activity

2,519 citations


Journal ArticleDOI
TL;DR: In this article, a b-carotene-linoleic acid (linoleate) model system was used to evaluate the scavenging effect on the DPPH free radical and capacity to scavenge hydroxyl free radicals.

1,067 citations


Journal ArticleDOI
TL;DR: In this article, the antioxidant properties of the essential oil from oregano in relation to its chemical composition were examined and the antioxidant activity was investigated with three different methods: the β-carotene bleaching (BCB) test, the 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method and the TBARS assay.

837 citations


Journal ArticleDOI
TL;DR: Ethanol extracts of propolis from Argentina, Australia, China, Hungary and New Zealand had relatively strong antioxidant activities, and were also correlated with the total polyphenol and flavonoid contents.

776 citations


01 Jan 2004
TL;DR: In this article, the antioxidant properties of the essential oil from oregano in relation to its chemical composition were examined and the antioxidant activity was investigated with three different methods: the b-carotene bleaching (BCB) test, the 2,2 0 -diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method and the TBARS assay.
Abstract: The antioxidant properties of the essential oil from oregano in relation to its chemical composition were examined. The antioxidant activity was investigated with three different methods: the b-carotene bleaching (BCB) test, the 2,2 0 -diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method and the thiobarbituric acid reactive species (TBARS) assay. It was found that the total essential oil, its fraction as well as its pure constituents have a significant antioxidant effect when tested by each method, respectively. Generally the antioxidant activity of the oregano essential oil is less effective than the ascorbic acid, but comparable with the a-tocopherol and the synthetic antioxidant butylated hydroxytoluene (BHT). The synergy among minor oxygen containing compounds was suggested as possible factor, which influenced the antioxidant power of the oregano essential oil. The antioxidant concentrations influenced its antioxidant power, too. # 2003 Elsevier Ltd. All rights reserved.

673 citations


Journal ArticleDOI
TL;DR: The antioxidant mechanism of FEHP might be attributed to its free radical scavenging activity, metal-chelation activity, and reactive oxygen quenching activity, which suggested that chelation of metal ion was the main antioxidant action.
Abstract: A flavonoid-rich extract of Hypericum perforatum L. (FEHP) was prepared by adsorption on macroporous resin and desorption by ethanol. Total flavonoid content of FEHP was determined by a colorimetric method. The major constituents of FEHP, including rutin, hyperoside, isoquercitrin, avicularin, quercitrin, and quercetin, were determined by HPLC analysis and confirmed by LC-MS. Different antioxidant assays were utilized to evaluate free radical scavenging activity and antioxidant activity of FEHP. FEHP was an effective scavenger in quenching DPPH and superoxide radical with IC50 of 10.63 microg/mL and 54.3 microg/mL, respectively. A linear correlation between concentration of FEHP and reducing power was observed with a coefficient of r2 = 0.9991. Addition of 150 microg of FEHP obviously decreased the peroxidation of linoleic acid during 84 h incubation, but the amount of FEHP over 150 microg did not show statistically significant inhibitory effect of peroxidation of linoliec acid (p > 0.05). FEHP exhibited inhibitory effect of peroxidation of liposome induced both by hydroxyl radical generated with iron-ascorbic acid system and peroxyl radical and showed prominent inhibitory effect of deoxyribose degradation in a concentration-dependent manner in site-specific assay but poor effect in non-site-specific assay, which suggested that chelation of metal ion was the main antioxidant action. According to the results obtained in the present study, the antioxidant mechanism of FEHP might be attributed to its free radical scavenging activity, metal-chelation activity, and reactive oxygen quenching activity.

614 citations


Journal ArticleDOI
TL;DR: In this paper, the antioxidant potency of freeze-dried aqueous extract of potato peel was investigated employing various established in vitro systems, such as lipid peroxidation in rat liver homogenate, 1, 1-diphenyl-2-picrylhydrazyl (DPPH)/superoxide/hydroxyl radical scavenging, reducing power, and iron ion chelation.

598 citations


Journal ArticleDOI
TL;DR: Kinetic analysis of the reaction sequence for the free acids leads to an expression for the observed rate constant, k(1), proportional to [ArOH](0)(-1/2) in excellent agreement with the experimental behavior of these phenols, interpreted in terms of the influence that adventitious acids or bases present in the solvent.
Abstract: The kinetic behavior of cinnamic acids, their methyl esters, and two catechols 1−10 (ArOH) in the reaction with DPPH• in methanol and ethanol is not compatible with a reaction mechanism that involv...

545 citations


Journal ArticleDOI
TL;DR: In this paper, extracts of different polarity from leaves and seeds of coriander (Coriandrum sativum ) and Coriander oil were investigated for their antioxidant activity.

498 citations


Journal ArticleDOI
TL;DR: In this article, the antimicrobial properties of essential oils and methanol extracts of Origanum vulgare ssp. were evaluated using a GC/MS system and the results showed that the essential oil of O. vulgaare possesses great potential of antimicrobial activity against all 10 bacteria and 15 fungi and yeast species tested.

475 citations


Journal ArticleDOI
TL;DR: The present study describes antimicrobial and free radical scavenging capacity (RSC) together with the effects on lipid peroxidation (LP) of Melissa officinalis essential oil and the most effective antibacterial activity was expressed on a multiresistant strain of Shigella sonei.
Abstract: The present study describes antimicrobial and free radical scavenging capacity (RSC) together with the effects on lipid peroxidation (LP) of Melissa officinalis essential oil. The chemical profile of essential oil was evaluated by the means of gas chromatography-mass spectrometry (GC-MS) and thin-layer chromatography (TLC). RSC was assessed measuring the scavenging activity of essential oil on the 2,2-diphenyl-1-picrylhydrazyl (DPPH(*)) and OH(*) radicals. The effect on LP was evaluated following the activities on Fe(2+)/ascorbate and Fe(2+)/H(2)O(2) systems of induction. The antimicrobial activity was tested against 13 bacterial strains and six fungi. The examined essential oil exhibited very strong RSC, reducing the DPPH radical formation (IC(50) = 7.58 microg/mL) and OH radical generation (IC(50) = 1.74 microg/mL) in a dose-dependent manner. According to the GC-MS and TLC (dot-blot techniques), the most powerful scavenging compounds were monoterpene aldehydes and ketones (neral/geranial, citronellal, isomenthone, and menthone) and mono- and sesquiterpene hydrocarbons (E-caryophyllene). Very strong inhibition of LP, particularly in the Fe(2+)/H(2)O(2) system of induction (94.59% for 2.13 microg/mL), was observed in both cases, also in a dose-dependent manner. The most effective antibacterial activity was expressed on a multiresistant strain of Shigella sonei. A significant rate of antifungal activity was exhibited on Trichophyton species.

Journal ArticleDOI
TL;DR: In this article, the antioxidant activity of two selected Malaysian honeys, as well as their ethyl acetate extracts, were evaluated, which indicated that honey has antioxidative and radical scavenging properties, which are mainly due to its phenolic content.

Journal ArticleDOI
TL;DR: The controversy as to whether the central keto-enol moiety or the peripheral phenolic hydroxyl groups of CU are involved in its radical trapping (antioxidant) activity is resolved and the SPLET process cannot occur in a nonionizing solvent.
Abstract: The rates of reaction of 1,1-diphenyl-2-picrylhydrazyl (dpph•) radicals with curcumin (CU, 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione), dehydrozingerone (DHZ, “half-curcumin”), and isoeugenol (IE) have been measured in methanol and ethanol and in two non-hydroxylic solvents, dioxane and ethyl acetate, which have about the same hydrogen-bond-accepting abilities as the alcohols. The reactions of all three substrates are orders of magnitude faster in the alcohols, but these high rates can be suppressed to values essentially equal to those in the two non-hydroxylic solvents by the addition of acetic acid. The fast reactions in alcohols are attributed to the reaction of dpph• with the CU, DHZ, and IE anions (see J. Org. Chem. 2003, 68, 3433), a process which we herein name sequential proton loss electron transfer (SPLET). The most acidic group in CU is the central keto−enol moiety. Following CU's ionization to a monoanion, ET from the [−(O)CCHC(O)−]- moiety to dpph• yields the neutral [−(O)CCH...

Journal ArticleDOI
TL;DR: In this article, the authors evaluated the effects of four selected solvent systems at ambient temperature for 15h and Soxhlet extraction with absolute ethanol on antioxidant activity measurements, and the results showed that the extracting solvent significantly altered the antioxidant property estimations of wheat bran, and 50% acetone is a recommended solvent for extracting phenolic antioxidants from wheat for analytical purpose.
Abstract: Significant levels of antioxidant activities and phenolic components have been detected in wheat and wheat-based food products, indicating that wheat may serve as an excellent dietary source of natural antioxidants for disease prevention and health promotion. Several solvent systems have been used to prepare antioxidant extracts from wheat and wheat-based food products. This makes it difficult to compare and understand the antioxidant activities of wheat reported from different research groups. The purpose of this study was to evaluate the effects of four selected solvent systems at ambient temperature for 15 h and Soxhlet extraction with absolute ethanol on antioxidant activity measurements. The four solvent systems included 50% acetone (v/v), 70% methanol (v/v), 70% ethanol (v/v), and ethanol, and antioxidant activities were tested using ORAC, radical scavenging activities against stable DPPH • and cation ABTS •+ , and total phenolic content. The results showed that the extracting solvent significantly altered the antioxidant property estimations of wheat bran, and 50% acetone is a recommended solvent for extracting phenolic antioxidants from wheat bran for analytical purpose.

Journal ArticleDOI
TL;DR: In this article, the in vitro antimicrobial and antioxidant properties of essential oil and methanol extracts from a unique and endemic plant, Thymus spathulifolius (Hausskn. and Velen.).

Journal ArticleDOI
TL;DR: In this paper, the essential oils and methanolic extracts of Salvia cryptantha and Salvia multicaulis were examined for their potential antimicrobial and radical scavenging activities.

Journal ArticleDOI
TL;DR: It can be argued that the ABTS(*+) assay may give an indication for the presence of antioxidants in a certain system but SARs cannot be readily inferred.
Abstract: Observations on the applicability of the ABTS•+ assay to define structure−activity relationships (SARs) among phenols (AH) were based on experimental data and theoretical calculations. All AH examined (hydroxycinnamic derivatives, simple polyphenols, polyhydroxybenzoates, and flavonoids) were found to be active toward ABTS•+. Moreover, known weak radical scavengers (i.e., coumaric and isoferulic acids) were found to be efficient or comparatively active to caffeic or rosmarinic acids in contradiction to the AH classification based on 1,1-diphenyl-2-picrylhydrazyl (DPPH) data or the bond dissociation enthalpy values. This behavior was observed both in ethanol and in buffered (pH 7.4) environment. Resorcinol and phloroglucin were found to be more active than catechol and hydroquinone, whereas, among polyhydroxybenzoates, 2,4-dihydroxybenzoic acid was the least active, in line with the DPPH and theoretical data. Therefore, it can be argued that the ABTS•+ assay may give an indication for the presence of antio...

Journal ArticleDOI
TL;DR: In this article, the antioxidant effectiveness of selected wines and pure (+)-catechin were determined using three different methods, including α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging, the reducing power was determined using ferric reducing/antioxidant power (FRAP) assay and β-carotene bleaching (BCB) method.

Journal ArticleDOI
TL;DR: High levels of LDL antioxidant activity in plant products for which such activity levels are underestimated are revealed in the DPPH radical scavenging assay and Folin-Ciocalteu assay.
Abstract: Oxidation of low-density lipoprotein (LDL) has been implicated in atherogenesis. Antioxidants that prevent LDL from oxidizing may reduce atherosclerosis. This study investigated LDL antioxidant activity in edible plant products for development of dietary supplementation to prevent atherosclerosis. Fifty-two kinds of edible plants were extracted using 70% aqueous ethanol solution, and the antioxidant activity of the extracts, which inhibit human LDL oxidation induced by copper ion, was determined on the basis of the oxidation lag time and represented as epigallocatechin 3-gallate equivalent. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and total phenolic content were also measured for comparisons with antioxidant activity in LDL. Plant products showing the greatest activity in LDL oxidation assay were akamegashiwa (Mallotus japonicus) leaf, Japanese privet (Ligustrum japonicum) leaf, green tea [Camellia sinensis (L.) O. Kuntze], and astringent persimmon (Diospyros kaki). The present study revealed high levels of LDL antioxidant activity in plant products for which such activity levels are underestimated in the DPPH radical scavenging assay and Folin-Ciocalteu assay.

Journal ArticleDOI
TL;DR: In this article, pine sawdust and almond hulls were solvent-extracted under different experimental conditions to optimize the yield of polyphenolic antioxidant compounds, which were quantified by ability to scavenge the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical.

Journal ArticleDOI
TL;DR: In this paper, three local varieties of Piper betle leaves were evaluated by several in vitro systems, e.g., DPPH radical scavenging activity, superoxide radical scavengence activity in a riboflavin/light/NBT system, hydroxyl radical scavenges activity and inhibition of lipid peroxidation induced by FeSO 4 in egg yolk.

Journal ArticleDOI
TL;DR: The results suggested that the substituents on the alkyl chain might contribute to both radical scavenging effect and inhibitory effect of autoxidation of oils, while inhibitory effects against the AAPH‐induced peroxidated of liposome was somewhat influenced by the alKYl chain length.
Abstract: Ginger (Zingiber officinale Roscoe) shows an antioxidant activity, and we have been engaging to determine the structures of more than 50 antioxidants isolated from the rhizomes of ginger. The isolated antioxidants are divided into two groups; gingerol related compounds and diarylheptanoids. In this study, structure-activity relationship of gingerol related compounds was evaluated. Gingerol related compounds substituted with an alkyl group bearing 10-, 12- or 14-carbon chain length were isolated from the dichloromethane extract of rhizomes using repeated chromatographic techniques. The antioxidant activities of these compounds were evaluated by the following measurements; 1) 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2) inhibitory effect on oxidation of methyl linoleate under aeration and heating by the Oil Stability Index (OSI) method, and 3) inhibitory effect on oxidation of liposome induced by 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH). These results suggested that the substituents on the alkyl chain might contribute to both radical scavenging effect and inhibitory effect of autoxidation of oils, while inhibitory effects against the AAPH-induced peroxidation of liposome was somewhat influenced by the alkyl chain length; the antioxidant activity might be due to not only radical scavenging activity of antioxidants but also their affinity of the antioxidants to the substrates.

Journal ArticleDOI
TL;DR: The results indicate that Echinacea roots and derivatives are a good source of natural antioxidants and could be used to prevent free-radical-induced deleterious effects.

Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the antioxidant activity of wine samples by different analytical methods, including oxygen radical absorbance capacity (ORAC), 2,2′-azinobis-(3-ethylbenzothiazoline)-6 sulfonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH).

Journal ArticleDOI
TL;DR: The phenyl propanoid pathway was stimulated in mung bean sprouts through the pentose phosphate and shikimate pathways, by natural elicitors such as fish protein hydrolysates (FPH), lactoferrin (LF) and oregano extract (OE), which significantly improved the phenolic, antioxidant and antimicrobial properties of mungbean sprouts.

Journal ArticleDOI
TL;DR: It is demonstrated that the antimutagenicities and antioxidant properties of ethyl acetate extract against mutagens were related to their phenols and flavonoids, which are heat stable and losses digestive juices are relatively low.

Journal ArticleDOI
TL;DR: The essential oil was particularly found to possess stronger antimicrobial activity, whereas other nonpolar extracts and subfractions showed moderate activity and polar extracts remained almost inactive.
Abstract: This study was designed to examine the in vitro antimicrobial and antioxidant activities of the essential oil and various extracts obtained from aerial parts of Thymus eigii. The essential oil was particularly found to possess stronger antimicrobial activity, whereas other nonpolar extracts and subfractions showed moderate activity and polar extracts remained almost inactive. GC-MS analysis of the oil resulted in the identification of 39 compounds, representing 93.7% of the oil; thymol (30.6%), carvacrol (26.1%), and p-cymene (13.0%) were the main components. The samples were also subjected to a screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and beta-carotene-linoleic acid assays. In the former case, the polar subfraction of the methanol extract was found to be superior to all extracts tested, only 16.8 microg/mL of which provided 50% inhibition, whereas all extracts, particularly the polar ones, seem to inhibit the oxidation of linoleic acid in the latter case. These data were further supported by total phenolics analysis, indicating that the antioxidative potential of the extracts was closely related to their phenolic constituents.

Journal Article
TL;DR: Higher antioxidant activity was observed during early germination, which correlates to higher phenolic content, suggesting that initially phenolics are antioxidant in nature, and higher L-DOPA content was observed in the elicited fenugreek sprout extract, correlating to high phenolics and antioxidant activity, suggest that L- DOPA also contributes to the high antioxidant activity.
Abstract: The phenylpropanoid pathway (PPP) was stimulated in fenugreek sprouts through the pentose phosphate and shikimate pathway, by natural elicitors such as Fish Protein Hydrolysates (FPH), Lactoferrin (LF) and Oregano Extract (OE). Among treatments 0.5 ml/L FPH elicited fenugreek sprouts had the highest phenolic content of 0.75 mg/g FW on day 3 of germination which was approximately 25 % higher than control on the same day. The antioxidant activity estimated by beta-carotene assay was highest for LF and OE elicited sprouts on day 2 and 4, respectively with an antioxidant protection factor (APF) of 1.47 for both. In all treatments and control, higher antioxidant activity was observed during early germination, which correlates to higher phenolic content, suggesting that initially phenolics are antioxidant in nature. This increased activity also correlates with high guaiacol peroxidase (GPX) activity indicating that the polymerized phenolics required for lignification with growth have antioxidant function. The antioxidant activity as estimated by beta-carotene and 1,1,-diphenyl-2-picryl hydrazyl (DPPH) assays indicate that fenugreek sprout extract can quench the superoxide free radical and also possibly scavenge the hydrogen peroxide generated in the reaction mix. OE elicited the highest levo dihydroxy phenylalanine (L-DOPA) synthesis of 1.59 mg/g FW, followed by FPH with 1.56 mg/g FW and LF 1.5 mg/g FW all on day 2 which was 24.5%, 23 % and 20 % higher than control, respectively. Higher L-DOPA content was observed in the elicited fenugreek sprouts during early germination, correlating to high phenolics and antioxidant activity, suggesting that L-DOPA also contributes to the high antioxidant activity. The glucose-6-phosphate dehydrogenase (G6PDH) activity was higher during early germination (day 1-4) and gradually decreased during later stages (day 5-8) for all treatments and control. The early increase is possibly due to the carbohydrate mobilization from the cotyledons directed towards the high nutrient requirements of the growing sprout. As mobilization occurred, an allosteric feedback inhibition by sugar-phosphates is suggested, as lower G6PDH activity was observed on days 6-8. The elevated levels of GPX during early germination coincide with the higher phenolic synthesis; SOD activity and antioxidant activity suggests the elevated production and quenching of reactive oxygen species by elicitation. High antimicrobial activity against peptic ulcer-linked Helicobacter pylori was observed in the fenugreek sprout extract from control and LF treatments only. We hypothesized that in fenugreek sprouts, simple free phenolics that are less polymerized have more antimicrobial function.

Journal ArticleDOI
TL;DR: In this paper, the formation of complexes of metal ions with the flavonoids quercetin (L1), rutin, galangin, and catechin (L4) has been investigated by using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method.
Abstract: The formation of complexes of metal ions with the flavonoids quercetin (L1), rutin (L2), galangin (L3) and catechin (L4) has been investigated by UV-visible spectroscopy. The antioxidant activities of the compounds were evaluated by using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicalscavenging method. In this work, we have shown that the complexed flavonoids are much more effective free radical scavengers than the free flavonoids. We suggest that the higher antioxidant activity of the complexes is due to the acquisition of additional superoxide dismutating centers. Radical scavenging activities of the compounds were also investigated from an electrochemical point of view. There is a relationship between the logarithm of the antioxidant activity (represented by EC50) and the oxidation potential. The synergic effect of the complexes and ascorbic acid were studied by [13C]-NMR analyses. The results show that ascorbic acid can protect flavonoids from oxidative degradation, and reveal antioxidant sy...

Journal ArticleDOI
TL;DR: Ferulic acid concentration was well correlated with scavenging activities against radical cation and superoxide anion, TPC, and other phenolic acid concentrations, suggesting the potential use of ferulic acid as a marker of wheat antioxidants.
Abstract: Swiss red wheat grain, bran, aleurone, and micronized aleurone were examined and compared for their free radical scavenging properties against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•), radical cation ABTS•+ and peroxide radical anion O2•-, oxygen radical absorbance capacity (ORAC), chelating capacity, total phenolic content (TPC), and phenolic acid composition. The results showed that micronized aleurone, aleurone, bran, and grain may significantly differ in their antioxidant properties, TPC, and phenolic acid composition. Micronized aleurone had the greatest antioxidant activities, TPC, and concentrations of all identified phenolic acids, suggesting the potential of postharvesting treatment on antioxidant activities and availability of TPC and phenolic acids. Ferulic acid was the predominant phenolic acid in Swiss red wheat and accounted for ∼57−77% of total phenolic acids on a weight basis. Ferulic acid concentration was well correlated with scavenging activities against radical cation and superoxi...