Determination Of Antioxidant Capacity Research Articles

The Effect of Refrigeration on Some Antioxidants and Soluble Proteins in Eggs

Normal 0 MicrosoftInternetExplorer4 In this study we aimed to investigate the effect of refrigeration of eggs from laying hens reared extensively. For this purpose, there were investigated the quantity of eggs polyphenols, their antioxidant activity, protein carbonyl concentration and electrophoretic protein pattern in eggs. Analyzed eggs, both fresh and chilled for 30 days at temperatures below 12°C, were obtained from hens fed with the same type of forage. The study was conducted in January and February, and the parameters analyzed were egg phenols, lycopene and I²-carotenoids, total antioxidant capacity, protein electrophoresis in denaturant system and protein carbonyl content. Egg polyphenols concentration was expressed as mg gallic acid equivalents / 100 g egg. The quantitative determination of antioxidant capacity was based on the reduction of Mo(VI) to Mo(V) by the sample analyte and the subsequent formation of a green phosphate/Mo(V) complex at acid pH, while the antioxidant activity was expressed relative to that of ascorbic acid. Total carbonyl content in egg proteins increased with the increase of refrigeration time. Carbonyl content can be considered a marker for protein oxidation. Amino acid residues affected by these changes in proteins may influence the functional properties of eggs. The amounts of I²-carotene and lycopene found in refrigerated and fresh eggs were very low; the high contents of phenolic compounds explained the good antioxidant activity determined in all assays . In the present research, we found that the refrigeration for a period of thirty days had no significant effects on polyphenols concentration and also electrophoretic pattern was not influenced by the refrigeration.

English

In addition to being consumed as food, caper (Capparis spinosa L.) fruits are also used in folk medicine to treat inflammatory disorders, such as rheumatism. C. spinosa L. is rich in phenolic compounds, making it increasingly popular because of its components’ potential benefits to human health. We analyzed a number of individual phenolic compounds and investigated in vitro biological activities of C. spinosa L. Sixteen phenolic constituents were identified using reverse phase-high performance liquid chromatography (RP-HPLC). Total phenolic compounds (TPCs), ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity were used as determinants of antioxidant capacity. C. spinosa L. exhibited strong antioxidant activity and contained high levels of antioxidant compounds. Gentisic, sinapic and benzoic acid were detected in C. spinosa L. No gallic acid, proto-catechuic acid, proto-catechuic aldehyde, chlorogenic acid, p-OH benzoic acid, vanillic acid, caffeic acid, syringic acid, vanillin, syringaldehyde, p-coumaric acid, ferulic acid or rosmarinic acid were identified. Iron and zinc were present at high levels in samples. C. spinosa L. appears to be a good source of antioxidants and minerals that might serve to protect health and combat several diseases.   Key words: Antioxidant, capers, Capparis spinosa L., phenolics.

Cultivar influence on total polyphenol and rutin contents and total antioxidant capacity in buckwheat, amaranth, and quinoa seeds

Five cultivars from each of the three types of pseudocereals, i.e. buckwheat, amaranth, and quinoa, were studied for total polyphenol and rutin contents as well as total antioxidant capacity of seeds. A spectrophotometric method was used for the determination of total polyphenol content (using the Folin-Ciocalteau reagent) and total antioxidant capacity (using DPPH). Rutin content in pseudocereal seeds was determined by HPLC. The determined total polyphenol content in seeds of buckwheat, amaranth, and quinoa cultivars was in the intervals of 15 874–71 359 mg/kg DM, 1381–2870 mg/kg DM, and 459–1839 mg/kg DM, respectively. Rutin content in buckwheat, amaranth, and quinoa seeds was in the intervals of 8722–17 125 mg/kg DM, 310–508 mg/kg DM, and 170–368 mg/kg DM,respectively. The presented results confirmed a statistically significant influence of cultivar on total polyphenol and rutin contents as well as on total antioxidant capacity of pseudocereal seeds.

A Novel Standardized Oxygen Radical Absorbance Assay for Evaluating Antioxidant Natural Products

Functional and quantitative evaluation of analytes in crude extracts or semipure mixtures has been considered challenging due to variation in generated results. Some of the drawbacks have been linked to the texture, form, and content of the samples. The crude extracts contain multiple components and, in oxygen radical absorbance capacity (ORAC) assays, have exhibited complex reaction kinetics due to interference or matrix effect. The conventional ORAC assay utilized a single dilution factor that brought about a wide CV difference (60-110%) in antioxidant activity for each extract compared to other dilution factors applied. Due to precision errors introduced from these extremely high CV% differences, determination of antioxidant capacity based on a single dilution may introduce discrepant results. A novel standardized ORAC (SORAC) assay for the determination of antioxidant capacity of dietary plant extracts is described in this study. Using the SORAC assay, positive linear correlations (R2 = 0.95-0.99) were obtained for the sample extracts tested when a multiple dilution strategy was applied. Thus, on the strength of our observations, SORAC has been proposed as an effective tool for assessing antioxidant analytes in a biological matrix. This technique could also be modified for use in other bioanalytical platforms concerned with the analyte matrix effect.

Determination of Total Antioxidant Capacity by Oxygen Radical Absorbance Capacity (ORAC) Using Fluorescein as the Fluorescence Probe: First Action 2012.23

An improved method for the measurement of oxygen radical absorbance capacity (ORAC) was developed and validated using fluorescein (3',6'-dihydroxyspiro[isobenzofuran-1[3H], 9'[9H]-xanthen]-3-one) as a new fluorescence probe (ORAC(FL)). Randomly methylated beta-cyclodextrin (RMCD) was introduced as the water-solubility enhancer for lipophilic antioxidants. 7% RMCD (w/v) in 50% acetone-H2O mixture sufficiently solubilized vitamin E compounds and other lipophilic phenolic antioxidants in 75 mM phosphate buffer (pH 7.4). Results indicated that fluorescein shows excellent photostability under the plate reader conditions. This ORAC(FL) was validated through linearity, precision, accuracy, and ruggedness. The validation results demonstrated that the ORACFL assay is reliable and robust. The mean of intraday and interday CVs were <15%; for hydrophilic ORAC, LOD and LOQ are 5 and 6.25 microM, respectively; for lipophilic ORAC, LOD and LOQ are 6.25 and 12.5 microM, respectively. It is concluded that unlike other popular methods, the ORAC(FL) assay provides a direct measure of total antioxidant capacity against the peroxyl radicals.

A novel method for the determination of ascorbic acid and antioxidant capacity in Opuntia ficus indica using in vivo microdialysis

A simple and rapid method was developed for in vivo simultaneous determination of ascorbic-acid and antioxidant capacity in microdialysates from cladodes of Opuntia ficus-indica (L.) Miller. The method is verified in water-stressed plants, as compared with a well-watered test controls. The microdialysis probe construction and insertion procedure was specifically developed to minimise the tissue trauma of the plant and to obtain optimal dialysis performance. Microdialysis was performed using a flow rate of 3μL/min and the samples were analysed by HPLC coupled to electrochemical detection of ascorbic-acid and DPPH-determined antioxidant capacity. Our data indicate exponential decay of the concentrations of the analysed compounds as a function of microdialysis sampling time. Water-stressed Opuntia show decreased ascorbic acid levels and increased the others antioxidants.

Antioxidant activity of selected phenols estimated by ABTS and FRAP methods

Phenols are the most abundant compounds in nature. They are strong antioxidants. Too high level of free radicals leads to cell and tissue damage, which may cause asthma, Alzheimer disease, cancers, etc. Taking phenolics with the diet as supplements or natural medicines is important for homeostasis of the organism. The ten most popular water soluble phenols were chosen for the experiment to investigate their antioxidant properties using ABTS radical scavenging capacity assay and ferric reducing antioxidant potential (FRAP) assay. Antioxidant properties of selected phenols in the ABTS test expressed as IC50 ranged from 4.332 μM to 852.713 μM (for gallic acid and 4- hydroxyphenylacetic acid respectively). Antioxidant properties in the FRAP test are expressed as μmol Fe2+/ml. All examined phenols reduced ferric ions at concentration 1.00 x 10-3 mg/ml. Both methods are very useful for determination of antioxidant capacity of water soluble phenols.

Direct Electroanalytical Method for Alternative Assessment of Global Antioxidant Capacity Using Microchannel Electrodes

A new electroanalytical method for the characterization of global antioxidant capacity is proposed based on chronoamperometric responses monitored at microchannel band electrodes. This approach does not require any titrating species, biological elements, or precalibration curves. A thin-layer regime is established at the working electrode according to the geometry of the device and hydrodynamic flow rate. Under these conditions, the currents are directly proportional to the total concentration of antioxidants and do not depend on their respective diffusion coefficients. Measurements were performed with synthetic solutions and mixtures of four antioxidants used as sample tests: trolox, ascorbic acid, gallic acid, and caffeic acid. Operating potentials were selected at the formal potentials of some reactive oxygen species to simulate their oxidative attacks. The very good agreement obtained between simulations and experimental data validated this new electroanalytical procedure. These results pave the way for the concept of innovative sensor-type microfluidic devices for alternative determination of antioxidant capacity.

Voltammetric and spectrometric determination of antioxidant capacity of selected wines

Considering the presence of phenolics in grapes and wines, as well as their importance for health promoting properties, the DPPH (1,1-diphenyl-2-picrylhidrazine) assay and a novel electroanalytical approach (differential pulse voltammetry – DPV) for analysis have been performed in order to compare the antioxidant activity of different grape beverages. A total of fifty-two wine samples from different regions around the world were analyzed. The antioxidant activity of the different wines analyzed was expresses as the amount of wine required to produce 50% of decolorization of DPPH relative to the blank control (EC50) and as an electrochemical index (EI), obtained by summing the ratios between peak current and peak potential values. Red wines presented higher antioxidant capacity than rose and white ones or red juices, evidencing the influence of the overall process of fabrication in phenolic extraction from the skin of grapes. A negative Pearson's correlation was found (−0.9110) and this result is consistent with what was expected due to the different principles inherent to these methods.

Determination of phenolic contents and antioxidant capacity of different parts of Withania somnifera (L.) Dunal. from three different growth stages

Withania somnifera (L.) Dunal. (Solanaceae) is a therapeutically important medicinal herb used in Ayurvedic and traditional systems of medicine for the treatment of an array of ailments. Diverse therapeutic properties reported from W. somnifera are mainly due to the high content of polyphenols and antioxidant activities present in different parts of the plant. Present study investigates the total phenolic content (TPC) and total antioxidant capacity (TAC) of different parts of three different growth stages of W. somnifera grown under three different spacing levels. The TAC and TPC were determined using Ferric Reducing Antioxidant Power assay and modified Folin–Ciocalteu colorimetric method respectively. Leaf extract exhibited significantly higher (p<0.05) TAC and TPC values for all three different growth stages. However, the highest TAC and TPC of leaf extract for all three spacing levels were observed just after flowering stage. The highest total phenolic content was exhibited in leaf extracts followed by flower, fruits, stem and roots respectively. With regard to the anti oxidant content, the highest amount was recorded from leaf followed by pods, flowers, stem and roots respectively. Presence of higher TPC and TAC just after flowering stage scientifically validates traditional claims of harvesting of W. somnifera after flowering stage. The higher content of TPC and TAC in leaf demonstrated the possibility of incorporation leaf for the development of newer, effective drugs instead of roots.

Evaluation of antioxidant capacities of green microalgae

Three strains of green microalgae, Chlorococcum sp.C53, Chlorella sp. E53, and Chlorella sp.ED53 were studied for their antioxidant activities. Crude extracts of these microalgae in hot water and in ethanol were examined for their total phenolic contents and for their antioxidant capacities. In order to determine their phenolic contents, the Folin–Ciocalteu method was used. As for the determination of their antioxidant capacities, four different assays were used: (1) total antioxidant capacity determination; (2) DPPH radical scavenging assay; (3) ferrous ion chelating ability assay; and (4) inhibition of lipid peroxidation (using thiobarbituric acid reactive substance). For all the strains we have studied, their ethanolic extract showed more antioxidant activities than their hot water extract. Categorically, the ethanolic extract of Chlorella sp.E53 exhibited both the highest total phenolic content of 35.5 ± 0.14 mg gallic acid equivalent (GAE) g−1 dry weight and the highest DPPH radical scavenging of 68.18 ± 0.38 % at 1.4 mg mL−1 (IC50 0.81 mg mL−1), whereas Chlorella sp.ED53 showed both the highest ferrous ion chelation activity of 42.78 ± 1.48 % at 1 mg mL−1 (IC50 1.23 mg mL−1) and the highest inhibition of lipid peroxidation of 87.96 ± 0.59 % at 4 mg mL−1. This high level of inhibition is comparable to 94.42 ± 1.39 % of butylated hydroxytoluene, a commercial synthetic antioxidant, at the same concentration.

Glutathione (GSH) and the GSH synthesis gene Gclm modulate plasma redox and vascular responses to acute diesel exhaust inhalation in mice

Context: Inhalation of fine particulate matter (PM2.5) is associated with acute pulmonary inflammation and impairments in cardiovascular function. In many regions, PM2.5 is largely derived from diesel exhaust (DE), and these pathophysiological effects may be due in part to oxidative stress resulting from DE inhalation. The antioxidant glutathione (GSH) is important in limiting oxidative stress-induced vascular dysfunction. The rate-limiting enzyme in GSH synthesis is glutamate cysteine ligase and polymorphisms in its catalytic and modifier subunits (GCLC and GCLM) have been shown to influence vascular function and risk of myocardial infarction in humans.Objective: We hypothesized that compromised de novo synthesis of GSH in Gclm−/+ mice would result in increased sensitivity to DE-induced lung inflammation and vascular effects.Materials and methods: WT and Gclm−/+ mice were exposed to DE via inhalation (300 μg/m3) for 6 h. Neutrophil influx into the lungs, plasma GSH redox potential, vascular reactivity of aortic rings and aortic nitric oxide (NO•) were measured.Results: DE inhalation resulted in mild bronchoalveolar neutrophil influx in both genotypes. DE-induced effects on plasma GSH oxidation and acetylcholine (ACh)-relaxation of aortic rings were only observed in Gclm−/+ mice. Contrary to our hypothesis, DE exposure enhanced ACh-induced relaxation of aortic rings in Gclm−/+ mice.Discussion and conclusion: These data support the hypothesis that genetic determinants of antioxidant capacity influence the biological effects of acute inhalation of DE. However, the acute effects of DE on the vasculature may be dependent on the location and types of vessels involved. Polymorphisms in GSH synthesis genes are common in humans and further investigations into these potential gene-environment interactions are warranted.

Fourier Transform Infrared Spectroscopy for Antioxidant Capacity Determination in Colored Glutinous Rice

The determination of total phenolic content and antioxidant capacity of 48 colored rice varieties and two white rice varieties from Thailand by Fourier transform infrared (FT-IR) spectroscopy (400–4,000 cm−1) was performed to explore the possibility of using FT-IR as an effective alternative technique for such determination. The peak at 1,635 cm−1 resulted from the ring C-C stretch of phenyl was clearly observed. The levels of phenolic content in rice samples as indicated with infrared spectrum were consistent with the results from chemical assays. Dark glutinous rice had the highest level of antioxidant capacity and phytochemicals followed by red rice, brown rice, and white rice. The hierarchical cluster analysis based on selected principal components from principal component analysis model was performed to produce dendrograms which discriminated rice varieties according to their color well. The partial least squares regression models were constructed, and validated models were used to predict total antioxidant capacity and total phenolic content of the rice varieties. Satisfactory precision of prediction was achieved. With technical advantages that FT-IR offers especially when large number of samples are to be analyzed, FT-IR spectral features with chemometrics are suggested to be applicable for quantification and prediction of antioxidant capacity and phenolic compound content of colored rice.

Black and green tea – How to make a perfect crime

The antioxidant properties of the black and green tea are well known. The latent bloodstains are detectable by luminol. The bloodstains also can be cover up by drinks and foods containing the antioxidants; thus their presence can cause a decrease of the luminol light emission (false-negative results). The aim of this study was to quantify the light emission decrease of the chemiluminescent mixture prepared according to Weber (containing NaOH) and the chemiluminescent mixture of pH 7.4 (for the determination of the total antioxidant capacity) for the open air-dried sample. The black and green teas and white wine were used as the antioxidant's samples (high and low total antioxidant capacity). The significant decrease of the luminol chemiluminescent emission caused by the presence of the black and green teas (and comparable for both of them) was observed in comparison with the presence of white wine.

A Comparative Study on Antioxidant Properties of Two Phyllanthus Species Growing in Bangladesh

A comparative study of antioxidant properties on two varieties of Phyllanthus (Phyllanthus niruiri L. &amp; Phyllanthus urinaria L. leaves) growing in Bangladesh was done in the present study. Five complimentary test methods namely DPPH free radical scavenging activity, reducing power assay, total antioxidant capacity, total phenolic and flavonoid contents determination were used for the evaluation of antioxidant properties of two species of Phyllanthus. In the present investigation for the evaluation of antioxidant activities the concentration is expressed by the ratio of crude sample per solvent volume instead of extract weight per solvent volume. Based on these concentrations the investigated P. niruri L. and P. urinaria L. leaves extracts exhibited significant results. At 2 mg/ml concentration DPPH radical scavenging capacity of the methanol extract of both the plants was found to show significant (&gt;90%) activity which is comparable to Ascorbic acid and BHA. In case of reducing power tests for both the extract, the activity of P. urinaria is comparable to that of BHA and AA and that of P. niruiri is comparable to BHA. P. niruiri showed better antioxidant potential than that of P. urinaria based on the observed results of their corresponding methanol extract. DOI: http://dx.doi.org/10.3329/dujps.v11i2.14579 Dhaka Univ. J. Pharm. Sci. 11(2): 191-197, 2012 (December)

Optimisation of ultrasonic-assisted extraction of antioxidant compounds from Artemisia absinthium using response surface methodology

Response surface methodology was used to optimise experimental conditions for ultrasonic-assisted extraction of phenolic compounds from Artemisia absinthium. The central composite design was employed, the extracts were characterised by the determination of total phenolic content and antioxidant capacity. The total phenolic contents of extracts were determined by Folin method and also total antioxidant capacities of extracts were determined by ABTS and CUPRAC methods. The phenolic compounds of A. absinthium at optimum extraction conditions were determined by HPLC-DAD. The optimum conditions were determined as HCl concentration between 0.41 and 0.44mol/L, methanol volume between 55% and 59% (v/v), extraction temperature between 64 and 70°C, extraction time between 101 and 107min. The experimental values agreed with those predicted within a 95% confidence level, thus indicating the suitability of response surface methodology in optimising the ultrasound-assisted extraction of phenolic compounds from A. absinthium.

Short-term effect of an aqueous Fraxinus excelsior L. seed extract in spontaneously hypertensive rats

We evaluate the short-term effect of a Fraxinus excelsior L. seed extract, named FraxiPure (FRP) on spontaneously hypertensive rats (SHR). Water, Captopril and different doses of FRP were orally administered. Blood pressure was recorded by the tail cuff method and plasma samples were collected to determine antioxidant capacity and malondialdehyde equivalents. In other trials, 18h fasted SHR were administered water, FRP, Furosemide, Torasemide, and Captopril. In these animals, urine was collected for 4h to obtain the urine volumetric excretion (UVE). Plasma samples of these animals were used to establish the fractional excretion (FE) of different ions (Na+, Cl−, K+, Ca2+ and PO43−) and metabolites (creatinine, urea and uric acid).FRP shows antihypertensive effect. The decrease in blood pressure caused by FRP was slightly lower than that of Captopril and more accentuated than that of Torasemide. FRP and Torasemide significantly increased UVE. Torasemide significantly increased FE(Na+) and FE(Cl−) and showed a clear uricosuric effect. FRP showed slight natriuretic effects and behaved as a potassium-sparing diuretic. FRP significantly increased plasma antioxidant capacity and decreased plasma malondialdehyde equivalents. The antihypertensive effect of FRP in SHR can therefore be related with its diuretic and antioxidant properties.

Effect of sample dilution on estimated values of antioxidant capacity by photochemiluminiscence method

This paper describes principles of a proper dilution of samples used for the determination of antioxidant capacity by means of a photochemiluminiscence method using the instrument Photochem (Analytik Jena AG). The authors used the method ACL (Lipid-soluble Antioxidant Capacity), which is one of two methods enabling to measure in this instrument. It was demonstrated that values measured by the photochemiluminiscence method ACL were influenced by the degree of sample dilution. When studying effects of dilution of samples of wine and rutin, it was demonstrated that there is a non-linear correlation between the degree of dilution and measured values of antioxidant capacity. At low molar amount of substance (i.e. at 0.5 and 1.0 nmol), the measured value of rutin inhibition was higher than the same that molar amount of trolox. At higher molar amounts (i.e. 3; 4 and 5 nmol), the inhibition value of trolox was higher. This dependent change can be explained by means of a different effectiveness of antioxidants and a different stability of their products with radicals.

Optimisation of assay conditions for the determination of antioxidant capacity and polyphenols in cereal food components

The measurement of the antioxidant activity of foods, food ingredients and plant extracts is an important parameter for determining their quality. Whole grain wheat flour, which is a key component of the human diet, was chosen as a food model to optimise 2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods by using different solvent extractions or assay conditions. The ABTS method was found to have a wide pH range of stability (at least pH 1–8), while for DPPH method, a pH range between 4 and 8 was needed. The reagent dilution (resulting from the addition of the sample to the reaction mixture) was the most relevant limiting factor of the ABTS assay with a sample/reagent volume ratio that should be at most 1/10. The direct ABTS assay for solid samples was optimised and compared with previously reported solvent extractions demonstrating that the various solvents have different antioxidant compound extraction capacities and that the residual bound molecules can be assayed by the direct method. Total polyphenol and flavonoid assays showed no evident pH-dependence. General guidelines regarding the optimal conditions for the extraction and measurement of the total antioxidant activity of foods and food extracts, can be recommended from the present results.

Study of the Effect of Surfactants on Extraction and Determination of Polyphenolic Compounds and Antioxidant Capacity of Fruits Extracts

Micelle/water mixed solutions of different surface active agents were studied for their effectiveness in the extraction of polyphenolic compounds from various varieties of apples from west Azerbaijan province in Iran. The total content of polyphenolic compound in fruit extracts were determined using ferrous tartrate and Folin–Ciocalteu assays methods and chromatographic methods and compared with theme. High performance liquid chromatography is one of the most common and important methods in biochemical compound identification. The effect of pH, ionic strength, surfactant type, surfactant concentration, extraction time and common organic solvent in the apple polyphenolics extractions was studied using HPLC-DAD. Mixtures of surfactants, water and methanol at various ratios were examined and micellar-water solutions of Brij surfactant showed the highest polyphenol extraction efficiency. Optimum conditions for the extraction of polyphenolic compounds from apple occurred at 7 mM Brij35, pH 3. Effect of ionic strength on extraction was determined and 2% (W/V) potassium Chloride was determined to be the optimum salt concentration. The procedure worked well with an ultrasound bath. Total antioxidant capacity also was determined in this study. The method can be safely scaled up for pharmaceutical applications.