Absorption of anthocyanins from blueberries and serum antioxidant status in human subjects

Flavonoids as modulators of memory and learning: molecular interactions resulting in behavioural effects

There is considerable interest in the potential of a group of dietary-derived phytochemicals known as flavonoids in modulating neuronal function and thereby influencing memory, learning and cognitive function. The present review begins by detailing the molecular events that underlie the acquisition and consolidation of new memories in the brain in order to provide a critical background to understanding the impact of flavonoid-rich diets or pure flavonoids on memory. Data suggests that despite limited brain bioavailability, dietary supplementation with flavonoid-rich foods, such as blueberry, green tea and Ginkgo biloba lead to significant reversals of age-related deficits on spatial memory and learning. Furthermore, animal and cellular studies suggest that the mechanisms underpinning their ability to induce improvements in memory are linked to the potential of absorbed flavonoids and their metabolites to interact with and modulate critical signalling pathways, transcription factors and gene and/or protein expression which control memory and learning processes in the hippocampus; the brain structure where spatial learning occurs. Overall, current evidence suggests that human translation of these animal investigations are warranted, as are further studies, to better understand the precise cause-and-effect relationship between flavonoid intake and cognitive outputs.

Cyanidin-3-O-β-glucoside and protocatechuic acid exert insulin-like effects by upregulating PPARγ activity in human omental adipocytes

OBJECTIVE

Insulin resistance (IR) represents an independent risk factor for metabolic, cardiovascular, and neoplastic disorders. Preventing/attenuating IR is a major objective to be reached to preserve population health. Because many insulin-sensitizing drugs have shown unwanted side effects, active harmless compounds are sought after. Dietary anthocyanins have been demonstrated to ameliorate hyperglycemia and insulin sensitivity. This study aimed at investigating whether cyanidin-3-O-β-glucoside (C3G) and its metabolite protocatechuic acid (PCA) might have a role in glucose transport activation in human omental adipocytes and 3T3-L1 cells.

RESEARCH DESIGN AND METHODS

In cells treated with 50 µmol/L C3G and 100 µmol/L PCA, [(3)H]-2-deoxyglucose uptake, GLUT4 translocation by immunoblotting, adiponectin secretion, and peroxisome proliferator-activated receptor-γ (PPARγ) activation by enzyme-linked immunosorbent assay kits were evaluated. Parallel experiments were carried out in murine adipocyte 3T3-L1. To define the role of PPARγ in modulating polyphenol effects, small interfering RNA technique and PPARγ antagonist were used to inhibit transcription factor activity.

RESULTS

C3G and PCA increased adipocyte glucose uptake (P < 0.05) and GLUT4 membrane translocation (P < 0.01). Significant increases (P < 0.05) in nuclear PPARγ activity, as well as in adiponectin and GLUT4 expressions (P < 0.01), were also shown. It is interesting that PPARγ inhibition counteracted the polyphenol-induced adiponectin and GLUT4 upregulations, suggesting a direct involvement of PPARγ in this process.

CONCLUSIONS

Our study provides evidence that C3G and PCA might exert insulin-like activities by PPARγ activation, evidencing a causal relationship between this transcription factor and adiponectin and GLUT4 upregulation. Dietary polyphenols could be included in the preventive/therapeutic armory against pathological conditions associated with IR.

A high antioxidant spice blend attenuates postprandial insulin and triglyceride responses and increases some plasma measures of antioxidant activity in healthy, overweight men

There is much interest in the potential of dietary antioxidants to attenuate in vivo oxidative stress, but little characterization of the time course of plasma effects exists. Culinary spices have demonstrated potent in vitro antioxidant properties. The objective of this study was to examine whether adding 14 g of a high antioxidant spice blend to a 5060-kJ (1200 kcal) meal exerted significant postprandial effects on markers of plasma antioxidant status and metabolism. Healthy overweight men (n = 6) consumed a control and spiced meal in a randomized crossover design with 1 wk between testing sessions. Blood was sampled prior to the meal and at 30-min intervals for 3.5 h (total of 8 samples). Mixed linear models demonstrated a treatment × time interaction (P < 0.05) for insulin and TG, corresponding with 21 and 31% reductions in postprandial levels with the spiced meal, respectively. Adding spices to the meal significantly increased the ferric reducing antioxidant power, such that postprandial increases following the spiced meal were 2-fold greater than after the control meal (P = 0.009). The hydrophilic oxygen radical absorbance capacity (ORAC) of plasma also was increased by spices (P = 0.02). There were no treatment differences in glucose, total thiols, lipophilic ORAC, or total ORAC. The incorporation of spices into the diet may help normalize postprandial insulin and TG and enhance antioxidant defenses.

Effect of the daily ingestion of a purified anthocyanin extract from grape skin on rat serum antioxidant capacity

The aim of this work was to study the effect of the daily ingestion of a purified anthocyanin extract from red grape skin on rat serum antioxidant capacity (ORAC) and its safety for the intestinal epithelium. The study was carried out in rats orally administered with the extract for 10 days in either normal physiological conditions or exposed to a pro-oxidant chemical (CCl(4)). The oral administration of the extract significantly (P<0.05) enhanced the ORAC value of the deproteinised serum of about 50 % after 10 days of ingestion. Anthocyanin administration was also able to reverse completely the decrease in the serum ORAC activity induced by the CCl(4) treatment. Experiments with Ussing chamber mounted intestine allowed to exclude any toxicity of the extract for the intestinal epithelium. In conclusion, our results demonstrate that the purified anthocyanin extract from red grape skin enhances the total antioxidant capacity of the serum in either normal physiological condition or during oxidative stress induction, revealing a protective role against the decrease in the serum antioxidant capacity induced by a pro-oxidant compound.

Antioxidant potential of rat plasma by administration of freeze-dried jaboticaba peel (Myrciaria jaboticaba Vell Berg)

The effect of the intake of freeze-dried jaboticaba peel powder on the antioxidant potential of rats' blood plasma was investigated in two experiments. In the first, 35 male rats, divided into 5 groups, received 7 mg of anthocyanins/100 g of body weight, by gavage. The blood was withdrawn 0, 30, 60, and 120 min after gavage. The antioxidant capacity was evaluated in plasma by ORAC and TEAC. There was no significant difference in the plasmatic antioxidant potential among the groups. In the second experiment, 40 male rats were divided into 4 groups that consumed, respectively, 0, 1, 2, and 4% of freeze-dried jaboticaba peel powder added to their diet. An increase in the plasmatic antioxidant potential was observed for groups that received 1 and 2% of jaboticaba peel powder (1.7 times by TEAC method and 1.3 times by ORAC); however, the group that received 4% of the powder did not show antioxidant effects according to the methods used.

Comparison of metabolic profiling of cyanidin-3-O-galactoside and extracts from blueberry in aged mice

The metabonomics changes of plasma and brain tissue after dietary supplementation with blueberry extracts (BBE) and cyanidin-3-O-galactoside from blueberry (BBM) in aged mice were investigated by (1)H NMR technique. The mice received intragastric administration of BBE (200 mg/kg/day), BBM (50 mg/kg/day), and saline water (0.9%) for 6 weeks, respectively, in the BBE, BBM, and control groups. At the end of the experiment, plasma and brain samples were collected for NMR analysis. The results demonstrated that the level of choline in plasma from BBE and BBM groups were obviously elevated relative to the control group, whereas the levels of lactate and phosphocholine in plasma were remarkably reduced. Compared with those in the control group, the levels of choline and GABA in the brain from the BBE group were obviously increased, whereas glutamate and phosphocholine in the BBE group were significantly decreased. The level of taurine in the brain from the BBM group was particularly higher than that in the control group. These results indicated supplementation with BBE or BBM might induce similar changes of endogenous plasma and brain metabolic profiles in aged mice.

Anthocyanins in cardiovascular disease

Anthocyanins are a group of abundant and widely consumed flavonoid constituents that occur ubiquitously in the plant kingdom, providing the bright red-orange to blue-violet colors present in many fruit- and vegetable-based food products. Their intake has been estimated to be up to 9-fold higher than that of other dietary flavonoids. Anthocyanins have become increasingly important to the food industry as their use as natural alternatives to artificial colors has become widespread and knowledge of their health-promoting properties has become more evident. Epidemiological studies suggest that increased consumption of anthocyanins lowers the risk of cardiovascular disease (CVD), the most common cause of mortality among men and women. Anthocyanins frequently interact with other phytochemicals, exhibiting synergistic biological effects but making contributions from individual components difficult to decipher. Over the past 2 decades, many peer-reviewed publications have demonstrated that in addition to their noted in vitro antioxidant activity, anthocyanins may regulate different signaling pathways involved in the development of CVD. This review summarizes the latest developments on the bioavailability/bioactivity and CVD preventative activities of anthocyanins, including results from in vitro cell culture and in vivo animal model systems as related to their multiple proposed mechanisms of action. Limited yet promising data from epidemiological studies and human clinical trials are also presented. Future studies aimed at enhancing the absorption of anthocyanins and characterizing their metabolic and/or breakdown products are necessary to ultimately evaluate their use for protection/prevention against the development of CVD.

Strawberries decrease atherosclerotic markers in subjects with metabolic syndrome

Strawberries have been reported to be potent antioxidants and reduce cardiovascular risk factors, such as elevated blood pressure, hyperglycemia, dyslipidemia, and inflammation in limited studies. We hypothesized that freeze-dried strawberry supplementation will improve blood pressure, impaired glucose, dyslipidemia, or circulating adhesion molecules in obese subjects with metabolic syndrome, thereby lowering cardiovascular risk factors in these subjects. Twenty-seven subjects with metabolic syndrome (2 males and 25 females; body mass index, 37.5 +/- 2.15 kg/m(2); age, 47.0 +/- 3.0 years [means +/- SE]) consumed 4 cups of freeze-dried strawberry beverage (50 g freeze-dried strawberries approximately 3 cups fresh strawberries) or equivalent amounts of fluids (controls, 4 cups of water) daily for 8 weeks in a randomized controlled trial. Anthropometrics and blood pressure measurements, assessment of dietary intakes, and fasting blood draws were conducted at screen and 8 weeks of the study. Strawberry supplementation significantly decreased total and low-density lipoprotein cholesterol (5.8 +/- 0.2 to 5.2 +/- 0.2 mmol/L and 3.5 +/- 0.2 to 3.1 +/- 0.1 mmol/L, respectively [means +/- SE], P < .05) and small low-density lipoprotein particles using nuclear magnetic resonance-determined lipoprotein subclass profile vs controls at 8 weeks (794.6 +/- 94.0 to 681.8 +/- 86.0 nmol/L [means +/- SE], P < .05). Strawberry supplementation further decreased circulating levels of vascular cell adhesion molecule-1 vs controls at 8 weeks (272.7 +/- 17.4 to 223.0 +/- 14.0 ng/mL [means +/- SE], P < .05). Serum glucose, triglycerides, high-density lipoprotein cholesterol, blood pressure, and waist circumference were not affected. Thus, short-term freeze-dried strawberry supplementation improved selected atherosclerotic risk factors, including dyslipidemia and circulating adhesion molecules in subjects with metabolic syndrome, and these results need confirmation in future trials.

Plant phenolics: extraction, analysis and their antioxidant and anticancer properties

Phenolics are broadly distributed in the plant kingdom and are the most abundant secondary metabolites of plants. Plant polyphenols have drawn increasing attention due to their potent antioxidant properties and their marked effects in the prevention of various oxidative stress associated diseases such as cancer. In the last few years, the identification and development of phenolic compounds or extracts from different plants has become a major area of health- and medical-related research. This review provides an updated and comprehensive overview on phenolic extraction, purification, analysis and quantification as well as their antioxidant properties. Furthermore, the anticancer effects of phenolics in-vitro and in-vivo animal models are viewed, including recent human intervention studies. Finally, possible mechanisms of action involving antioxidant and pro-oxidant activity as well as interference with cellular functions are discussed.

Preliminary studies on the antinociceptive activity of Vaccinium ashei berry in experimental animal models

The aim of this study was to carry out pharmacological screening in order to evaluate the potential effects of lyophilized fruits of different cultivars of Vaccinium ashei Reade (Family Ericaceae) berries, commonly known as rabbiteye blueberries, on nociception. This was achieved using the formalin, hot plate, tail-flick, and writhing tests in mice. During this experiment the mice consumed approximately 3.2-6.4 mg/kg/day (p.o.) of the anthocyanins. The extract was administered for 21 days or 60 minutes before test. Morphine and diclofenac (10 mg/kg, p.o.) as the standard drug (positive control) and water (via oral gavage) as the negative control were administered before all tests. The blueberry extract produced a significant decrease in constrictions induced by acetic acid and caused graded inhibition of the second phase of formalin-induced pain. Moreover, in both the hot plate and tail-flick tests, it significantly increased the threshold. These data suggest that the extract from V. ashei produced antinociceptive effects, as demonstrated in the experimental models of nociception in mice. Additional experiments are necessary in order to clarify the true target for the antinociceptive effects of rabbiteye blueberry extract.

Bioavailability of dietary flavonoids and phenolic compounds

This paper reviews recent human studies on the bioavailability of dietary flavonoids and related compounds, including chlorogenic acids and ellagitannins, in which the identification of metabolites, catabolites and parent compounds in plasma, urine and ileal fluid was based on mass spectrometric methodology. Compounds absorbed in the small intestine appear in the circulatory system predominantly as glucuronide, sulfate and methylated metabolites which seemingly are treated by the body as xenobiotics as they are rapidly removed from the bloodstream. As a consequence, while analysis of plasma provides valuable information on the identity and pharmacokinetic profiles of circulating metabolites after acute supplementation, it does not provide accurate quantitative assessments of uptake from the gastrointestinal tract. Urinary excretion, of which there are great variations with different classes of flavonoids, provides a more realistic figure but, as this does not include the possibility of metabolites being sequestered in body tissues, this too is an under estimate of absorption, but to what degree remains to be determined. Even when absorption occurs in the small intestine, feeding studies with ileostomists reveal that substantial amounts of the parent compounds and some of their metabolites appear in ileal fluid indicating that in volunteers with a functioning colon these compounds will pass to the large intestine where they are subjected to the action of the colonic microflora. A diversity of colonic-derived catabolites is absorbed into the bloodstream and passes through the body prior to excretion in urine. There is growing evidence that these compounds, which were little investigated until recently, are produced in quantity in the colon and form a key part of the bioavailability equation of dietary flavonoids and related phenolic compounds.

Phytochemicals of cranberries and cranberry products: characterization, potential health effects, and processing stability

Emerging evidence is elucidating how non-nutrient phytochemicals underlie the health promotion afforded by fruits and vegetables. This review focuses on Vaccinium macrocarpon, the American cranberry, compiling a comprehensive list of its known phytochemical components, and detailing their prevalence in cranberry fruit and its products. Flavonoids, especially colored anthocyanins, abundant flavonols, and unique proanthocyanidins, have attracted major research attention. Other notable active components include phenolic acids, benzoates, hydroxycinnamic acids, terpenes and organic acids. Health effects of cranberries, cranberry products, and isolated cranberry components in humans and animals, as well as in vitro, are debated. Evidence for protection from several bacterial pathogens, cancer, cardiovascular disease, and inflammation is compelling, while neuroprotection and anti-viral activity also have begun to draw new consideration. Emerging bioavailability data is considered and potential molecular mechanisms are evaluated, linking phytochemicals to health effects through their biochemical properties and reactions. Finally, the effects of processing and storage on cranberry phytochemicals is discussed, with a focus on identifying research gaps and novel means to preserve their natural, health-promoting components.

Berries: emerging impact on cardiovascular health

Berries are a good source of polyphenols, especially anthocyanins, micronutrients, and fiber. In epidemiological and clinical studies, these constituents have been associated with improved cardiovascular risk profiles. Human intervention studies using chokeberries, cranberries, blueberries, and strawberries (either fresh, or as juice, or freeze-dried), or purified anthocyanin extracts have demonstrated significant improvements in LDL oxidation, lipid peroxidation, total plasma antioxidant capacity, dyslipidemia, and glucose metabolism. Benefits were seen in healthy subjects and in those with existing metabolic risk factors. Underlying mechanisms for these beneficial effects are believed to include upregulation of endothelial nitric oxide synthase, decreased activities of carbohydrate digestive enzymes, decreased oxidative stress, and inhibition of inflammatory gene expression and foam cell formation. Though limited, these data support the recommendation of berries as an essential fruit group in a heart-healthy diet.

Flavonoid transport across RBE4 cells: A blood-brain barrier model

There is a growing interest in dietary therapeutic strategies to combat oxidative stress-induced damage to the Central Nervous System (CNS), which is associated with a number of pathophysiological processes, including Alzheimer's and Parkinson's diseases and cerebrovascular diseases. Identifying the mechanisms associated with phenolic neuroprotection has been delayed by the lack of information concerning the ability of these compounds to enter the CNS. The aim of this study was to evaluate the transmembrane transport of flavonoids across RBE-4 cells (an immortalized cell line of rat cerebral capillary endothelial cells) and the effect of ethanol on this transport. The detection and quantification of all of the phenolic compounds in the studied samples (basolateral media) was performed using a HPLC-DAD (Diode Array Detector). All of the tested flavonoids (catechin, quercetin and cyanidin-3-glucoside) passed across the RBE-4 cells in a time-dependent manner. This transport was not influenced by the presence of 0.1% ethanol. In conclusion, the tested flavonoids were capable of crossing this blood-brain barrier model.

Bioavailability of strawberry antioxidants in human subjects

Strawberries contain many antioxidant phytochemicals such as vitamin C, carotenoids and phenolic compounds including anthocyanins (ACN). In the present study, antioxidant composition of fresh strawberries (FS) and stored strawberries (SS) and the bioavailability of the main strawberry bioactive compounds were determined in human subjects. Thirteen healthy volunteers consumed 300 g of FS and SS on two separate occasions. Blood, before and at different time points from meal consumption, as well as 24 h urine, was collected, and parent compounds and metabolites of the different compounds were determined by HPLC or LC/MS/MS. A reduction in α-carotene plasma concentrationsv.baseline values was recorded after the consumption of FS, although the amount of this carotenoid was higher in the SS. On the contrary, a significant increase of plasma vitamin C after 2, 3 and 5 h (P < 0·05) of FS and SS consumption was recorded. No quercetin and ACN were found in plasma, while coumaric acid, 4-hydroxybenzoic acid (4HBA, 56 and 54 % of pelargonidin-3-glucoside (Pel-glc) ingested with FS and SS, respectively) and protocatechuic acid (59 and 34 % of cyanidin-3-glucoside ingested with FS and SS, respectively) over 8 h from strawberry consumption were retrieved in the plasma. Pelargonidin glucuronide, pelargonidin glucoside and pelargonidin aglycone peaked in urine within 2 h of strawberry consumption, and the 24 h amount excreted was always approximately 0·9 % of the Pel-glc dose ingested. The data indicated that the content of phytochemicals in strawberries may influence the bioavailability of individual compounds. Furthermore, in the present study, the metabolism of Pel-glc was elucidated, and, for the first time, 4HBA was suggested to be a major human metabolite of Pel-glc.

Raspberries and human health: a review

Dietary guidelines around the world recommend the increased consumption of fruits and vegetables as good sources of antioxidant phytochemicals for the prevention of chronic diseases. Red raspberries are a common and important fruit in the Western diet due to their content of essential nutrients and beneficial phytochemicals. Anthocyanins and ellagitannins are polyphenolic compounds and the major antioxidant phytochemicals present in raspberries. Whereas individual phytochemical constituents of raspberries have been studied for their biological activities, human intervention studies using whole berries are lacking in the literature. The nutritional and phytochemical compositions of red raspberries and their absorption, metabolism, and biological activity are reviewed. Finally, future directions of research are also identified.

Bioavailability of various polyphenols from a diet containing moderate amounts of berries

Berries are a rich source of various polyphenols. The objective of this study was to investigate the bioavailability of polyphenols from berries. Middle-aged subjects (n = 72) consumed moderate amounts of berry or control products for 8 weeks in a randomized, placebo-controlled dietary intervention trial. Average intake of berries was 160 g/day (bilberries, lingonberries, black currants, and chokeberries). Plasma and urine polyphenols were analyzed by GC-MS and HPLC and berry polyphenols by HPLC. The total intake of polyphenols was 837 mg/day. Plasma quercetin, p-coumaric acid, 3-hydroxyphenylacetic acid, caffeic acid, protocatechuic acid, vanillic acid, homovanillic acid, and 3-(3-hydroxyphenyl)propionic acid increased significantly from the baseline in the berry group compared to the control group (p < 0.05). The urinary excretion of quercetin, p-coumaric acid, and 3-hydroxyphenylacetic acid increased significantly in the berry group compared to the control group (p < 0.05). In conclusion, a number of polyphenols are bioavailable from a diet containing moderate amounts of blue and red berries.

Dietary anthocyanin-rich bilberry extract ameliorates hyperglycemia and insulin sensitivity via activation of AMP-activated protein kinase in diabetic mice

Blueberries or bilberries contain large amounts of anthocyanins, making them one of the richest sources of dietary anthocyanin. These berries are widely consumed as fresh and dried fruits, jams, or juices. Considerable attention has been focused on the health benefits of bilberry fruits beyond their antioxidant content or their ability to improve vision. In this study, we tested the effect of dietary bilberry extract (BBE) on hyperglycemia and insulin sensitivity in type 2 diabetic mice. We found that dietary BBE ameliorates hyperglycemia and insulin sensitivity via activation of AMP-activated protein kinase (AMPK). Dietary BBE significantly reduced the blood glucose concentration and enhanced insulin sensitivity. AMPK was activated in white adipose tissue (WAT), skeletal muscle, and the liver of diabetic mice fed BBE. This activation was accompanied by upregulation of glucose transporter 4 in WAT and skeletal muscle and suppression of glucose production and lipid content in the liver. At the same time, acetyl-CoA carboxylase was inactivated and PPARalpha, acyl-CoA oxidase, and carnitine palmitoyltransferase-1A were upregulated in the liver. These changes resulted in improved hyperglycemia and insulin sensitivity in type 2 diabetes. These findings provide a biochemical basis for the use of bilberry fruits and have important implications for the prevention and treatment of type 2 diabetes via activation of AMPK.

Anthocyanin absorption, metabolism, and distribution from a wild blueberry-enriched diet (Vaccinium angustifolium) is affected by diet duration in the Sprague-Dawley rat

The effect of wild blueberry consumption on anthocyanin (ACNs) distribution and metabolism in Sprague-Dawley (SD) rats was investigated. Thirty-two rats were fed for 4 or 8 weeks with a control (C) or a wild blueberry-enriched diet (8%) (WB). Anthocyanin profile in plasma, urine, feces, brain, and liver was evaluated by LC-MS/MS, and significantly increased in urine and not in feces after 8 weeks on the WB diet compared to that in 4 weeks, but no anthocyanins were detected in plasma, liver, and brain samples either in the C or WB groups. Metabolites of ACNs were detected in the plasma, urine, feces, and tissues of both the C and WB groups, but the urinary excretion of hippuric acid increased significantly after 4 and 8 weeks of WB consumption. Thus, it seems that ACNs are metabolized by the intestinal microflora to respective phenyl-alkyl acids, which can be further metabolized to benzoic acid. In conclusion, ACNs are bioavailable in rats, and the extent of their metabolism and excretion is based on diet duration. Additionally, urinary hippuric acid content could represent a potential biomarker of ACNs absorption and metabolism in the SD rat under the present experimental conditions.

Anti-inflammatory and antinociceptive properties of blueberry extract (Vaccinium corymbosum)

Blueberries are among the edible fruits that are recognized best for their potential health benefits. The crude extract from Vaccinium corymbosum was assessed in anti-inflammatory and antinociceptive models. The crude hydroalcoholic extract was administered orally at doses of 100, 200 or 300 mg kg−1 for all the assays. In the carrageenan test, the crude extract reduced rat paw oedema by 9.8, 28.5 and 65.9%, respectively. For the histamine assay, the reductions of oedema were 70.1, 71.7 and 81.9%, respectively. In the myeloperoxidase (MPO) assay, 300 mg kg−1 crude extract produced a significant inhibition of the MPO activity, at 6 h and 24 h after injection of carrageenan, by 42.8 and 46.2%, respectively. With the granulomatous tissue assay dexamethasone displayed significant activity, whereas the blueberry extract was inactive. For the abdominal constriction test, inhibitions of 49.0, 54.5, 53.5%, respectively, were observed for the crude extract, and 61.4% for indometacin. In the formalin test, the crude extract (200 and 300 mg kg−1) and indometacin inhibited only the second phase by 36.2, 35.3 and 45.8%, respectively. Considering that the crude extract of blueberry displayed antinociceptive and anti-inflammatory activity, its consumption may be helpful for the treatment of inflammatory disorders.

Absorption of anthocyanins through intestinal epithelial cells - Putative involvement of GLUT2

Anthocyanins bioavailability is a major issue regarding their biological effects and remains unclear due to few data available on this matter. This work aimed to evaluate the absorption of anthocyanins at the intestine using Caco-2 cells. Anthocyanin extract, rich in malvidin-3-glucoside, was obtained from red grape skins and tested on Caco-2 cells. The absorption of anthocyanins, in absence or presence of 1% ethanol, was detected by HPLC/DAD/LC-MS. Our results showed that this transport was significantly increased in the presence of ethanol especially after 60 min of incubation. In addition, cells that were pretreated for 96 h with anthocyanins (200 microg/mL) showed an increase of their own transport (about 50% increase). Expression of glucose transporters sodium-dependent glucose transporter 1, facilitative glucose transporters 5, and facilitative glucose transporters 2 was assessed by RT-PCR. It was found that facilitative glucose transporters 2 expression was increased (60%) in Caco-2 cells pretreated with anthocyanins, by comparison with controls. When the effect of anthocyanin extract on (3)H-2-deoxy-D-glucose uptake was tested, an inhibitory effect was observed (about 60% decrease). However, the malvidin aglycone was tested and had no effect. In conclusion, anthocyanins could be absorbed through Caco-2 cells, and can interfere with their own transport and also with glucose intestinal uptake.

Effect of a blueberry nutritional supplement on macronutrients, food group intake, and plasma vitamin E and vitamin C in US athletes

Antioxidants from a blueberry beverage may impact plasma vitamins. We examined vitamins/food selection in 12 college athletes during 30 days compared with placebo. Blood was collected before and after exercise at the beginning of the study (day 1) and then after a 30-day period of taking a daily supplemental beverage (day 30). The six trials involved blood that was drawn pre-beverage ingestion/pre-exercise (trials 1 and 4), post-beverage ingestion/pre-exercise (trials 2 and 5), and post-beverage ingestion/1 h post-exercise (trials 3 and 6), on day 1 (trials 1, 2, and 3) and day 30 (trials 4, 5, and 6). Analysis of variance revealed non-significant differences for macronutrient or gamma-tocopherol and vitamin C intakes by food frequency questionnaire or plasma vitamins by liquid chromatography. There was a trend (P = 0.083) in the group x time interaction for alpha-tocopherol intake by repeated-measures analysis of variance. Blueberry alpha-tocopherol (23.91 +/- 9.31 mg) was significantly (P < 0.05) higher than placebo alpha-tocopherol intake (7.59 +/- 0.95 mg) on day 1, but not on day 30 (blueberry, alpha-tocopherol = 9.04 +/- 2.35 mg, placebo, alpha-tocopherol = 11.46 +/- 3.65 mg) by pairwise comparisons. Blueberry supplementation did not affect plasma vitamin concentrations or gamma-tocopherol and vitamin C intakes, and may reduce alpha-tocopherol intake in those starting with a higher alpha-tocopherol intake, yet not altering athletes' eating habits.

Short-term blackcurrant extract consumption modulates exercise-induced oxidative stress and lipopolysaccharide-stimulated inflammatory responses

Exercise-induced oxidative stress is instrumental in achieving the health benefits from regular exercise. Therefore, inappropriate use of fruit-derived products (commonly applied as prophalytic antioxidants) may counteract the positive effects of exercise. Using human exercise and cellular models we found that 1) blackcurrant supplementation suppressed exercise-induced oxidative stress, e.g., plasma carbonyls (0.9 ± 0.1 vs. 0.6 ± 0.1 nmol/mg protein, placebo vs. blackcurrant), and 2) preincubation of THP-1 cells with an anthocyanin-rich blackcurrant extract inhibited LPS-stimulated cytokine secretion [TNF-α (16,453 ± 322 vs. 10,941 ± 82 pg/ml, control vs. extract, P < 0.05) and IL-6 (476 ± 14 vs. 326 ± 32 pg/ml, control vs. extract, P < 0.05)] and NF-κB activation. In addition to its antioxidant and anti-inflammatory properties, we found that postexercise plasma collected after blackcurrant supplementation enhanced the differential temporal LPS-stimulated inflammatory response in THP-1 cells, resulting in an early suppression of TNF-α (1,741 ± 32 vs. 1,312 ± 42 pg/ml, placebo vs. blackcurrant, P < 0.05) and IL-6 (44 ± 5 vs. 36 ± 3 pg/ml, placebo vs. blackcurrant, P < 0.05) secretion after 24 h. Furthermore, by using an oxidative stress cell model, we found that preincubation of THP-1 cells with hydrogen peroxide (H2O2) prior to extract exposure caused a greater suppression of LPS-stimulated cytokine secretion after 24 h, which was not evident when cells were simultaneously incubated with H2O2 and the extract. In summary, our findings support the concept that consumption of blackcurrant anthocyanins alleviate oxidative stress, and may, if given at the appropriate amount and time, complement the ability of exercise to enhance immune responsiveness to potential pathogens.

Anthocyanin stability and recovery: implications for the analysis of clinical and experimental samples

The proportion of ingested anthocyanins to reach the systemic circulation is reported to be a small percentage of their ingested dose. This may be due to physiochemical degradation in vivo or following routine sample treatment. Therefore, this study aimed to quantitatively investigate the effect of anthocyanin structure on their stability under simulated (in vitro) physiological conditions and to assess their degradation and recovery following routine preanalytical sample extraction and storage. It was demonstrated that B-ring hydroxylation mediated the degradation of anthocyanins to their phenolic acid and aldehyde constituents, successful anthocyanin extraction is dependent on both sample preparation technique and anthocyanin structure, and anthocyanins are stable through multiple freeze-thaw cycles. These data indicate that significant portions of ingested anthocyanins are likely to degrade to phenolic acids and aldehyde in vivo. Consequently, these compounds should be the target of future bioavailability and bioactivity studies to establish the true occurrence and impact of anthocyanins on human health.

Effect of Vaccinium myrtillus and its polyphenols on angiotensin-converting enzyme activity in human endothelial cells

This study investigates if the connection between Vaccinium myrtillus and angiotensin-converting enzyme (ACE) might be an explanation of the pharmacological effects on circulation. Cultured endothelial cells from human umbilical veins were incubated with bilberry 25E extract. The main anthocyanidins combined in myrtillin chloride and separately in cyanidin, delphinidin, and malvidin, respectively, were examined concerning their effects on ACE. After 10 min of incubation with bilberry 25E, a significant, dose-dependent inhibition of ACE activity was seen, and after incubation with myrtillin chloride a significant inhibition was seen. No effect was seen with the anthocyanidins. The effect seems to be dependent on this specific mixture of anthocyanins in the bilberry. V. myrtillus may thus have the potential to prevent and protect against cardiovascular diseases.

Antioxidant activity of blueberry fruit is impaired by association with milk

The antioxidant properties of dietary phenolics are believed to be reduced in vivo because of their affinity for proteins. In this study we assessed the bioavailability of phenolics and the in vivo plasma antioxidant capacity after the consumption of blueberries (Vaccinium corymbosum L.) with and without milk. In a crossover design, 11 healthy human volunteers consumed either (a) 200 g of blueberries plus 200 ml of water or (b) 200 g of blueberries plus 200 ml of whole milk. Venous samples were collected at baseline and at 1, 2, and 5 h postconsumption. Ingestion of blueberries increased plasma levels of reducing and chain-breaking potential (+6.1%, p<0.001; +11.1%, p<0.05) and enhanced plasma concentrations of caffeic and ferulic acid. When blueberries and milk were ingested there was no increase in plasma antioxidant capacity. There was a reduction in the peak plasma concentrations of caffeic and ferulic acid (-49.7%, p<0.001, and -19.8%, p<0.05, respectively) as well as the overall absorption (AUC) of caffeic acid (p<0.001). The ingestion of blueberries in association with milk, thus, impairs the in vivo antioxidant properties of blueberries and reduces the absorption of caffeic acid.

Dietary protection against free radicals: a case for multiple testing to establish structure-activity relationships for antioxidant potential of anthocyanic plant species

DNA damage by reactive species is associated with susceptibility to chronic human degenerative disorders. Anthocyanins are naturally occurring antioxidants, that may prevent or reverse such damage. There is considerable interest in anthocyanic food plants as good dietary sources, with the potential for reducing susceptibility to chronic disease. While structure-activity relationships have provided guidelines on molecular structure in relation to free hydroxyl-radical scavenging, this may not cover the situation in food plants where the anthocyanins are part of a complex mixture, and may be part of complex structures, including anthocyanic vacuolar inclusions (AVIs). Additionally, new analytical methods have revealed new structures in previously-studied materials. We have compared the antioxidant activities of extracts from six anthocyanin-rich edible plants (red cabbage, red lettuce, blueberries, pansies, purple sweetpotato skin, purple sweetpotato flesh and Maori potato flesh) using three chemical assays (DPPH, TRAP and ORAC), and the in vitro Comet assay. Extracts from the flowering plant, lisianthus, were used for comparison. The extracts showed differential effects in the chemical assays, suggesting that closely related structures have different affinities to scavenge different reactive species. Integration of anthocyanins to an AVI led to more sustained radical scavenging activity as compared with the free anthocyanin. All but the red lettuce extract could reduce endogenous DNA damage in HT-29 colon cancer cells. However, while extracts from purple sweetpotato skin and flesh, Maori potato and pansies, protected cells against subsequent challenge by hydrogen peroxide at 0 degrees C, red cabbage extracts were pro-oxidant, while other extracts had no effect. When the peroxide challenge was at 37 degrees C, all of the extracts appeared pro-oxidant. Maori potato extract, consistently the weakest antioxidant in all the chemical assays, was more effective in the Comet assays. These results highlight the dangers of generalising to potential health benefits, based solely on identification of high anthocyanic content in plants, results of a single antioxidant assay and traditional approaches to structure activity relationships. Subsequent studies might usefully consider complex mixtures and a battery of assays.

Anthocyanins and their metabolites are weak inhibitors of cytochrome P450 3A4

The cytochrome P450 enzyme cytochrome P450 3A4 (CYP3A4) controls the metabolism of about 60% of all drugs, and its inhibition may dramatically affect drug safety. Modulation of cytochrome P450 activity has been observed by constituents of fruit extracts including several flavonoids. The present investigation addresses CYP3A4 inhibition by anthocyanins, their aglycons, proanthocyanidins, and phenolic metabolites using a chemiluminescent assay. Test compounds inhibited CYP3A4 activity in a concentration-dependent manner featuring IC(50) values from 12.2 up to 7,842 microM. In the order of decreasing effect size, anthocyanidins were followed by anthocyanins, proanthocyanidins, and phenolic acids. When compared to earlier data on furanocoumarins from grapefruit extract, the inhibitory activity of tested anthocyanins, and anthocyanidins was shown to be about 10,000-fold weaker, and was negligible for phenolic acids (>100 000-fold weaker). Future studies are invited to address effects of the above flavonoids on other CYP isoforms for more detailed toxicity profiles.

Antioxidant status in humans after consumption of blackberry (Rubus fruticosus L.) juices with and without defatted milk

The present study was designed to evaluate the possible effect of the consumption of blackberry juices (BJ) prepared with water (BJW) and defatted milk (BJM) on the plasma antioxidant capacity and the enzymatic and nonenzymatic antioxidants. A significant (p < 0.05) increase in the ascorbic acid content in the plasma was observed after intake of both BJs. However, no changes were observed in the plasma urate and alpha-tocopherol levels. An increase on the plasma antioxidant capacity, by ORAC assay, was observed only after consumption of BJW but not statistically significant. Plasma antioxidant capacity had a good positive correlation with ascorbic acid (r = 0.93) and a negative correlation with urate level (r = -0.79). No correlation was observed between antioxidant capacity and total cyanidin or total ellagic acid contents. Further, it was observed that plasma catalase increased following intake of BJ's. No change was observed on the plasma and erythrocyte CAT and glutathione peroxidase activities. A significant decrease (p < 0.05) in the urinary antioxidant capacity between 1 and 4 h after intake of both BJs was observed. A good correlation was observed between total antioxidant capacity and urate and total cyanidin levels. These results suggested association between anthocyanin levels and CAT and a good correlation between antioxidant capacity and ascorbic acid in the human plasma after intake of BJs. Follow-up studies investigating the antioxidant properties and health benefits are necessary to demonstrate the health benefits of polyphenols.

Effect of a polyphenol-rich wild blueberry extract on cognitive performance of mice, brain antioxidant markers and acetylcholinesterase activity

The aim of this study was to examine the effect of a polyphenol-rich extract (PrB) of Vaccinium angustifolium (wild blueberries) introduced intraperitoneally (i.p.) at 30 (PrB30) and 60 (PrB60) mg/kg body weight for 7 days, on cognitive performance, brain oxidative status and acetylcholinesterase activity in adult, male, 3-4-month-old Balb-c mice. Evaluation of rodent learning and memory was assessed by a step-through test on day 6 after a double training and an initial acquisition trial on day 5. Antioxidant status was determined by ferric reducing antioxidant power (FRAP), ascorbic acid concentration (FRASC), malondialdehyde and reduced glutathione levels in whole brain homogenates. Acetylcholinesterase (AChE) activity was determined by Ellman's colorimetric method. Results showed that the PrB60-treated mice exhibited a significant improvement in learning and memory (step-through latency time of 228+/-38 s compared to 101+/-32 s of the control group). PrB extract administration also resulted in reduced lipid peroxidation products (38 and 79%) and higher brain ascorbic acid levels (21 and 64%) in both PrB30 and PrB60-treated groups, respectively, and higher glutathione levels (28%) in the PrB60-treated group. Furthermore, salt- and detergent soluble AChE activity significantly decreased in both PrB-treated groups. Thus, the significant cognitive enhancement observed in adult mice after short-term i.p. supplementation with the blueberry extract concentrated in polyphenols, is closely related to higher brain antioxidant properties and inhibition of AChE activity. These findings stress the critical impact of wild blueberry bioactive components on brain function.

Stability of anthocyanins from commercial black currant juice under simulated gastrointestinal digestion

Anthocyanins are effective antioxidants but they have also been proposed to have other biological activities independent of their antioxidant capacities that produce health benefits. Examples range from inhibition of cancer cell growth in vitro, induction of insulin production in isolated pancreatic cells, reduction of starch digestion through inhibition of a-glucosidase activity, suppression of inflammatory responses as well as protection against age-related declines in cognitive behavior and neuronal dysfunction in the central nervous system. However, to achieve any biological effect in a specific tissue or organ, anthocyanins must be bioavailable; i.e. effectively absorbed from the gastrointestinal tract (GIT) into the circulation and delivered to the appropriate location within the body. In this study, we assess the stability of anthocyanins from commercial Black currant (Ribes nigrum L.) juice using an in vitro digestion procedure that mimics the physiochemical and biochemical conditions encountered in the gastrointestinal tract (GIT). The main objective of this work was the evaluation of stability of anthocyanins during in vitro digestion in gastric and intestinal fluid regarding whether appropriate enzyme (pepsin or pancreatin) was added or not. Anthocyanins present in commercial black currant juice remain stable during in vitro digestion in gastric fluid regardless whether pepsin was added into the medium or not. Also, they remain stable during in vitro digestion in simulated intestinal fluid without pancreatin. The stability studies of anthocyanins in the intestinal fluid containing pancreatin indicated reduced stability, which also mainly contribute to slight reduction of total anthocyanins content (-1.83%) in commercial black currant juice.