Antioxidants capacity determination

G8. Girotti, S., Ferri, E., Maccagnani, L., Budini, R., and Bianchi, G., Plasma antioxidant capacity determination Comparative evaluation of chemiluminescent and spectrophotometric assays. Talanta 56, 407-414 (2002). 

While we have demonstrated the successful application of our integrated organic photodiode-based test platform to antioxidant capacity determination, we regard this as a first step towards a universal platform for chemiluminescence-based testing at the point-of-care. To this end we have investigated the use of passive fluid delivery schemes (to circumvent the use of valves and external pumps) and the implementation of low-cost electronic read-out circuits (for both size and cost reduction). 

Bonpadre, S., L. Leone, A. Politi et al. 2004. Improved FIA-ABTS method for antioxidant capacity determination in different biological samples. Free Rad. Res. 38 831-838. 

The CL methods can be applied with very good results for the analysis of lipid peroxides in food quality assessment and also to measure the ability of the natural or synthetic food antioxidants to quench free radicals in foods. For antioxidant capacity determination of foods, the measurements are based on competitive kinetics, in which the antioxidants compete with a CL reagent for the free radicals, resulting in a decrease in the light emission compared with the CL intensity obtained in the absence of the antioxidants. 

The results obtained for the antioxidant capacity determination of the edible oils by CL were compared with those obtained by a standard DPPH test, but the results were not comparable. One of the possible explanations for these differences is the nature of the free radicals employed in the determinations. In the DPPH test, the 2,2-diphenyl-l-picrylhydrazyl radical, a very voluminous compound, is used, and its reaction with the antioxidants may be affected by steric impediments. In the case of the CL method, the small reactive oxygen species generated from the Fenton s reagent are the species that react with antioxidants, and they are also responsible for the luminol CL. Moreover, the DPPH test measures the antioxidant activity of the hydrophilic and hydrophobic compounds present in the oil, while the CL method accounts especially for the hydrophilic fraction. 

The described FI-CL system provides a simple, sensitive, and accurate method for antioxidant capacity determination in lipidic media. Another advantage of this FI-CL method compared with the DPPH method is its rapidity of measurement it requires less than 5 min for the complete evaluation of each sample, while the DPPH method needs about 15 min. 

The on-line measurement of reducing capacity can be performed with either a single or a series of electrochemical detectors, and linear correlations have been demonstrated between total antioxidative activities determined by the electrochemical detection and those determined by DPPH- reduction or by the ORAC assay (Guo et al, 1997 Peyrat-Maillard et al, 2000). The reducing capacity must also be quantified by post-column reactions, either with DPPH- or by the reduction of phosphomolybdenum complexes followed by UV-VIS-detection (Bandoniene and Murkovic, 2002 Cardenosa et al, 2002). A combination of HPLC and semi-automatic ORAC analysis has also been described (Caldwell, 2001). 

Cho, M.J. et al., Llavonoid glycosides and antioxidant capacity of various blackberry, blueberry and red grape genotypes determined by high-performance liquid chroma-tography/mass spectrometry, J. Sci. Food Agric., 84, 1771, 2004. 

Antioxidant capacities of common individual curcuminoids were determined in vitro by phosphomolybdenum and linoleic acid peroxidation methods. Antioxidant capacities expressed as ascorbic acid equivalents (pmol/g) were 3099 for curcumin, 2833 for demethoxycurcumin, and 2677 for bisdemethoxycurcumin at concentrations of 50 ppm. The same order of antioxidant activity (curcumin > demethoxycurcumin > bisdemethoxycurcumin) was observed when compared with BHT (buty-lated hydroxyl toluene) in linoleic peroxidation tests. The antioxidant activity of curcumin in the presence of ethyl linoleate was demonstrated and six reaction products were identified and structurally characterized. The mechanism proposed for this activity consisted of an oxidative coupling reaction at the 3 position of the curcumin with the lipid and a subsequent intramolecular Diels-Alder reaction. ... 

Alvarez-Suarez, J. M., TuUpani, S., Romandini, S., Vidal, A., and Battino, M. (2009). Methodological aspects about determination of phenolic compounds and in vitro evaluation of antioxidant capacity in the honey A review. Curr. Ami. Client. 5, 293-302. 

Freedman and others (2001) determined the effects of purple grape juice and its main flavonoids on the functionality of platelets and the production of NO. They observed that incubation of platelets with diluted grape juice resulted in the inhibition of aggregation, increased production of NO, and decreased production of superoxide. To confirm the relevance of these findings, 20 healthy subjects were supplemented with 7 mL of black grape juice/kg/day for 14 days. The inhibition of platelet aggregation was also observed ex vivo there was an increase in the production of NO from 3.5 1.2 to 6.0 1.5 pmol/108 platelets and a decrease in the release of superoxide, from 29.5 5.0 to 19.2 3.1 arbitrary units. Under these conditions the antioxidant capacity of protein-free plasma increased by 50% (Freedman and others 2001). 

The photochemiluminiscence (PCL) assay was initially used by Popov and others (1987). Popov and Lewin (1994 1996) have extensively studied this technique to determine water-soluble and lipid-soluble antioxidants. The PCL assay measures the antioxidant capacity, toward the 02 radical, in lipidic and water phase. This method allows the quantification of both the antioxidant capacity of hydrophilic and/or lipophilic substances, either as pure compounds or complex matrices from different origin synthetic, vegetable, animal, human, etc. The PCL method is based on an approximately 1,000-fold acceleration of the oxidative reactions in vitro by the presence of an appropriate photosensitizer. The PCL is a very quick and sensitive method. Chua and others (2008) used this assay to determine the antioxidant potential of Cin-namomum osmophloeum, whereas Kaneh and Wang and others (2006) determined the antioxidant capacity of marigold flowers. The antioxidant activity of tree nut oil extracts was also assessed by this method (Miraliakbari and Shahidi 2008). 

Sanchez-Morcno (2002) considered that this assay is an easy and accurate method for determining antioxidant capacity in fruit and vegetable samples. The DPPH assay has been used to determine the antioxidant activity of polyphenols (Sanchez-Moreno and others 1998 Bao and others 2004) flavonols (Jimenez and others 1998 1999 Choi and others 2002) anthocyanin-based natural colorants from berries (Espin and others... 

Many methods are available for determining food antioxidant capacity, which is an important topic in food and nutrition research. However, there is a great need to standardize these methods because the frequent lack of an actual substrate in the procedure, the system composition, and the method of inducing oxidation could limit their accuracy. In fact, antioxidant activities in complex systems cannot be evaluated satisfactorily using a single test, and several test procedures may be required. The search for more specific assays that can be more directly related to oxidative deterioration of foods and biological systems should be the objective of future investigations. 

Honer K and Cervellati R. 2003. Determination of the antioxidative capacity of apples using the Briggs-Rauscher method. Ernahrungs-Umschau 50(1) 13. 

MacDonald-Wicks LK, Wood LG and Garg ML. 2006. Methodology for the determination of biological antioxidant capacity in vitro A review. J Sci Food Agric 86(13) 2046-2056. 

Prior RL, Wu X and Schaich K. 2005. Standardized methods for the determination of antioxidant capacity and phenolics in foods and dietary supplements. J Agric Food Chem 53(10) 4290-4302. 

The experiment with 0.5 g/mL of erode extracts of different parts of Allium plants (bulb, green leaf, white stalk) showed the inhibition of acrosin and trypsin activities, mostiy the red onion and garlic extracts. These results demonstrated that spermicidal effect of Allium extracts is determined also by their capacity of protease inhibition. The red onion extract shows the higher antioxidant capacity and a very low cytotoxicity. 

The aim of this work was to evaluate the inhibition effect of ome Allium aqueous extracts on acrosin and trypsin activities, a new aspect in the wide spectrum of Allium compound activities. The antioxidant capacity, probably responsible for antithrombosis and antitumoral effects, was determined for different parts of Allium plants (bulb, green leaf, white stalk). The toxicity of crude extracts was also determined. 

L. Campanella, A. Bonanni, E. Finotti and M. Tomassetti, Biosensors for determination of total and natural antioxidant capacity of red and white wines comparison with other spectrophotometric and fluorimetric methods, Biosens. Bioelectron., 19(7) (2004) 641-651. 

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