Showing papers on "Ascorbic acid published in 2006"
TL;DR: Guava fruit extracts were analyzed for antioxidant activity measured in methanol extract and dichloromethane extract (AOAD), ascorbic acid, total phenolics, and total carotenoids contents.
2,737 citations
TL;DR: The present “gold standard” management of NASH is modest weight reduction, particularly correction of central obesity achieved by combining dietary measures with increased physical activity, which improves insulin resistance and reverses steatosis, hepatocellular injury, inflammation, and fibrosis.
2,325 citations
TL;DR: It is found that gold particles can be produced in a wide range of sizes, from 9 to 120 nm, with defined size distribution, following the earlier work of Turkevich and Frens.
Abstract: The growth of gold nanoparticles by reduction by citrate and ascorbic acid has been examined in detail to explore the parameter space of reaction conditions. It is found that gold particles can be produced in a wide range of sizes, from 9 to 120 nm, with defined size distribution, following the earlier work of Turkevich and Frens. The reaction is initiated thermally or in comparison by UV irradiation, which results in similar final products. The kinetics of the extinction spectra show the multiple steps of primary and secondary clustering leading to polycrystallites.
1,906 citations
Journal Article•
TL;DR: In this paper, the authors highlight the potential role of flavonoids, phenylopropanoids andphenolicacidsaseffectiveantioxidants in the scavenging process.
Abstract: as a consequence of industrial development, the environment is increasingly polluted with heavy met - als.�Plantspossesshomeostaticmechanismsthatallowthemtokeepcorrectconcentrationsofessential� metalionsincellularcompartmentsandtominimizethedamagingeffectsofanexcessofnonessential� ones. one of their adverse effects on plants is the generation of harmful active oxygen species, leading to oxidativestress.�Besidesthewell-studiedantioxidantsystemsconsistingoflow-molecularantioxidantsand� specific enzymes, recent works have begun to highlight the potential role of flavonoids, phenylopropanoids andphenolicacidsaseffectiveantioxidants.� Duringheavymetalstressphenoliccompoundscanactas� metalchelatorsandontheotherhandphenolicscandirectlyscavengemolecularspeciesofactiveoxygen.�� phenolics, especially flavonoids and phenylopropanoids, are oxidized by peroxidase, and act in h 2 O 2 - scavenging, phenolic/asc/poX system. their antioxidant action resides mainly in their chemical struc -
1,066 citations
TL;DR: Wang et al. as mentioned in this paper extracted antioxidants from pomegranate peel, using a mixture of ethanol, methanol and acetone, and the antioxidant properties of the extract were further investigated as compared with the pulp extract.
913 citations
TL;DR: A modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method for fruits is presented and its performance is compared with the other commonly used antioxidant methods of2,2'-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP).
Abstract: The measurement of antioxidant capacity in fruits differs from that of other biological samples due to their low pH and very low lipophilic antioxidant capacity. In this report, we present a modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method for fruits and compare its performance with the other commonly used antioxidant methods of 2,2‘-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). The antioxidant capacity and reaction kinetics of four phenolic compounds, two antioxidant standards, and five fruits were also investigated. The modified ABTS method prepared at a pH of 4.5 with sodium acetate buffer is highly stable and easily applied to fruit samples as compared to the standard (pH 7.4) version. The measured antioxidant capacity of samples varied with the assay method used, pH, and time of reaction. Traditional antioxidant standards (trolox, ascorbic acid) displayed stable, simple reaction kinetics, which allowed end point analysis with all of assays. ...
753 citations
TL;DR: Concomitant supplementation with vitamin C and vitamin E does not prevent pre-eclampsia in women at risk, but does increase the rate of babies born with a low birthweight, and use of these high-dose antioxidants is not justified in pregnancy.
694 citations
TL;DR: In this paper, the authors show that training can have positive or negative effects on oxidative stress depending on training load, training specificity and the basal level of training, which may lead to overtraining.
Abstract: Free radicals are reactive compounds that are naturally produced in the human body. They can exert positive effects (e.g. on the immune system) or negative effects (e.g. lipids, proteins or DNA oxidation). To limit these harmful effects, an organism requires complex protection - the antioxidant system. This system consists of antioxidant enzymes (catalase, glutathione peroxidase, superoxide dismutase) and non-enzymatic antioxidants (e.g. vitamin E [tocopherol], vitamin A [retinol], vitamin C [ascorbic acid], glutathione and uric acid). An imbalance between free radical production and antioxidant defence leads to an oxidative stress state, which may be involved in aging processes and even in some pathology (e.g. cancer and Parkinson's disease). Physical exercise also increases oxidative stress and causes disruptions of the homeostasis. Training can have positive or negative effects on oxidative stress depending on training load, training specificity and the basal level of training. Moreover, oxidative stress seems to be involved in muscular fatigue and may lead to overtraining.
648 citations
TL;DR: Microemulsions were found as an effective vehicle of the solubilization of certain drugs and as protecting medium for the entrapped of drugs from degradation, hydrolysis, and oxidation.
628 citations
TL;DR: The very high values of antioxidant activity were found in intensely colored vegetables, and the values were very low in watery vegetables such as potato, marrow, and cucumber.
Abstract: This research studies in detail the contents of phenolic compounds determined by the Folin-Ciocalteu reagent and the antioxidant activities determined by the TEAC (Trolox equivalent antioxidant capacity), DPPH (using diphenyl-p-picrylhydrazyl radical), and FRAP (ferric reducing antioxidant power) methods, and their correlations for used standards with these methods (catechine, gallic acid, caffeic acid, ferulic acid, Trolox, ascorbic acid, and ferrous sulfate) and extracts from several species of commonly consumed vegetables were studied in detail. The comparison of absolute values of absorption coefficients for used standards and for individual methods allows one to choose optimal common standards for methods to be compared. The procedures applied for the same sets of the extracts using identical calibration procedures and common standards allowed better comparison of the results obtained by the TEAC, DPPH, and FRAP methods. The values of content of phenolic substances and total antioxidant activity of the sets of samples correlate very well for all used methods. The very high values of antioxidant activity were found in intensely colored vegetables (red cabbage, red onion, etc.), and the values were very low in watery vegetables such as potato, marrow, and cucumber.
620 citations
TL;DR: A ranked antioxidant food table with values for total content of redox-active compounds above a certain cutoff reduction potential provides a useful tool for investigations into the possible health benefit of dietary antioxidants.
TL;DR: In this paper, the authors evaluated the antioxidant activity (AA), total phenolic content, and reducing power of the crude extract, fractions, and subfractions derived from a red alga, Polysiphonia urceolata, were evaluated and determined.
TL;DR: An overview of the evidence supporting a link between inflammation and AF, and some of the drug therapies that might be efficacious in the prevention of AF by modulating inflammatory pathways are presented.
Abstract: There is mounting evidence to support the influence of inflammation in the pathogenesis of atrial fibrillation (AF). Indeed, AF is associated with increased levels of known inflammatory markers, even after adjustment for confounding factors. The renin-angiotensin-aldosterone system (RAAS) appears to play a key role in this process. Atrial biopsies from patients with AF have also confirmed the presence of inflammation. Furthermore, there is preliminary evidence to support a number of drug therapies that have the potential to reduce the clinical burden of AF. In this review, we present an overview of the evidence supporting a link between inflammation and AF, and some of the drug therapies, such as the angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, steroids, fish oils, and vitamin C, that might be efficacious in the prevention of AF by modulating inflammatory pathways.
TL;DR: The results showed that oxidative stress could be induced in 5-week old broiler chickens by acute heat exposure and suggest that the elevated body temperature can induce the metabolic changes that are involved in the induction of oxidative stress.
Abstract: The stress responses and possible oxidative damage in plasma, liver and heart were investigated in broiler chickens acutely exposed to high temperature. Eighty 5-week old broiler chickens were exposed to 32 degrees C for 6h. The extent of lipid peroxidation, activities of superoxide dismutase and total antioxidant power in plasma, liver and heart tissues were investigated. Meanwhile, the blood metabolites such as glucose, urate, triiodothyronine, thyroxine, corticosterone, ceruloplasmin and creatine kinase were measured before and after 3 and 6h of heat exposure. The results showed that oxidative stress could be induced in 5-week old broiler chickens by acute heat exposure (32 degrees C, 6h). The results suggest that the elevated body temperature can induce the metabolic changes that are involved in the induction of oxidative stress. The liver is more susceptible to oxidative stress than heart during acute heat exposure in broiler chickens. The oxidative stress should be considered as part of the stress response of broiler chickens to heat exposure.
TL;DR: Scanning electron microscopy images indicate significant improvement in the microstructure of the proposed electrode compared to carbon paste electrodes, which allows sensitive, low-potential, simple,low-cost, and stable electrochemical sensing of biomolecules and other electroactive compounds.
Abstract: Ionic liquid, n-octylpyridinum hexafluorophosphate (OPFP) has been used to fabricate a new carbon composite electrode with very attractive electrochemical behavior. This type of carbon electrode has been constructed using graphite mixed with OPFP as the binder. The electrode has combined advantages of edge plane characteristics of carbon nanotubes and edge plane pyrolytic graphite electrodes together with the low cost of carbon paste electrodes and robustness of metallic electrodes. It provides a remarkable increase in the rate of electron transfer of different organic and inorganic electroactive compounds and offers a marked decrease in the overvoltage for biomolecules such as NADH, dopamine, and ascorbic acid. It also circumvents NADH surface fouling effects as well as furnishing higher current density for a wide range of compounds tested. Depending on the choice of the electrolyte, the electrode can have the ion-exchange property and adsorptive characteristics of clay-modified electrodes. The proposed electrode thus allows sensitive, low-potential, simple, low-cost, and stable electrochemical sensing of biomolecules and other electroactive compounds. Scanning electron microscopy images indicate significant improvement in the microstructure of the proposed electrode compared to carbon paste electrodes. Such abilities promote new opportunities for a wide range of electrochemical and biosensing applications.
TL;DR: In this paper, seven different extracts, fractions and residues of Navel sweet orange (Citrus sinensis) peel were evaluated for their radical scavenging activity by the DPPH and luminol induced chemiluminescence methods.
TL;DR: It is suggested that differential sensitivity of C3 and C4 plants to water stress appear to be partially governed by their ability to counter oxidative stress, pertinently involving ascorbic acid and glutathione.
TL;DR: Nigerian medicinal plants (Aspilia africana and Bryophyllum pinnatum) were analyzed for their chemical composition, vitamins and minerals in this article, and the results revealed the presence of bioactive constituents comprising alkaloids (1.24 to 1.48 mg/100 g), saponins ( 1.46 to1.72 mg/ 100 g), flavonoids (0.86mg/100g), phenols ( 0.04 to 0.5 mg/1.5mg), riboflavin(0.20
Abstract: Nigerian medicinal plants (Aspilia africana and Bryophyllum pinnatum) were analyzed for their chemical composition, vitamins and minerals. The results revealed the presence of bioactive constituents comprising alkaloids (1.24 to 1.48 mg/100 g), saponins (1.46 to 1.72 mg/100 g), flavonoids (1.46 to 1.86 mg/100 g), phenols (0.06 mg/100g) and tannins (0.04 to 0.5 mg/100g). The medicinal plants contained ascorbic acid (26.42 to 44.03 mg/100 g), riboflavin (0.20 to 0.42 mg/100 g), thiamine (0.11 to 0.18 mg/100 g), and niacin (0.02 to 0.09 mg/100 g). These herbs are good sources of minerals such as Ca, P, K, Mg, Na, Fe and Zn. The importance of these chemical constituents is discussed with respect to the role of these herbs in ethnomedicine in Nigeria.
TL;DR: In this article, a greenhouse experiment was carried out to determine the effects of salinity and different ripening states of pepper fruits on several compounds with antioxidant properties, including lycopene, β-carotene, and sugars.
TL;DR: In this article, two varieties of tomatoes (Lycopersicon esculentum mill, I-Tien-Hung (ITH) and Sheng-Neu (SN) were used to study the effects of different drying processes, freeze-dried (FD) and hot-air-dry (AD), on the antioxidant properties of tomatoes.
TL;DR: There were no significant differences between the vitamin and placebo groups in the risk of preeclampsia, death or serious outcomes in the infants, and delivering an infant whose birth weight was below the 10th percentile for gestational age.
Abstract: Background Supplementation with antioxidant vitamins has been proposed to reduce the risk of preeclampsia and perinatal complications, but the effects of this intervention are uncertain. Methods We conducted a multicenter, randomized trial of nulliparous women between 14 and 22 weeks of gestation. Women were assigned to daily supplementation with 1000 mg of vitamin C and 400 IU of vitamin E or placebo (microcrystalline cellulose) until delivery. Primary outcomes were the risks of maternal preeclampsia, death or serious outcomes in the infants (on the basis of definitions used by the Australian and New Zealand Neonatal Network), and delivering an infant whose birth weight was below the 10th percentile for gestational age. Results Of the 1877 women enrolled in the study, 935 were randomly assigned to the vitamin group and 942 to the placebo group. Baseline characteristics of the two groups were similar. There were no significant differences between the vitamin and placebo groups in the risk of preeclampsia ...
TL;DR: Recrystallization of the more reactive iron oxides into more crystalline phases, induced by the appearance of Fe2+ in anoxic aquifers, may be an important trapping mechanism for arsenic.
TL;DR: The free radical scavenging capacity and antioxidant activities of the methanolic extract of Cinnamomum verum leaf were studied and compared to antioxidant compounds like trolox, butylated hydroxyl anisole, gallic acid and ascorbic acid.
TL;DR: The hypothesis that gradual cone cell death after rod cell death in RP is due to oxidative damage, and that antioxidant therapy may provide benefit, is supported.
Abstract: Retinitis pigmentosa (RP) is a label for a group of diseases caused by a large number of mutations that result in rod photoreceptor cell death followed by gradual death of cones. The mechanism of cone cell death is uncertain. Rods are a major source of oxygen utilization in the retina and, after rods die, the level of oxygen in the outer retina is increased. In this study, we used the rd1 mouse model of RP to test the hypothesis that cones die from oxidative damage. A mixture of antioxidants was selected to try to maximize protection against oxidative damage achievable by exogenous supplements; α-tocopherol (200 mg/kg), ascorbic acid (250 mg/kg), Mn(III)tetrakis (4-benzoic acid) porphyrin (10 mg/kg), and α-lipoic acid (100 mg/kg). Mice were treated with daily injections of the mixture or each component alone between postnatal day (P)18 and P35. Between P18 and P35, there was an increase in two biomarkers of oxidative damage, carbonyl adducts measured by ELISA and immunohistochemical staining for acrolein, in the retinas of rd1 mice. The staining for acrolein in remaining cones at P35 was eliminated in antioxidant-treated rd1 mice, confirming that the treatment markedly reduced oxidative damage in cones; this was accompanied by a 2-fold increase in cone cell density and a 50% increase in medium-wavelength cone opsin mRNA. Antioxidants also caused some preservation of cone function based upon photopic electroretinograms. These data support the hypothesis that gradual cone cell death after rod cell death in RP is due to oxidative damage, and that antioxidant therapy may provide benefit.
TL;DR: In this paper, an attempt has been made to test individual curcuminoids such as Curcumin, bisdemethoxycurcumin and demethoxyCurcumin for their antioxidant activities by in vitro model systems, such as the phosphomolybdenum and linoleic acid peroxidation methods.
TL;DR: The development of an effective prophylaxis strategy for contrast-induced nephropathy has been limited by poor understanding of the pathophysiology and the clinical significance of this condition, and evidence supports the use of hydration, bicarbonate, and low volumes of iso- or low-osmolar contrast in patients at risk.
Abstract: ContextContrast-induced nephropathy is associated with significant economic and clinical consequences, including prolonged hospitalization, the requirement for dialysis, and an increased risk of death.ObjectivesTo summarize the current state of evidence for prophylaxis of contrast-induced nephropathy, provide evidence-based recommendations regarding management of high-risk patients undergoing angiographic procedures, and identify new avenues for research.Data SourcesSystematic searches of peer-reviewed publications were performed in MEDLINE, EMBASE, and the Cochrane database from 1966 to January 2006. Search terms included radio contrast nephropathy, contrast media, acetylcysteine, theophylline, sodium bicarbonate, HMG Co-A reductase inhibitors, ascorbic acid, kidney diseases, renal insufficiency, kidney failure, nephropathy, fenoldopam, diuretics, and saline or half saline.Study SelectionObservational studies of risk factors and randomized controlled trials of prophylaxis strategies for contrast-induced nephropathy that specified a definition of contrast-induced nephropathy or postprocedure creatinine level as an outcome measure.Evidence SynthesisImportant patient-related risk factors for contrast-induced nephropathy include chronic kidney disease, diabetes mellitus, heart failure, older age, anemia, and left ventricular systolic dysfunction. Non–patient-related risk factors include high-osmolar contrast, ionic contrast, contrast viscosity, and contrast volume. Practice guidelines recommend obtaining preprocedural serum creatinine levels among patients with renal disease, diabetes, proteinuria, hypertension, gout, or congestive heart failure. Available evidence, largely based on small- to medium-sized trials, supports the use of hydration, bicarbonate, and low volumes of iso- or low-osmolar contrast in patients at risk. N-acetylcysteine or ascorbic acid may be of value in very high-risk patients.ConclusionsWhile several risk factors for contrast-induced nephropathy have been identified, the development of an effective prophylaxis strategy for contrast-induced nephropathy has been limited by our poor understanding of the pathophysiology and the clinical significance of this condition. Future research should focus on correctly identifying higher-risk patients and testing therapies in the setting of large well-powered clinical trials.
TL;DR: Bananas contained higher concentrations of lutein than of the provitamin A pigments, α- and β-carotene, and papayas contained 9% of the dietary reference intake (DRI) for Cu, 6–8% ofThe DRI for Mg, but less than 3% for other minerals.
TL;DR: In this paper, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the fruit extracts was tested.
Abstract: Total polyphenols, total anthocyanins, and reduced ascorbic acid were evaluated in berries belonging to the genera Rubus, Ribes, and Aronia by means of spectrophotometric and high-performance liquid chromatography (HPLC) techniques. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the fruit extracts was tested. Total polyphenols ranged from 140.6 to 888.5 mg/100 g fresh weight (FW), total anthocyanins ranged from 22.0 to 460.5 mg/100 g FW, and reduced ascorbic acid ranged from 12.4 to 153.8 mg/ 100 g FW. The average EC50 values for Aronia melanocarpa, Ribes nigrum, Ribes rubrum, Rubus fruticosus, and Rubus idaeus were 1.8, 2.8, 5.3, 6.4, and 8.2 mg FW, respectively. The results indicate that the fruits tested are good sources of natural antioxidants.
TL;DR: The results show that carbon ionic liquid electrode (CILE) reduces the overpotential of DA, AA, and UA oxidation, without showing any fouling effect due to the deposition of their oxidized products.
TL;DR: The antioxidant activities evaluated by both ORAC and DPPH showed similar trends where red guava and carambola exhibited the highest and sapodilla and green papaya exhibited the lowest levels and many of the tropical fruits were shown to contain an abundance of hydrolyzable tannins, ellagic acid conjugates, and flavone glycosides.
Abstract: Fourteen tropical fruits from south Florida (red guava, white guava, carambola, red pitaya (red dragon), white pitaya (white dragon), mamey sapote, sapodilla, lychee, longan, green mango, ripe mango, green papaya, and ripe papaya) were evaluated for antioxidant activity, total soluble phenolics (TSP), total ascorbic acid (TAA), total dietary fiber (TDF), and pectin. ORAC (oxygen radical absorbance capacity) and DPPH (1,1-diphenyl-2-picrylhydrazyl, radical scavenging activity) assays were used to determine antioxidant activity. The TSP, ORAC, and DPPH ranged from 205.4 to 2316.7 g gallic acid equiv/g puree, <0.1 to 16.7 Imol Trolox equiv/g puree, and 2.1 to 620.2 Ig gallic acid equiv/g puree, respectively. The TAA, TDF, and pectin ranged from 7.5 to 188.8 mg/100 g, 0.9 to 7.2 g/100 g, and 0.20 to 1.04 g/100 g, respectively. The antioxidant activities, TSP, TAA, TDF, and pectin were influenced by cultivar (papaya, guava, and dragon fruit) and ripening stage (papaya and/or mango). Antioxidant activity showed high correlations with levels of TSP compounds (r ) 0.96) but low correlations with levels of ascorbic acid (r ) 0.35 and 0.23 for ORAC and DPPH data, respectively). The antioxidant activities evaluated by both ORAC and DPPH showed similar trends where red guava and carambola exhibited the highest and sapodilla and green papaya exhibited the lowest levels. Guava and mamey sapote exhibited the highest TDF and pectin levels. Many of the tropical fruits were shown to contain an abundance of hydrolyzable tannins, ellagic acid conjugates, and flavone glycosides. Preliminary descriptions are given of the phenols in red/white pitaya (dragonfruit), lychee, and mamey sapote, these fruit being thus far uncharacterized in the literature.