Functional food science and defence against reactive oxidative species

Smoking and exposure to environmental tobacco smoke decrease some plasma antioxidants and increase gamma-tocopherol in vivo after adjustment for dietary antioxidant intakes

BACKGROUND

Free radicals in cigarette smoke may cause oxidative damage to macromolecules, contributing to cardiovascular diseases and cancer. Decreased plasma antioxidant concentrations may indicate cigarette smoke-related oxidative stress.

OBJECTIVE

We compared the effects on plasma antioxidant concentrations in cotinine-confirmed active and passive smokers with those in nonsmokers, independent of differences in dietary intakes and other covariates.

DESIGN

Plasma samples from 83 smokers, 40 passive smokers, and 36 nonsmokers were analyzed for total ascorbic acid, alpha- and gamma-tocopherols, 5 carotenoids, retinol, and cotinine. Groups were compared by using analysis of variance with adjustment for sex, age, race, body mass index, alcohol intake, triacylglycerol concentration, fruit and vegetable intakes, and dietary antioxidants.

RESULTS

After adjustment for dietary antioxidant intakes and other covariates, smokers and passive smokers had significantly lower plasma beta-carotene concentrations than did nonsmokers (0.15, 0.17, and 0.24 micro mol/L, respectively) and significantly higher gamma-tocopherol concentrations (7.8, 7.8, and 6.5 micro mol/L, respectively). Smokers had significantly lower plasma ascorbic acid and beta-cryptoxanthin concentrations than did nonsmokers and passive smokers (ascorbic acid: 43.6, 54.5, and 54.6 micro mol/L, respectively; beta-cryptoxanthin: 0.12, 0.16, and 0.16 micro mol/L, respectively) and significantly lower concentrations of lutein and zeaxanthin than did nonsmokers (0.33 compared with 0.41 micro mol/L). The P values for all the differences described above were < 0.05. No significant differences in plasma concentrations of alpha-tocopherol, alpha-carotene, total carotenoids, lycopene, or retinol were observed.

CONCLUSIONS

These results indicate that cigarette smokers and nonsmokers exposed to cigarette smoke have a significantly lower plasma antioxidant status than do unexposed nonsmokers, independent of differences in dietary antioxidant intakes. Further research is required to explain why plasma gamma-tocopherol concentrations were significantly higher in smokers and passive smokers than in nonsmokers.

Folate content in strawberries (Fragaria x ananassa): effects of cultivar, ripeness, year of harvest, storage, and commercial processing

Folate concentrations in strawberries and folate retention during storage and commercial processing of strawberries were investigated. No previous study has focused on the effects of cultivar, ripeness, and year of harvest of strawberries with respect to the folate content. This study showed the folate concentration in strawberries to significantly depend on all of these different factors. Total folate was quantified using a modified and validated radioprotein-binding assay with external calibration (5-CH(3)-H(4)folate). Folate content in 13 different strawberry cultivars varied from 335 microg/100 g of dry matter (DM) for cv. Senga Sengana to 644 microg/100 g of DM for cv. Elsanta. Swedish harvests from 1999 and 2001 yielded higher folate concentrations than did the harvest from 2000, and the grade of ripeness affected the folate content in strawberries. This study indicated high folate retention in intact berries during storage until 3 or 9 days at 4 degrees C (71-99%) and also in most tested commercial products (79-103%). On the basis of these data fresh strawberries as well as processed strawberry products are recommended to be good folate sources. For instance, 250 g (fresh weight) of strawberries ( approximately 125 microg of folate) supplies approximately 50% of the recommended daily folate intake in various European countries (200-300 microg/day) or 30% of the U.S. recommendation (400 microg/day).

Valorization of grape (Vitis vinifera) byproducts. Antioxidant and biological properties of polyphenolic fractions differing in procyanidin composition and flavonol content

Many byproducts and wastes generated by agroindustries contain polyphenols with potential application as food antioxidants and preventive agents against skin cancer and other diseases. The performance of polyphenolic fractions from Parellada grape (Vitis vinifera) pomace as antioxidants in different physicochemical environments was tested. Fractions containing oligomers with mean degree of polymerization between 3 and 4 and percentage galloylation ca. 30% were the most potent free radical scavengers and efficient antioxidants in an oil-in-water emulsion. A fraction including glycosylated flavonols was also efficient in the emulsion. All the fractions showed low aquatic toxicity and weak influence on proliferation of human melanoma cells.

The biochemistry and medical significance of the flavonoids

Flavonoids are plant pigments that are synthesised from phenylalanine, generally display marvelous colors known from flower petals, mostly emit brilliant fluorescence when they are excited by UV light, and are ubiquitous to green plant cells. The flavonoids are used by botanists for taxonomical classification. They regulate plant growth by inhibition of the exocytosis of the auxin indolyl acetic acid, as well as by induction of gene expression, and they influence other biological cells in numerous ways. Flavonoids inhibit or kill many bacterial strains, inhibit important viral enzymes, such as reverse transcriptase and protease, and destroy some pathogenic protozoans. Yet, their toxicity to animal cells is low. Flavonoids are major functional components of many herbal and insect preparations for medical use, e.g., propolis (bee's glue) and honey, which have been used since ancient times. The daily intake of flavonoids with normal food, especially fruit and vegetables, is 1-2 g. Modern authorised physicians are increasing their use of pure flavonoids to treat many important common diseases, due to their proven ability to inhibit specific enzymes, to simulate some hormones and neurotransmitters, and to scavenge free radicals.

High intakes of vegetables, berries, and apples combined with a high intake of linoleic or oleic acid only slightly affect markers of lipid peroxidation and lipoprotein metabolism in healthy subjects

BACKGROUND

A high consumption of vegetables and fruit is associated with decreased risk of ischemic heart disease and several cancers. The pathophysiology of these diseases involves free radical mechanisms. Diet may either enhance or diminish oxidative stress in the body.

OBJECTIVE

We studied the effects of high and low intakes of vegetables, berries, and apples on markers of lipid peroxidation and lipoprotein metabolism in subjects consuming diets high in linoleic or oleic acid.

DESIGN

For 6 wk, healthy men and women (n = 77; aged 19-52 y) consumed 1 of 4 controlled isoenergetic diets rich in either linoleic acid (11% of energy) or oleic acid (12% of energy) and containing either 815 or 170 g vegetables, berries, and apples/10 MJ. Nineteen healthy volunteers served as control subjects. Several markers of dietary compliance (plasma fatty acids, vitamin C, carotenoids, and quercetin), lipid peroxidation [ex vivo LDL oxidation, plasma and LDL thiobarbituric acid-reactive substances, paraoxonase (EC 3.1.8.1), and urinary 8-iso-prostaglandin F(2)(alpha)], and lipoprotein metabolism (plasma lipids, apolipoproteins, and lipid transfer protein activities) were measured from samples collected before and at the end of the experimental period.

RESULTS

Plasma fatty acid composition and antioxidant concentrations showed that compliance with the diets was good. However, there were no significant differences between the diets in the markers of lipid peroxidation and lipoprotein metabolism.

CONCLUSIONS

In healthy volunteers with adequate vitamin intakes, 6-wk diets differing markedly in the amounts of linoleic and oleic acid and vegetables, berries, and apples did not differ in their effects on lipid peroxidation or lipoprotein metabolism.

Functional foods and health: a US perspective

Linkages between diet habits and the quality of life continue to surface on numerous fronts. Collectively these epidemiological, pre-clinical and clinical studies provide rather compelling evidence that numerous essential and non-essential dietary components are capable of influencing growth, development and performance and disease prevention. Scientific discoveries and widespread interest in the potential medicinal benefits of foods and food components have fostered a variety of content, health and structure-function claims. Unfortunately, defining the ideal diet is complicated by the numerous and diverse components that may influence biological processes. Inconsistencies in the literature may reflect the multi-factorial nature of these processes and the specificity that individual dietary constituents have in modifying genetic and epigenetic events. New and emerging genomic and proteonomic approaches and technologies offer exciting opportunities for identifying molecular targets for dietary components and thus determining mechanisms by which they influence the quality of life. All cells have unique 'signatures' that are characterized by active and inactive genes and cellular products. It is plausible that bridging knowledge about unique cellular characteristics with molecular targets for nutrients can be used to develop strategies to optimize nutrition and minimize disease risk.

Cation-exchange micropreparative separation of galloylated and non-galloylated sulphur conjugated catechins

Catechin conjugates bearing an amino function can be separated from underivatized monomers by cation-exchange chromatography. Here, chromatographic conditions for the separation of epicatechin gallate-containing conjugates from the non-galloylated conjugates at micropreparative scale are described. The separation was achieved by exploiting either the hydrophobic or hydrophilic interactions of the conjugates with the core polymer. The retention was modulated by changing the amount of organic co-solvents (MeOH, EtOH, CH3CH, THF) in the elution buffers. The best resolution compatible with small peak widths was obtained at 20-30% EtOH. The experiments were reproducible.

The effect of wild blueberry (Vaccinium angustifolium) consumption on postprandial serum antioxidant status in human subjects

The aim of the present study was to determine whether the consumption of wild blueberries (Vaccinium angustifolium), a concentrated source of non-nutritive antioxidant phytochemicals, would enhance postprandial serum antioxidant status in healthy human subjects. A single-blinded crossover study was performed in a group of eight middle-aged male subjects (38-54 years). Subjects consumed a high-fat meal and a control supplement followed 1 week later by the same high-fat meal supplemented with 100.0 g freeze-dried wild blueberry powder. Upon brachial vein catheterization, fasting and postprandial serum samples were taken sequentially and analysed for lipids and glucose and for serum antioxidant status. Serum antioxidant status was determined using the oxygen radical absorbance capacity (ORAC) assay and the total antioxidant status (TAS) assay. The wild-blueberry treatment was associated with a significant treatment effect as determined by the ORAC assay (water-soluble fraction ORAC(perchloric acid (PCA)), P=0.04). Significant increases in serum antioxidant status above the controls were observed at 1 h (ORAC(PCA) (8.5 % greater), P=0.02; TAS (4.5 % greater), P=0.05), and 4 h (ORAC(total) (15.0 % greater), P=0.009; ORAC(acetone) (16.0 % greater), P=0.007) post-consumption of the high-fat meal. In conclusion, the consumption of wild blueberries, a food source with high in vitro antioxidant properties, is associated with a diet-induced increase in ex vivo serum antioxidant status. It has been suggested that increasing the antioxidant status of serum may result in the reduced risk of many chronic degenerative diseases.

C11-BODIPY(581/591), an oxidation-sensitive fluorescent lipid peroxidation probe: (micro)spectroscopic characterization and validation of methodology

C11-BODIPY(581/591) is a fluorescent radio-probe for indexing lipid peroxidation and antioxidant efficacy in model membrane systems and living cells, with excellent characteristics: (i) emission in the visible range of the electromagnetic spectrum, with good spectral separation of the nonoxidized (595 nm) and oxidized (520 nm) forms; (ii) has a high quantum yield and because of this, low labeling concentrations can be used, ensuring minimal perturbation of the membrane whilst retaining favorable signal to noise ratios; (iii) has a good photo-stability and displays very few fluorescence artifacts; (iv) is virtually insensitive to environmental changes, i.e., pH or solvent polarity; (v) is lipophilic and as such easily enters membranes; (vi) once oxidized, C11-BODIPY(581/591) remains lipophilic and does not spontaneously leave the lipid bilayer; (vii) C11-BODIPY(581/591) localizes in two distinct pools within the lipid bilayer, a shallow pool at 18 A and a deep pool at < 7.5 A from the center of the bilayer; (viii) is not cytotoxic to rat-1 fibroblasts up to 50 microM; (ix) is sensitive to a variety of oxy-radicals and peroxynitrite, but not to superoxide, nitric oxide, transition metal ions, and hydroperoxides per se; (x) its sensitivity to oxidation is comparable to that of endogenous fatty acyl moieties.

Oxidative damage shifts from lipid peroxidation to thiol arylation by catechol-containing antioxidants

Catechol-containing antioxidants are able to protect against lipid peroxidation by nonenzymatic scavenging of free radicals with their catechol moiety. During their antioxidant activity, catechol oxidation products such as semiquinone radicals and quinones are formed. These oxidation products of 4-methylcatechol inactivate the GSH-dependent protection against lipid peroxidation and the calcium sequestration in liver microsomes. This effect is probably due to arylation by oxidation products of 4-methylcatechol of free thiol groups of the enzymes responsible for the GSH-dependent protection and calcium sequestration, i.e. the free radical reductase and calcium ATPase. It is concluded that a catechol-containing antioxidant might shift radical damage from lipid peroxidation to sulfhydryl arylation.

Cysteinyl-flavan-3-ol conjugates from grape procyanidins. Antioxidant and antiproliferative properties

New bio-based antioxidant compounds have been obtained by depolymerisation of grape polymeric flavanols in the presence of cysteine. Their preparation and purification, as well as their antiradical/antioxidant and antiproliferative properties are reported. 4beta-(S-cysteinyl)epicatechin 5, 4beta-(S-cysteinyl)catechin 6 and 4beta-(S-cysteinyl)epicatechin 3-O-gallate 7 were efficiently purified from the crude depolymerised mixture by cation-exchange chromatography and preparative reversed-phase chromatography. The new compounds were more efficient than the underivatised (-)-epicatechin 1 as scavengers of the 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) and weak growth inhibitors of human colon carcinoma HT29 cells. The order of antiradical and antiproliferative efficiency was 7 >5 approximately 6 >1, the same for both assays.

Effect of feeding supplemental copper on performance, fatty acid profile and on cholesterol contents and oxidative stability of meat of rabbits

One hundred and four rabbits, five weeks old at the beginning of the experiment, were divided into four groups according to a feed additive treatment. Rabbits of the 1st, 2nd, 3rd and 4th group were fed a basal granulated feed (control), basal feed supplemented with CuSO4.5H2O at 50 mg Cu.kg-1, basal feed supplemented with 150 mg Cu.kg-1, and the latter feed supplemented with 100 mg.kg-1 vitamin E, respectively. The duration of the experiment was 42 days. Addition of Cu at 150 mg.kg-1 increased weight gain non-significantly by 9.1%. This effect was the most pronounced in the first two weeks of fattening. The lowest mortality was observed in rabbits fed the highest amount of additives (7.7% vs. 19.2% in the control). Rabbits were slaughtered at the age of 11 weeks. Neither treatment influenced proportions of saturated, monounsaturated and polyunsaturated fatty acids in lipids extracted from the loin and hindleg muscles. In rabbits fed the highest amount of copper and vitamin E, the cholesterol concentration was significantly decreased by 13.6% and 17.9% in the loin and hindleg meat, respectively. Effects of Cu added at 50 mg.kg-1 were marginal. Copper had no effect on the oxidative stability of meat, measured as thiobarbituric acid-reactive substances in meat stored at 4 degrees C for 0, 3 and 8 days. Vitamin E added in excess of nutritional requirement improved the oxidative stability of meat. In copper-fed rabbits, Cu accumulated in the liver, but not in muscles. Feeding of the basal feed for 7 days to rabbits previously fed copper sulphate decreased the hepatic Cu concentration by 14.0 to 24.4%.

Diet and coronary heart disease: advice on a cardioprotective diet

Coronary heart disease is a major disease leading to early morbidity and mortality in the UK. The causes are multifactorial, a combination of modifiable and non-modifiable risk factors. Although recent statistics show a reduction in the coronary heart disease mortality rate, the disease continues to be a major focus in health care, with strategies being developed to improve prevention and treatment. Dietary modification has a role to play in both primary and secondary prevention.

The pro-oxidant chemistry of the natural antioxidants vitamin C, vitamin E, carotenoids and flavonoids

Natural antioxidants like vitamin C, vitamin E, carotenoids, and polyphenols like flavonoids, are at present generally considered to be beneficial components from fruit and vegetables. The anti-oxidative properties of these compounds are often claimed to be responsible for various beneficial health effects of these food ingredients. Together these studies provide the basis for the present rapidly increasing interest for the use of natural antioxidants as functional food ingredients and/or as food supplements. However, at higher doses or under certain conditions antioxidant-type functional food ingredients may exert toxic pro-oxidant activities. The present manuscript gives an overview of especially this pro-oxidative chemistry and toxicity of well-known natural antioxidants including vitamin C, vitamin E, carotenoids and flavonoids.

Dietary orotic acid affects antioxidant enzyme mRNA levels and oxidative damage to lipids and proteins in rat liver

We investigated the effects of the dietary addition of orotic acid on liver antioxidant enzymes, mRNA levels of these enzymes, and peroxidative products by comparing casein with soy protein as the source of dietary protein. Rats fed the casein diet accumulated more liver lipids than those fed the soy protein diet when orotic acid was added. The addition of orotic acid lowered both the activity of liver Cu, Zn-superoxide dismutase and the level of Cu, Zn-superoxide dismutase mRNA. The addition of orotic acid led to a significant increase in the contents of conjugated dienes and protein carbonyls in the liver. In addition, dietary soy protein protected the increase in the levels of lipids and proteins peroxide induced by orotic acid. The addition of orotic acid to the casein diet increased the activities of both serum ornithine carbamoyltransferase and alanine aminotransferase. Thus, liver damage might result from the increased superoxide anion due to the decrease in the activity of hepatic superoxide dismutase, as well as increase in the production of hepatic peroxidative products in rats fed the casein diet with orotic acid.

Effects of an antioxidant-rich juice (sea buckthorn) on risk factors for coronary heart disease in humans

There is increasing evidence to support the hypothesis that free radical-mediated oxidative processes contribute to atherogenesis. More recently the ability of antioxidant nutrients to affect cell response and gene expression has been reported in vitro, providing a novel mechanistic perspective for the biological activity of antioxidants. Sea buckthorn (Hippophaë rhamnoides L.) is a rich source of antioxidants both aqueous and lipophilic, as well as polyunsaturated fatty acids. The objective of the study was to characterize the antioxidant profile of Sea buckthorn juice (SBJ) and to evaluate its effect on plasma lipids, LDL oxidation, platelet aggregation and plasma soluble cell adhesion protein concentration. Twenty healthy male volunteers were given either a placebo or SBJ for 8 weeks. Additional daily intakes of vitamin C, alpha-tocopherol, beta-carotene and flavonoids through SBJ supplementation were 462, 3.2, 1.0 and 355 mg respectively. There were no significant changes in plasma total cholesterol, LDL-C, platelet aggregation or plasma intercellular cell adhesion molecule 1 (ICAM-1) levels between treatment groups. Although not significant, a 20% and 17% increase in plasma HDL-C and triacylglycerol (TAG) concentrations were observed. SBJ supplementation also resulted in a moderate decrease in the susceptibility of LDL to oxidation.

Buckwheat extract inhibits progression of renal failure

Rats subjected to partial resection of the parenchyma showed reduced radical-scavenging activity in the remaining kidney and increased severity of renal tissue lesions. However, in similarly nephrectomized rats given buckwheat extract, the state of oxidative stress improved by restoring the decreased activities of reactive oxygen species-scavenging enzymes such as superoxide dismutase and catalase. The degree of mesangial proliferation, severity of extratubular lesions such as crescents and adhesions, glomerulosclerosis index, and severity of tubular interstitial lesions also improved. In addition, nephrectomized rats given buckwheat extract showed improvement in renal function, as indicated by decreased serum level of creatinine, with a significant decrease in the level of methylguanidine, a uremic toxin produced from creatinine in the presence of hydroxyl radical.

Regioselectivity of phase II metabolism of luteolin and quercetin by UDP-glucuronosyl transferases

The regioselectivity of phase II conjugation of flavonoids is expected to be of importance for their biological activity. In the present study, the regioselectivity of phase II biotransformation of the model flavonoids luteolin and quercetin by UDP-glucuronosyltransferases was investigated. Identification of the metabolites formed in microsomal incubations with luteolin or quercetin was done using HPLC, LC-MS, and (1)H NMR. The results obtained demonstrate the major sites for glucuronidation to be the 7-, 3-, 3'-, or 4'-hydroxyl moiety. Using these unequivocal identifications, the regioselectivity of the glucuronidation of luteolin and quercetin by microsomal samples from different origin, i.e., rat and human intestine and liver, as well as by various individual human UDP-glucuronosyltransferase isoenzymes was characterized. The results obtained reveal that regioselectivity is dependent on the model flavonoid of interest, glucuronidation of luteolin and quercetin not following the same pattern, depending on the isoenzyme of UDP-glucuronosyltransferases (UGT) involved. Human UGT1A1, UGT1A8, and UGT1A9 were shown to be especially active in conjugation of both flavonoids, whereas UGT1A4 and UGT1A10 and the isoenzymes from the UGTB family, UGT2B7 and UGT2B15, were less efficient. Due to the different regioselectivity and activity displayed by the various UDP-glucuronosyltransferases, regioselectivity and rate of flavonoid conjugation varies with species and organ. Qualitative comparison of the regioselectivities of glucuronidation obtained with human intestine and liver microsomes to those obtained with human UGT isoenzymes indicates that, in human liver, especially UGT1A9 and, in intestine, UGT1A1 and UGT1A8 are involved in glucuronidation of quercetin and luteolin. Taking into account the fact that the anti-oxidant action as well as the pro-oxidant toxicity of these catechol-type flavonoids is especially related to their 3',4'-dihydroxyl moiety, it is of interest to note that the human intestine UGT's appear to be especially effective in conjugating this 3',4' catechol unit. This would imply that upon glucuronidation along the transport across the intestinal border, the flavonoids loose a significant part of these biological activities.

A dietary oxidative balance score of vitamin C, beta-carotene and iron intakes and mortality risk in male smoking Belgians

The purpose of this study was to investigate, in smokers, whether the oxidative balance of their dietary pattern affected mortality risk. To evaluate the oxidative balance of the dietary pattern, an oxidative balance score was constructed that summarized the combined intake of dietary antioxidants (vitamin C and beta-carotene) and a prooxidant (iron). The low oxidative balance score group included smokers with a diet high in vitamin C and beta-carotene and/or low in iron and the high oxidative balance score group included those with a diet low in vitamin C and beta-carotene and/or high in iron. Using the 10-y follow-up mortality data from the Belgian Interuniversity Research on Nutrition and Health (BIRNH) study, the association of this oxidative balance score with all-cause, cardiovascular disease (CVD) and total cancer mortality was investigated in 2814 male smokers. In multivariate-adjusted Cox models, men in the highest oxidative balance score group had a higher relative risk (RR) of all-cause [RR = 1.44, 95% confidence interval (CI): 1.13, 1.82] and of total cancer mortality (RR = 1.62, 95% CI: 1.07, 2.45) compared with men in the lowest score group. This association was less pronounced for CVD mortality risk and was not significant (RR = 1.31, 95% CI: 0.86, 2.00). The risk of all-cause and total cancer mortality was driven principally by the high score group, which suggested a threshold effect for risk rather than a linear trend. The findings are consistent with the hypothesis that the oxidative balance of the diet is associated with subsequent mortality. Smokers whose diet is unbalanced in terms of anti- and prooxidants may therefore benefit from a recommendation to consume more servings of fresh fruits and vegetables and less meat.

Oral administration of pharmacological doses of vitamins C and E reduces reproductive fitness and impairs the ovarian and uterine functions of female mice

This study aims to ascertain whether oral administration of pharmacological doses of Vitamins C and E has any detrimental effect on reproductive fitness of female mice. We fed hybrid female mice from the first day of weaning a standard diet supplemented or not supplemented with pharmacological doses of Vitamins C and E. At the age of 28 weeks, we individually caged females with a male for the rest of their reproductive life. We performed a series of mating experiments to ascertain the number of oocytes ovulated and the potential for embryo development in vitro to the blastocyst stage and in vivo to Day 12 of gestation. The antioxidant diet decreased the frequency of litters, litter size, total number of offspring born and survival of male pups to weaning. This effect was associated with lower number of corpora lutea in the left ovary, decreased percentage of viable fetuses, and higher number of fetal resorptions in the left uterine horn when compared to the control group. The strategy of supplementing the diet with antioxidant vitamins to prevent the age associated decrease in reproductive potential should not be implemented in human beings until a safe and efficient diet is designed.

Oral antioxidants counteract the negative effects of female aging on oocyte quantity and quality in the mouse

This study aims to compare the effect of early and late onset administration of oral antioxidants on number and quality of oocytes retrieved from aged mice after exogenous ovarian stimulation. Control hybrid females were fed a standard diet supplemented or not supplemented with pharmacological doses of vitamins C and E either from the first day of weaning or from the age of 32 weeks until they were autopsied at the age 40-42, 50-52, or 57-62 weeks after exogenous ovarian stimulation. Analysis of chromosomal distribution, DNA organization and cellular morphology was performed in ovulated cumulus-enclosed and -free oocytes, ovarian non-germinal vesicle oocytes enclosed by or free of mucous cumulus cells and in vitro-matured ovarian germinal-vesicle oocytes. Both early and late onset administration of oral antioxidants counteracted the negative effects of female aging on number of ovarian oocytes and total percentage of oocytes retrieved from oviducts and ovaries exhibiting a normal distribution of chromosomes in the metaphase-II plate and/or morphological traits of apoptosis. Although both early and late onset administration of oral antioxidants can counteract the negative effects of female aging on number and quality of oocytes, transference of these results to human beings should be made with caution because of the potential side effects of high doses of vitamins on reproductive function as well as many other undesirable systemic disorders.

Comparison of antioxidative capacities and inhibitory effects on cholesterol biosynthesis of quercetin and potential metabolites

The flavonol quercetin is known to be rapidly metabolized after ingestion by enterocytes and bacteria in the intestinal tract which may influence the biological, e.g. antioxidative potency of this compound. Therefore, quercetin and several of its possible metabolites were compared with regard to their antioxidant activity and their capacity to inhibit hepatocellular cholesterol biosynthesis. Using the 2,2,-diphenylpicrylhydrazyl radical scavenger assay, all compounds with an ortho diphenolic structure acted as strong antioxidants. In contrast, in a cellular assay focusing on lipid peroxidation in cultured rat hepatocytes challenged with tert.-butylhydroperoxide only the lipophilic compounds quercetin and 3,4-dihydroxytoluene were active. Concerning the inhibition of cholesterol biosynthesis, 3,4-dihydroxytoluene surprisingly mimicked the effect of quercetin in primary rat hepatocytes, but much less so in HepG2 cells. All other metabolites were almost ineffective in both cell types. These results suggest that some of the biological functions of flavonoids detectable by in vitro assays may persist in vivo as long as comparably potent metabolites are systemically present.

Dietary catechins in relation to coronary heart disease death among postmenopausal women

Catechins, one of the major groups of flavonoids, are bioactive compounds present in a variety of plant foods and beverages. Experimental data suggest that they might prevent chronic diseases in humans. We studied whether the intake of catechins was inversely associated with the risk of coronary heart disease death in a prospective study of postmenopausal women from Iowa. Between 1986 and 1998, 767 of 34,492 participants initially free of cardiovascular diseases died from coronary heart disease. There was a strong inverse association between the intake of (+)-catechin and (-)-epicatechin and coronary heart disease death, which was somewhat attenuated after multivariate adjustment (risk ratios from lowest to highest quintile: 1.00, 0.95, 0.97, 0.77, 0.76). This inverse association was most pronounced in women at low risk of coronary heart disease (non-smokers, free of diabetes mellitus and cardiovascular diseases). A high intake of "gallates," catechins typical of tea, was not associated with coronary heart disease death. Of the major catechin sources, apples and wine were inversely associated with coronary heart disease death. Our data suggest that preventive effects might be limited to certain types of catechins, or that these are indicators of other dietary components or a healthy lifestyle in general.

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.

New flavanol derivatives from grape (Vitis vinifera) byproducts. Antioxidant aminoethylthio-flavan-3-ol conjugates from a polymeric waste fraction used as a source of flavanols

A new family of antioxidants has been obtained from a residual fraction of polymeric polyphenols of grape origin. The integral exploitation of resources is important in any sustainable production scheme. Many byproducts and residues generated by the agroindustries contain polyphenols with potential application as preventative agents against cancer and cardiovascular diseases. Among these polyphenols oligomeric proanthocyanidins are particularly significant. The polymeric forms, considered of less interest because of their astringent properties, constitute the largest portion of the biologically active plant proanthocyanidins. The new compounds described here result from the breakdown of polymeric flavanols in the presence of cysteamine and bear an amino function, which facilitates their isolation from complex mixtures by cation-exchange gels or resins. In this way, valuable antioxidant molecules can be efficiently obtained from otherwise wasted polymers. The new molecules appear to be as effective as their underivatized counterparts (flavan-3-ols) as antioxidants.

Determination of L-ascorbic acid in Lycopersicon fruits by capillary zone electrophoresis

This study shows an improved method for the determination of L-ascorbic acid (l-AA) in fruits of Lycopersicon by capillary zone electrophoresis (CZE). Two backgrounds electrolytes (BGEs) have been tested: (i) 400 mM borate at pH 8.0 and 1 x 10(-2)% hexadimethrine bromide, for the separation of Eulycopersicon subgenus species; and (ii) as in BGE(i) but supplemented with 20% (v/v) acetonitrile, for the separation of species of the Eriopersicon subgenus. The present procedures were compared with two routine methods-enzymatic assay and potentiometric titration with 2,6-dichlorophenol-indophenol. While these routine methods presented some difficulties in quantifying l-AA in several Lycopersicon fruits, CZE was successfully applied in all the analyzed samples. The proposed CZE protocols give lower detection limits (<0.4 microg ml(-1)); are cheaper, quicker, and highly reproducible; and can be applied to analyze large series of samples (ca. 50 samples per day) which is utmost importance, not only in screening trials for internal quality and tomato breeding programs, but also in systematic and routine characterization of Lycopersicon fruits.

Peroxynitrite scavenging of flavonoids: structure activity relationship

Peroxynitrite can oxidise and nitrosylate biomolecules and is associated with several diseases. The peroxynitrite scavenging of substituted phenols and several flavonoids was studied. The activity of phenol (poor scavenger) is positively influenced by electron donating substituents. A good correlation was found between the peroxynitrite scavenging activity of the substituted phenols and the Hammett σ or the E(HOMO). Flavonols containing a catechol group (3'- and 4'-OH) in ring B (rutin and monohydroxyethyl rutoside) or an AC-ring with three OH groups (3-, 5- and 7-OH) were potent scavengers. Evidence has been produced that in the AC-ring the 3-OH group was the reactive centre and that the reactivity of this group was positively influenced by electron donating groups at the 5 and/or 7 position (galangin, kaempferol, trihydroxyethyl quercetin).

A critical assessment of some biomarker approaches linked with dietary intake

In this review many examples are given of the complexities involved in using some biomarkers in relation to assessing the effects of dietary exposure, when there is frequently a need to determine changes following long-term low level exposure to dietary components. These range from understanding why the biomarker might be valuable and how best it can be measured, to the pitfalls which can occur in the interpretation of data. Analytical technique is considered in relation to folate and selenium, and flavonoid and carotenoid species are used to illustrate how the metabolism of a compound may alter the validity or adequacy of a marker. Vitamin A is discussed in relation to the difficulties which can arise when there are several biomarkers that may be available to assess exposure to one nutrient. Vitamin B12 is discussed in relation to the dietary choices made by individuals. Possible interactions and the role of measuring total antioxidant capacity is considered in some detail. In contrast to most nutrients, there is a marked lack of biomarkers of either exposure or effect for most non-nutrients. The role of biological effect monitoring is considered for dietary contaminants, fumonisins and polyhalogenated aromatic hydrocarbons. Aflatoxins are discussed to exemplify food contaminants for which the biomarker approach has been extensively studied. Finally some compounds which are deliberately added to foods and some which appear as processing contaminants are each considered briefly in relation to the requirement for a biomarker of exposure to be developed.

Comparison of quercetin and a non-orthohydroxy flavonol as antioxidants by competing in vitro oxidation reactions

Two structurally related flavonols, quercetin and morin, along with protocatechuic acid (PA), beta-resorcylic acid (DHBA), and phloroglucinol carboxylic acid (PCA), which represent quercetin and morin degradation products, were assessed with respect to their antioxidant potency by chemical comparisons in competing oxidation reactions. The measurement of the antioxidant capacity was performed with the beta-carotene bleaching method, and the compounds were also tested with respect to their abilities to prevent lipid, protein, and DNA oxidation. The effect of concentration was also considered. The results obtained strongly suggested that quercetin is a powerful antioxidant in every system used, whereas morin is a much weaker antioxidant and in some cases may also have pro-oxidant action. PA and PCA were always inferior antioxidants compared to the parent molecule quercetin; DHBA and PCA exhibited activities comparable to that of morin in reaction comparisons.

A review of latest research findings on the health promotion properties of tea

Important progress has been made in the past five years concerning the effects of green and black tea on health. Experimentation with new accurate tools provide useful information about the metabolism of tea components in the body, their mode of action as antioxidants at the cellular level and their protective role in the development of cancer, cardiovascular disease and other pathologies. The use of tea components as nutraceuticals and functional foods are also discussed.

Electrophilic methyl groups present in the diet ameliorate pathological states induced by reductive and oxidative stress: a hypothesis

Reductive stress, characterised by an increased NADH:NAD+ ratio, may be as common and as important a consequence of redox imbalance as oxidative stress. It may also be an important predisposing cause of the generation of reactive oxygen species. Considerable experimental and indirect clinical evidence suggests that protection against reductive stress depends on biomolecules with electrophilic methyl groups (EMG) such as S-adenosylmethionine, betaine, carnitine and phosphatidylcholine. Pathological processes leading to reductive stress and their relief by such protective agents is reviewed and the proposed molecular mechanism is outlined. These and other EMG-containing biomolecules are part of the daily diet and may represent an important control system for redox balance.

The importance of proteins in defense against oxidation

Free radicals are a normal feature of cellular oxygen metabolism. However, free radical-associated damage is an important factor in many pathological and toxicological processes. For a long time, lipid peroxidation, mediated by oxygen-derived free radicals, was probably the most extensively investigated process. From more recent studies, it has become evident that proteins are also the targets of free radicals, and this has important implication for their activity, unfolding, and degradation, as well as in cell functioning. After giving a brief overview of the key role of proteins in the overall antioxidant defense, this review examines their role as targets of oxidation reactions, taking into account the reactivity of amino acid residues and some of their oxidation products. In light of recent data, we then consider the specific role of sulfur-containing amino acids in protein degradation and their possible interplay with the reversal of limited oxidative lesions. The participation of proteins in the overall antioxidant defense is also discussed, specifically the role of metallothionein as an intracellular antioxidant and that of albumin as a circulating antioxidant.

Properties of tomato powders as additives for food fortification and stabilization

The antioxidant activities of two freeze-dried tomato powders as additives for food fortification and stabilization were studied. The two tomato powders were obtained from the whole fruit and from the pulp after "serum" separation, respectively. The antioxidant activity was studied by measuring (a) the inhibition of the singlet oxygen-catalyzed oxidation of alpha-linolenic acid, in the presence or absence of copper ions, as a model of the oxidative processes occurring in foods, and (b) the inhibition of xanthine oxidase (XOD)- and myeloperoxidase (MPO)-catalyzed reactions and copper-induced lipid peroxidation. The partial separation of "serum" decreased the freeze-drying time by 50%. The partially fractionated tomato powder had a 60% lower phenolic content and an 11-fold higher lycopene content than the whole tomato powder, on a dry weight basis. Ascorbic acid was almost completely removed by fractionation. Both the powder obtained from the whole tomato and that obtained from the partially fractionated tomato had antioxidant activity in all the model systems used. Based on these results, we conclude that tomato powders have multifunctional properties, which could address the prevention of oxidative degradations both in foods and in vivo. Therefore, tomato can be regarded as source of food additives for fortification and stabilization, even if it is submitted to technological processes that can cause the loss of the more labile hydrophilic antioxidants.

Flavonoids as peroxynitrite scavengers: the role of the hydroxyl groups

It has been reported that flavonoids efficiently protect against peroxynitrite toxicity. Two pharmacophores have been identified in flavonoids, namely the catechol group in ring B and the hydroxyl (OH) group at the 3-position. In this study, this structure-activity relationship was further examined. It was found that catechol (1,2-dihydroxybenzene) is a potent peroxynitrite scavenger, whereas phenol (hydroxybenzene) is not. Of the flavonols tested without a catechol group in ring B, kaempferol (OH groups at positions 3,5,7,4') and galangin (OH groups at positions 3,5,7) are also potent scavengers, whereas apigenin (OH groups at positions 5,7,4') and chrysin (OH groups at positions 5,7) are not. This confirms the importance of the OH group at the 3-position. However, the synthetic flavonol TUM 9761 and 3-hydroxyflavone (OH group only at position 3) are poor scavengers. Based on these results, the structure-activity relationship on the peroxynitrite scavenging activity of flavonols was refined. The catechol in ring B remains important. Also the 3-OH group remains important, but the activity of this pharmacophore is influenced by the substituents at position 5 and at position 7.

Skin wrinkling: can food make a difference?

OBJECTIVES

This study addressed whether food and nutrient intakes were correlated with skin wrinkling in a sun-exposed site.

METHODS

177 Greek-born subjects living in Melbourne (GRM), 69 Greek subjects living in rural Greece (GRG), 48 Anglo-Celtic Australian (ACA) elderly living in Melbourne and 159 Swedish subjects living in Sweden (SWE) participating in the International Union of Nutritional Sciences IUNS "Food Habits in Later Life" study had their dietary intakes measured and their skin assessed. Food and nutrient intakes were assessed using a validated semi-quantitative food frequency questionnaire (FFQ). Skin wrinkling was measured using a cutaneous microtopographic method.

RESULTS

SWE elderly had the least skin wrinkling in a sun-exposed site, followed by GRM, GRG and ACA. Correlation analyses on the pooled data and using the major food groups suggested that there may be less actinic skin damage with a higher intake of vegetables (r(s)=-0.31, p<0.0001), olive oil (r(s)=-0.29, p<0.0001), fish (r(s)=-0.24, p<0.0001) and legumes (r(s)=-0.16, p<0.0001), and lower intakes of butter (r(s)=0.46, p<0.0001) and margarine (r(s)=0.24, p<0.001), milk products (r(s)=0.16, p<0.01) and sugar products (r(s)=0.12, p<0.01). Similar findings were obtained using regression analyses, except fish was no longer significant; 32% of the variance for actinic skin damage was predicted by six out of the ten major food groups. In particular, a high intake of vegetables, legumes and olive oil appeared to be protective against cutaneous actinic damage (collectively explaining 20% of the variance); a high intake of meat, dairy and butter appeared to be adverse (explaining <5% of the variance). Prunes, apples and tea explained 34% of variance amongst ACA.

CONCLUSION

This study illustrates that skin wrinkling in a sun-exposed site in older people of various ethnic backgrounds may be influenced by the types of foods consumed.

Protective effects of Mangifera indica L. extract, mangiferin and selected antioxidants against TPA-induced biomolecules oxidation and peritoneal macrophage activation in mice

We compared the protective abilities of Mangifera indica L. stem bark extract (Vimang) 50-250 mgkg(-1), mangiferin 50 mgkg(-1), vitamin C 100 mgkg(-1), vitamin E 100 mgkg(-1)and beta -carotene 50 mgkg(-1)against the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced oxidative damage in serum, liver, brain as well as in the hyper-production of reactive oxygen species (ROS) by peritoneal macrophages. The treatment of mice with Vimang, vitamin E and mangiferin reduced the TPA-induced production of ROS by the peritoneal macrophages by 70, 17 and 44%, respectively. Similarly, the H(2)O(2)levels were reduced by 55-73, 37 and 40%, respectively, when compared to the control group. The TPA-induced sulfhydryl group loss in liver homogenates was attenuated by all the tested antioxidants. Vimang, mangiferin, vitamin C plus E and beta -carotene decreased TPA-induced DNA fragmentation by 46-52, 35, 42 and 17%, respectively, in hepatic tissues, and by 29-34, 22, 41 and 17%, in brain tissues. Similar results were observed in respect to lipid peroxidation in serum, in hepatic mitochondria and microsomes, and in brain homogenate supernatants. Vimang exhibited a dose-dependent inhibition of TPA-induced biomolecule oxidation and of H(2)O(2)production by peritoneal macrophages. Even if Vimang, as well as other antioxidants, provided significant protection against TPA-induced oxidative damage, the former lead to better protection when compared with the other antioxidants at the used doses. Furthermore, the results indicated that Vimang is bioavailable for some vital target organs, including liver and brain tissues, peritoneal exudate cells and serum. Therefore, we conclude that Vimang could be useful to prevent the production of ROS and the oxidative tissue damages in vivo.

Improved growth and viability of lactobacilli in the presence of Bacillus subtilis (natto), catalase, or subtilisin

In an effort to demonstrate the potential usefulness of Bacillus subtilis (natto) as a probiotic, we examined the effect of this organism on the growth of three strains of lactobacilli co-cultured aerobically in vitro. Addition of B. subtilis (natto) to the culture medium resulted in an increase in the number of viable cells of all lactobacilli tested. Since B. subtilis (natto) can produce catalase, which has been reported to exhibit a similar growth-promoting effect on lactobacilli, we also examined the effect of bovine catalase on the growth of Lactobacillus reuteri JCM 1112 and L. acidophilus JCM 1132. Both catalase and B. subtilis (natto) enhanced the growth of L. reuteri JCM 1112, whereas B. subtilis (natto) but not catalase enhanced the growth of L. acidophilus JCM 1132. In a medium containing 0.1 mM hydrogen peroxide, its toxic effect on L. reuteri JCM 1112 was abolished by catalase or B. subtilis (natto). In addition, a serine protease from B. licheniformis, subtilisin, improved the growth and viability of L. reuteri JCM 1112 and L. acidophilus JCM 1132 in the absence of hydrogen peroxide. These results indicate that B. subtilis (natto) enhances the growth and (or) viability of lactobacilli, possibly through production of catalase and subtilisin.

Mechanism of protection by the flavonoids, quercetin and rutin, against tert-butylhydroperoxide- and menadione-induced DNA single strand breaks in Caco-2 cells

Protection by the flavonoids, quercetin and rutin, against tert-butylhydroperoxide (tert-BOOH)- and menadione-induced DNA single strand breaks was investigated in Caco-2 cells. Both tert-BOOH and menadione induced DNA single strand breaks in a concentration-dependent manner. Pre-incubation of Caco-2 cells with either quercetin or rutin for 24 h significantly decreased the formation of DNA single strand breaks evoked by tert-BOOH (P <.05). Iron chelators, 1,10-phenanthroline (o-Phen) and deferoxamine mesylate (DFO), also protected against tert-BOOH-induced DNA damage, whereas butylated hydroxytoluene (BHT) had no effect. Quercetin, and not rutin, decreased the extent of menadione-induced DNA single strand breaks. DFO and BHT, and not o-Phen, protected against menadione-induced DNA strand break formation (P <.05). From the results of this study, iron ions were involved in tert-BOOH-induced DNA single strand break formation in Caco-2 cells, whereas DNA damage evoked by menadione was far more complex. We demonstrated that the flavonoids, quercetin and rutin, protected against tert-BOOH-induced DNA strand breaks by way of their metal ion chelating mechanism. However, quercetin, and not rutin, protected against menadione-induced DNA single strand breaks by acting as both a metal chelator and radical scavenger.

Probe-assisted flow cytometric analysis of erythrocyte membrane response to site-specific oxidant stress

BACKGROUND

Probe-assisted flow cytometry was used to monitor the response of membranes of living cells to oxidant stress in the presence and absence of antioxidants. Test conditions (fluorophore loading, oxidant concentration) were investigated and storage-related changes in erythrocyte response to oxidant stress explored.

METHODS

Erythrocytes were incubated with a lipophilic fluorescent probe and exposed to site-specific oxidant challenge, induced by cumene hydroperoxide, in the presence and absence of urate, ascorbate, or alpha tocopherol in physiological amounts. Fluorescence of labeled and treated erythrocytes was measured for 120 min using a Coulter EPICS Elite ESP flow cytometer.

RESULTS

Probe loading was dose and time dependent. Cumene hydroperoxide exhibited a potent and dose-dependent oxidant effect on erythrocyte membranes. Alpha tocopherol slowed, but did not prevent, membrane oxidation. Ascorbate appeared to have no effect on peroxidation initially, but then slowed and stopped propagation of membrane oxidation. The effect of urate was slight.

CONCLUSIONS

This technique can provide insight into oxidative processes at the cellular level. Results indicated that lipophilic alpha tocopherol was the most effective antioxidant in slowing membrane peroxidation, but ascorbate appears to stop chain propagation. This effect may be owing to vitamin C/E interaction. Further study is needed.