Procyanidin content of grape seed and pomace, and total anthocyanin content of grape pomace as affected by extrusion processing.

UNLABELLED: Grape juice processing by-products, grape seed and pomace are a rich source of procyanidins, compounds that may afford protection against chronic disease. This study was undertaken to identify optimal extrusion conditions to enhance the contents of monomers and dimers at the expense of large molecular weight procyanidin oligomers and polymers in grape seed and pomace. Extrusion variables, temperature (160, 170, and 180 degrees C in grape seed, and 160, 170, 180, and 190 degrees C in pomace) and screw speed (100, 150, and 200 rpm in both) were tested using mixtures of grape seed as well as pomace with decorticated white sorghum flour at a ratio of 30 : 70 and moisture content of 45%. Samples of grape seed and pomace were analyzed for procyanidin composition before and after extrusion, and total anthocyanins were determined in pomace. Additionally, chromatograms from diol and normal phase high-performance liquid chromatography were compared for the separation of procyanidins. Extrusion of both grape by-products increased the biologically important monomer and dimers considerably across all temperature and screw speeds. Highest monomer content resulted when extruded at a temperature of 170 degrees C and screw speed of 200 rpm, which were 120% and 80% higher than the unextruded grape seed and pomace, respectively. Increases in monomer and dimer contents were apparently the result of reduced polymer contents, which declined by 27% to 54%, or enhanced extraction facilitated by disruption of the food matrix during extrusion. Extrusion processing reduced total anthocyanins in pomace by 18% to 53%. PRACTICAL APPLICATIONS: Extrusion processing can be used to increase procyanidin monomer and dimer contents in grape seed and pomace. Procyanidins in grape by-products have many health benefits, but most are present as large molecular weight compounds, which are poorly absorbed. Extrusion processing appears to be a promising technology to increase levels of the bioactive low molecular weight procyanidins.

Influence of extrusion processing on procyanidin composition and total anthocyanin contents of blueberry pomace.

Blueberry juice processing by-products are a rich source of procyanidins, which comprise a group of compounds shown to possess numerous health benefits, including protection against coronary heart disease, type II diabetes, and obesity. Most of the procyanidins present in blueberry pomace, however, are large molecular weight compounds that are poorly absorbed and show weak bioactivity compared to the smaller molecular weight monomers and dimers. The objective of our study was to identify optimal extrusion variables to enhance the contents of monomers and dimers at the expense of large molecular weight procyanidin oligomers and polymers. Extrusion variables temperature (160 and 180 degrees C) and screw speed (150 and 200 rpm) were tested using mixtures of blueberry pomace with decorticated white sorghum flour at a ratio of 30 : 70 and 45% moisture content. Extrudates were analyzed for procyanidin composition and total anthocyanin content. Extrusion of blueberry pomace increased the monomer, dimer, and trimer contents considerably at both temperature and screw speeds. The highest monomer content, obtained at 180 degrees C and 150 rpm screw speed, was 84% higher than the nonextruded control. Significantly higher levels of dimer and trimer contents were also obtained under these conditions. Increases in monomer, dimer, and trimer contents apparently were the result of reduced polymer contents, which was approximately 40% lower for samples extruded at 180 degrees C temperature and 150 rpm screw speed. Extrusion processing reduced total anthocyanin contents by 33% to 42% indicating that additional treatments are needed to retain the pigments. These results demonstrate that extrusion processing can be used to increase procyanidin monomer and dimers in blueberry pomace.

Processing and storage effects on monomeric anthocyanins, percent polymeric color, and antioxidant capacity of processed blueberry products.

This study evaluated the effects of processing and 6 mo of storage on total monomeric anthocyanins, percent polymeric color, and antioxidant capacity of blueberries that were canned in syrup (CS), canned in water (CW), pureed, and juiced (clarified and nonclarified). Total monomeric anthocyanins, percent polymeric color, and oxygen radical absorbing capacity (ORAC) assay using fluorescein (ORAC(FL)) were determined postprocessing after 1 d, and 1, 3, and 6 mo of storage. Thermal processing resulted in marked losses in total anthocyanins (28% to 59%) and ORAC(FL) values (43% to 71%) in all products, with the greatest losses occurring in clarified juices and the least in nonclarified juices. Storage at 25 degrees C for 6 mo resulted in dramatic losses in total anthocyanins, ranging from 62% in berries CW to 85% in clarified juices. This coincided with marked increases in percent polymeric color values of these products over the 6-mo storage. The ORAC(FL) values showed little change during storage, indicating that the formation of polymers compensated for the loss of antioxidant capacity due to anthocyanin degradation. Methods are needed to retain anthocyanins in thermally processed blueberries.

Processing and storage effects on monomeric anthocyanins, percent polymeric color, and antioxidant capacity of processed black raspberry products.

This study evaluated the effects of processing and 6 mo of storage on total monomeric anthocyanins, percent polymeric color, and antioxidant capacity of black raspberries that were individually quick-frozen (IQF), canned-in-syrup, canned-in-water, pureed, and juiced (clarified and nonclarified). Total monomeric anthocyanins, percent polymeric color, and ORAC(FL) were determined 1 d postprocessing and after 1, 3, and 6 mo of storage. Thermal processing resulted in marked losses in total anthocyanins ranging from 37% in puree to 69% to 73% in nonclarified and clarified juices, respectively, but only the juices showed substantial losses (38% to 41%) in ORAC(FL). Storage at 25 degrees C of all thermally processed products resulted in dramatic losses in total anthocyanins ranging from 49% in canned-in-syrup to 75% in clarified juices. This coincided with marked increases in percent polymeric color values of these products over the 6-mo storage. ORAC(FL) values showed little change during storage, indicating that the formation of polymers compensated for the loss of antioxidant capacity due to anthocyanin degradation. Total anthocyanins and ORACFL of IQF berries were well retained during long-term storage at -20 degrees C.

Antioxidant status of young children: response to an antioxidant supplement.

OBJECTIVE: To study oxidative stress indicators in healthy young children and their response to a commercially available fruit- and vegetable-based antioxidant supplement. DESIGN: Healthy children were randomly assigned to a placebo and a supplement (commercial antioxidant supplement produced from dried fruit and vegetable extracts and fortified with antioxidants, resembling a gummy-type candy). The placebo and the supplement were taken in 2 doses per day for 21 days. SUBJECTS: Participants were 39 children (26 boys and 13 girls) aged 5 to 10 years. Research was conducted at Primary Children's Medical Center and the University of Utah, Salt Lake City. MAIN OUTCOME MEASURES: Breath and urine samples were collected on days 1 and 21 and assayed for breath pentane and urine 8-hydroxydeoxyguanosine, malondialdehyde, nitrites, and 8-isoprostane as noninvasive indicators of oxidative stress. Urine oxygen radical absorbance capacity was measured at days 1 and 21 as an indirect indicator of the antioxidant capacity of the body. Three-day food records were collected at the beginning and end of the study to measure intake of dietary fruit; vegetable; and antioxidant vitamins A, C, and E. STATISTICAL ANALYSIS: Descriptive statistics, repeated measures analysis of variance, paired t tests, and Pearson r correlations. RESULTS: Markers of oxidative stress were not significantly different between the placebo and supplement groups at day 1 or day 21. The oxidative stress indicators of the healthy children in this study appear to be similar to those of healthy adults and were not changed by antioxidant supplementation. The diet record analyses indicated that mean fruit and vegetable intakes (2.75 servings/day) were similar to the national average intake for children in the United States. APPLICATIONS/CONCLUSIONS: This research presents original information on the subject of oxidative stress in healthy children. The results of this study may be useful as reference baseline markers to use in conjunction with clinical dietary evaluations and for future research with healthy children and with children in disease states who are subject to elevated levels of oxidative stress.

Development and validation of an improved oxygen radical absorbance capacity assay using fluorescein as the fluorescent probe.

An improved method of oxygen radical absorbance capacity (ORAC) assay has been developed and validated using fluorescein (3',6'-dihydroxyspiro[isobenzofuran-1[3H],9'[9H]-xanthen]-3-one) as the fluorescent probe. Our results demonstrate that fluorescein (FL) is superior to B-phycoerythrin. The oxidized FL products induced by peroxyl radical were identified by LC/MS, and the reaction mechanism was determined to follow a classic hydrogen atom transfer mechanism. In addition, methodological and mechanistic comparison of ORAC(FL) with other widely used methods was discussed. It is concluded that, unlike other popular methods, the improved ORAC(FL) assay provides a direct measure of hydrophilic chain-breaking antioxidant capacity against peroxyl radical.

Interspecific variation in anthocyanins, phenolics, and antioxidant capacity among genotypes of highbush and lowbush blueberries (Vaccinium section cyanococcus spp.).

Recent interest in the possible protective effects of dietary antioxidant compounds against human degenerative disease has prompted investigation of foods such as blueberries (Vaccinium sp.), which have a high antioxidant capacity. Fruit obtained from genotypes of highbush blueberries (Vaccinium corymbosum L.) and lowbush blueberries (Vaccinium angustifolium Aiton) were analyzed for their antioxidant capacity, their content of anthocyanins, and total phenolic compounds, to evaluate the intraspecific and interspecific variation in these parameters. The method of extraction influenced the composition of fruit extracts; the highest anthocyanin and total phenolic contents and antioxidant capacity were found in extracts obtained using a solvent of acidified aqueous methanol. Regardless of the method, lowbush blueberries were consistently higher in anthocyanins, total phenolics, and antioxidant capacity, compared with highbush blueberries. There was no relationship between fruit size and anthocyanin content in either species.

Antioxidant and pro-oxidant capacity of catecholamines and related compounds. Effects of hydrogen peroxide on glutathione and sphingomyelinase activity in pheochromocytoma PC12 cells: potential relevance to age-related diseases.

The antioxidant and pro-oxidant capacity of catecholamines (CA) and related compounds were analyzed using the oxygen radical absorbance capacity (ORAC) assay. In the assay 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPH), a peroxyl radical generator, ROO*; H2O2-Cu2+, mainly a hydroxyl radical generator, *OH; and Cu2+ a transition metal were used. The antioxidant effect of CA and its related compounds were in the order: neurotransmitters: dopamine (DA), norepinephrine (NE) > metabolites > amino acid precursors as measured by using AAPH. The antioxidant effect of CA and related compounds as measured by using AAPH were linearly correlated with concentration, while the antioxidant effect of CA in scavenging *OH produced by H2O2-Cu2+ increased proportionally to concentration at low concentration, but after reaching a maximum declined with increasing concentration. In the presence of Cu2+, CA acted as pro-oxidant. Glutathione (GSH) acted as a pro-oxidant when H2O2-Cu2+ or when Cu2+ alone was used as an oxidant and showed much higher pro-oxidant effect than DA, which could have relevance in the vulnerability of dopaminergic neurons to oxidative stress in the aging and aging related diseases. The antioxidant capacity of CA and many related compounds seems to be correlated with the numbers of hydroxyl groups and their position on the benzoic ring. The O-methylation and sulfate conjugation of the hydroxyl substitution inactivates both the antioxidant and pro-oxidant activities of CA. Our results show that oxidative stress induced by low (5 microM) or high (300 microM) doses H2O2 in pheochromocytoma PC12 cells significantly up-regulate the activity of Mg-dependent neutral sphingomyelinase (Sase), and significantly decreased GSH.

Oxygen radical absorbance capacity (ORAC) and phenolic and anthocyanin concentrations in fruit and leaf tissues of highbush blueberry.

Antioxidant capacity, as measured by oxygen radical absorbance capacity (ORAC), and total phenolic and total anthocyanin contents were evaluated in fruit tissues of 87 highbush blueberry (Vacciniumcorymbosum L.) and species-introgressed highbush blueberry cultivars. ORAC and phenolic levels were evaluated in leaf tissues of the same materials. Average values for ORAC, phenolics, and anthocyanins in fruit were 15.9 ORAC units, 1.79 mg/g (gallic acid equivalents), and 0.95 mg/g (cyanidin-3-glucoside equivalents), respectively. Cv. Rubel had the highest ORAC per gram of fresh weight values, at 31.1 units, and cv. Elliott had the highest values on the basis of ORAC per square centimeter of surface area. In leaf tissue, values for both ORAC and phenolics were significantly higher than in fruit tissue, with mean values of 490 ORAC units and 44.80 mg/g (gallic acid equivalents), respectively. Leaf ORAC had a low, but significant, correlation with fruit phenolics and anthocyanins, but not with fruit ORAC. An analysis of ORAC values versus calculated midparent values in 11 plants from the 87-cultivar group in which all parents were tested suggested that, across cultivars, ORAC inheritance is additive. An investigation of ORAC values in a family of 44 cv. Rubel x Duke seedlings showed negative epistasis for ORAC values, suggesting Rubel may have gene combinations contributing to ORAC that are broken up during hybridization.

Anthocyanins are absorbed in glycated forms in elderly women: a pharmacokinetic study.

BACKGROUND: Anthocyanins are potent antioxidants that are widely distributed in fruit, vegetables, and red wines. Anthocyanin products are also prescribed as medicines in many countries for treating various diseases. However, the pharmacokinetics of dietary anthocyanins are not known in humans because these glycosides were long considered nonabsorbable. OBJECTIVE: The objective of this study was to determine whether anthocyanins can be absorbed as glycosides and to evaluate their pharmacokinetics in humans. DESIGN: Four healthy elderly women consumed 720 mg anthocyanins. A series of blood and urine samples were collected before and after consumption of the anthocyanins. Anthocyanins were measured in plasma and urine by combining an octadecylsilane solid-phase extraction for sample preparation and an HPLC system with diode array for anthocyanin separation and detection. The structures of anthocyanins as glycosides in plasma and urine were further confirmed by using liquid chromatography-mass spectrometry. RESULTS: Anthocyanins were detected as glycosides in plasma and urine. The maximum plasma concentration of total anthocyanins varied from 55.3 to 168.3 nmol/L, with an average of 97.4 nmol/L, and was reached within 71.3 min. The elimination of plasma anthocyanins appeared to follow first-order kinetics. The elimination half-life of plasma total anthocyanins was calculated to be 132.6 min. Most anthocyanin compounds were excreted in urine during the first 4 h. The excretion rate of total anthocyanins was 77 microg/h during the first 4 h and 13 microg/h during the second 4 h. CONCLUSION: Anthocyanins are absorbed in their unchanged glycated forms in elderly women.

Identification of procyanidins and anthocyanins in blueberries and cranberries (Vaccinium spp.) using high-performance liquid chromatography/mass spectrometry.

Blueberries and cranberries were analyzed for procyanidins using normal-phase HPLC/MS. Monomers, identified as (+)-catechin and (-)-epicatechin, and a series of oligomers were detected in blueberries, and MS data confirmed that the oligomers consisted of (epi)catechin units that were exclusively singly linked (B-type). The procyanidin "fingerprints" were similar for Tifblue and Rubel but higher than that for lowbush blueberries. In whole cranberries, (-)-epicatechin was present, along with a complex series of oligomers. Both A-type (contained only one double linkage per oligomer) and B-type oligomers were present. Two commercial cranberry juices exhibited similar procyanidin profiles, except that one contained increased quantities. There were processing effects on the procyanidin content of cranberry extract and juices when compared to those of the unprocessed fruits. Monomer, dimers, and A-type trimers were the primary procyanidins, with only trace levels of the B-type trimers and A-type tetramers and with an absence of the higher oligomers in cranberry extract and juices.

Effect of long-term dietary antioxidant supplementation on influenza virus infection.

This study compared the effect of vitamin E on the course of influenza infection with that of other antioxidants. (In a previous study we showed that short-term vitamin E supplementation significantly decreased pulmonary viral titer in influenza-infected old mice). Eighteen-month-old C57BL/6NCrlBR mice were fed one of the following semisynthetic diets for 6 months: control, vitamin E supplemented, glutathione supplemented, vitamin E and glutathione supplemented, melatonin supplemented, or strawberry extract supplemented. After influenza virus challenge, mice fed vitamin E-supplemented diet had significantly lower pulmonary viral titers compared to those fed the control diet (10(2.6) vs 10(4.0), p < .05) and were able to maintain their body weight after infection (1.8+/-0.9 g weight loss/5 days postinfection in vitamin E group vs 6.8+/-1.4 g weight loss/5 days postinfection in control group, p < .05). Other antioxidants did not have a significant effect on viral titer or weight loss. There was a significant inverse correlation of weight loss with food intake (r = -.96, p < .01), indicating that the observed weight changes were mainly due to decreased food intake. Pulmonary interleukin (IL)-6, IL-1beta, and tumor necrosis factor (TNF)-alpha levels increased significantly postinfection. The vitamin E group had lower lung IL-6 and TNF-alpha levels following infection compared to the control group. In addition, there was a significant positive correlation between weight loss and lung IL-6 (r = .77, p < .01) and TNF-alpha (r = .68, p < .01) levels. Because IL-6 and TNF-alpha have been shown to contribute to the anorexic effect of infectious agents, the prevention of weight loss by vitamin E might be due to its reduced production of IL-6 and TNF-alpha following infection. Thus, among the antioxidants tested, only vitamin E was effective in reducing pulmonary viral titers and preventing an influenza-mediated decrease in food intake and weight loss. Other dietary antioxidant supplementations that reduced one or more measures of oxidative stress (4-hydroxynonenal, malondialdehyde, and hydrogen peroxide) did not have an effect on viral titer, which suggests that, in addition to its antioxidant activity, other mechanisms might be involved in vitamin E's beneficial effect on lowering viral titer and preventing weight loss.

The effects of a multivitamin/mineral supplement on micronutrient status, antioxidant capacity and cytokine production in healthy older adults consuming a fortified diet.

BACKGROUND: Inadequate micronutrient intake among older adults is common despite the increased prevalence of fortified/enriched foods in the American diet. Although many older adults take multivitamin supplements in an effort to compensate, studies examining the benefits of this behavior are absent. OBJECTIVE: To determine whether a daily multivitamin/mineral supplement can improve micronutrient status, plasma antioxidant capacity and cytokine production in healthy, free-living older adults already consuming a fortified diet. METHODS: An eight-week double-blind, placebo-controlled clinical trial among 80 adults aged 50 to 87 years (mean = 66.5 +/- 8.6 years). RESULTS: Multivitamin treatment significantly increased (p<0.01, compared to placebo) plasma concentrations of vitamins D (77 to 100 nmol/L), E (27 to 32 micromol/L), pyridoxal phosphate (55.1 to 75.2 nmol/L), folate (23 to 33 nmol/L), B12 (286 to 326 pmol/L)), C (55 to 71 micromol/L), and improved the riboflavin activity coefficient (1.23 to 1.15), but not vitamins A and thiamin. The multivitamin reduced the prevalence of suboptimal plasma levels of vitamins E (p=0.003), B12 (p=0.004), and C (p=0.08). Neither glutathione peroxidase activity nor antioxidant capacity (ORAC) were affected. No changes were observed in interleukin-2, -6 or -10 and prostaglandin E2, proxy measures of immune responses. CONCLUSIONS: Supplementation with a multivitamin formulated at about 100% Daily Value can decrease the prevalence of suboptimal vitamin status in older adults and improve their micronutrient status to levels associated with reduced risk for several chronic diseases.

Analysis of botanicals and dietary supplements for antioxidant capacity: a review.

Free radicals and other reactive species are considered to be important causative factors in the development of diseases of aging such as cancer and cardiovascular diseases. This relationship has led to considerable interest in assessing the antioxidant capacity of foods and botanicals and other nutritional antioxidant supplements. The use of the oxygen radical absorbance capacity (ORAC) assay as a tool for antioxidant assessment is described and proposed as a method for comparing botanical sources and for standardizing nutritional supplements. The free radical or oxidant source is important and direct comparisons cannot be made between procedures that use different sources. The ORAC procedure uses 2,2'-azobis(2-amidinopropane) dihydrochloride as a peroxyl radical source, which is relevant to biological systems because the peroxyl radical is the most abundant free radical. Other oxidant sources (hydroxyl radical and Cu++) can also be used to characterize antioxidants in botanicals. Phenolics or polyphenolics are responsible for most of the antioxidant capacity in fruits, vegetables, and most botanical antioxidant supplements. Although little is known about the absorption and metabolism of these components, improvement in the in vivo antioxidant status has been observed in human subjects following consumption of antioxidant botanicals. The ORAC method provides a basis from which to establish appropriate dietary intakes that might impact health outcomes.

Postprandial increases in serum antioxidant capacity in older women.

Eight women were recruited for studying the effects of a meal on overall antioxidant status. Subjects resided in a metabolic research unit for two 36-h periods. During period A, subjects fasted overnight (12 h) and were then given a breakfast, a lunch, a snack, and a dinner. During period B, subjects fasted for 23 h and were then given a dinner. These meals were designed to contain negligible antioxidants. Blood samples were collected for analyzing total antioxidant capacity (TAC) and individual antioxidants. The results showed that serum TAC significantly increased by up to 23% after the consumption of the lunch and dinner during period A. Serum TAC did not increase until after the consumption of the dinner during period B. Among the antioxidants (vitamin C, alpha-tocopherol, bilirubin, and uric acid) examined, serum uric acid was the only one that showed a significant postprandial increase, which was also parallel to the postprandial response in serum TAC. These results indicate that food intake, even if low in antioxidants, can increase the serum total antioxidant activity.

HPLC method for the quantification of procyanidins in cocoa and chocolate samples and correlation to total antioxidant capacity.

Monomeric and oligomeric procyanidins present in cocoa liquors and chocolates were separated and quantified in four different laboratories using a normal-phase high-performance liquid chromatography (HPLC) method with fluorescence detection. Procyanidin standards through decamers were obtained by extraction from cocoa beans, enrichment by Sephadex LH-20 gel permeation chromatography, and final purification by preparative normal-phase HPLC. The purity of each oligomeric fraction was assessed using HPLC coupled to mass spectrometry. A composite standard was then prepared, and calibration curves were generated for each oligomeric class using a quadratic fit of area sum versus concentration. Results obtained by each of the laboratories were in close agreement, which suggests this method is reliable and reproducible for quantification of procyanidins. Furthermore, the procyanidin content of the samples was correlated to the antioxidant capacity measured using the ORAC assay as an indicator for potential biological activity.

Antioxidant capacity, vitamin C, phenolics, and anthocyanins after fresh storage of small fruits.

Fresh strawberries (Fragaria x ananassa Duch.), raspberries (Rubus idaeus Michx.), highbush blueberries (Vaccinium corymbosum L.), and lowbush blueberries (Vaccinium angustifolium Aiton) were stored at 0, 10, 20, and 30 degrees C for up to 8 days to determine the effects of storage temperature on whole fruit antioxidant capacity (as measured by the oxygen radical absorbing capacity assay, Cao et al., Clin. Chem. 1995, 41, 1738-1744) and total phenolic, anthocyanin, and ascorbate content. The four fruit varied markedly in their total antioxidant capacity, and antioxidant capacity was strongly correlated with the content of total phenolics (0.83) and anthocyanins (0.90). The antioxidant capacity of the two blueberry species was about 3-fold higher than either strawberries or raspberries. However, there was an increase in the antioxidant capacity of strawberries and raspberries during storage at temperatures >0 degrees C, which was accompanied by increases in anthocyanins in strawberries and increases in anthocyanins and total phenolics in raspberries. Ascorbate content differed more than 5-fold among the four fruit species; on average, strawberries and raspberries had almost 4-times more ascorbate than highbush and lowbush blueberries. There were no ascorbate losses in strawberries or highbush blueberries during 8 days of storage at the various temperatures, but there were losses in the other two fruit species. Ascorbate made only a small contribution (0.4-9.4%) to the total antioxidant capacity of the fruit. The increase observed in antioxidant capacity through postharvest phenolic synthesis and metabolism suggested that commercially feasible technologies may be developed to enhance the health functionality of small fruit crops.

Antioxidant capacity of oat (Avena sativa L.) extracts. 1. Inhibition of low-density lipoprotein oxidation and oxygen radical absorbance capacity.

Milled oat groat pearlings, trichomes, flour, and bran were extracted with methanol and the fractions tested in vitro for antioxidant capacity against low-density lipoprotein (LDL) oxidation and R-phycoerythrin protein oxidation in the oxygen radical absorbance capacity (ORAC) assay. The oxidative reactions were generated by 2,2'-azobis(2-amidinopropane) HCl (AAPH) or Cu(2+) in the LDL assay and by AAPH or Cu(2+) + H(2)O(2) in the ORAC assay and calibrated against a Trolox standard to calculate Trolox equivalents (1 Trolox equivalent = 1 TE = activity of 1 micromol of Trolox). The antioxidant capacity of the oat fractions was generally consistent with a potency rank of pearlings (2.89-8.58 TE/g) > flour (1.00-3.54 TE/g) > trichome (1.74 TE/g) = bran (1.02-1.62 TE/g) in both LDL and ORAC assays regardless of the free radical generator employed. A portion of the oat antioxidant constituents may be heat labile as the greatest activity was found among non-steam-treated pearlings. The contribution of oat tocols from the fractions accounted for <5% of the measured antioxidant capacity. AAPH-initiated oxidation of LDL was inhibited by the oat fractions in a dose-dependent manner, although complete suppression was not achieved with the highest doses tested. In contrast, Cu(2+)-initiated oxidation of LDL stimulated peroxide formation with low oat concentrations but completely inhibited oxidation with higher doses. Thus, oats possess antioxidant capacity most of which is likely derived from polar phenolic compounds in the aleurone.

Effect of vitamin E intake on levels of vitamins E and C in the central nervous system and peripheral tissues: implications for health recommendations.

Vitamin E (alpha-gamma-tocopherol) is an important component in biological membranes. A decrease in its concentration imposes structural and functional damage to the cells. The object of this study was to assess the effect of a graded dietary vitamin E (E) intake on E concentration in specific regions of the brain, and its influence on vitamin C levels and neurological function. Following a 2-month period, rats supplemented with 5, 30, 60, 250 or 500 mg all-rac-alpha-tocopherol-acetate/kg diet (mg E/kg diet) exhibited a significant increase of E concentration in brain and peripheral tissues. However, while blood and liver showed a dose response increase in E concentration which correlated well with the different levels of E in the diet, the central nervous system (CNS) followed the same pattern of increase of vitamin E in brain tissue only when the diet was supplemented with 5, 30, or 60 mg E/kg diet. No further increase in E concentration was observed when the diet was supplemented with 250 or 500 mg E/kg diet. Similarly, the heart tissue showed a significant increase in its E concentration when the was enriched with 5, 30, or 60 mg E/kg diet, with no further increases at 250 or 500 mg. Vitamin C concentration in brain cortex and cerebellum, plasma, liver, and heart was reduced in the groups receiving 250 or 500 mg E/kg diet. Compared to the low E group, rats supplemented with the 60, 250 or 500 mg E/kg diet showed a significant enhancement in striatal dopamine (DA) release, but no differences were observed among the latter three groups.

Hyperoxia-induced changes in antioxidant capacity and the effect of dietary antioxidants.

We investigated, by measuring oxygen radical absorbance capacity (ORAC), whether hyperoxia causes alterations in antioxidant status and whether these alterations could be modulated by dietary antioxidants. Rats were fed for 8 wk a control diet or a control diet supplemented with vitamin E (500 IU/kg) or with aqueous extracts (ORAC: 1.36 mmol Trolox equivalents/kg) from blueberries or spinach and then were exposed to air or >99% O2 for 48 h. Although the constituents of the extracts were not extensively characterized, HPLC indicated that blueberry extract was particularly rich in anthocyanins, and the spinach extract did not contain any anthocyanins. The ORAC was determined in samples without proteins [serum treated with perchloric acid (PCA); ORACPCA] and with proteins (ORACtot). Hyperoxia induced a decrease in serum protein concentration, an increase in serum ORACPCA, decreases in lung ORACPCA and ORACtot, and an equilibration of proteins and ORACPCA between serum and pleural effusion. These alterations suggested a redistribution of antioxidants between tissues and an increase in capillary permeability during hyperoxia. Only the blueberry extract was effective in alleviating the hyperoxia-induced redistribution of antioxidants between tissues.