Showing papers on "DPPH published in 1999"

Antioxidant composition and activity of barley (Hordeum vulgare) and malt extracts and of isolated phenolic compounds

Abstract: Phenolics have been identified and quantified in nine varieties of barley and their corresponding malts as flavan-3-ols, flavonols, phenolic acids and apolar esters. Flavan-3-ols are monomers, (+)-catechin and (−)-epicatechin, and polymers constituted mainly by units of (+)-catechin and (+)-gallocatechin. The most abundant compounds were the dimers procyanidin B3 and prodelphinidin B3. The main trimeric procyanidin was procyanidin C2. After malting, the phenolic content decreased for all varieties. Catechin monomers were the most affected. Beside polyphenols, barley and malt extracts contained other antioxidants: carotenoids (lutein and zeaxanthin) and tocopherols (α, δ and γ). The antioxidant activity was measured using three methods: capacity to react with DPPH. (ARP), inhibition of lipoxygenase activity (LoxI) and inhibition of cooxidation of β-carotene in a linoleate model system (AOP). The inhibition of cooxidation of β-carotene in a linoleate model system did not allow varieties to be discriminated. They all have high antioxidative properties. Using this assay, tocopherols were the best antioxidants. The ARP (antiradical power) was correlated positively with the amount of total flavan-3-ols (r = 0.89) and increased with the degree of polymerisation. The LoxI assay allowed discrimination of the nine varieties of barley and their corresponding malts but was not correlated with any compound, although flavan-3-ols were good inhibitors of lipoxygenase activity. © 1999 Society of Chemical Industry

Fucoxanthin as the Major Antioxidant in Hijikia fusiformis, a Common Edible Seaweed

Abstract: The radical scavenging activity of Japanese edible seaweeds was screened by the DPPH (1-diphenyl-2-picrylhydrazyl) assay to evaluate the DPPH radical scavenging activity in organic extracts. The fresh brown alga Hijikia fusiformis showed the strongest DPPH radical scavenging activity, followed by Undaria pinnatifida and Sargassum fulvellum. The major active compound from Hijikia fusiformis in its acetone extract was identified as fucoxanthin by 13C-NMR spectroscopy.

2,2-Diphenyl-1-picrylhydrazyl radical-scavenging active components from Polygonum multiflorum thunb.

Abstract: An activity-directed fractionation and purification process was used to identify the antioxidative components of Polygonum multiflorum Thunb. (PM). Dried root of PM was extracted with 95% ethanol and then separated into water, ethyl acetate, and hexane fractions. Among these only the ethyl acetate phase showed strong antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test when compared with water and hexane phases. The ethyl acetate fraction was then subjected to separation and purification using silica gel column chromatography and Sephadex LH-20 chromatography. Three compounds showing strong antioxidant activity were identified by spectral methods ((1)H NMR, (13)C NMR, and MS) and by comparison with authentic samples to be gallic acid, catechin, and 2,3,5, 4'-tetrahydroxystilbene 2-O-beta-D-glucopyranoside.

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(*).

Total antioxidant potential of resinous exudates from Heliotropium species, and a comparison of the ABTS and DPPH methods.

Abstract: Total reactive antioxidant potential (TRAP) of resinous exudates from Heliotropium species was evaluated by measuring the bleaching of stable free radicals. The antioxidant capacity of the resinous exudates in Trolox equivalents, evaluated from the bleaching of ABTS derived radical cations, ranged from 2.0 M (H. huascoense) to 5.2 M (H. stenophyllum), indicating a very high concentration of phenolic compounds. Considerably smaller values were obtained by measuring the bleaching of DPPH radicals. The ratio between the values obtained employing ABTS derived radicals and DPPH, ranged from 37 (H. megalanthum) to 4.5 (H. chenopodiaceum variety typica). The magnitude of the difference can be considered as an indication of the relative reactivity of the antioxidants present in the exudates. Similar ratios were observed when stoichiometric coefficients were evaluated for representative purified flavonoids obtained from the resinous exudates.

Antioxidant flavonoids and chlorogenic acid from the leaves of Eriobotrya japonica.

Abstract: The antioxidant activity ofEriobotrya japonica was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl) radical and lipid peroxidation produced when mouse liver homogenate was exposed to the air at 37°C, using 2-thiobarbituric acid (TBA). The methanol extract and its fractions ofEriobotrya japonica leaves showed strong antioxidant activity. The antioxidant activity of EtOAc andn-BuOH soluble fractions were stronger than the others, and were further purified by repeated silica gel, MCI gel CHP-20P, and Sephadex LH-20 column chromatography. Antioxidant chlorogenic acid, quercetin-3-sambubioside fromn-BuOH fraction, and methyl chlorogenate, kaempferol- and quercetin-3-rhamnosides, together with the inactive ursolic acid and 2α-hydroxyursolic acid from EtOAc fraction were isolated. Antioxidant flavonoids and chlorogenic acid also showed prominent inhibitory activity against free radical generation in dichlorofluorescein (DCF) method.

Evaluation of resveratrol derivatives as potential antioxidants and identification of a reaction product of resveratrol and 2, 2-diphenyl-1-picryhydrazyl radical.

Abstract: Resveratrol (3,4',5-trihydroxy-trans-stilbene), an antioxidant from grapes, and five other polyhydroxystilbenes were synthesized. Their antioxidative properties were evaluated in two model systems [pure lipid oxidation using the Rancimat method and 2, 2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging model.] 3, 3',4,5'-Tetrahydroxystilbene, 3,3',4,5,5'-pentahydroxystilbene, and 3,4,4',5-tetrahydroxystilbene were found to be more active than resveratrol in both models. A dimer of resveratrol was identified as the major radical reaction product when resveratrol was reacted with DPPH radicals.

Extraction and identification of antioxidants in the roots of yacon (Smallanthus sonchifolius)

Abstract: Yacon, Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson, Asteraceae, an important economic species grown for its juicy tuberous root, is potentially beneficial in the diet to diabetics. The antioxidative activity of yacon root was studied by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Antioxidants were extracted by methanol and isolated and purified by gel permeation chromatography and preparative reverse-phase HPLC. Two of the major antioxidants were identified as chlorogenic acid and tryptophan by NMR and mass spectrometry.

Flavonoid constituents of Chorizanthe diffusa with potential cancer chemopreventive activity.

Abstract: An ethyl acetate-soluble extract of Chorizanthe diffusa was found to exhibit significant antioxidant activity, as judged by scavenging stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals and inhibition of 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced free radical formation with cultured HL-60 cells. Bioassay-directed fractionation of this extract using the DPPH antioxidant assay as a monitor led to the isolation of five structurally related flavonoids (1−5), including the novel compound 5,8,3‘,4‘,5‘-pentahydroxy-3,7-dimethoxyflavone (1). Isolates 1−5 demonstrated varying degrees of antioxidant or antimutagenic activity. Two of the compounds, 5,7,3‘,4‘-tetrahydroxy-3-methoxyflavone (2) and quercetin (4), were subsequently found to inhibit carcinogen-induced preneoplastic lesions in a mouse mammary organ culture model. Inhibitory activity of this type is known to correlate with cancer chemopreventive effects in full-term models of tumorigenesis. Keywords: Chorizanthe diffusa; Polygonaceae; flavon...

Screening of antioxidant action of various molds and protection of Monascus anka against experimentally induced liver injuries of rats.

Abstract: Antioxidant action of various molds, which are traditionally used for the production of foods or alcoholic beverages in Japan, was studied in vitro and in vivo. Antioxidant action was evaluated by scavenging stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and lipid peroxidation of rat liver microsomes. Among 40 molds, 16 species showed the DPPH scavenging action, and the molds that can scavenge the DPPH radical inhibited lipid peroxidation. The mold with the strongest action, Monascus anka , was chosen for the investigation of a protective action against liver injury of rats. When galactosamine (GalN, 400 mg/kg) or GalN plus lipopolysaccharide (LPS, 0.5 μg/kg) was given intraperitoneally to rats (Sprague-Dawley), aspartate aminotransferase (AST) and glutathione (GSH) S-transferase (GST) activities in serum were significantly increased. However, such hepatotoxicities seen in the increase in serum enzyme levels were depressed when the extract prepared from M. anka was given 1 and 15 h before the toxic insultant. Liver microsomal GST activity, which is known to be activated by oxidative stress, was increased by GalN or GalN plus LPS treatment and the increase was also inhibited by pretreatment with the extract. Pathomorphological changes in the liver caused by GalN treatment also were prevented by the mold extract. These results indicate that the extract of M. anka has radical scavenging action and ameliorates chemically induced hepatotoxicity.

Stopped-Flow and Spectrophotometric Study on Radical Scavenging by Tea Catechins and the Model Compounds

Abstract: Radical scavenging of four tea catechins, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg) and (-)-eppigallocatechin gallate (EGCg), and the model compounds of their partial structure was examined against the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical using stopped-flow and spectrophotometric methods. The number of DPPH radicals scavenged by a polyphenol molecule was larger than that of phenolic hydroxyl groups, suggesting that hydrogens which bond directly to the aromatic ring can also participate in radical scavenging. A model for the scavenging reaction was proposed in which the reaction proceeded with successive dehydrogenation from a polyphenol molecule. Analysis of the second order reaction rate constants and the activation parameters between DPPH and polyphenol at the early stage of the reaction showed that the values depended on the number of phenolic hydroxyl groups and their mutual position. Contribution of the A ring of catechins to the rate constants was estimated to be far smaller than that from the B ring. In the EGCg molecule, the B ring and the gallate group were not independent, but acted as a single group for DPPH radical scavenging.

Free radical scavenging activity in the nonenzymatic fraction of human saliva: a simple DPPH assay showing the effect of physical exercise.

Abstract: Free-radicals and other reactive oxygen species (ROS) have been implicated as being major damaging species in pathology and they have been widely investigated. Using 1,1′-diphenyl-2-picrylhydrazyl (DPPH), we estimated total free radical scavenging activity in the low-molecular-weight nonenzymatic fraction (LMNEF) of human whole saliva. The activity of the whole saliva and serum were measured in terms of the rate of decrease in the absorbance at 517 nm in a 40% ethanol DPPH solution (pH 7.4) at room temperature. The DPPH activity of saliva and serum showed a significant linear relationship. The mean DPPH activities of saliva from 257 subjects aged 4–72 was found to be 0.389±.190 μmol/ml and bore no relation to age or sex. The activity in saliva of 86 subjects aged 4–11 was significantly different before and after exhaustive aerobic dance exercise for 1 hr. Physical exercise markedly decreased free radical scavenging activity in whole saliva of children. On the basis of the above results, we conclud...

Free radical scavenging activity in the non-enzymatic fraction of human saliva : A simple DPPH assay showing the effect of physical exercise

Abstract: Free-radicals and other reactive oxygen species (ROS) have been implicated as being major damaging species in pathology and they have been widely investigated. Using 1,1'-diphenyl-2-picrylhydrazyl (DPPH), we estimated total free radical scavenging activity in the low-molecular-weight nonenzymatic fraction (LMNEF) of human whole saliva. The activity of the whole saliva and serum were measured in terms of the rate of decrease in the absorbance at 517 nm in a 40% ethanol DPPH solution (pH 7.4) at room temperature. The DPPH activity of saliva and serum showed a significant linear relationship. The mean DPPH activities of saliva from 257 subjects aged 4-72 was found to be 0.389+/-.190 micromol/ml and bore no relation to age or sex. The activity in saliva of 86 subjects aged 4-11 was significantly different before and after exhaustive aerobic dance exercise for 1 hr. Physical exercise markedly decreased free radical scavenging activity in whole saliva of children. On the basis of the above results, we concluded that DPPH is useful for evaluating the total antioxidant capacity of LMNEF of human saliva.

Antioxidative Activity of Phenolic Compounds in Roasted Safflower (Carthamus tinctorius L.) Seeds

Abstract: Antioxidative compounds contained in roasted safflower seeds were investigated. Six phenolic compounds, N-feruloylserotonin, N-(p-coumaroyl) serotonin, matairesinol, 8′-hydroxyarctigenin, acacetin 7-O-β-D-glucoside (tilianine) and acacetin were isolated and identified from the extract of seeds. The inhibitory effects of six phenolic compounds on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and lipid peroxidation induced by H₂O₂/FeSO₄in rat liver microsomes were determined. Two serotonins showed more potent DPPH radical scavenging activity, and a stronger inhibitory effect on the lipid peroxidation than that of α-tocopherol. In addition, acacetin and matairesinol also considerably inhibited lipid peroxidation, while 2-hydroxy- arctigenin and tilianine were inactive. These results suggest that phenolic compounds, including serotonins, lignans and flavonoids in the roasted safflower seeds can be used as potential dietary natural antioxidants.

chlorogenic acid content and antioxidant properties of potato tubers as related to nitrogen fertilisation

Abstract: The chlorogenic acid and the total polyphenol content were analysed in two different potato varieties (Kennebec, Agria) grown under five different nitrogen fertiliser rates (0, 75, 150, 225, 300 kg ha-1). Chlorogenic acid content ranged between 6.0-22.3 mg kg-1 fresh weight and was not influenced by fertiliser levels. The chlorogenic acid in potato tubers accounted for almost 90% of the total polyphenols. Free radical scavenging and antioxidant activities of the tubers were also analysed. Ethanolic extracts if the tubers showed marked hydrogen-donating activity in the experiment using 1,1-diphenyl-2-picrylhydrazyl (DPPH), they had reducing power as measured by the Fe(III)?Fe(II) reaction, but did not exhibit H2O2 scavenging activity assessed with a chemiluminescence method. Potato extracts showed significant, although weak Cu(II)-chelating activity and inhibited the autoxidation of linolenic acid as measured by the thiocyanate method. Chlorogenic acid containing extract of potato, can act as primary and secondary antioxidant in prevention of oxidative stress. The strong correlation between the antioxidant activity and the level of total pholyphenols suggests that the phenolic compounds are important antioxidant components of whole potato tubers. Variety had minimal, while nitrogen fertiliser rate had no effects on the levels of the studied characteristics.

Graft polymerization of methyl methacrylate onto radiation‐peroxidized ultrahigh molecular weight polyethylene in the presence of metallic salt and acid

Abstract: Using a radiation peroxide grafting technique, a ultrahigh molecular weight polyethylene (UHMWPE) stored at room temperature for 10 days after irradiation in air was graft copolymerized with methyl methacrylate (MMA) in the presence of metallic salt and acid. The MMA-grafted UHMWPE samples were analyzed by measuring Fourier transform infrared spectroscopy in attenuated total reflectance (FTIR-ATR) and by electron spectroscopy for chemical analysis (ESCA). The 1,1-diphenyl-2-picrylhydrzyl (DPPH) technique was utilized to evaluate the concentration of peroxide formed in the peroxidized UHMWPE samples by counting the quantity of DPPH consumed from the reaction of peroxide radicals with DPPH. It was shown that the inclusion of an FeSO 4 .7H 2 O and sulfuric acid in MMA grafting solutions was extremely beneficial and led to a most unusual synergistic effect in the radiation-peroxidized grafting.

Isolation of a 2-pyrone compound as an antioxidant from a fungus and its new reaction product with 1,1-diphenyl-2-picrylhydrazyl radical

Abstract: The indophenol-reducing compound, 4-hydroxy-3,6-dimethyl-2H-pyrane-2-one (I), was isolated from the culture filtrate of an unidentified fungus. I also reacted with the DPPH radical to form a reaction product IV which was determined to be 1-[4-(3,4-dihydro-3,6-dimethyl-2,4-dioxo- 2H-pyran-3-yl)phenyl]-1-phenyl-2-picrylhydrazine. This is the first report describing the formation of an adduct of the DPPH radical and its scavenger.

Some remarks on reported inconsistencies in the high-field EPR spectrum of DPPH

Abstract: Previous conflicting reports concerning the EPR lineshape of commercially obtained 2,2′-diphenyl-1-picrylhydrazyl (DPPH) at frequencies above 200 GHz are investigated. The magnetic parameters of dilute DPPH in polystyrene film determined at 220 GHz are presented. It is demonstrated that commercially obtained crystalline samples of DPPH which produce a broad line at 220 GHz when used without purification do produce a narrow line at 220 GHz when recrystallized from carbon disulfide. This observation suggests that the reported discrepancies in the high-field EPR spectrum of DPPH may be reconciled without invoking chemical impurities or misidentification. It also suggests a standard preparation procedure for DPPH that should be employed ifDPPH is to be used as a marker for high-field EPR.

Isolation and Structure Determination of Antioxidants from the Root of Paeonia lactiflora

Abstract: On the purpose of development of novel antioxidative compounds from natural sources, 38 plants expected to show antioxidant activity have been examined concerning DPPH radical scavenging activity. Among them, thirteen plants, including Paeoniae radix, the root of Paeonia lactiflora, exhibited the activity. In order to isolate active component, the root was extracted in 80% aqueous MeOH and solvent fractionated with EtOAc, n-BuOH and water, successively. Silica gel column chromatographies of the EtOAc and n-BuOH fraction exhibiting antioxidant activity. were repeatedly carried out with monitoring by DPPH assay to afford three active compounds. On the basis of spectral data and the chemical characteristics, the structures of the compounds were determined as (+)-catechin, and .

Isolation and Structure of a Novel Indophenol-reducing and 1,1-Diphenyl-2-picrylhydrazyl Radical-scavenging Compound from a Fungus

Abstract: A novel indophenol-reducing and DPPH radical-scavenging compound (1) was isolated from a fungal metabolite. The structure of 1 was determined by a spectroscopic analysis, and the absolute configuration of 1 was determined by the modified Mosher’s method. Compound 1 showed slow-reacting DPPH radical-scavenging activity (ED50 value of 298 μM after 96 hr).

Antioxidative Compounds in Extracts of Acer ginnala Max.

Abstract: To search for antioxidative compounds from plant resources, methanol extracts of 45 plant species were investigated using DPPH method. The highest activity was shown in the methanol extract of Acer ginnala(), followed by Stewartia koreana() and Carpinus laxiflora(). Two antioxidative compounds were isolated from the methanolic extract of Acer ginnala Max and identified as acertannin(2, 6-di-O-galloyl-1, 5-anhydro-D-glucitol) and gallicin (methyl-3, 4, 5-trihydroxybenzoic acid) on the basis of mass spectroscopy, data. The DPPH free radical scavenging activities of acertannin() and gallicin() were more effective than those of BHA() and ().

The Production of Caramel with the DPPH Radical Scavenging Activity.

Abstract: 単糖類を塩基性化合物の存在下でカラメル化反応を行い,強いDPPHラジカル捕捉能を有するカラメルを得た.(1) ペントース,ヘキソースは塩基性化合物の存在下で強いDPPHラジカル捕捉能を有するカラメルとなるが,スクロース,ソルビトールのカラメルは,ほとんどDPPHラジカル捕捉能を示さなかった.(2) カラメルの色価,DPPHラジカル捕捉能及びカラメル調製時の作業性,食品への利用性から,カラメル化助剤としてはクエン酸ナトリウム,カラメル化温度は130℃が適当であった.(3) カラメル中の非透析物含量は約75%,透析物は約25%であり,カラメルの着色度,還元力,DPPHラジカル捕捉能の主体は非透析物に依存していた.

Antioxidative and Antimicrobial Effects of Water Extracts with Castanea crenata Leaf Tea

Abstract: Antioxidative and antimicrobial effects of the extracts of Castanea crenata leaf tea, steamed tea and semi-fermented tea were investigated. Antioxidative effects were by measuring the 1,1-diphenyl-2-picrylhydrazyl(DPPH)-radical scavening activity of the extracts. The effects were stronger than that of synthetic antioxidant such as BHT at the same concentration. The value (50% radical scavening effects of M DPPH) of steamed tea, semi-fermented tea and BHT were 53.3 , 49.9 and 101.0 , respectively. The antimicrobial effects of methanol extracts (8 mg, 20 mg) of 0.2 g and 0.5 g. eq. of Castanea crenata leaf tea were stronger than those of 0.65 mg of benzoic acid, against gram(+) bacteria such as S. aureus, S. epidermidis, M. luteus, L. mesenteroides and B. subtilis and gram(-) bacteria such as E. coli, S. typhimurium, and P. aeruginosa.

Isolation, Identification, and Activity of Rosmarinic Acid, a Potent Antioxidant Extracted from Korean Agastache rugosa

Abstract: Thirty plants were screened for their antioxidative activity The extracts of Agastache rugosa, Schizonepeta tenuifolia and Lycopus lucidus had high free radical(2,2-diphenyl-1-picrylhydrazyl) scavenging activities Methanol extract of Agastache rugosa was fractionated with hexane, chloroform, ethyl acetate, and water The ethyl acetate fraction showed the highest antioxidant activity in the DPPH test The ethyl acetate fraction was applied to Sephadex LH-20 column, and the fractions showing antioxidative activity were collected and used for identification of the substance The purified substance was applied to mass, IR, UV and NMR spectroscopy The spectra of mass, IR, UV and NMR implied that the substance is a rosmarinic acids as a kind of phenolic compound The rosmarinic acid has more antioxidative effect than those of BHT and in the Rancimat test