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DPPH Radical Scavenging Activity (dpph + radical_scavenging_activity)
Selected AbstractsDPPH Radical Scavenging Activity of Ten Natural p -Terphenyl Derivatives Obtained from Three Edible Mushrooms Indigenous to ChinaCHEMISTRY & BIODIVERSITY, Issue 4 2004Ji-Kai Liu The antioxidant activities of ten natural p -terphenyl derivatives, 1,10, obtained from the fruiting bodies of three edible mushrooms (Thelephora ganbajun, Thelephora aurantiotincta, Boletopsis grisea) indigenous to China were evaluated in comparison with BHA (,butylated hydroxyanisole'=(1,1-dimethylethyl)-4-methoxyphenol) and , -tocopherol by the DPPH (,1,1-diphenyl-2-picrylhydrazyl'=2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl) radical-scavenging method. The compounds 1,3 showed significant antioxidant activity. The antioxidant activities of compounds 1,10 and reference compounds followed the order: 2>BHA>1>3>, -tocopherol>10>9>6,>, 5>8>7>4. The compound 2 exhibited the strongest radical-scavenging activity with an EC50 value of 0.07 (EC50(BHA) 0.09; EC50(, -tocopherol) 0.25). [source] The variation of antioxidant activities and chemical composition of essential oils of Teucrium orientale L. var. orientale during harvesting stagesFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2004Ali Yildirim Abstract The aerial parts of Teucrium orientale L. var. orientale were collected at the budding, ,owering and vegetative stages. In the each stage, essential oils were obtained by hydrodistillation and steam distillation. The chemical compositions of the essential oils were analysed by GC and GC,MS; 43 different compounds were determined in total, and more than 96% of the essential oils were identi,ed by GC and GC,MS. They contain mainly linalool, , -caryophyllene, 3-octanol, phytol, , -bourbonene and germacrene D. Among the steam distillation oils, the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was found at the budding stage and the lowest at the vegetative stage. At all stages, the DPPH radical scavenging activities of hydrodistillation oils were markedly lower than those of steam distillation oils. Steam distillation oils of the budding and ,owering stages showed the highest antioxidant activities. However, steam distillation oils of the vegetative stage in two doses (200 and 400 µg) did not show antioxidant activities (p > 0.05, between these and control). None of the hydrodistillation oils showed detectable antioxidant activity. In contrast, in the presence of 400 µg hydrodistillation oils of ,owering stage, prooxidant activity was found in the linoleic acid emulsion. Copyright © 2004 John Wiley & Sons, Ltd. [source] Characterization of fermented black soybean natto inoculated with Bacillus natto during fermentationJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2010Yongjin Hu Abstract BACKGROUND: To make nutrients more accessible and further increase biological activity, cooked black soybeans were inoculatedwith Bacillus natto and fermented at 37 °C for 48 h. The changes in physiochemical properties of fermented black soybean natto were investigated. RESULTS: The inoculation procedure significantly increased moisture, viscosity, color, polyphenol compounds and anthocyanin, and significantly decreased hardness after 48 h fermentation. Fibrinolytic and caseinolytic protease, ,-glucosidase activities, TCA-soluble nitrogen, and ammonia nitrogen contents in the inoculated samples significantly increased as fermentation time increased. Genistin and daidzin concentrations gradually decreased with increased fermentation time. However, genistein and daidzein increased with fermentation time, which reached 316.8 and 305.2 µg g,1 during 48 h fermentation, respectively. DPPH radical scavenging activities of the fermented black soybeans increased linearly with fermentation time and concentration. Compared with the soaked black soybeans and cooked black soybeans, the fermented black soybeans with B. natto resulted in higher scavenging activity towards DPPH radicals, which correlated well with the content of total phenols (r = 0.9254, P < 0.05) and aglycone isoflavone (r = 0.9861, P < 0.05). CONCLUSION: Black soybean natto fermented by B. natto has the potential to become a functional food because of its high antioxidant activity. Copyright © 2010 Society of Chemical Industry [source] Screening of chemiluminescence constituents of cereals and DPPH radical scavenging activity of ,-oryzanolLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2001Yoshinobu Akiyama Abstract The chemiluminescence (CL) constituents of cereals were detected by CL using the H2O2,acetaldehyde system. The cereals tested, such as rice, millet and sorghum, exhibited various levels of CL activity. The ,-oryzanol fraction was extracted from brown rice and separated into four constituents by HPLC. The four constituents were identified as cycloartenyl ferulate, 24-methylenecycroartanyl ferulate, campesteryl ferulate and ,-sitosteryl ferulate. Free radical scavenging activities with 1,1-diphenyl-2-picrylhydrazyl (DPPH) and CL intensities of four constituents (,-oryzanol components) were measured and compared with that of gallic acid, which is a typical free radical scavenger. Four constituents scavenged DPPH radicals and scavenging activities were proportional to CL intensities. Concentrations of four CL constituents required to quench 50% (IC50) of the free radicals ranged from 0.9 to 1.1,mmol/L. We demonstrated that measurement of CL intensities was a rapid and convenient method for screening DPPH radical scavenging activities of rice. Copyright © 2001 John Wiley & Sons, Ltd. [source] EFFECT OF OXYGEN CONCENTRATION ON THE BIOCHEMICAL AND CHEMICAL CHANGES OF STORED LONGAN FRUITJOURNAL OF FOOD QUALITY, Issue 1 2009G. CHENG ABSTRACT Longan fruits were stored for 6 days in atmosphere of 5, 21 (air) or 60% O2 (balance N2) at 28C and 90,95% relative humidity to examine effects of low and high O2 concentration on enzymatic browning and quality attributes of the fruit. Changes in pericarp browning, pulp breakdown, disease development, total phenol content, activities of phenol metabolism-associated enzymes, relative leakage rate, ,,, -diphenyl- , -picrylhydrazy (DPPH) radical scavenging activity, and contents of total soluble solids, titratable acidity and ascorbic acid were evaluated. Storage of fruit in a 5% O2 atmosphere markedly delayed pericarp browning in association with maintenance of high total phenolic content and reduced activities of polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonia lyase. Moreover, the fruit stored in a 5% O2 atmosphere exhibited a lower relative leakage rate and higher DPPH radical scavenging activity than fruit stored in air. This presumably was beneficial in maintaining compartmentation of enzymes and substrates, and thus, reducing pericarp browning. Pulp breakdown and disease development were also reduced by exposure to a 5% oxygenatmosphere. On the contrary, exposure of longan fruit to a 60% O2 atmosphere accelerated pericarp browning, pulp breakdown and decay development. PPO and POD activities and relative leakage rate were similar for control and 60% O2 -treated fruit after 4 and 6 days of storage. Furthermore, treatment with 60% O2 significantly decreased the phenolic content and DPPH scavenging activity of fruit. In addition, exposure to 5 or 60% O2 resulted in a higher level of total soluble solids, but a lower level of ascorbic acid of longan fruit flesh. In conclusion, exposure to a 5% O2 atmosphere showed great potential to reduce pericarp browning and extend shelf life of longan fruit. PRACTICAL APPLICATIONS Pericarp browning and pulp breakdown are the major causes of deterioration in postharvest longan. Conventional controlled atmosphere with low O2 and high CO2 is effective in maintaining quality and extending shelf life of fruits and vegetables, including inhibition of tissue browning. In this study, 5%-controlled atmosphere reduced significantly pericarp browning, pulp breakdown and rot development. It could potentially be useful as a postharvest technology of longan fruit for reducing or replacing the use of chemicals such as SO2 and fungicides, but it requires further investigation. [source] Scavenging of reactive oxygen species by the plant phenols genistein and oleuropeinLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2005Irena Kruk Abstract The plant-derived phenolic compounds genistein and oleuropein are known to exhibit several biological properties, many of which may result from their antioxidant and free radical scavenger activity. In this paper we report the results of a complex study of antioxidant activity of genistein and oleuropein, using electron spin resonance (ESR), chemiluminescence, fluorescence and spectrophotometric techniques. Different reaction systems were applied to study the inhibitory effect of the phenolic compounds studied: (a) the potassium superoxide[sol ]18- crown -6 dissolved in DMSO system, which generates superoxide radical (O2·,) and hydrogen peroxide (H2O2); (b) the Co(II),EDTA,H2O2 system (the Fenton-like reaction), which generates hydroxyl radical (HO·); (c) 2,2,-azobis(2-amidino-propane)dichloride (AAPH) as the peroxyl radical (ROO·) generator, and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical test. Results showed that genistein and oleuropein decreased the chemiluminescence sum from the O2·, generating system, an inhibitory effect that was dependent on their concentration. These compounds also reacted with ROO radicals and they showed activity about two-fold greater than the standard Trolox. The antioxidant effects were studied at different concentrations and reflected in protection against the fluorescence decay of , -phycoerythrin (, -PE), due to ROO· attack on this protein. Using the Fenton-like reaction and the spin trap agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), the phenolic compounds examined were found to inhibit DMPO,·OH radical formation in the range 10,90% at concentrations of 0.1 mmol[sol ]L to 2 mmol[sol ]L. Furthermore, these compounds also inhibited HO· -dependent deoxyribose degradation; about 20% and 60% inhibitions were observed in the presence of 0.5 mmol[sol ]L genistein and oleuropein, respectively. It was also demonstrated that genistein had a weaker DPPH radical scavenging activity than oleuropein. Our results confirm good scavenging activity towards O2·,, HO· and ROO· and the antioxidant effect of genistein and oleuropein. Copyright © 2005 John Wiley & Sons, Ltd. [source] Screening of chemiluminescence constituents of cereals and DPPH radical scavenging activity of ,-oryzanolLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2001Yoshinobu Akiyama Abstract The chemiluminescence (CL) constituents of cereals were detected by CL using the H2O2,acetaldehyde system. The cereals tested, such as rice, millet and sorghum, exhibited various levels of CL activity. The ,-oryzanol fraction was extracted from brown rice and separated into four constituents by HPLC. The four constituents were identified as cycloartenyl ferulate, 24-methylenecycroartanyl ferulate, campesteryl ferulate and ,-sitosteryl ferulate. Free radical scavenging activities with 1,1-diphenyl-2-picrylhydrazyl (DPPH) and CL intensities of four constituents (,-oryzanol components) were measured and compared with that of gallic acid, which is a typical free radical scavenger. Four constituents scavenged DPPH radicals and scavenging activities were proportional to CL intensities. Concentrations of four CL constituents required to quench 50% (IC50) of the free radicals ranged from 0.9 to 1.1,mmol/L. We demonstrated that measurement of CL intensities was a rapid and convenient method for screening DPPH radical scavenging activities of rice. Copyright © 2001 John Wiley & Sons, Ltd. [source] Dolichandroside A, a new , -glucosidase inhibitor and DPPH free-radical Scavenger from Dolichandrone falcata seemPHYTOTHERAPY RESEARCH, Issue 4 2009P. Aparna Abstract A new phenylpropanoid glycoside, dolichandroside-A, together with seven known compounds , -lapachone, lapachol, aloesaponarin II, 8-hydroxydehydroiso- , -lapachone, , -sitosterol, 3,8-dihydroxydehydroiso- , -lapachone and verbascoside were isolated from the active ethyl acetate soluble extract of heartwood of Dolichandrone falcata. All except for dolichandroside-A are known compounds, but have been isolated for the first time from this plant. The structure of all these compounds was determined on the basis of 1D- and 2D-NMR spectral data. All the isolates were tested for , -glucosidase inhibitory and DPPH radical scavenging activity. This is the first report identifying DPPH scavenging activity and , -glucosidase inhibitory activity in D. falcata. Furthermore, along with a new compound, dolichandroside-A, this study also assigns for the first time , -glucosidase inhibitory activity to verbascoside and aloe saponarin-II. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||