Assessment Of Total Antioxidant Capacity Research Articles

Novel Colorimetric Sensor for Cupric Reducing Antioxidant Capacity (CUPRAC) Measurement

A novel optic sensor was developed for screening the total antioxidant capacity based on the use of cupric – neocuproine (Cu(II)−Nc) immobilized into a polymethacrylate matrix (PMM) with spectrophotometric measurement. The absorption change associated with the formation of the colored Cu(I)−Nc chelate in the PMM as a result of reaction with antioxidants was measured at 450nm. The colorimetric CUPRAC sensor can be used for quantitative assessment of total antioxidant capacity of complex matrices such as food extracts. The sensor is small and cheap, suitable to fit in a portable instrument for in situ antioxidant analysis.

High-sensitivity programmable flow method for assessment of total antioxidant capacity in biological samples

A programmable flow system is proposed for assessment of total antioxidant capacity of biological fluids based on Cu(II) reduction. A high-sensitivity procedure was implemented by using a 1m pathlength liquid core waveguide capillary cell (LWCC), fostering high oxidant to antioxidant ratio. This feature promoted a faster reaction development and the response of the developed method towards several model antioxidant compounds, including ascorbic acid, Trolox (soluble analogue of vitamin E), uric acid, cysteine, glutathione and serum albumin, was studied. Application to less studied biological samples available at low volumes (tear, saliva), and also to serum samples, was performed. Analytical features include the low limit of detection (200nM) and application range up to 10μM Trolox with intraday repeatability of <3%. Trolox equivalent antioxidant capacity (TEAC) values between 26±1 and 155±7μM were found for tears and saliva samples, while values between 421±3 and 759±14μM were found for serum samples. The mean recovery was 101.9±7.3% when uric acid was added to the different biological sample matrices, showing the suitability of the proposed method towards this application at low μM levels.

Assessment of Total Antioxidant Capacity and Antiradical Scavenging Activity of Three Egyptian Wild Plants

Assessment of Total Antioxidant Capacity and Antiradical Scavenging Activity of Three Egyptian Wild Plants

High-throughput Total Cupric Ion Reducing Antioxidant Capacity of Biological Samples Determined Using Flow Injection Analysis and Microplate-based Methods

High-throughput cupric ion reducing antioxidant capacity (CUPRAC) methods were developed for assessment of total antioxidant capacity (TAC) in urine and serum, based on reduction of Cu(II)-neocuproine complex to highly colored Cu(I)-neocuproine complex, measured spectrophotometrically at 450 nm. The reaction time was significantly reduced from 30 to 4 min by application of a calibration compound (uric acid) with kinetic behavior similar to that shown by urine samples. The method was implemented in a microformat (96 well plates) and also in an automatic fashion (flow injection analysis, FIA). A determination throughput value of 288 h(-1) (microplate method) or of 15 h(-1) (automatic FIA) was attained. Application of both methods to human serum (SRM 909b, level I) and urines (n = 9) provided TAC values in agreement with those of the end-point batch method.

Assessment of Total Antioxidant Capacity and the Use of Vitamin C in the Treatment of Non‐Smokers With Chronic Periodontitis

Several recent studies have indicated that total antioxidant capacity (TAOC) of plasma seems to be compromised in chronic periodontitis (ChP). The aim of this study is to investigate plasma TAOC in patients with ChP and to assess the effects of vitamin C as an adjunct to non-surgical periodontal treatment. The study population consisted of 60 subjects: 30 diagnosed with ChP and 30 matched controls. Furthermore, patients from the ChP group were randomly allocated into ChP1 (15 patients received non-surgical treatment with adjunctive dose of vitamin C) and ChP2 (15 patients received non-surgical periodontal treatment alone). Plasma TAOC levels were measured by an ABTS assay at baseline and 1 month post-therapy. Plasma TAOC levels were significantly lower in ChP patients than controls (P <0.001). The periodontal therapy resulted in increasing plasma TAOC and improvements in clinical measures among both ChP1 and ChP2 groups (P <0.001). However, the adjunctive dose of vitamin C did not offer additional effect (P >0.05). ChP is significantly associated with lower levels of plasma TAOC. The non-surgical periodontal therapy seems to reduce the oxidative stress during the periodontal inflammation. However, the use of adjunctive vitamin C still needs further investigation.

Evaluation of the total antioxidant capacity by using a multipumping flow system with chemiluminescent detection

An automated flow-based procedure for assessment of total antioxidant capacity was developed. It involved a multipumping flow system, a recent approach to flow analysis, and exploited the ability of selected compounds to inhibit the chemiluminescence reactions of luminol or lucigenin with hydrogen peroxide. The system included several discretely actuated solenoid micropumps as the only active components of the flow manifold. This enabled the reproducible insertion and efficient mixing of very low volumes of sample and reagents as well as the transportation of the sample zone toward a flow-through luminometer, where the chemiluminometric response was monitored. With luminol as the chemiluminogenic reagent, linearity of the analytical curves was noted up to 3.2 × 10 −4, 1.1 × 10 −3, and 8.8 × 10 −8 mol L −1 for Trolox, ascorbic acid, and resveratrol, respectively. With lucigenin, linear calibration plots up to 2 × 10 −5 mol L −1 of Trolox and 5.7 × 10 −5 mol L −1 of ascorbic acid were obtained. As favorable analytical figures of merit, the measurement precision (RSD typically between 0.2 and 2.0%, n = 10), low operational costs, low reagent consumption, sampling rate (160 and 70 h −1), and versatility should be highlighted. The proposed system can be used in distinct analytical circumstances without requiring physical reconfiguration.

Assessment of total antioxidant capacity (TAC) of human blood plasma

Oxidative stress, initiated by reactive oxygen species is recognized as a pathogenic factor in a variety of organs, e.g. brain, heart, gastric, duodenum, lung. The aim of this study was to estimate plasma TAC of healthy volunteers aged 35–60 years and patients with chronic obstructive pulmonary disease (POCHP). The ferric reducing/antioxidant power (FRAP) assay was used to measure the TAC of human blood plasma. At a low pH a ferric tripyridyltiazine (Fe3+‐TPTZ) complex is reduced to the ferrous (Fe2+) form that causes changes at 593 nm. The antioxidant capacity of the control plasma corresponded to 17.59 ± 1.17 μmol of Trolox activity (a water‐soluble analog of vitamin E). The antioxidant capacity of the plasma obtained from patients with POCHP corresponded to 23.82 ± 1.82 μmol of Trolox activity and was higher (P &lt; 0.02) than from healthy volunteers. This may represent the adaptive response to oxidative stress related to chronic inflammation.Acknowledgement: This study was financed by a 502‐11‐809 grant.

Pitfalls in a Method for Assessment of Total Antioxidant Capacity

A relatively simple and widely applied method for quantitating the total antioxidant capacity of body fluids and drug solutions based on the absorbance of the ABTS radical cation was evaluated. In this assay, the end-point is an antioxidant-induced decrease in absorbance at a fixed time. This decrease is used as an index of total antioxidant capacity. It is shown that Trolox, potassium cyanide and quercetin all decrease the absorbance of ABTS radical cations at a fixed time, but by different mechanisms. Trolox scavenges the ABTS radical, potassium cyanide inhibits radical formation, while quercetin acts by both mechanisms. Using this method antioxidant capacity may be overestimated, due to both a scavenger effect and an effect on the rate of ABTS oxidation. To distinguish between these effects, a post-addition assay was used in which the sample is added when the formation of radicals is stable. Using post- addition assay conditions enables discrimination between effects on radical scavenging and on the radical formation, two major mechanisms for antioxidant action. In extrapolating the results to an ill vivo situation it should be questioned: (i) whether the peroxidase process does indeed mimic the process of radical formation in vivo, and (ii) whether the ABTS radicals do resemble the radical species involved in an in vivo situation. Results obtained in the ABTS radical-based methods should therefore be reviewed critically before the antioxidant capacity can be assessed.