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The moderate consumption of alcoholic beverages has been associated with protection against the development of coronary heart disease. Although alcohol itself can help prevent coronary heart disease through a number of mechanisms, red wine appears to offer protection above and beyond that attributable to alcohol alone. Red wine is a complex fluid containing grape, yeast, and wood-derived phenolic compounds, the majority of which have been recognized as potent antioxidants. The aim of this study was to investigate the major phenolic contributors to the antioxidant activity of wine. To this end, four wines were followed during the first 7-9 days of vinification. Individual phenolic compounds were quantified by HPLC, and antioxidant activity was determined by electron spin resonance spectroscopy. The extraction of the phenolics was found to be influenced by vinification procedure, grape quality, and grape variety. Although fermenting wines reached a total phenolic content comparable to that of a bottled wine after 9 days of vinification, the antioxidant activity was significantly lower than that of a finished wine. This suggests that the larger polyphenolic complexes and condensation products that appear during aging make a sizable contribution to the overall antioxidant activity of red wines.

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Anthocyanins are secondary plant metabolites responsible for the blue, purple, and red color of many plant tissues. The phenolic structure of anthocyanins conveys marked antioxidant activity in model systems via donation of electrons or hydrogen atoms from hydroxyl moieties to free radicals. Dietary intakes of anthocyanins may exceed 200 mg/day, however, little is known about their antioxidant potency in vivo. Consequently, the aim of this study was to establish whether anthocyanins could act as putative antioxidant micronutrients. Rats were maintained on vitamin E-deficient diets for 12 weeks in order to enhance susceptibility to oxidative damage and then repleted with rations containing a highly purified anthocyanin-rich extract at a concentration of 1 g/kg diet. The extract consisted of the 3-glucopyranoside forms of delphinidin, cyanidin, petunidin, peonidin, and malvidin. Consumption of the anthocyanin-repleted diet significantly improved (p <.01) plasma antioxidant capacity and decreased (p <.001) the vitamin E deficiency-enhanced hydroperoxides and 8-Oxo-deoxyguanosine concentrations in liver. These compounds are indices of lipid peroxidation and DNA damage, respectively. Dietary consumption of anthocyanin-rich foods may contribute to overall antioxidant status, particularly in areas of habitually low vitamin E intake.

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OBJECTIVE: To assess whether consumption of 500 ml of blueberry juice or cranberry juice by healthy female subjects increased plasma phenolic content and antioxidant capacity. DESIGN: Latin square arrangement to eliminate ordering effects. After an overnight fast, nine volunteers consumed 500 ml of blueberry juice, cranberry juice or a sucrose solution (control); each volunteer participated on three occasions one week apart, consuming one of the beverages each time. Blood samples were obtained by venipuncture at intervals up to four hours after consumption of the juices. Urine samples were also obtained four hours after consuming the juice. RESULTS: Consumption of cranberry juice resulted in a significant increase in the ability of plasma to reduce potassium nitrosodisulphonate and Fe(III)-2,4, 6-Tri(2-pyridyl)-s-triazine, these measures of antioxidant capacity attaining a maximum after 60-120 min. This corresponded to a 30% increase in vitamin C and a small but significant increase in total phenols in plasma. Consumption of blueberry juice had no such effects. CONCLUSION: The increase in plasma antioxidant capacity following consumption of cranberry juice could mainly be accounted for by an increase in vitamin C rather than phenolics. This also accounted for the lack of an effect of the phenolic-rich but vitamin C-low blueberry juice. SPONSORSHIP: Funded by the Scottish Executive Rural Affairs Department and the Danish Government.

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The relationship among antioxidant activity, based on the electron-spin resonance determination of the reduction of Fremy's radical, vasodilation activity, and phenolic content was investigated in 16 red wines. The wines were selected to provide a range of origins, grape varieties, and vinification methods. Sensitive and selective HPLC methods were used for the analysis of the major phenolics in red wine: free and conjugated myricetin, quercetin, kaempferol, and isorhamnetin; (+)-catechin, (-)-epicatechin, gallic acid, p-coumaric acid, caffeic acid, caftaric acid, trans-resveratrol, cis-resveratrol, and trans-resveratrol glucoside. Total anthocyanins were measured using a colorimetric assay. The total phenolic content of the wines was determined according to the Folin-Ciocalteu colorimetric assay and also by the cumulative measurements obtained by HPLC. The 16 wines exhibited a wide range in the values of all parameters investigated. However, the total phenol contents, measured both by HPLC and colorimetrically, correlated very strongly with the antioxidant activity and vasodilation activity. In addition, the antioxidant activity was associated with gallic acid, total resveratrol, and total catechin. In contrast, only the total anthocyanins were correlated with vasodilation activity. The results demonstrate that the different phenolic profiles of wines can produce varying antioxidant and vasodilatant activities, which opens up the possibility that some red wines may provide enhanced health benefits for the consumer.

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Electron spin resonance (ESR) spectroscopy has been used to assess the antioxidant capacity of eight Scotch whiskeys by measuring the extent by which the original spirits, or pyridine solutions of their residues, reduced Fremy's radical or galvinoxyl radical. All whiskeys displayed antioxidant activity greater than that of a 0.2 mM solution of Trolox in the Fremy's assay and of a 0.1 mM solution of quercetin in the galvinoxyl assay. The relative antioxidant capacities determined according to the two assays were highly correlated and strongly related to the total phenol content as determined by using the Folin-Ciocalteu method. Activity was a consequence of maturation in oak casks with the "newmake" spirit showing no effect. Of 10 aromatic constituents analyzed, activity was most strongly correlated with ellagic acid and gallic acid in both assays. The reductive capacities of four major phenolics were determined, which, in summation, accounted for 31-53% of the total antioxidant activity of the whiskeys. There was no evidence for synergistic interaction between the phenols investigated.

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Phytoestrogens (PEs) are diphenolic compounds from plants which can bind to estrogen receptors and have estrogen and antiestrogen effects in man and animals. Like other plant phenolics, PEs may have antioxidant properties through hydrogen/electron donation via hydroxyl groups. They might therefore act as free radical scavengers and inhibit development of coronary heart disease and cancers. The hydrogen-donating ability of a range of phytoestrogens was assessed using electron spin resonance spectroscopy, the ferric-reducing ability of plasma assay, and the Trolox equivalent antioxidant capacity. In addition, the ability of compounds to inhibit lipid peroxidation was examined in vitamin E-deficient liver microsomes. Genistein had the highest activity of the isoflavones; however, the isoflavones were relatively poor hydrogen donors compared with the other estrogenic compounds examined. Coumestrol and equol were more effective antioxidants than genistein but had relatively limited activity in comparison with Trolox. The only estrogenic compound with significant antioxidant activity was kaempferol which is better known as a dietary antioxidant than a phytoestrogen. As the concentrations of PEs used in this study exceed the estimated serum concentrations, their relatively poor antioxidant ability in vitro may indicate little significance as antioxidants in vivo.

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OBJECTIVE: To assess whether consumption of 100 ml of whisky or red wine by healthy male subjects increased plasma total phenol content and antioxidant capacity. DESIGN: A Latin square arrangement to eliminate ordering effects whereby, after an overnight fast, nine volunteers consumed 100 ml of red wine, malt whisky or unmatured 'new make' spirit. Each volunteer participated on three occasions one week apart, consuming one of the beverages each time. Blood samples were obtained from the anticubital vein at intervals up to 4h after consumption of the beverages when a urine sample was also obtained. RESULTS: Within 30 min of consumption of the wine and whisky, there was a similar and significant increase in plasma total phenol content and antioxidant capacity as determined by the ferric reducing capacity of plasma (FRAP). No changes were observed following consumption of 'new make' spirit. CONCLUSIONS: Consumption of phenolic-containing alcoholic beverages transiently raises total phenol concentration and enhances the antioxidant capacity of plasma. This is compatible with suggestions that moderate alcohol usage and increased antioxidant intake decrease the risk of coronary heart disease.

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