Effects of vitamin E supplementation on lipid peroxidation and color retention of salted calf muscle from a diet rich in polyunsaturated fatty acids.

The color of fresh meat is one of the most important quality criteria of raw muscle foods. This red color is principally due to the presence of oxymyoglobin. The present study was undertaken to examine the effect of a diet rich in polyunsaturated fatty acids (PUFA), the addition of NaCl, and the influence of dietary supplementation with vitamin E on calf muscle oxymyoglobin oxidation (color) and lipid peroxidation. Vitamin E was added to the feed at a concentration of 4000 mg/day for 90 days before slaughter. This diet increased the alpha-tocopherol concentration in muscle membrane from 2.6-2.8 to 6.5-7.0 microg/g of fresh weight. It was found that the diet rich in PUFA and, especially, the addition of NaCl increased muscle lipid peroxidation and oxymyoglobin oxidation as indicated by the contents of thiobarbituric acid-reactive substances and substances that impaired color value readings during storage at 4 degrees C. Both undesirable reactions during storage were controlled very efficiently by the presence of a critically high concentration of alpha-tocopherol in the muscle tissues. The findings concerning the antioxidant activity of alpha-tocopherol in this study form additional evidence of its efficient protection against oxidative reactions during storage of muscle tissues and its potential to maintain a high nutritional value in them.     

Dose and duration effect of alpha-tocopheryl acetate supplementation on chicken meat fatty acid composition, tocopherol content, and oxidative status

The effects of dietary alpha-tocopheryl acetate (alpha-TA) doses (75, 150, and 225 mg/kg) and the duration of this supplementation (0, 10, 21, 32, and 43 days prior to slaughter) on fatty acid composition, alpha-tocopherol content, and oxidative status were studied either in raw or in cooked dark chicken meat with its skin. With regard to fatty acid composition, raw meat was affected by both dietary factors. Various polyunsaturated fatty acids decreased as a result of higher alpha-TA doses, whereas these fatty acids increased with longer supplementation periods. Cooked meat showed similar trends for the duration of alpha-TA supplementation. On the other hand, alpha-tocopherol content in raw and cooked meat increased as a result of the dose and duration of alpha-TA supplementation. Formation of lipid hydroperoxides and thiobarbituric acid values of these meats were also influenced by these two dietary factors, and the dietary combination of 150 mg/kg of alpha-TA during the last 32 days was optimal in terms of supplementation costs and meat oxidative stability.     

Antioxidant activity of dietary oregano essential oil and alpha-tocopheryl acetate supplementation in long-term frozen stored turkey meat

The effects of dietary oregano essential oil and alpha-tocopheryl acetate supplementation on the oxidative stability of long-term frozen stored turkey meat were investigated. Thirty 12-week-old turkeys, randomly divided into five groups, were given a basal diet or a basal diet supplemented with 200 mg of alpha-tocopheryl acetate kg(-1), or 100 or 200 mg of oregano oil kg(-1), or 100 mg of oregano oil plus 100 mg of alpha-tocopheryl acetate kg(-1) for 4 weeks prior to slaughter. Lipid oxidation in breast and thigh meat was assessed after 1, 3, 6, and 9 months of frozen storage at -20 degrees C prior to or following 7 days of refrigerated storage at 4 degrees C. Results showed that oregano oil increased the oxidative stability of breast and thigh meat during the frozen storage. Dietary oregano oil at the inclusion level of 200 mg kg(-1) feed was significantly (p < 0.05) more effective in delaying lipid oxidation compared to the level of 100 mg kg(-1), but equivalent to dietary alpha-tocopheryl acetate supplementation at 200 mg kg(-1), which in turn was inferior to dietary supplementation of 100 mg kg(-1) oregano essential oil plus 100 mg kg(-1) alpha-tocopheryl acetate that was significantly (p < 0.05) superior to all other treatments. Thigh meat was more susceptible to oxidation than breast meat, although the former contained alpha-tocopherol at markedly higher levels. Mean alpha-tocopherol levels in breast and thigh meat from all treatments decreased during the frozen storage, the decrease being sharper between 1 and 3 months of frozen storage for breast and between 3 and 6 months for thigh meat. Oregano oil supplementation increased (p < 0.05) the retention of alpha-tocopherol in meat, the increase being positively correlated with the supplementation level. However, the retention of alpha-tocopherol in meat could only partly elucidate the antioxidant activity exhibited by dietary oregano oil supplementation.     

Dietary grape-seed procyanidins decreased postweaning diarrhea by modulating intestinal permeability and suppressing oxidative stress in rats

This study was conducted to evaluate the effects of grape-seed procyanidins in controlling weaning diarrhea using a rat model. Weaned rats were fed either the basal diet or basal diet supplemented with either 250 mg/kg grape-seed procyanidins or 2000 mg/kg ZnO. Treated rats had better performance with a reduced incidence of diarrhea (P < 0.05). Both ZnO and grape-seed procyanidins significantly reduced urinary lactulose to mannitol ratios (P < 0.05) and enhanced the mRNA and protein expression of the intestinal mucosal tight junction proteins Ocln/ZO-1 (P < 0.05). Grape-seed procyanidins increased the activities of SOD, GSH-Px, and GSH while decreasing the level of MDA in the intestinal mucosa (P < 0.05). Furthermore, an in vitro investigation revealed that supplementation with grape-seed procyanidins in IEC-6 intestinal epithelial cells significantly enhanced the expression of Ocln/ZO-1 under H(2)O(2)-induced oxidative stress. Collectively, these results indicate that grape-seed procyanidins have the potential to prevent weaning diarrhea by reducing intestinal permeability and improving antioxidant indices.     

LDL isolated from plasma-loaded red wine procyanidins resist lipid oxidation and tocopherol depletion

Dietary phenolic compounds may act as antioxidants in vitro, but because of structural modifications during absorption, its role based on concentrations high enough to afford an antioxidant protection needs to be re-evaluated. We have explored the hypothesis that red wine procyanidins interact with low density lipoproteins (LDL) and that, at this location, the phenolic compounds efficiently protect LDL from oxidation and maintain LDL alpha-tocopherol at a high steady state concentration by recycling it back from the alpha-tocopheroxyl radical. To this end, human plasma was supplemented with wine procyanidins and isolated LDL were challenged with a constant flux of peroxyl radicals. As compared with LDL from plasma-free procyanidins, those LDL better resisted lipid oxidation and exhibited longer lag-phases of alpha-tocopherol consumption. The procyanidins, depending on their structure, were able to reduce the UV-induced alpha-tocopherol radical in a micellar system, as evidenced by electron paramagnetic ressonance. Mechanistically, the protection of LDL was interpreted in terms of quenching of peroxyl radicals and the recycling of alpha-tocopherol by the procyanidins bound to the lipoproteins. These results support the notion that, in human plasma, the procyanidins, via binding to LDL, may act as efficient local antioxidants.     

Antioxidant activity of flavonoids isolated from young green barley leaves toward biological lipid samples

Natural plant flavonoids, saponarin/lutonarin=4.5/1, isolated from young green barley leaves were examined for their antioxidant activity using cod liver oil, omega-3 fatty acids, phospholipids, and blood plasma. The saponarin/lutonarin (S/L) mixture inhibited malonaldehyde (MA) formation from cod liver oil by 76.47+/-0.11% at a level of 1 micromol and 85.88+/-0.12% at a level of 8 micromol. The S/L mixture inhibited MA formation from the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) by 45.60+/-1.08 and 69.24+/-0.24%, respectively, at a level of 8 micromol. The S/L mixture inhibited MA formation from the phospholipids lecithin I and II by 43.08+/-0.72 and 69.16+/-2.92%, respectively, at a level of 8 micromol. It also inhibited MA formation from blood plasma by 62.20+/-0.11% at a level of 8 micromol. The antioxidant activities obtained from the S/L mixture were comparable to those obtained from alpha-tocopherol and butylated hydroxy toluene (BHT) in all lipids tested.     

Protective effect of supplementation of fish oil with high n-3 polyunsaturated fatty acids against oxidative stress-induced DNA damage of rat liver in vivo

The present study was undertaken to know the effect of supplementation of fish oil with high n-3 polyunsaturated fatty acids (PUFA) on oxidative stress-induced DNA damage of rat liver in vivo. Male Wistar rats were fed a diet containing fish oil or safflower oil with high n-6 PUFA at 50 g/kg of diet and an equal amount of vitamin E at 59 mg/kg of diet for 6 weeks. Livers of rats fed fish oil were rich in n-3 PUFA, whereas those of rats fed safflower oil were rich in n-6 PUFA. Ferric nitrilotriacetate was intraperitoneally injected to induce oxidative stress. The degree of lipid peroxidation of the liver was assessed by the levels of phospholipid hydroperoxides and thiobarbituric acid-reactive substances (TBARS), and the degree of oxidative DNA damage was assessed by comet type characterization in alkaline single-cell gel electrophoresis and 8-hydroxy-2'-deoxyguanosine levels. The levels of TBARS of the livers of the fish oil diet group increased to a greater extent than those of the safflower oil diet group, whereas the levels of the hydroperoxides of the livers of both diet groups increased to a similar extent. The vitamin E level of livers of the fish oil diet group was remarkably decreased. The degree of DNA damage of both diet groups was increased, but the increased level of the fish oil diet group was remarkably lower than that of the safflower oil diet group. The above results indicate that fish oil supplementation does not enhance but appears to protect against oxidative stress-induced DNA damage and suggest that lipid peroxidation does not enhance but lowers the DNA damage.     

Glutathione peroxidase activity, TBARS, and alpha-tocopherol in meat from chickens fed different diets.

This study investigated the effect of feeding broilers with diets differing in dietary fat source (lard, sunflower oil, olive oil) and vitamin E (basal vs supplemented with 200 mg of alpha-tocopheryl acetate/kg) on meat lipid oxidative stability. The diets differed by their degree of unsaturation and included the natural antioxidant alpha-tocopherol (vitamin E). Glutathione peroxidase (GSHPx) activity was measured in raw meat and ranged from 3.62 to 8.06 nmol NADPH/min/mg protein. The enzyme activity was influenced by the degree of unsaturation of the diet. Capillary gas chromatography analyses showed that dietary alpha-tocopherol accumulated in the muscle tissue and contributed to a better oxidative stability of the raw and cooked meat. Thigh meat alpha-tocopherol levels ranged from 2.73 to 3.62 microg/g in unsupplemented chickens whereas levels from 8.69 to 13.37 microg/g were observed in the thigh meat from alpha-tocopherol supplemented animals. The inclusion of olive oil and alpha-tocopherol in the animal diet gave lower thiobarbituric acid reactive substance (TBARS) values and lower GSHPx activity. High correlations were found between the parameters studied. The results suggest that the glutathione peroxidase activity could be used as an indicator of the meat oxidative stability. A negative relationship was observed between GSHPx activity and tissue alpha-tocopherol levels, and a positive relationship was evidenced between TBARS and antioxidant enzyme activity.     

Direct in vivo evidence of protective effects of grape seed procyanidin fractions and other antioxidants against ethanol-induced oxidative DNA damage in mouse brain cells

Ethanol is a principle ingredient of alcoholic beverages with potential neurotoxicity and carcinogenicity, and the ethanol-associated oxidative DNA damage in the central nervous system is well documented. The present work studied the possible protective effects of grape seed oligomer and polymer procyanidin fractions against ethanol-induced toxicity and compared these with resveratrol and other well-known antioxidants (ascorbic acid and vitamin E). By using the single cell gel electrophoresis (comet assay), a simple and sensitive technique for genotoxicity studies, the potential genotoxicity of acute and chronic ethanol administration in the different brain regions was investigated. Acute ethanol administration, at the dose of 2.5 or 5.0 g kg(-1) i.p., could induce significant DNA damage in cerebellum and hippocampus. Chronic administration of ethanol at the dose of 2.5 or 5.0 g kg-1 p.o. for 30 days could induce significant DNA damage in cerebellum, hippocampus, hypothalamus, and cortex, which could be auto-repaired at least 3 days after ethanol withdrawal. Oral administration of grape seed oligomer and polymer procyanidins and resveratrol (25, 50, and 100 mg kg(-1)) for 3 days before acute ethanol (5.0 g kg(-1), i.p.) or repeated administration of these substances together with ethanol (5.0 g kg(-1), p.o.) for 30 consecutive days could significantly inhibit DNA damage in brain cells induced by ethanol. As compared, ascorbic acid (50, 100, and 200 mg kg(-1)) and vitamin E (100, 200, and 400 mg kg(-1)) could also present protective effects on ethanol-induced DNA damage. Furthermore, the concentrations of ethanol and acetaldehyde in brain regions of the mice were detected by gas chromatography after administration of ethanol plus antioxidants. All of the results indicated that ethanol could induce region-specific oxidative DNA damage in which the cerebellum and hippocampus were more vulnerable, but intake of grape seed procyanidins or other natural antioxidants could protect the brain against ethanol-induced genotoxicity.     

Importance of insoluble-bound phenolics to antioxidant properties of wheat

Two commercial samples of soft (70% Canadian Eastern soft red spring and 30% Canadian Eastern soft white winter) and hard (90% Canadian western hard red spring and 10% Canadian Eastern hard red winter) wheats were used to obtain different milling fractions. Phenolics extracted belonged to free, soluble esters and insoluble-bound fractions. Soluble esters of phenolics and insoluble-bound phenolics were extracted into diethyl ether after alkaline hydrolysis of samples. The content of phenolics was determined using Folin-Ciocalteu's reagent and expressed as ferulic acid equivalents (FAE). The antioxidant activity of phenolic fractions was evaluated using Trolox equivalent antioxidant capacity, 2,2-diphenyl-1-picrylhydrazyl radical scavenging, reducing power, oxygen radical absorbance capacity, inhibition of oxidation of human low-density lipoprotein cholesterol and DNA, Rancimat, inhibition of photochemilumenescence, and iron(II) chelation activity. The bound phenolic content in the bran fraction was 11.3 +/- 0.13 and 12.2 +/- 0.15 mg FAE/g defatted material for hard and soft wheats, respectively. The corresponding values for flour were 0.33 +/- 0.01 and 0.46 +/- 0.02 mg FAE/g defatted sample. The bound phenolic content of hard and soft whole wheats was 2.1 (+/-0.004 or +/-0.005) mg FAE/g defatted material. The free phenolic content ranged from 0.14 +/- 0.004 to 0.98 +/- 0.05 mg FAE/g defatted milling fractions of hard and soft wheats examined. The contribution of bound phenolics to the total phenolic content was significantly higher than that of free and esterified fractions. In wheat, phenolic compounds were concentrated mainly in the bran tissues. In the numerous in vitro antioxidant assays carried out, the bound phenolic fraction demonstrated a significantly higher antioxidant capacity than free and esterified phenolics. Thus, inclusion of bound phenolics in studies related to quantification and antioxidant activity evaluation of grains and cereals is essential.     

Novel approach to study oxidative stability of extra virgin olive oils: importance of alpha-tocopherol concentration

The stability of extra virgin olive oils is mainly due to their relatively low fatty acids unsaturation and to the antioxidant activity of some of the unsaponifiable components. We studied the activity of alpha-tocopherol in extra virgin olive oil in its natural state, using new and simple oxidizing conditions in "thin layer" and "bulk phase". Oxidation time course was monitored at 37 degrees C or 75 degrees C. A storage test was also performed. Two parameters were evaluated: depletion of alpha-tocopherol and formation of PUFA hydroperoxides, measured as conjugated dienes (CD) and peroxide value. The value of complex polyphenols was also measured. alpha-Tocopherol concentration decreased in function of time and temperature and showed a strong inverse correlation with the increase of CD. When alpha-tocopherol reached a "threshold value" of 60-70 mg/kg, a significant increase of CD formation was observed, together with a good correlation between CD and peroxide value. The initial amount of alpha-tocopherol is one of the components that influences oil oxidative susceptibility.     

Polyphenol content and total antioxidant activity of vini novelli (young red wines)

Eight commercial Italian vini novelli (red wines prepared by carbonic maceration and supposed to be consumed within three months from their wine-making) were evaluated for their total antioxidant activity. The wines had an average total phenol content (1605.4 +/- 337.4 mg/L gallic acid equivalents) lower than that of wines prepared by traditional maceration and consumable after aging (2057. 3 +/- 524.0 mg/L gallic acid equivalents). The average flavanol content (424.7 +/- 121.3 mg/L catechin equivalents) and the total antioxidant activity (16.8 +/- 3.8 mmol/L Trolox equivalents) of vini novelli were higher than the corresponding values (382.7 +/- 174.5 mg/L catechin equivalents and 12.3 +/- 3.3 mmol/L Trolox equivalents) found for aged wines. Three couples of experimental wines were prepared from the same grapes by traditional or carbonic maceration. These wines showed a different phenolic pattern, anthocyanins being more abundant in vini novelli. However, the average total antioxidant activities of the wines were similar, suggesting that aging (and not the wine-making technique) is the main factor influencing the antioxidant activity of red wines.     

Green tea protects cytoskeleton from oxidative injury in cardiomyocytes

Cardiac ischemia/reperfusion injury results in oxidative stress and poor physiological recovery. Episodes of hypoxia/reoxygenation (H/R) cause some subtle functional and structural alterations in sarcolemma, mithocondria, sarcoplasmic reticulum, nucleus, as well as cytoskeleton. In this report, by using cultured rat cardiomyocytes and laser confocal microscopy we have verified the possibility to counteract cytoskeleton alterations induced by H/R with the supplementation of an antioxidant agent, a green tea extract (GTE), and compared its effects to those of alpha-tocopherol. Moreover the effects of GTE on cell viability and cytosolic antioxidant activity have been evaluated. H/R induced myocardial damage occurs as histological alterations such as degeneration and disorganization of the cytoskeleton and loss of structural integrity of the nucleus. GTE supplementation increases cytosolic antioxidant activity and shows protective effects on cardiomyocyte cytoarchitecture and viability.     

Antioxidant activity and phenolic content of Oregon caneberries

Five types of caneberries [evergreen blackberries (Rubus laciniatus), marionberries (Rubus ursinus), boysenberries (Rubus ursinus x idaeus), red raspberries (Rubus idaeus), and black raspberries (Rubus occidentalis)] were analyzed for antioxidant activity by measuring their oxygen radical absorbance capacity (ORAC). In addition, the berries were analyzed for total phenolics, anthocyanins, procyanidins, and ellagic acid content. All of the berries had high ORAC activity ranging from 24 to 77.2 micromol of Trolox equiv/g of fresh berries. Anthocyanin content ranged from 0.65 to 5.89 mg/g, and phenolics ranged from 4.95 to 9.8 mg/g. Black raspberries had the highest ORAC and anthocyanin and phenolic contents. Only red raspberries had detectable amounts of procyanidin oligomers (monomer, dimers, and trimers). All berries had high levels of ellagic acid (47-90 mg/g), but boysenberries had the highest level prior to hydrolysis. The results from this study indicate that these caneberries were high in antioxidant activity and were rich sources of anthocyanins and phenolics.     

Potentiality of red sorghum for producing stilbenoid-enriched beers with high antioxidant activity

trans-Piceid and trans-resveratrol were authenticated for the first time by high-resoution mass spectrometry in red sorghum grains. A 0.4-1 mg/kg amount of trans-piceid and up to 0.2 mg/kg trans-resveratrol were quantified by reversed phase high-performance liquid chromatography-atmospheric pressure chemical ionization(+)-tandem mass spectrometry. The white sorghum samples contained only traces of trans-piceid (up to 0.1 mg/kg), and trans-resveratrol was absent. In much lower amounts than procyanidins, stilbenoids are not able to contribute significantly to the exceptional antioxidant activity of red sorghum (ORAC, 83-147 μmol TE/g; AAPH, 0.61-1.79 min/mg kg(-1)). More than 10 mg/kg of total stilbenoids have been reported in some hop varieties. Yet, as hop is a minor wort ingredient as compared to cereals, red sorghum could be the main source of trans-piceid in beer. Hop remains, however, the single source of cis-piceid.     

Effect of storage on secoiridoid and tocopherol contents and antioxidant activity of monovarietal extra virgin olive oils

The degradation of secoiridoid, tocopherol, and antioxidant activity in extra virgin olive oils (EVOOs) was studied during 8 months of storage in closed bottles in the dark, at 40 and 25 degrees C. Picual, Arbequina, Taggiasca, and Colombaia monovarietal EVOOs possessing quite different fatty acid and antioxidant contents were used. The secoiridoid aglycones, namely, the oleuropein and ligstroside derivatives, and alpha-tocopherol decreased following pseudo-first-order kinetics. In all EVOOs oleuropein derivatives were less stable than the corresponding ligstroside derivatives and alpha-tocopherol. Accordingly, overall antioxidant activity decreased following pseudo-first-order kinetics, with rate constants ranging from 0.85 x 10(-)(3) to 4.1 x 10(-)(3) days(-)(1) at 40 degrees C and from 0.8 x 10(-)(3) to 1.5 x 10(-)(3) days(-)(1) at 25 degrees C. According to both the antioxidant activity and the hydrolysis and oxidation indices established by EU regulation to assess EVOO quality, Colombaia oil was the least stable, followed by Taggiasca, Arbequina, and Picual oils. Despite antioxidant degradation, EVOOs with high antioxidant contents were still "excellent" after 240 days of storage at 40 degrees C. These data led to the conclusion that the beneficial properties of EVOOs due to antioxidant activity can be maintained throughout their commercial lives.     

Effect of different dosage and administration schedules of folic acid on blood folate levels in a population of Honduran women of reproductive age

BACKGROUND: Observational studies and clinical trials have shown conclusive evidence that periconceptional folic acid supplementation prevents up to 70 % of neural tube defects (NTD). The Honduran government wanted to implement a supplementation programme of folic acid but needed to assess the relative effects of two dosages of folic acid. OBJECTIVE: To determine the effect of two dosages of folic acid on blood folate levels in Honduran female factory workers aged 18 to 49 years. DESIGN: This was a randomized, double-blind control supplementation trial conducted in Choloma, Honduras. A total of 140 eligible women were randomly assigned to two dosage groups and followed up for 12 weeks. One group received a daily dosage of 1 mg folic acid and the other a once weekly dosage of 5 mg. Serum folate and red blood cell folate levels were determined by radioassay at baseline, 6 weeks and 12 weeks. RESULTS: Serum folate levels increased from 6.3 (se 0.2) to 14.9 (se 0.6) ng/ml (P < 0.0001) in women assigned to the 1 mg/d group and from 6.9 (se 0.3) to 10.1 (se 0.4) ng/ml (P < 0.0001) in those assigned to the 5 mg/week group. Red blood cell folate concentrations also increased significantly in both groups, albeit more slowly. Educational level, age and BMI were not associated with the changes in serum and red blood cell folate levels during the supplementation period. However, a differential effect on serum folate levels by dosage group and time was observed. CONCLUSIONS: Although both folate supplementation regimens increased serum and red blood cell folate levels significantly among the women studied, blood folate levels that are considered to be protective of NTD were reached faster with the daily dosage of 1 mg folic acid.     

Effect of heated sunflower oil and dietary supplements on the composition, oxidative stability, and sensory quality of dark chicken meat

A factorial design was used to study the effect of dietary oxidized sunflower oils (fresh, heated at low temperatures, and heated at high temperatures), DL-alpha-tocopheryl acetate (0 or 100 mg/kg), and Zn supplementation (0 or 600 mg/kg) on the composition, oxidative stability, and sensory quality of dark chicken meat with skin from animals fed with a Se supplement (Se-enriched yeast, 0.6 mg of Se/kg). The positional and geometrical isomers of linoleic acid were increased in raw meat from chickens fed oils oxidized at high temperatures. In addition, supplementation with alpha-tocopheryl acetate increased the alpha-tocopherol content, whereas 2-thiobarbituric acid (TBA) values and lipid hydroperoxide content were reduced. Likewise, TBA values, rancid aroma, and rancid flavor also decreased in cooked dark meat. However, none of the dietary factors studied affected consumer acceptability scores of cooked meat. Furthermore, Zn supplementation increased the Se content in raw meat.     

Inhibition of induced DNA oxidative damage by beers: correlation with the content of polyphenols and melanoidins

Beers are a source of dietary flavonoids; however, there exist differences in composition, alcohol concentration, and beneficial activities. To characterize these differences, three kinds of lager beer of habitual consumption in Spain, dark, blond, and alcohol-free, were assayed for total phenolic content, antioxidant activity, superoxide and hydroxyl radical scavenging activities, and in vitro inhibitory effect on DNA oxidative damage. Furthermore, their melanoidin content and correlation with antioxidant activity were evaluated. Dark beer contained the highest total phenolic (489 +/- 52 mg/L) and melanoidin (1.49 +/- 0.02 g/L) contents with a 2-fold difference observed when compared to the alcohol-free beer. For the three kinds of beer, the antioxidant activity measured as N,N-dimethyl-p-phenylenediamine dihydrochloride concentration was strongly correlated with the total polyphenol content (R(2) = 0.91102, p < 0.005) and with the melanoidin content (R(2) = 0.7999, p < 0.05). The results support a positive effect of beers on the protection of DNA oxidative damage, by decreasing the deoxyribose degradation, DNA scission (measured by electrophoresis), and inhibition of 8-hydroxydeoxyguanosine (8-OH-dG) formation. Furthermore, a correlation between the total melanoidin content (R(2) = 0.7309, p < 0.01) and inhibition of 8-OH-dG was observed.     

Procyanidin and catechin contents and antioxidant capacity of cocoa and chocolate products

Cocoa and chocolate products from major brands were analyzed blind for total antioxidant capacity (AOC) (lipophilic and hydrophilic ORAC(FL)), catechins, and procyanidins (monomer through polymers). Accuracy of analyses was ascertained by comparing analyses on a NIST standard reference chocolate with NIST certified values. Procyanidin (PC) content was related to the nonfat cocoa solid (NFCS) content. The natural cocoa powders (average 87% of NFCS) contained the highest levels of AOC (826 +/- 103 micromol of TE/g) and PCs (40.8 +/- 8.3 mg/g). Alkalized cocoa (Dutched powders, average 80% NFCS) contained lower AOC (402 +/- 6 micromol of TE /g) and PCs (8.9 +/- 2.7 mg/g). Unsweetened chocolates or chocolate liquor (50% NFCS) contained 496 +/- 40 micromol of TE /g of AOC and 22.3 +/- 2.9 mg/g of PCs. Milk chocolates, which contain the least amount of NFCS (7.1%), had the lowest concentrations of AOC (80 +/- 10 micromol of TE /g) and PCs (2.7 +/- 0.5 mg/g). One serving of cocoa (5 g) or chocolate (15 or 40 g, depending upon the type of chocolate) provides 2000-9100 micromol of TE of AOC and 45-517 mg of PCs, amounts that exceed the amount in a serving of the majority of foods consumed in America. The monomers through trimers, which are thought to be directly bioavailable, contributed 30% of the total PCs in chocolates. Hydrophilic antioxidant capacity contributed >90% of AOC in all products. The correlation coefficient between AOC and PCs in chocolates was 0.92, suggesting that PCs are the dominant antioxidants in cocoa and chocolates. These results indicate that NFCS is correlated with AOC and PC in cocoa and chocolate products. Alkalizing dramatically decreased both the procyanidin content and antioxidant capacity, although not to the same extent.