Epicatechin , effect

The total antioxidant activity of teas and tea polyphenols in aqueous phase oxidation reactions has been deterrnined using an assay based on oxidation of 2,2 -azinobis-(3-ethylbenzothiazoline-sulfonate) (ABTS) by peroxyl radicals (114—117). Black and green tea extracts (2500 ppm) were found to be 8—12 times more effective antioxidants than a 1-mAf solution of the water-soluble form of vitamin E, Trolox. The most potent antioxidants of the tea flavonoids were found to be epicatechin gallate and epigallocatechin gallate. A 1-mAf solution of these flavanols were found respectively to be 4.9 and 4.8 times more potent than a 1-mAf solution of Trolox in scavenging an ABT radical cation. 

Rizvi s I and zaid m a (2001), Insulin-like effect of (-)-epicatechin on erythroc)de membrane acetylcholinesterase activity in type 2 diabetes mellitus , Clin Exp Pharmacol Physiol, 28 (9), 776-8. 

SUGANUMA M, OKABE s, KAi Y, suEOKA N, suEOKA E and FUJiKi H (1999) Synergistic effects of (-)-epigallocatechin gallate with (-)-epicatechin, sulindac, or tamoxifen on cancer-preventive activity in human lung cancer cell line PC-9 , Cancer Res, 59, 44-7. 

TERAO J, PiSKULA M and YAO Q (1994) Protective effect of epicatechin, epicatechin gallate, and quercetin on lipid peroxidation in phospholipid bilayers , Arch Biochem Biophys, 308, 278-84. 

In the water-like solvent tert-butyl alcohol, a-tocopherol was found to prevent lipid oxidation, showing a distinct lag-phase for oxygen consumption. This was in contrast to quercetin or epicatechin, which were only weak retarders of lipid oxidation without any clear antioxidative effect. Quercetin or epicatechin, when combined with a-tocopherol, increased the lag-phase for oxygen consumption as seen for a-tocopherol alone. The stoichiometric factor for a-tocopherol, a-TOH, as chain-breaking antioxidant has the value n = 2 according to the well-established mechanism ... 

PEDRiELLi p and SKIBSTED L H (2002) Antioxidant syneigy and regeneration effect of quercetin, (-)epicatechin, and (+)-catechin on a-tocopherol in homogeneous solutions of peroxidating methyl linoleate, JAgric Food Chem, 50, 7138-44. 

PEDRIELLI p, PEDULLi G F and SKIBSTED L H (2001a) Antioxidant mechanism of flavonoids. Solvent effect on rate constant for chain-braining reaction of quercetin and epicatechin in autoxidation of methyl linoleate, JAgric Food Chem, 49, 3034-40. 

The effects of catechin, epicatechin, procyanidin B2, caffeic acid, / -coumaric acid, myricetrin, and quercetrin on the color intensity and stability of malvidin 3-glucoside at a molar ratio of 1 1 under conditions similar to red wine were evaluated. " Flavan 3-ols appeared to have the lowest protective effects and flavonols the highest strong color changes were visually perceptible. " In the complexation of malvin chloride and natural polyphenols, flavonol glycosides by far exerted the best protector effect. ... 

Red wine contains quercetin, rutin, catechin, and epicatechin, among other flavonoids (Frankel and others 1993). Quercetin and other phenolic compounds isolated from wines were found to be more effective than a-tocopherol in inhibiting copper-catalyzed LDL oxidation. It has been determined that quercetin has also several anti-inflammatory effects it inhibits inflammatory cytokine production (Boots and others 2008), inducible NO synthase expression and activation of inflammatory transcription factors (Hamalainen and others 2007), and activity of cyclooxygenase and lipooxygenase (Issa 2006), among others. 

Rein D, Lotito S, Holt R, Keen C, Schmitz H and Fraga C. 2000. Epicatechin in human plasma in vivo determination and effect of chocolate consumption on plasma oxidation status. J Nutr 130 2109S—2114S. 

Wang J, Schramm D and Holt R. 2000. A dose-response effect from chocolate consumption on plasma epicatechin and oxidative damage. J Nutr 130 2115S-2119S. 

The effects of flavonoids on in vitro and in vivo lipid peroxidation have been thoroughly studied [123]. Torel et al. [124] found that the inhibitory effects of flavonoids on autoxidation of linoleic acid increased in the order fustin < catechin < quercetin < rutin = luteolin < kaempferol < morin. Robak and Gryglewski [109] determined /50 values for the inhibition of ascorbate-stimulated lipid peroxidation of boiled rat liver microsomes. All the flavonoids studied were very effective inhibitors of lipid peroxidation in model system, with I50 values changing from 1.4 pmol l-1 for myricetin to 71.9 pmol I 1 for rutin. However, as seen below, these /50 values differed significantly from those determined in other in vitro systems. Terao et al. [125] described the protective effect of epicatechin, epicatechin gallate, and quercetin on lipid peroxidation of phospholipid bilayers. 

Flavonoids exhibit protective action against LDL oxidation. It has been shown [145] that the pretreatment of macrophages and endothelial cells with tea flavonoids such as theaflavin digallate diminished cell-mediated LDL oxidation probably due to the interaction with superoxide and the chelation of iron ions. Quercetin and epicatechin inhibited LDL oxidation catalyzed by mammalian 15-lipoxygenase, and are much more effective antioxidants than ascorbic acid and a-tocopherol [146], Luteolin, rutin, quercetin, and catechin suppressed copper-stimulated LDL oxidation and protected endogenous urate from oxidative degradation [147]. Quercetin was also able to suppress peroxynitrite-induced oxidative modification of LDL [148],... 

Iron-, copper-, and zinc complexes of rutin, dihydroquercetin, and green tea epicatechins were found to be much more efficient inhibitors than parent flavonoids of toxic effects of chrysotile asbestos fibers on peritoneal macrophages and erythrocytes [168], It was proposed that in this case the enhanced activity of metal-flavonoid complexes was increased by the absorption on chrysotile fibers. 

Quine SD, Raghu PS. (2005) Effects of (-)-epicatechin, a flavonoid on lipid peroxidation and antioxidants in streptozotocin-induced diabetic liver, kidney and heart. Pharmacol Rep 57 610-615. 

Wang, J.F., Schramm, D.D., Holt, R.R., Ensunsa, J.L., Fraga, C.G., Schmitz, H.H., and Keen, C.L., A dose-response effect from chocolate consumption on plasma epicatechin and oxidative damage, J. Nutr., 130, 2115S, 2000. 

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