Catechins antioxidant properties

Therefore depending upon the conditions used to simulate either in vitro or in vivo oxidation, catechins or other phenolic compounds display differences in their antioxidant properties. Catechins also limited the consumption of a-tocopherol, allowing it to act as a scavenger within cell membranes whilst the catechins scavenged aqueous peroxyl radicals near the membrane surface (Pietta and Simonetti, 1998). 

Superoxide anion scavenging activity of the enzymatically synthesized poly(catechin) was evaluated. Poly(catechin), synthesized by HRP catalyst, greatly scavenged superoxide anion in a concentration-dependent manner, and almost completely scavenged at 200 p.M of a catechin unit concentration. The laccase-catalyzed synthesized poly(catechin) also showed excellent antioxidant property. Catechin showed pro-oxidant property in concentrations lower than 300 jlM. These results demonstrated that the enzymatically synthesized poly(catechin) possessed much higher potential for superoxide anion scavenging, compared with intact catechin. 

Jo and others (2006) applied this assay to determine the antioxidant properties of methanolic extracts from Japanese apricot in chicken breast meat. Likewise, Pearson and others (1998) assessed two types of Japanese green tea from Japan and two of their active compounds, catechin and epicatechin, for their relative abilities to inhibit the oxidation of LDL. Also, Pearson and others (1999) assessed the ability of compounds in apple juices and extracts from fresh apple to protect LDL. Heinonen and others (1998b) observed that berry phenolics inhibited hexanal formation in oxidized human LDL. 

Synthetic analogues or derivatives of a-tocopherol which have better antioxidant properties can be introduced. Many natural antioxidants such as flavonols, flavones, tea leaf catechins, rosemary antioxidants and spice extracts have been reported to be more active than BHA, BHT or the tocopherols in model systems. The food applications of these compounds need to be explored further. 

Kim, Y.J. et al.. Superoxide anion scavenging and xanthine oxidase inhibition of (-l-)-catechin-aldehyde polycondensates. Amplification of the antioxidant property of (-l-)-catechin by polycondensation with aldehydes. Biomacromolecules, 5, 547, 2004. 

In the past 20 years, laboratory research and epidemiological findings suggest that tea catechins may reduce the risk of several diseases, such as cancer and coronary heart disease, which could be due, at least in part, to the presence of catechins that have antioxidant properties and can inhibit cell proliferation, regulate carcinogen-metabolizing enzymes, and induce apoptosis. ... 

The most widely recognized property of tea catechins is their antioxidant property that results from their ability to scavenge reactive oxygen and nitrogen species and... 

Havonoids are also an important subgroup of phenolic compounds and one of meir functions in foods includes meir antioxidant properties. They may also contribute to flavor such as bitterness [47]. In raw European chesmut, flavonoids were found in trace amonnts (0.01 mg catechin and 0.01 mg gallocatechin in lOOg of edible portion) [48]. 

Chung, J. E., Kurisawa, M., Uyama, H. Kobayashi, S. (2003) Enz3miatic synthesis and antioxidant property of gelatin-catechin conjugates. Biotechnol Lett, 25, 1993-7. 

Dangles, O., Fargeixa, G., Dufoxu b, C. Antioxidant properties of anthocyanins and tarmins a mechanistic investigation with catechin and the 3, 4, 7-trihydroxyflavylium ion. J. Chem. Soc. (Perkin Trans) 2, 1653-63, 2000. 

Phenolic compounds, primarily flavonoids, have antioxidant properties which may contribute to health benefits of wine consumption (Kanner et ai, 1994 Frankel, 1994). Wine consumption has a possible cardioprotective effect and may prevent thrombosis (Frankel, 1994). Epicatechin and quercetin are more effective in preventing LDL (low density lipoprotein) oxidation than a-tocopherol (vitamin E) (Frankel, 1994). Quercetin is found at an average concentration of 25 mg/L in red wine. Catechin and epicatechins are among the most abundant phenolics in wine and are present at about 150 mg/ L in red wine and about 15 mg/ L in white wine. Resveratrol is thought to be of major importance as a dietary antioxidant in red wines, but levels are much lower than catechin/epicatechin (Frankel, 1994). 

Plumb GW, De Pascual-Teresa S, Santos-Buelga C, Cheynier V, Williamson G (1998) Antioxidant properties of catechins and proanthocyanidins effect of polymerisation, galloylation and glycosylation. Free Radic Res 29 351-358... 

Indeed, with these selectively methylated catechin analogues, it has been possible to determine thermodynamic constants (redox potentials, pKa) and to study the intrinsic reactivity of each catechin moiety. Each moiety, the A- or B-ring, presents its own reactivity whereas the A-ring is more specifically involved in H-atom transfer, the B-ring is specifically involved in electron transfer. These results lead to a new interpretation of the antioxidant properties of these molecules since B-ring of flavan-3-ols has been shown to be the active moiety of the molecule [12], the antioxidant activity involves mainly an electron transfer and not only an H-atom transfer as is so often proposed. 

Phenolic substances in red wine were shown to inhibit LDL oxidation in vitro [95]. In previous studies, red wine-derived phenolic acids [115,116], resveratrol [117], flavonols (quercetin, myricetin) [68,118,119], catechins [66,120], and the grape extract itself [121,122] have been shown to possess antioxidant properties. The finding that ethanol and wine stripped of phenols did not affect LDL oxidation further confirmed that the active antioxidant components in red wine are phenolic compounds [123]. Red wine fractionation revealed major antioxidative potency to monomeric catechins, procyanidins, monomeric anthocyanidins, and phenolic acids [123]. The flavonol quercetin and the flavonol catechin were both tested for antioxidative and antiatherogenic effects in the atherosclerotic E° mice [111]. E° mice at the age of 4 weeks were supplemented for up to 6 weeks in their drinking water with placebo (1.1% alcohol) or with catechin or quercetin (50 pg/day/mouse). The atherosclerotic lesion area was smaller by 39% or by 46%, respectively, in the treated mice than in E° mice that were treated with placebo (Fig. 4A-E). 

Certain constituents found in tea, especially the tannic substances catechin, epigallocatechin, and epigallocatechin gallate, have been reported to have antioxidative properties, with epigallocatechin being the strongest. Following this line are many reports on the anti-inflammatory, " chemopreventive, hepatoprotective, and anticataract effects of different tea extracts and their constituents in various in vitro and in vivo models. The chemopreventive, antioxidant, traditional, and future therapeutic uses of tea have been reviewed. 

Plumb, G.W. et al.. Antioxidant properties of catechins and proanthocyanidins Effect of polymerisation, galloylation and glycosylation. Free Radio. Res., 29, 351, 1998. Bomser, J.A. et al.. Inhibition of TPA-induced tumor promotion in CD-I mouse epidermis by a polyphenolic fraction from grape seeds. Cancer Lett., 135, 151, 1999. Sato, M. et al.. Grape seed proanthocyanidin reduces cardiomyocyte apoptosis by inhibiting ischemia/reperfusion-induced activation of JNK-1 and C-JUN, Free Radio. Biol. Med., 31, 729, 2001. 

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