Antioxidative capacity

Therefore, there is substantial evidence that GA can play a positive health-related role in addition to its well-known properties as an emulsifier. Therefore, the aim of this chapter is to describe general aspects of the source, composition, and already known uses of GA as well as some new aspects of its antioxidant capacity against some reactive oxygen substances (ROS), and its antimicrobial activity (AMA). 

Consequently, the antioxidant activity of GA in biological systems is still an unresolved issue, and therefore it requires a more direct knowledge of the antioxidant capacity of GA that can be obtained by in vitro experiments against different types of oxidant species. The total antioxidant activity of a compound or substance is associated with several processes that include the scavenging of free radical species (eg. HO, ROO ), ability to quench reactive excited states (triplet excited states and/ or oxygen singlet molecular 1O2), and/or sequester of metal ions (Fe2+, Cu2+) to avoid the formation of HO by Fenton type reactions. In the following sections, we will discuss the in vitro antioxidant capacity of GA for some of these processes. 

Gliszczyhska-Swigl, A. (2006). Antioxidant activity of water soluble vitamins in the TEAC (trolox equivalent antioxidant capacity) and the FRAP (ferric reducing antioxidant power) assays. Food Chemistry, Vol.96, No.l, (May 2006), pp. 131-136, ISSN 0308-8146. 

CARBONNEAU M-A, LEGER c L, MONNIER L (1997) Supplementation with wine phenolic compormds increases the antioxidant capacity of plasma and vitamin E of low-density lipoprotein without changing the lipoprotein Cu -oxidizability possible explanation by phenolic location, European Journal of Clinical Nutrition, 51, 682-90. 

MANZOCCO L, CALLiGARis s, MASTROCOLA D, NicoLi M c and LERici c R (2001) Review of non-enzymatic browning and antioxidant capacity in processed foods . Trends Food Sci Technol, 11 340-6. 

NICOLI M c, CALLIGARIS s and MANZOCCO L (2000) Effect of enzymatic and chemical oxidation on the antioxidant capacity of catechin model systems and apple derivatives , JAgric Food Chem, 48 (10) 4576-80. 

Table 16.1 Thermodynamic and kinetic parameters for plant phenols of relevance for their antioxidant capacity and antioxidant activity... 

Both thermodynamic and kinetic factors are of importance for antioxidant capacity. The antioxidant has to be located in the right position at the right time in order to prevent oxidative damage to vital cell components and will need to be regenerated from the one-electron oxidised form in a recycling process ... 

The terminology describing the action of antioxidants is unfortunately not clear. Terms such as antioxidant power , antioxidant effectiveness , antioxidant ability , antioxidant activity , and antioxidant capacity are often used interchangeably and without discrimination. Here we use the term antioxidant activity as meaning a measure of the rate of antioxidant action, and the term antioxidant capacity as meaning a measure of the extent of antioxidant action, i.e. the amount of radicals or intermediates and products produced during oxidation that are quenched by a given antioxidant. Thus antioxidant activity is related to the kinetics of the antioxidant action and antioxidant capacity to the stoichiometry. 

DPPH- has an intense absorption maximum around 520 run (Yordanov and Christova, 1997), and antioxidant capacity and activity measured by the reduction of DPPH- are easily quantified by VIS-spectroscopy (Brand-Williams et al, 1995 Bondet et al, 1997, Espin et al, 2000). The stable radicals Fremy s salt (potassium nitrosodisulphonate) and galvinoxyl (2,6-di-tert-butyl-a-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-l-ylidene)-p-tolyloxy radical) have been used in a similar manner but with ESR detection, which can be used with samples that are not optically transparent (Gardner et al, 1998). 

An interesting development is the combination of HPLC and on-line measurement of reducing capacity or antioxidative activity. This approach allows both direct identification of antioxidative species in complex foods and quantification of the contribution to the overall antioxidative capacity in the absence of synergistic and antagonistic effects. Major advantages are less sample handling and the ability to rim large series of samples in an automated process. 

HU M and SKIBSTED L H (2002a) Antioxidative capacity of rhizome extract and rhizome knot extract of edible lotus, Food Chem, 76, 329-33. 

PRIOR R L and CAO G (1999) "In vivo total antioxidant capacity Comparison of different analytical methods, Free Rad Biol Med, 27, 1173-81. 

Wu, X. et al.. Characterization of anthocyanins and proanthocyanidins in some cul-tivars of Rihes, Aronia and Samhucus and their antioxidant capacity, J. Agric. Food Chem., 52, 7846, 2004. 

The protective effects of carotenoids against chronic diseases appear to be correlated to their antioxidant capacities. Indeed, oxidative stress and reactive oxygen species (ROS) formation are at the basis of oxidative processes occurring in cardiovascular incidents, cancers, and ocular diseases. Carotenoids are then able to scavenge free radicals such as singlet molecular oxygen ( O2) and peroxyl radicals particularly, and protect cellular systems from oxidation. 

Epidemiological studies and intervention trials with food and beverages rich in flavonoids are not conclusive although flavonoids were recognized to display numerous antioxidant, anti-inflammatory, anti-tumoral, and anti-microbial activities. The antioxidant capacity of flavonoids has been largely reported in numerous in vitro and ex vivo systems. Numerous reviews "" have been published on the antioxidant properties of flavonoids. Degenerative diseases are largely associated with oxidative mechanisms that may be counteracted by flavonoids. 

Curcumin possesses strong antioxidant capacities, which may explain its effects against degenerative diseases in which oxidative stress plays a major role. As previously described for flavonoids, it is unlikely that curcumin acts as a direct antioxidant outside the digestive tract since its concentration in peripheral blood and organs is very low (near or below 1 pM, even after acute or long-term supplementation). Indeed, it has been shown that the intestinal epithelium limits its entry into the body, as reflected by absorption studies in various models (portal blood perfusion, everted bags). ... 

Many different methods have been used to evaluate the antioxidant capacities of isolated molecules, carotenoids, and other natural antioxidants and of foods and food extracts containing antioxidants. It is not the purpose of this chaper to review all the methods, but some general points can be made. First, when using only one test to evaluate the antioxidant capacities of carotenoids, one should be very careful in the interpretation of obtained data. Indeed, different results can be obtained with different tests applied to the same molecules. At least two different methods should be used to evaluate the antioxidant activity of a molecule or a food extract. " Second, lipophilicity is an important factor to consider in testing the antioxidant activities... 

Another point is the concentration of the antioxidant which, in order to have physiological relevance, should be in the physiological range, i.e., not above 1 to 5 aM. Finally, when evaluating antioxidant capacities of foods and food extracts, one should take into account the presence of all the possible antioxidant molecules (phenols, vitamin E, etc.) to explain the results because interactions can occur between antioxidant molecules. 

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. 

Pellegrini, N. et al.. Total antioxidant capacity of plant foods, beverages and oils consumed in Italy assessed by three different in vitro assays, J. Nutr. 133, 2812, 2003. 

Data about curcunfin encapsulated in liposomes have been reported recently. The authors encapsulated curcumin into a liposomal delivery system in order to study the in vitro and in vivo effects of this compound on proliferation, apoptosis, signaling, and angiogenesis using human pancreatic carcinoma cells. Carotenoids of different polarities and in competition with cholesterol were specifically incorporated into liposomes in order to mimic the physiological uptake by cells and monitor their antioxidant capacities. ... 

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. ... 

French researchers provided an alternative to the tartrazine synthetic colorant (E 102), valorizing a phloridzine oxidation product (POP) generated as a by-product of the cider industry. Phloridzine is a polyphenol specific to apples and shows good antioxidant capacity. When apples are pressed to yield juice, phloridzine, oxygen, and polyphenoloxidase enzyme combine to form POP. This brilliant yellow natural colorant with nuances dependent on pH level can be incorporated easily into water-based foods such as beverages (juices, syrups) and confectionery creams because it is stable during production processes. Details about the specific formulations of these colorants are presented in Section 5.1. 

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