Showing papers on "DPPH published in 1998"

A procedure to measure the antiradical efficiency of polyphenols

Abstract: The kinetic behaviour of polyphenols common in fruits as free radical scavengers was studied using 2,2-diphenyl-1-picrylhydrazyl (DPPH.). After addition of different standard concentrations to DPPH. (0.025 g litre-1), the percentage of remaining DPPH. was determined at different times from the absorbances at 515 nm. The percentage remaining DPPH. against reaction time followed a multiplicative model equation: In [DPPH.REM] = b 1n t + 1n a. The slopes of these equations may be useful parameters to define the antioxidant capacity. The steeper the slope, the lower the amount of antioxidant necessary to decrease by 50% the initial DPPH. concentration (EC50). This parameter, EC50, is widely used to measure antioxidant power, but it does not takes into account the reaction time. Time needed to reach the steady state to the concentration corresponding at EC50 (T(EC50)) was calculated, and antiradical efficiency (AE) was proposed as a new parameter to characterise the antioxidant compounds where AE = 1/EC50 T(EC50). It was shown that AE is more discriminatory than EC50. AE values are more useful because they also take into account the reaction time. The results have shown that the order of the AE (x 10(-3)) in the compounds tested was: ascorbic acid (11.44) > caffeic acid (2.75) greater than or equal to gallic acid (2.62) > tannic acid (0.57) greater than or equal to DL-alpha-tocopherol (0.52) > rutin (0.21) greater than or equal to quercetin (0.19) > ferulic acid (0.12) greater than or equal to 3-tert-butyl-4-hydroxyanisole, BHA (0.10) > resveratrol (0.05).

HPLC method for evaluation of the free radical-scavenging activity of foods by using 1,1-diphenyl-2-picrylhydrazyl

Abstract: An HPLC method for evaluation of the free radical-scavenging activity of foods by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) is reported. The activity was evaluated by measuring the decrease of DPPH detected at 517 nm. By using this novel method, we determined the free radical-scavenging activity of several antioxidants: ascorbic acid, α-tocopherol, Trolox, and cysteine. The results gave good correlation between the radical-scavenging activity determined by HPLC and by conventional colorimetry. This methodology was applied to determine the free radical-scavenging activity of 8 beverages. The activity of coffee was the highest, followed by red wine, green tea, oolong tea, black tea, rose wine, white wine, and orange juice. The results well agree with those of previous reports. This method is expected to be useful for a simple and rapid determination of free radical-scavenging activity in colored foods, because coloring substances in foods do not interfere with the measurement.

Antioxidative Phenolic Compounds from Sage (Salvia officinalis)

Abstract: Ten phenolic compounds were isolated from a butanol fraction of sage extracts. Their structures were determined by spectral methods (NMR, MS, IR). Among them, a novel compound, 4-hydroxyacetophenone-4-O-β-d-apiofuranosyl-(1→6)-O-β-d-glucopyranoside, was identified. Two test systems, DPPH free radical scavenging activity and radical cation ABTS•+ scavenging activity, were used to evaluate their antioxidant activity. The most active compounds were found to be rosmarinic acid and luteolin-7-O-β-glucopyranoside. Keywords: Sage; Salvia officinalis; phenolic compounds; antioxidant activity

Evaluation of the antioxidant potential of natural products.

Abstract: Since reactive oxygen radicals play an important role in carcinogenesis and other human disease states, antioxidants present in consumable fruits, vegetables, and beverages have received considerable attention as cancer chemopreventive agents Thus, in order to identify antioxidants in plant extracts, test materials were assessed for potential to scavenge stable 1,2-diphenyl-2-picrylhydrazyl (DPPH) free radicals, reduce TPA-induced free radical formation in cultured HL-60 human leukemia cells, and inhibit responses observed with a xanthine/xanthine oxidase assay system Approximately 700 plant extracts were evaluated, and 28 were found to be active in the DPPH free radical scavenging assay Based on secondary analyses performed to assess inhibition of 7,12-dimethylbenz(a)anthracene-induced preneoplastic lesion formation with a mouse mammary organ culture model, Chorizanthe diffusa Benth (Polygonaceae), Mezoneuron cucullatum Roxb (Leguminosae), Cerbera manghas L (Apocynaceae) and Daphniphyllum calycinum Benth (Daphniphyllaceae) were selected and subjected to bioassay-guided fractionation 5,7,3',5'-Tetrahydroxy-8,4'-dimethoxyflavonol, 5,8,4'-trihydroxy-7,3'-dimethoxyflavonol, 5,3',4'-trihydroxy-7-methoxyflavonol, and 6,3',4'-trihydroxy-7-methoxyflavonol were identified as active principles from C diffusa Piceatannol, trans-resveratrol, apigenin and scirpusin A were found as the active principles of M cucullatum, olivil, (-)-carinol, and (+)-cycloolivil were active principles from C manghas, and 5,6,7,4'-tetrahydroxyflavone 3-O-rutinoside and kaempferol 3-O-neohesperidoside were active principles from D calycinum Of these substances, the hydroxystilbenes piceatannol and transresveratrol have thus far been shown to inhibit carcinogen-induced preneoplastic lesion formation in the mouse mammary gland organ culture model

Antioxidants from a heated histidine-glucose model system. I: Investigation of the antioxidant role of histidine and isolation of antioxidants by high-performance liquid chromatography

Abstract: The radical-combining activity of Maillard reaction products [MRP(aq)], produced by heating d-glucose and l-histidine (3:1) in a 0.1 M phosphate buffer for 10 h at 105°C (final pH 6.53), was estimated directly by means of a diphenylpicrylhydrazyl radical (DPPH·) method. Additionally, the indirect methods of peroxide values changes (oven test), hexanal formation, and protection factors (Rancimat method) were determined on a lipid model system that consisted of sunflower seed oil/water (1:2), emulsified with 3% (w/w) Tween 40. Results from the DPPH· method showed a potential antioxidant activity of MRP(aq), which was confirmed by the indirect methods. Surprisingly, histidine in solution alone (heated or not) exhibited an antioxidant activity greater than or similar to the MRP(aq) activity in the indirect methods with the lipid model system, in contrast to the results from the DPPH· method. The suitability of various solvents for extraction of potential antioxidant compounds from freeze-dried MRP(aq) was examined, and ethanol extracts showed the greatest activity by the DPPH· method. Consequently, the ethanol extract of freeze-dried MRP(aq) was separated by means of preparative reverse-phase high-performance liquid chromatography (HPLC) with a 0.05 M phosphate buffer (pH 4.4)/water/acetonitrile gradient system. The antioxidant activity of the eluate was measured through the DPPH· method, and a fraction (Fraction A) with antiradical activity was further purified by preparative HPLC. Fraction B was collected, and its freeze-dried residue exhibited potent antiradical activity, significantly greater than that of the same level of n-propyl gallate.

Novel DPPH Radical Scavengers, Bisorbicillinol and Demethyltrichodimerol, from a Fungus

Abstract: In our screening program for antioxidants with DPPH radical scavenging activity, we isolated four yellowish compounds from the fermentation broth of Trichoderma sp. USF-2690 strain isolated from a soil sample: two were novel compounds designated bisorbicillinol (1) and demethyltrichodimerol (2), and two were known compounds bisvertinolone (3) and trichodimerol (4). The structures of 1 and 2 were elucidated by spectroscopic evidence and chemical modification. Two compounds seemed to be the oxidized dimers of sorbicillin. In the evaluation of DPPH radical scavenging activity, bisorbicillinol gave the lowest ED50 value (31.4 μM) among the four compounds, equal to that of BHT (27.0 μM).

Antioxidative activities in some common seaweeds.

Abstract: Dietary antioxidants from plants are believed to help prevent aging and other diseases through radical scavenging activity. Free radical scavenging activities by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and deoxyribose assay were ascertained among 27 species of common seaweeds using a sequential extraction method. The results indicated that, DPPH scavenging activity existed in 15 species; Gelidium amansii, Gloiosiphonia capillaris, Polysiphonia urceolata, Sargassum kjellmanianum, Desmarestia viridis, and Rhodomela teres showed the strongest activities. On the other hand, the deoxyribose results showed that almost all the seaweed species had good ability to scavenge hydroxyl radicals. The most active species were Rhodomela teres and Chorda filum.

Antioxidant and lipophilic constituents of Tinospora crispa.

Abstract: TLC autographic assays revealed in the CH(2)Cl(2) extract of Tinospora crispa Miers (Menispermaceae) the presence of three compounds exhibiting antioxidant and radical scavenging properties towards beta-carotene and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. They were isolated and identified as N-CIS-feruloyltyramine, N-trans-feruloyltyramine and secoisolariciresinol. When tested in dilution assays on the reduction of the DPPH radical, these 3 compounds proved to be more active than the synthetic antioxidant butylhydroxytoluene (BHT). Further investigation of the CH(2)Cl(2) extract led to the isolation of vanillin, syringin, the alkaloid N-formylnornuciferin and the diterpene derivatives borapetosides B and C. In addition, a LC/UV/MS analysis enabled the on-line identification of borapetoside F and N-formylannonain.

Antioxidant flavonoid glycosides from Daphniphyllum calycinum

Abstract: A novel flavonoid diglycoside, 5,6,7,4'-tetrahydroxyflavonol 3-O-rutinoside (1), and a previously known compound, kaempferol 3-O-neohesperidoside (2), were isolated from an ethyl acetate extract of Daphniphyllum calycinum leaves that showed significant activity in a 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assay. The structure of 1 was elucidated by a combination of spectroscopic methods, and compounds 1 and 2 were found to be moderately active as antioxidants in the DPPH assay.

Radical Scavenging Activity and Antioxidant Properties of Tannins from Guiera senegalensis (Combretaceae).

Abstract: The antioxidant properties of nine tannins isolated and characterized from different parts of Guiera senegalensis were evaluated. Interesting results showed that galloylquinic acids (hydrolysable tannins), resulting from a tri- or tetra-substitution of galloyl groups on the quinic acid skeleton, played a crucial role in the inhibitory effect on Fe2+-induced lipid peroxidation in rat liver microsomes and radical scavenger activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) test. The effects of all tannins were markedly higher than that of gallic acid. Condensed tannins such as epicatechin and epigallocatechin gallate also showed fairly significant effects in both tests. © 1998 John Wiley & Sons, Ltd.

Antioxidant and radical-scavenging activities of buckwheat seed components

Abstract: The search for endogenous components in food ingredients exhibiting antioxidant activity has been intensified in order to eliminate synthetic antioxidants. Tocopherols are widely used as natural antioxidants, although their protective ability is not always sufficient. Buckwheat seed components were evaluated for antioxidant and free radical-scavenging activities using solvents of different polarities to isolate components from hulls and groats. Components extracted from buckwheat hulls were pro-oxidant in canola oil. Antioxidant activity of extracts from buckwheat groats increased when more polar solvents were used for extraction. The highest activity was observed for the methanolic extract. Radical-scavenging activity of buckwheat extracts was analyzed with DPPH (2,2-diphenyl-2-picryl-hydrazyl). This activity increased when the more polar solvents were used for extraction, with the highest activity observed for the methanolic extract. It was also observed that the radical scavenging effectiveness of extracts was concentration dependent. Analysis revealed the presence of tocopherols in the hexane extract, while methanolic extracts were rich in phenolic acids and flavonoids.

Characterization of phenolic antioxidants from Maté (Ilex Paraguayensis) by liquid chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry

Abstract: Liquid chromatography/ion trap mass spectrometry with an atmospheric pressure chemical ionization (APCI) interface in the negative-ion mode, using collision-induced dissociation (CID) of precursor ions in parallel with UV-diode-array detection (DAD), was applied to the characterization in crude extracts of the water-soluble antioxidant phenolics from Mate leaves (Ilex paraguayensis). APCI gives unequivocal information about both the molecular mass of these compounds and some indications about their structure, which were confirmed by the UV-DAD fingerprints and by the diagnostic CID patterns. This allowed the identification of 10 constituents, including the 3 naturally occurring isomers of caffeoylquinic acid (CGA), namely neo-chlorogenic acid, chlorogenic acid and crypto-chlorogenic acid, as well as 3 isomeric dicaffeoyl quinic acids, rutin (quercetin-3-rutinoside), a diglycosyl derivative of luteolin, and 2 isomeric caffeoyl-glucosides. The aqueous extract of Mate, quantitatively analyzed for polyphenol and CGA content (HPLC), was tested for antioxidant activity in both a cell-free system (quenching of the stable free radical DPPH, 2,2-diphenyl-1-picryl-hydrazyl) and in a model membrane system (phosphatidylcholine liposomes). The results demonstrate that the extract is a strong radical scavenger, considerably more potent than the prototype chlorogenic acid, and this indicates a cooperative antioxidant interaction among its polyphenol components. © 1998 John Wiley & Sons, Ltd.

In vitro antioxidant activity and in vivo photoprotective effect of a red orange extract

Abstract: Ultraviolet radiation causes damage to the skin, which may result in both precancerous and cancerous skinlesions and acceleration of skin ageing. Topical administration of enzymatic and non-enzymatic antioxidants is an effective strategy for protecting the skin against UV-mediated oxidative damage. Hence, a systematic study to evaluate the in vitro antioxidant activity and in vivo photoprotective effect of a standardized red orange extract (ROE) has been undertaken, where the main active ingredients are anthocyanins, hydroxycinnamic acids, flavanones and ascorbic acid. For the in vitro experiments, the ROE was tested in three models: (1) bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH test); (2) peroxidation, induced by the water-soluble radical initiator 2,2'-azobis(2-amidinopropane) hydrochloride, of mixed dipalmitoylphosphatidylcholine/linoleic acid unilamellar vesicles (LUVs) (LP-LUV test); and (3) UV-induced peroxidation of phospatidylcholine multilamellar vesicles (UV-IP test). The in vivo antioxidant/radical scavenger activity was assessed by determining the ability of topically applied ROE to reduce UVB-induced skin erythema in healthy human volunteers. The results obtained in the DPPH, LP-LUV and UV-IP tests demonstrated the strong antioxidant properties of ROE, with a clear relationship between ROE scavenger efficiency and its content in antioxidant compounds. In particular, the findings obtained in the UV-IP test provide a strong rationale for using this extract as a photoprotective agent. During in vivo experiments, ROE provided to efficiently protect against photooxidative skin damage when topically applied immediately after skin exposure to UVB radiations. Interestingly, the protective effect of ROE appears higher than that elicited by another natural antioxidant (tocopherol) commonly employed in cosmetic formulations. In conclusion, the present findings demonstrate that ROE affords excellent skin photoprotection, which is very likely a result of the antioxidant/radical scavenger activity of its active ingredients. Thus, ROE might have interesting applications in both anti-photoageing and after-sun cosmetic products.

Antioxidant activity of Osbeckia aspera

Abstract: Plants of the Osbeckia family have been shown to possess hepatoprotective properties, which could be due to the presence of antioxidant compounds. The plant extract was shown to inhibit significantly in a dose-dependent manner, the activities of the DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical (EC50 of 27.5 μg/mL), xanthine oxidase (EC50 of 1.16 mg/mL) and demonstrate a scavenging effect on hydroxyl radical mediated damage to deoxyribose (EC50 of 140 μg/mL). The plant extract possessed some prooxidant activity from the effect on bleomycin-induced DNA damage, but this was less than that shown by comparable concentrations of (+)-catechin or silymarin. © 1998 John Wiley & Sons, Ltd.

Antiinflammatory and antioxidative effects of Morus spp. fruit extract

Abstract: Antiinflammatory and antioxidative effects of mulberry fruit were investigated by using bioassay screening system. The extract of muberry fruits showed inhibitory effect in phospholipase activity and cyclooxygenase II activity. Among nine varieties of mulberry tree, the antiinflammatory activities of the Shingwangppong, Ficus, Cheongilppong and Keomseolppong were higher than that of the other varieties. Also, antioxidative activity of mulberry fruit was examined by DPPH free radical scavenging method. The radical scavenging activity of the mulberry fruit decreased as following order : Shingwangppong > Keomseolppong > tetraploid Ficus> diploid Ficus.

Isolation and identification of antioxidative flavonoid glycosides from thyme (thymus vulgaris l.)

Abstract: Five flavonoid glycosides were isolated from the butanol-soluble fraction of thyme extracts. Their structures were determined by spectral analyses (NMR, MS). Their antioxidant activity was evaluated in two models (DPPH radical scavenging and Trolox equivalent antioxidant activity). The most active compounds were found to be eriodictyol-7-rutinoside and luteolin-7-O-β-glucopyranoside.

Screening of Korean medicinal and food plants with antitumoral activity

Abstract: Sixty medicinal and food plants native to Korea were mainly selected with old traditional habit and antioxidant activity was investigated. The 80% EtOH extracts of sixty medicinal and food plants were screened for antioxidant activity. Antioxidant activity was measured by the TBA (Thiobarbituric acid), DPPH (1, 1-Diphenyl-2-picrylhydrazyl), SOD (superoxide dismutase) which was evaluated by the nitro blue tetrazolium(NBT) reduction method. Among sixty plants, black Glycine max(87. 3%) and Solanum nigrum (80.6%) exhibited the highest antioxidant activity by TBA and DPPH methods, respectively. Also, 10 species extracts including black Glycine max showed the high activity value in these two methods. The SOD characteristics on black Glycine max seed extracts which showed the highest SOD activity (53.5%) exhibited four major SODs; two Cu/ZnSODs and two FeSODs. However, Adenophaora vertidllata which showed lowest SOD value (10.4%) had only Cu/Zn SOD. No varietal differences in the high SOD value were detected in the Cu/Zn SOD isozyme patterns.

Mineral Content and Antioxidative Activity in Some Herb Plants

Abstract: This study was conducted to determine mineral contents and anti oxidative activity of some herb plants cultivated in Korea. Herb plants contained various amount of mineral substances. Borage and chicory were abundant in calcium, and coriander and comfrey contained higher amount of iron compared with other herb plants. Potassium was found high in comfrey, borage and parsley. Strong antioxidative activity measured on MeOH extracts of herb plants using DPPH method was observed from spearmint, sweet basil, which was as strong as synthetic antioxidant, BHA and natural antioxidant, tocopherol.

The Antioxidant Activity in Extracts of Symphyocladia latiuscula

Abstract: The antioxidant activity of Symphyocladia latiuscula was determined by measuring lipid peroxide produced when a mouse liver homogenate was exposed to the air at , using 2-thiobarbituric acid (TBA) and radical scavenging effect on 1,1 - diphenyl - 2 - picrylhydrazyl (DPPH) radical, and free radical generation inhibition by (Hepatocyte). The methanol extract of S. latiuscula showed high antioxidant activity. And the methanol extract was fractionated with several solvents. With regard their fractions, the antioxidant activity were in the order of dichloromethane > hexane > butanol > ethyl acetate > water fraction. The dichloromethane fraction showed the strongest radical scavenging activity ( inhibitory concentration[]=3,14 g/ml), and strong inhibitory effect on the lipid peroxidation of the mouse liver homogenate, which was compared with lascorbic acid, inhibition effect was stronger than Lascorbic acid. The methanol extract of S. latiuscula and its dichlromethane soluble fraction also inhibited over at concentration of 0.2 mg/ml and 0.1 mg/ml on free radical generation of hepatocyte (). While the water fraction was inactive in all the assay for antioxidant activity.

Quality Assurance Of Chyavanprash Through Determination Of Free Radical Scavenging Activity

Abstract: Free radical scavenging activity of ethyl acetate, alcohol and aqueous extracts of fresh amla fruits, freeze dried amla powder and Chyavanprash was determined by DPPH assay method. Freeze dried amla powder and fresh amla fruits exhibited very good scavenging activity in all the extracts comparable to that of vitamin C. The alcoholic and aqueous extracts of Chyavanprash exhibited a very low level of activity compared to its ethyl acetate extract. The scavenging activity of ethyl acetate extract of Chyavanprash is very high (EC50 3.4 I¼g/ml) comparable to that of pure vitamin C (EC50 2.99 I¼g/ml). All the three market samples of Chyavanprash showed comparable activity even though vitaminc C is absent. The results indicate that free radical scavenging activity by DPPH assay method may be used as one of the quality control parameters for Chyavanprash.

Antioxidative Activity Estimation of Methanol Extracts of Crude Drugs by Electrochemical Detection-High Performance Liquid Chromatography (ECD-HPLC) and Correlation with 1, 1-Diphenyl-2-picrylhydrasyl (DPPH) Radical Scavenging Activities

Abstract: As a method for estimation of the antioxidative activity of methanol extracts of crude drugs, cyclic voltammograms (CV), 1, 1-diphenyl-2-picrylhydrasyl (DPPH) radical scavenging activities, and electrochemical detection (ECD)-HPLC were investigated. From a comparison of results, crude drugs which show oxidative peaks in the low potential region in CV, had strong and rapid radical scavenging activities. A correlation (r2=0.76) between DPPH radical scavenging ability and total peak area detected by ECD-HPLC, was obtained. The ECD-HPLC method is therefore useful for evaluation of antioxidative activities, as well as a separational analysis method for antioxidative ingredients.