Nanoencapsulation in low-molecular-weight chitosan improves in vivo antioxidant potential of black carrot anthocyanin

BACKGROUND

Anthocyanins are flavonoids that are potential antioxidant, anti-inflammatory, anti-obesity, and anti-carcinogenic nutraceutical ingredients. However, low chemical stability and low bioavailability limit the use of anthocyanins in food. Nanoencapsulation using biopolymers is a recent successful strategy for stabilization of anthocyanins. This study reports the development, characterization, and antioxidant activity of black carrot anthocyanin-loaded chitosan nanoparticles (ACNPs).

RESULTS

The ionic gelation technique yielded the ACNPs. The mean hydrodynamic diameter d and polydispersity index PDI of chitosan nanoparticles and ACNPs were found to be d = 455 nm and PDI = 0.542 respectively for chitosan nanoparticles and d = 274 nm and PDI = 0.376 respectively for ACNPs. The size distribution was bimodal. The surface topography revealed that the ACNPs are spherical and display a coacervate structure. Fourier transform infrared analysis revealed physicochemical interactions of anthocyanins with chitosan. The loading process could achieve an encapsulation efficiency of 70%. The flow behavior index η of encapsulated ACNPs samples revealed Newtonian and shear thickening characteristics. There was a marginal reduction in the in vitro antioxidant potential of anthocyanins after nanoencapsulation, as evidenced from 2,2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assays. Interestingly, the in vivo antioxidant potential of anthocyanins improved following nanoencapsulation, as observed in the serum antioxidant assays.

CONCLUSION

The optimized nanoencapsulation process resulted in spherical nanoparticles with appreciable encapsulation efficiency. The nanoencapsulation process improved the in vivo antioxidant activity of anthocyanins, indicating enhanced stability and bioavailability. The promising antioxidant activity of the ACNPs suggests a potential for utilization as a nutraceutical supplement. © 2021 Society of Chemical Industry.

Sweetener influences plasma concentration of flavonoids in humans after an acute intake of a new (poly)phenol-rich beverage

BACKGROUND AND AIM

The overconsumption of sucrose is closely related to sugar-sweetened beverages and one of the main factors associated with the increase of metabolic diseases, such as type 2 diabetes, obesity, and insulin resistance. So, the addition of alternative sweeteners to new fruit-based drinks could contribute to minimizing the incidence or severity of these pathologies. Nevertheless, current knowledge on the influence of these additives on the bioactive compounds present in these beverages is still scarce.new-onset hypertension, but few data were published in Asian. We aimed to investigate the association of lipid profiles with new-onset hypertension in a Chinese community-based non-hypertensive cohort without lipid-lowering treatment (n = 1802).

METHODS AND RESULTS

Hence, to contribute to the understanding of this issue, the plasma concentration of phenolic compounds (anthocyanins and flavanones), after the ingestion of a new maqui-citrus-based beverage, supplemented with sucrose (natural high caloric), stevia (natural non-caloric), or sucralose (artificial non-caloric), was evaluated as evidence of their intestinal absorption and metabolism previous to renal excretion. The beverages were ingested by volunteers (n = 20) and the resulting phenolic metabolites in plasma were analyzed by UHPLC-ESI-MS/MS. A total of 13 metabolites were detected: caffeic acid sulfate, caffeic acid glucuronide, 3,4-dihydroxyfenylacetic, 3,4-dihydroxyfenylacetic sulfate. 3,4-dihydroxyfenylacetic acid di-sulfate, 3,4-dihydroxyfenylacetic di-glucuronide, 3,4-dihydroxyfenylacetic glucuronide-sulfate, trans-ferulic acid glucuronide, naringenin glucuronide, vanillic acid, vanillic acid sulfate, vanillic acid glucuronide-sulfate, and vanillic acid di-glucuronide, being recorded their maximum concentration after 30-60 min.

CONCLUSION

In general, sucralose provided the greatest absorption value for most of these metabolites, followed by stevia. Due to this, the present study proposes sucralose and stevia (non-caloric sweeteners) as valuable alternatives to sucrose (high caloric sweetener), to avoid the augmented risk of several metabolic disorders.

The Blood-Cerebrospinal Fluid Barrier Is Selective for Red Cabbage Anthocyanins and Their Metabolites

The study aim was to determine whether strongly bioactive hydrophilic red cabbage anthocyanins possess the ability to cross the blood-cerebrospinal fluid barrier (blood-CSF barrier) and whether there is a selectivity of this barrier toward these compounds. To fulfill objectives, red cabbage preparation, containing nonacylated and acylated anthocyanins, was administered to 16 sheep with implanted cannulas into the brain third ventricle, and next, within 10 h, blood, urine, and the cerebrospinal fluid (CSF) were collected and analyzed with HPLC-MS/MS. Though, in blood plasma and urine after red cabbage intake, both, acylated and nonacylated anthocyanins and their metabolites occurred, but only nonacylated derivatives were present in the CSF, and their changes in the profile and concentration in the CSF resulted from the fluctuation of these pigments' concentration and profile in blood, their different abilities to permeate via the blood-CSF barrier, and their transformations in this barrier. Results indicate that the blood-CSF barrier is selective for red cabbage anthocyanins.

Development and Validation of Methods for the Determination of Anthocyanins in Physiological Fluids via UHPLC-MSn

Recent in vitro and in vivo studies on anthocyanins confirmed numerous health-promoting effects in humans. Daily anthocyanin intake can be estimated via food databases, but the amount absorbed by the organism still remains uncertain because anthocyanin bioavailability is yet to be elucidated in its entirety. For this purpose, suitable and validated methods of sample preparation and analysis are required. Therefore, a sample preparation method for anthocyanin metabolite analysis in plasma was successfully established and validated. The validation yielded acceptable results for the anthocyanins in terms of recovery (54–108%) and precision (coefficient of variation (CV) < 15%). The UHPLC-MS method used in the consecutive reaction monitoring (CRM) mode was sufficiently sensitive, resulting in limits of detection <2.3 ng/mL and limits of quantification < 8.1 ng/mL with associated repeatability of the MS system with CVs of <5.1%. In addition, a method for the sum parameter determination of anthocyanidins in urine comprising solely the evaporation of acidified samples was developed, validated, and successfully applied to real samples. The results showed that this method is applicable for the methylated anthocyanidins, but not for the hydroxylated anthocyanidins, due to the chosen CRM modes required for optimum selectivity.

Assessment of in vitro Effects of Anthocyanins on Platelet Function

BACKGROUND

Increased platelet activity plays a significant role in the development of arterial thrombosis and cardiovascular disease (CVD). Natural antioxidants including anthocyanin (AC) have gained considerable interest due to their hypothesized antithrombotic potential.

PRIMARY STUDY OBJECTIVE

Our study aimed to examine the in vitro effect of AC compounds on platelet activation and aggregation.

METHODS

Fasting blood samples were collected from healthy volunteers (n = 13). A full blood examination was done to exclude any abnormal specimen. Flow cytometer assessed platelet activity by recording platelet surface markers expression of P-selectin (CD62P) and PAC-1. Platelet aggregation studies were performed by stimulating platelets using three different agonists adenosine diphosphate (ADP), collagen and arachidonic acid (AA).

SETTING

The study was done in the school of Medical Sciences, Griffith University.

PARTICIPANTS

Thirteen healthy adult participants were involved for blood collection.

INTERVENTION

AC was prepared using hemicellulose capsules sourced from Bilberries and Black Currants.

RESULTS

Anthocyanin (50 mg/L) significantly inhibited AA-induced platelet aggregation. Expression of P-selectin was significantly suppressed by 50 mg/L AC as measured by flow cytometer.

CONCLUSIONS

AC attenuates platelet function by suppressing P-selectin expression and influencing Thromboxane A2 pathway (AA stimulation). These results provide further evidence for the effect of AC and the possible mechanism by which AC reduces platelet aggregation and activation. This study supports future human intervention trials to show that AC may act as a complement to other antiplatelet agents in reducing the risk of thrombosis.

Overexpression of ThMYC4E Enhances Anthocyanin Biosynthesis in Common Wheat

The basic helix-loop helix (bHLH) transcription factor has been inferred to play an important role in blue and purple grain traits in common wheat, but to date, its overexpression has not been reported. In this study, the bHLH transcription factor ThMYC4E, the candidate gene controlling the blue grain trait from Th. Ponticum, was transferred to the common wheat JW1. The positive transgenic lines displayed higher levels of purple anthocyanin pigments in their grains, leaves and glumes. Stripping the glumes (light treatment) caused white grains to become purple in transgenic lines. RNA-Seq and qRT-PCR analysis demonstrated that the transcript levels of structural genes associated with anthocyanin biosynthesis were higher in transgenic wheat than the wild-type (WT), which indicated that ThMYC4E activated anthocyanin biosynthesis in the transgenic lines. Correspondingly, the anthocyanin contents in grains, roots, stems, leaves and glumes of transgenic lines were higher than those in the WT. Metabolome analysis demonstrated that the anthocyanins were composed of cyanidin and delphinidin in the grains of the transgenic lines. Moreover, the transgenic lines showed higher antioxidant activity, in terms of scavenging DPPH radicals, in the ethanol extracts of their grains. The overexpression of ThMYC4E sheds light on the traits related to anthocyanin biosynthesis in common wheat and provide a new way to improve anthocyanin content.

Absorption of Anthocyanin Rutinosides after Consumption of a Blackcurrant ( Ribes nigrum L.) Extract

The dominant anthocyanins in blackcurrant are delphinidin-3-O-rutinoside and cyanidin-3-O-rutinoside. Data on their absorption and distribution in the human body are limited. Therefore, we performed a human pilot study on five healthy male volunteers consuming a blackcurrant ( Ribes nigrum L.) extract. The rutinosides and their degradation products gallic acid and protocatechuic acid were determined in plasma and urine. The rutinosides' concentrations peaked in both plasma and urine samples within 2 h of extract ingestion. The recoveries of delphinidin-3-O-rutinoside and cyanidin-3-O-rutinoside from urine samples were 0.040 ± 0.011% and 0.048 ± 0.016%, respectively, over a 48 h period. Protocatechuic acid concentration increased significantly after ingestion of the blackcurrant extract. Our results show that after ingestion of a blackcurrant extract containing delphinidin-3-O-rutinoside and cyanidin-3-O-rutinoside, significant quantities of biologically active compounds circulated in the plasma and were excreted via urine. Furthermore, these results contribute to the understanding of anthocyanin metabolism in humans.

Freeze-dried bilberry (Vaccinium myrtillus) dietary supplement improves walking distance and lipids after myocardial infarction: an open-label randomized clinical trial

Bilberries, Vaccinium myrtillus, have a high content of phenolic compounds including anthocyanins, which could provide cardiometabolic health benefits following acute myocardial infarction (AMI). We hypothesized that standard medical therapy supplemented with freeze-dried bilberry after AMI would have a more beneficial effect on cardiovascular risk markers and exercise capacity than medical therapy alone. Patients were allocated in a 1:1 ratio within 24 hours of percutaneous coronary intervention in an 8-week trial either to V myrtillus powder (40 g/d, equivalent to 480 g fresh bilberries) and standard medical therapy or to a control group receiving standard medical therapy alone. High-sensitivity C-reactive protein and exercise capacity measured with the 6-minute walk test were the primary biochemical and clinical end points, respectively. Fifty subjects completed the study. No statistically significant difference in high-sensitivity C-reactive protein was detected between groups. The mean 6-minute walk test distance increased significantly more in the bilberry group compared to the control group: mean difference 38 m at follow-up (95% confidence interval 14-62, P = .003). Ex vivo oxidized low-density lipoprotein was significantly lowered in the bilberry group compared to control, geometric mean ratio 0.80 (95% confidence interval 0.66-0.96, P = .017), whereas total cholesterol and low-density lipoprotein cholesterol did not differ significantly between groups. Anthocyanin-derived metabolites in blood increased significantly in the bilberry group during the intervention and were different after 8 weeks between the bilberry group and control. Findings in the present study suggest that bilberries may have clinically relevant beneficial effects following AMI; a larger, double-blind clinical trial is warranted to confirm this.

Bioavailability Study of Maqui Berry Extract in Healthy Subjects

Several health promoting effects have been reported for maqui berry, rich in anthocyanins. Direct effects of anthocyanins as well as bioactive metabolites might be involved. Within the study, bioavailability of a proprietary standardized maqui berry extract Delphinol^® was investigated based on two selected anthocyanins (delphinidin-3-O-glucoside (DS) + cyanidin-3-O-sambubioside (CS)) and two breakdown products (protocatechuic acid (PCA) + gallic acid (GA)) after a single-dose supplementation in humans. Pharmacokinetic parameters were calculated from individual concentration time curves. In all 12 subjects a significant increase was noted in plasma values of DG and CS after intake of maqui berry extract. Maximum concentration of DG was observed after 1.0 ± 0.3 h and CS after 2.0 ± 1.1 h. Within 8 h, concentrations nearly returned to baseline levels. The results confirm a fast uptake and metabolism of the two selected key substances. Additionally, the phenolic acids GA and PCA were observed as breakdown products of anthocyanins. In summary, the study clearly confirms the bioavailability of maqui berry extract and its specific anthocyanin compounds and related breakdown products in healthy subjects.

An LC-MS/MS method for quantitation of cyanidin-3-O-glucoside in rat plasma: Application to a comparative pharmacokinetic study in normal and streptozotocin-induced diabetic rats

A sensitive and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed to determine cyanidin-3-O-glucoside (Cy-3G) in normal and streptozotocin-induced diabetic rat plasma. Chromatographic separation was carried out on a Zorbax SB-C₁₈ (50 × 4.6 mm, 5 μm) column and mass spectrometric analysis was performed using a Thermo Finnigan TSQ Quantum Ultra triple-quadrupole mass spectrometer coupled with an ESI source in the negative ion mode. Selected reaction monitoring mode was applied for quantification using target fragment ions m/z 447.3 → 285.2 for Cy-3G and m/z 463.0 → 300.1 for quercetin-3-O-glucoside (internal standard). The calibration curve was linear over the range 3.00-2700 ng/mL (r²  ≥ 0.99) with the lower limit of quantitation at 3.00 ng/mL. Intra- and inter-day precision was <14.5% and mean accuracy was from -11.5 to 13.6%. Stability testing showed that Cy-3G remained stable during the whole analytical procedure. After validation, the assay was successfully used to support a preclinical pharmacokinetic comparison of Cy-3G between normal and diabetic rats. Results indicated that diabetes mellitus significantly altered the in vivo pharmacokinetic characteristics of Cy-3G after oral administration in rats.

A Critical Review on Polyphenols and Health Benefits of Black Soybeans

Polyphenols are plant secondary metabolites containing antioxidant properties, which help to protect chronic diseases from free radical damage. Dietary polyphenols are the subject of enhancing scientific interest due to their possible beneficial effects on human health. In the last two decades, there has been more interest in the potential health benefits of dietary polyphenols as antioxidant. Black soybeans (Glycine max L. Merr) are merely a black variety of soybean containing a variety of phytochemicals. These phytochemicals in black soybean (BSB) are potentially effective in human health, including cancer, diabetes, cardiovascular diseases, cerebrovascular diseases, and neurodegenerative diseases. Taking into account exploratory study, the present review aims to provide up-to-date data on health benefit of BSB, which helps to explore their therapeutic values for future clinical settings. All data of in vitro and in vivo studies of BSB and its impact on human health were collected from a library database and electronic search (Science Direct, PubMed, and Google Scholar). The different pharmacological information was gathered and orchestrated in a suitable spot on the paper.

Pharmacokinetic Characterization and Bioavailability of Strawberry Anthocyanins Relative to Meal Intake

Plasma strawberry anthocyanins were characterized in overweight (BMI: 26 ± 2 kg/m(2)) adults (n = 14) on the basis of meal timing. At each visit, subjects ingested three study drinks: two control and one strawberry drink. A strawberry drink was given at either 2 h before the breakfast meal (BM), with the meal (WM), or 2 h after the meal (AM), and control drinks were given at the alternative time points. Plasma anthocyanins and their metabolic conjugates were assessed hourly for 10 h using a triple-quadrupole liquid chromatography mass spectrometer. Maximum concentrations (Cmax), area under the curve (AUC), and bioavailability of pelargonidin-based anthocyanins determined from the main conjugated metabolite (pelargonidin glucuronide) were greater when a strawberry drink was consumed 2 h before the meal (BM) compared to consumption WM or AM (p < 0.05). Our results indicate that the timing of strawberry consumption relative to a meal impacts anthocyanin pharmacokinetic variables.

Consumption of anthocyanin-rich cherry juice for 12 weeks improves memory and cognition in older adults with mild-to-moderate dementia

PURPOSE

Dietary flavonoids, including anthocyanins, may positively influence cognition and may be beneficial for the prevention and treatment of dementia. We aimed to assess whether daily consumption of anthocyanin-rich cherry juice changed cognitive function in older adults with dementia. Blood pressure and anti-inflammatory effects were examined as secondary outcomes.

METHODS

A 12-week randomised controlled trial assessed cognitive outcomes in older adults (+70 year) with mild-to-moderate dementia (n = 49) after consumption of 200 ml/day of either a cherry juice or a control juice with negligible anthocyanin content. Blood pressure and inflammatory markers (CRP and IL-6) were measured at 6 and 12 weeks. ANCOVA controlling for baseline and RMANOVA assessed change in cognition and blood pressure.

RESULTS

Improvements in verbal fluency (p = 0.014), short-term memory (p = 0.014) and long-term memory (p ≤ 0.001) were found in the cherry juice group. A significant reduction in systolic (p = 0.038) blood pressure and a trend for diastolic (p = 0.160) blood pressure reduction was evident in the intervention group. Markers of inflammation (CRP and IL-6) were not altered.

CONCLUSION

Inclusion of an anthocyanin-rich beverage may be a practical and feasible way to improve total anthocyanin consumption in older adults with mild-to-moderate dementia, with potential to improve specific cognitive outcomes.

Inhibition of pancreatic cancer cell migration by plasma anthocyanins isolated from healthy volunteers receiving an anthocyanin-rich berry juice

PURPOSE

Pancreatic cancer is an aggressive cancer type, of which the most important characteristics are migration and metastasis. Anthocyanins (ACN) are discussed to be protective phytochemicals; however, up to now only scarce data are available regarding their effects on cancer prevention. In this study, we aimed to determine whether ACN and their metabolites from plasma (PAM), isolated from blood of healthy volunteers after ingestion of an ACN-rich juice, are effective in modulating cancer cell migration in vitro.

METHODS

PAM were isolated from blood of healthy volunteers (n = 10) after consumption of an ACN-rich berry juice. Before ingestion (PAM_0min) and after 60 min (PAM_60min), blood was taken and PAM were isolated from plasma by solid-phase extraction. Migration of pancreatic cancer cells PANC-1 and AsPC-1 was assayed in a Boyden chamber. The influence of PAM on cellular reactive oxygen species (ROS) or mitochondria-specific ROS was measured fluorimetrically. mRNA expression levels of matrix metalloproteinases (MMP-2 and MMP-9) and NF-κB mRNA were determined by real-time PCR.

RESULTS

After application of PAM_60min to PANC-1, we observed a reduced cell migration, which was associated with reduced levels of endogenously generated ROS concomitant with reduced NF-κB as well as MMP-2 and MMP-9 mRNA expression levels. In AsPC-1 cells, however, migration was not affected by PAM_60min.

CONCLUSION

It can be assumed that physiologically relevant ACN and their metabolites were able to inhibit pancreatic cancer cell migration in dependency of the phenotype of cells and may thus deserve further attention as potential bioactive phytochemicals in cancer prevention.

Absorption of Acylated Anthocyanins in Rats and Humans after Ingesting an Extract ofIpomoea batatasPurple Sweet Potato Tuber

We evaluated the absorbability of anthocyanins in humans and rats administered with a beverage prepared from an extract of the tuber of purple sweet potato (Ipomoea batatas Cultivar Ayamurasaki), or with an anthocyanin concentrate. Two major anthocyanin components, cyanidin 3-O-(2-O-(6-O-(E)-caffeoyl-beta-D-glucopyranosyl)-beta-D-glucopyranoside)-5-O-beta-D-glucopyranoside) and peonidin 3-O-(2-O-(6-O-(E)-caffeoyl-beta-D-glucopyranosyl)-beta-D-glucopyranoside)-5-O-beta-D-glucopyranoside), were detected in the plasma and urine of both rats and humans by HPLC or liquid chromatography/mass spectrometry (LC/MS). The plasma concentration of anthocyanins in humans reached a maximum 90 minutes after ingestion, and the recovery of anthocyanins in the urine was estimated as 0.01-0.03%. These results indicate that acylated anthocyanins could be selectively absorbed after ingesting food.

Structural elucidation and biological fate of two glucuronyl metabolites of pelargonidin 3-O-β-D-glucopyranoside in rats

A high proportion of pelargonidin 3-O-β-D-glucopyranoside (Pg3G) is metabolized to glucuronides and excreted in mammal urine after ingestion of strawberry fruit, suggesting that these metabolites play important functional roles in vivo. The aim of the present study was to elucidate the structures and determine the biological fate of the two dominant metabolites of Pg3G in rats to enable an accurate discussion of the biological properties of anthocyanins. Authentic Pg3G was orally administered to rats. One pelargonidin monoglucuronide and three Pg3G-monoglucuronides (glucuronides of the glucoside) were identified together with intact Pg3G in both blood plasma and urine samples. The structures of the two dominant metabolites were elucidated as pelargonidin 3-O-β-D-glucuronide (Pg3GlcA) and pelargonidin 3-O-β-D-glucuronyl-(1→2)-β-D-glucoside by means of (1)H and (13)C nuclear magnetic resonance spectroscopy and heteronuclear multiple-bond connective spectroscopy. The bioavailability of Pg3G in its intact form was 0.31% of the orally administered dose, and 0.65% was absorbed in the Pg3GlcA form.

Blanching improves anthocyanin absorption from highbush blueberry ( Vaccinium corymbosum L.) purée in healthy human volunteers: a pilot study

Blueberries ( Vaccinium corymbosum L.) are rich sources of phenolics and anthocyanins (ACNs). We investigated the absorption of ACNs after consumption of one portion (300 g) of minimally processed blueberry purée (P) obtained from blanched (BL) or unblanched (NB) berries. A repeated-measures, crossover design study was conducted on healthy human volunteers. Blood was drawn between baseline and 24 h after BL-P or NB-P consumption, while urine were collected from the day before the experiment up to 48 h. Total plasma ACN content was not significantly different, while phenolics content was higher in BL-P with respect to NB-P. The maximum ACN absorption in plasma was observed after 1.5 h from the intake of the purées and was significantly higher (p ≤ 0.05) after the intake of BL-P. Both products increased the excretion of hippuric acid in urine. In conclusion, blanching had no significant effect on total ACN content and enhanced their absorption from minimally processed purées.

Exceptionally fast uptake and metabolism of cyanidin 3-glucoside by rat kidneys and liver

To asses the hypothesis that anthocyanins are rapidly taken up from the blood into tissues, where they accumulate up to their bioactivity threshold, an intravenous dose of cyanidin 3-glucoside (1) was administered to anaesthetized rats. Cyanidin 3-glucoside (1) and its metabolites were analyzed in the plasma, kidneys, liver, urine, and bile, using last-generation mass spectrometry. Compound 1 was found to rapidly disappear from plasma (t/2=0.36 min). As soon as 15 s after its administration, both 1 and its methylation product, peonidin 3-glucoside (2), were detected in the plasma, kidneys, and liver. At 1 min, both 1 and 2 had almost disappeared from the plasma, but attained their peak concentrations in the kidneys and in the liver. Compound 2 was rapidly excreted both in the bile and in the urine. Three additional methylated metabolites were detected in traces, namely, delphinidin 3-glucoside (3), petunidin 3-glucoside (4), and malvidin 3-glucoside (5). These data contribute to solving the paradox of the high bioactivity of anthocyanins in spite of their apparent low bioavailability.

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.

Bioavailability of anthocyanins and ellagitannins following consumption of raspberries by healthy humans and subjects with an ileostomy

The fate of anthocyanins, ellagic acid, and ellagitannins was studied following the consumption of 300 g of raspberries by healthy human volunteers and subjects with an ileostomy. Postingestion plasma and urine from the former and ileal fluid and urine from the latter group were collected and analyzed by HPLC-PDA-MS(2). Plasma from the healthy volunteers did not contain detectable quantities of either the native raspberry polyphenolics or their metabolites. The three main raspberry anthocyanins were excreted in urine in both healthy and ileostomy volunteers 0-7 h after ingestion, in quantities corresponding to <0.1% of intake. This indicates a low level of absorption in the small intestine. With ileostomy volunteers 40% of anthocyanins and 23% of the ellagitannin sanguiin H-6 were recovered in ileal fluid with the main excretion period being the first 4 h after raspberry consumption. The recovery of ellagic acid in ileal fluid was 241%, indicating hydrolysis of ellagitannins in the stomach and/or the small intestine. Urinary excretion of ellagic acid and an ellagic acid-O-glucuronide was <1% of intake. No intact or conjugated forms of ellagitannins were detected in urine from either healthy subjects or ileostomy volunteers. However, in healthy subjects, but not the ileostomists, ellagitannins were catabolized with the appearance of urolithin A-O-glucuronide, two of its isomers, and urolithin B-O-glucuronide in urine collected 7-48 h after raspberry consumption. There was marked variation in the urolithin profile of individual volunteers, indicating differences in the colonic microflora responsible for ellagitannin degradation.

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.

Identification of metabolites in human plasma and urine after consumption of a polyphenol-rich juice drink

A polyphenol-rich (P-R) juice drink was developed as a potential approach to increase intake of dietary polyphenols. Analysis of the beverage by HPLC with PDA, fluorescence, and MS detection facilitated the identification/partial identification of 40 flavonoids and related phenolic compounds. The main constituents were (-)-epigallocatechin and other green tea flavan-3-ols, phloretin-2'-O-glucoside, gallic acid, hesperetin-7-O-rutinoside, 5-O-caffeoylquinic acid, and procyanidins, with trace levels of several flavonols and purple grape juice anthocyanins also being present. Healthy human subjects (n = 10) consumed 350 mL of the P-R juice drink, after which plasma and urine samples were collected over a 0-24 h period. HPLC-MS analysis identified 13 metabolites in plasma and a further 20 in urine. Qualitatively, the profiles of the glucuronide, sulfated, and methylated metabolites were very similar to those detected in earlier investigations when the main components in the juice drink were consumed separately in feeding studies with coffee, green tea, orange juice, and apple cider.

Development and validation of a liquid chromatography tandem mass spectrometry method for simultaneous determination of four anthocyanins in human plasma after black currant anthocyanins ingestion

Black currant anthocyanins consist of delphinidin-3-glucoside (1), delphinidin-3-rutinoside (2), cyanidin-3-glucoside (3), and cyanidin-3-rutinoside (4). A liquid chromatography tandem mass spectrometry method for simultaneous determination of four anthocyanins in human plasma was developed and validated. Samples were prepared using solid phase extraction, followed by chromatographic separation with a reverse phase C(18) column with gradient elution using mobile phases containing water, acetonitrile, and formic acid. The quantification of four anthocyanins was determined by multiple reaction monitoring using electrospray ionization. The method showed good selectivity, sensitivity (limits of quantification for four anthocyanins were 0.2 nmol/L), linearity (0.2-20 nmol/L; r > 0.999), intra- and interday precision, accuracy (<14%), and recovery (62.5-85.7%). Analyte stability was investigated in detail. This method was successfully applied to the determination of delphinidin-3-glucoside (1), delphinidin-3-rutinoside (2), cyanidin-3-glucoside (3), and cyanidin-3-rutinoside (4) concentrations in human plasma after ingestion of a single dose of black currant anthocyanins (87.9 micromol (58.8 mg) total anthocyanins).

Metabolism of berry anthocyanins to phenolic acids in humans

We studied the metabolism of berry anthocyanins to phenolic acids in six human subjects by giving them bilberry-lingonberry puree with and without oat cereals. Puree + cereals contained 1435 micromol of anthocyanins and 339 micromol of phenolic acids. The urinary excretion of measured 18 phenolic acids increased 241 micromol during the 48 h follow-up after the puree + cereals supplementation. The excretion peak of dietary phenolic acids was observed at 4-6 h after the puree + cereals supplementation and 2 h earlier after the supplementation of the puree alone. Homovanillic and vanillic acids were the most abundant metabolites, and they were partly produced from anthocyanins. No gallic acid, a fragmentation product of delphinidin glycosides, was detected, and only a very low amount of malvidin glycosides was possibly metabolized to syringic acid. Although anthocyanins were partly fragmented to phenolic acids, still a large part of metabolites remained unknown.

Pharmacokinetics of anthocyanins and antioxidant effects after the consumption of anthocyanin-rich acai juice and pulp (Euterpe oleracea Mart.) in human healthy volunteers

The acai berry is the fruit of the acai palm and is traditionally consumed in Brazil but has gained popularity abroad as a food and functional ingredient, yet little information exists on its health effect in humans. This study was performed as an acute four-way crossover clinical trial with acai pulp and clarified acai juice compared to applesauce and a non-antioxidant beverage as controls. Healthy volunteers (12) were dosed at 7 mL/kg of body weight after a washout phase and overnight fast, and plasma was repeatedly sampled over 12 h and urine over 24 h after consumption. Noncompartmental pharmacokinetic analysis of total anthocyanins quantified as cyanidin-3-O-glucoside showed Cmax values of 2321 and 1138 ng/L at t max times of 2.2 and 2.0 h, and AUC last values of 8568 and 3314 ng h L(-1) for pulp and juice, respectively. Nonlinear mixed effect modeling identified dose volume as a significant predictor of relative oral bioavailability in a negative nonlinear relationship for acai pulp and juice. Plasma antioxidant capacity was significantly increased by the acai pulp and applesauce. Individual increases in plasma antioxidant capacity of up to 2.3- and 3-fold for acai juice and pulp, respectively were observed. The antioxidant capacity in urine, generation of reactive oxygen species, and uric acid concentrations in plasma were not significantly altered by the treatments. Results demonstrate the absorption and antioxidant effects of anthocyanins in acai in plasma in an acute human consumption trial.

Bioavailability of pelargonidin-3-O-glucoside and its metabolites in humans following the ingestion of strawberries with and without cream

Plasma and urine were collected over a 24 h period after the consumption by humans of 200 g of strawberries, containing 222 micromol of pelargonidin-3- O-glucoside, with and without cream. The main metabolite, a pelargonidin- O-glucuronide, reached a peak plasma concentration ( C max) of 274 +/- 24 nmol/L after 1.1 +/- 0.4 h ( t max) when only strawberries were ingested. When the strawberries were eaten with cream, the C max was not statistically different but the t max at 2.4 +/- 0.5 h was delayed significantly ( p < 0.001). The pelargonidin- O-glucuronide, along with smaller quantities of other metabolites, was also excreted in urine in quantities corresponding to ca. 1% of anthocyanin intake. The quantities excreted over the 0-24 h collection period were not influenced significantly by cream. However, the 0-2 h excretion of anthocyanin metabolites was significantly lower when the strawberries were eaten with cream, whereas the reverse occurred during with the 5-8 h excretion period. In keeping with these observations, measurement of plasma paracetamol and breath hydrogen revealed that cream delayed gastric emptying and extended mouth to cecum transit time.

The bioavailability of raspberry anthocyanins and ellagitannins in rats

The fate of anthocyanins and ellagitannins in rats was monitored following ingestion of raspberry juice. After 1 h low nM concentrations of unmetabolised anthocyanins were present in plasma but these declined by 2 h and after 4 h they were no longer detectable. For the first 2 h there was an almost full recovery of anthocyanins as they passed from the stomach through the duodenum/jejunum and into the ileum. After 3 h less than 50% were recovered, and the levels declined rapidly thereafter. Excretion of raspberry anthocyanins in urine over a 24 h period was equivalent to 1.2% of the amount ingested. Trace quantities of anthocyanins were detected in the caecum, colon and faeces and they were absent in extracts of liver, kidneys and brain. Urine also contained a number of phenolic acids but most were present in quantities well in excess of the 918 nmol of anthocyanins present in the ingested juice. These findings indicate that raspberry anthocyanins per se are poorly absorbed, probably prior to reaching the ileum, and that substantial amounts pass from the small to the large intestine where they are degraded by colonic bacteria. Ellagitannins disappeared in the stomach without accumulation of ellagic acid.

Formulation and in-vitro and in-vivo evaluation of a mucoadhesive gel containing freeze dried black raspberries: implications for oral cancer chemoprevention

PURPOSE

The purpose of these studies was to formulate mucoadhesive gels containing freeze dried black raspberries (FBR) and to determine optimum parameters for a subset of FBR bioactive compounds including anthocyanin stability, absorption and penetration in-vitro and in-vivo.

MATERIALS AND METHODS

Berry gels were prepared having FBR at 5% and 10% w/w and final pHs ranging from 3.5 to 7.5. A HPLC assay was developed to quantify and determine the stability of the anthocyanins in the gels. A single time-point study was performed to determine anthocyanin uptake when the gels were applied to oral mucosa. Penetration of anthocyanins into human oral tissue explants was determined as a function of gel pH and FBR content. A HPLC-mass spectroscopy assay was utilized to quantify the anthocyanin levels in human oral tissue explants, saliva, and blood.

RESULTS

The stability of anthocyanins in the gel was directly related to gel pH and storage temperature. Maximum stability of anthocyanins was found at lower pH (pH 3.5) and storage temperature (4 degrees C). Anthocyanins contained in mucoadhesive berry gel formulations were readily absorbed into human oral mucosa tissue as evidenced by detectable blood levels within 5 min after gel application. There was a trend for greater penetration of anthocyanins into tissue explants for berry gels with a final pH of 6.5 versus pH 3.5.

CONCLUSIONS

Formulation and characterization of a novel gel formulation for local delivery of chemopreventive compounds to human oral mucosal tissues has been described. The results show anthocyanin stability was dependent upon gel pH and storage temperature and also demonstrate that the gel composition is well-suited for absorption and penetration into the target oral mucosal tissue site.

Development of analyses by high-performance liquid chromatography and liquid chromatography/tandem mass spectrometry of bilberry (Vaccinium myrtilus) anthocyanins in human plasma and urine

Anthocyanins are potent antioxidants that may possess chronic disease preventive properties. Here, rapid, reliable, and reproducible solid-phase extraction, high-performance liquid chromatography (HPLC), and mass spectrometry techniques are described for the isolation, separation, and identification of anthocyanins in human plasma and urine. Recoveries of cyanidin-3-glucoside (C3G) were 91% from water, 71% from plasma, and 81% from urine. Intra- and interday variations for C3G extraction were 9 and 9.1% in plasma and 7.1 and 9.1% in urine and were less than 15% for all anthocyanins from a standardized bilberry extract (mirtoselect). Analysis of mirtoselect by HPLC with UV detection produced spectra with 15 peaks compatible with anthocyanin components found in mirtoselect within a total run time of 15 min. Chromatographic analysis of human urine obtained after an oral dose of mirtoselect yielded 19 anthocyanin peaks. Mass spectrometric analysis employing multiple reaction monitoring suggests the presence of unchanged anthocyanins and anthocyanidin glucuronide metabolites.

Comparative assessment of distribution of blackcurrant anthocyanins in rabbit and rat ocular tissues

Anthocyanins (ACs) are phenolic compounds that are distributed widely in fruits and vegetables. Although consumption of these compounds has been shown to improve visual function, the distribution of ACs in ocular tissue has not been examined in detail. The aim of this study was therefore to evaluate the ocular distribution of blackcurrant anthocyanins (BCAs) in rats and rabbits after oral, intravenous (i.v.) and intraperitoneal (i.p.) administration. Identification and quantification of ACs were carried out using high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) and high-performance liquid chromatography (HPLC) with UV-visible detection, respectively. BCAs were identified in the plasma and whole eye after oral and i.p. administration in rats. No other peaks were detected in either plasma or ocular tissues after administration when the absorbance of the eluate was monitored at 520 nm. This finding indicates that intact forms of ACs were present in rats after administration of BCA. In rats given i.p. administration, the concentration of total ACs in the whole eye and some ocular tissues was higher than that measured in plasma. These results suggested that ACs detected in the ocular tissues were not due to residual blood. Following i.v. administration in rabbits, four ACs were identified in the plasma and several ocular tissues including the aqueous humor, cornea, sclera, choroid, ciliary body, iris and retina. A small amount of ACs was also detected in the vitreous and lens. In conclusion, this study demonstrated that BCAs were absorbed and distributed in ocular tissues as intact forms. Our data show clearly that intact forms of BCAs pass thorough the blood-aqueous barrier and blood-retinal barrier in both rats and rabbits.

Pharmacokinetics of anthocyanins and ellagic acid in healthy volunteers fed freeze-dried black raspberries daily for 7 days

Eleven subjects completed a clinical trial to determine the safety/tolerability of freeze-dried black raspberries (BRB) and to measure, in plasma and urine, specific anthocyanins-cyanidin-3-glucoside, cyanidin-3-sambubioside, cyanidin-3-rutinoside, and cyanidin-3-xylosylrutinoside, as well as ellagic acid. Subjects were fed 45 g of freeze-dried BRB daily for 7 days. Blood samples were collected predose on days 1 and 7 and at 10 time points postdose. Urine was collected for 12 hours predose on days 1 and 7 and at three 4-hour intervals postdose. Maximum concentrations of anthocyanins and ellagic acid in plasma occurred at 1 to 2 hours, and maximum quantities in urine appeared from 0 to 4 hours. Overall, less than 1% of these compounds were absorbed and excreted in urine. None of the pharmacokinetic parameters changed significantly between days 1 and 7. In conclusion, 45 g of freeze-dried BRB daily are well tolerated and result in quantifiable anthocyanins and ellagic acid in plasma and urine.

Intact Anthocyanins and Metabolites in Rat Urine and Plasma After 3 Months of Anthocyanin Supplementation

Anthocyanins are polyphenols responsible for most red to purple colors in plants. Human consumption of these pigments is increasing because of their potential health benefits and use as natural colorants. With more than 600 different anthocyanins found in nature, the impact of chemical structure on their absorption and metabolism needs to be investigated. Urine and plasma samples were collected from 32 rats receiving control diet or chokeberry-, bilberry-, and grape-enriched (3.85 g cyanidin 3-galatoside equivalent/kg) diet for 14 wk. Below 2 micromol/l of anthocyanins and relatively higher levels of presumable metabolites were detected by high-performance liquid chromatography-photodiode array in the plasma. In the urine the total concentration of intact anthocyanins and methylated derivatives ranged from 17.4 (bilberry) to 52.6 (chokeberry) nmol/l. The type and number of anthocyanin glycosylations affected the absorption remarkably. Detection of an acylated anthocyanin in plasma and urine suggests bioavailability of these anthocyanin derivatives that are commonly found in commercially available colorants.

Anthocyanins exist in the circulation primarily as metabolites in adult men

Anthocyanins are reported to have many "health promoting" properties; however, despite numerous reports of their bioactivities, their absorption and metabolism in humans are poorly understood. The objective of this research was to detail the pharmacokinetic parameters of anthocyanins after the administration of a 721-mg oral dose of cyanidin 3-glycosides from chokeberry extract to human subjects. Solid-phase extraction, preparative-HPLC, preparative-TLC, HPLC-diode array detection, HPLC-MS, and NMR were utilized to isolate, identity, and quantify anthocyanins in 0- to 7-h (0, 1, 2, 3, 4, 5, 6, 7 h) serum and 0- to 24-h urine samples (total individual urine voids over 24 h). The cumulative concentration of total anthocyanins (parent and metabolites) detected in the serum (0-7 h) was 376.65 +/- 16.20 (nmol x h)/L (area under the concentration time curve), reaching a maximum concentration (C(max) = 96.08 +/- 6.04 nmol/L) within 2.8 h. The parent anthocyanins represented only 32.0% [120.63 +/- 2.85 (nmol x h)/L] of the total anthocyanins detected with 68.0% [256.02 +/- 5.23 (nmol x h) identified as conjugated metabolites. Additionally, the total urinary excretion of anthocyanins over 24 h was 1071.54 +/- 375.46 microg, reaching a maximal rate of excretion (R(max) = 202.74 +/- 85.06 microg/h) at 3.72 +/- 0.83 h. Parallel to the serum data, only 32.5% (347.85 +/- 60.61 microg) of the anthocyanins excreted in the urine (total 24 h) were the parent compounds with 67.5% (723.69 +/- 92.59 microg) occurring as conjugated metabolites. The metabolites were identified as glucuronidated and methylated derivatives of the parent cyanidin 3-glycosides. The above results indicate that cyanidin 3-glycosides are rapidly absorbed and metabolized extensively following a moderate-to-high oral dose in humans.

Aglycones and sugar moieties alter anthocyanin absorption and metabolism after berry consumption in weanling pigs

To investigate the absorption and metabolism of anthocyanins (ACNs) with different aglycones and sugar moieties, weanling pigs (11.4 +/- 3.8 kg) were fed, in a single meal, a freeze-dried powder of chokeberry, black currant, or elderberry at a single dose of 229, 140, or 228 mumol total ACN/kg body weight (BW), respectively. These berries provided ACNs with differences in aglycone as well as some unique differences in the sugar moieties. The relative proportions of the different metabolites depended upon concentrations, quantities consumed, and types of glycoside of ACNs in the berry. Delphinidin ACNs were not metabolized to any measurable extent. Cyanidin ACNs were metabolized via methylation and glucuronidation as well as by formation of both derivatives on the same ACN molecule. ACNs with either a di- or trisaccharide attached to them were excreted in the urine primarily as the intact form. Over 80% of the ACN compounds containing rutinose or sambubiose, which were excreted in the urine from black currant, elderberry, or Marion blackberry, were excreted as the intact molecule. The limited metabolism of these ACNs that did occur was via methylation. ACN monoglycosides other than the glucoside were metabolized via methylation and/or glucuronide formation. The monoglucuronide that formed represented a small proportion of the metabolites relative to the methylated or the mixed methylated and glucuronide forms of ACNs. The data clearly demonstrate that the aglycone and the sugar moieties can alter the apparent absorption and metabolism of ACNs.

Fast access of some grape pigments to the brain

Anthocyanins represent the main flavonoid pigments in red grape and wine, in red berries, and in many other fruits and vegetables and are widespread in the human diet. After ingestion, these complex, hydrophilic compounds quickly appear as intact molecules in the plasma. This study investigated their presence in the brain of anesthetized rats that received 8 mg/kg of body weight of a pure anthocyanin mixture extracted from Vitis vinifera grapes. The mixture was maintained in the stomach for 10 min. After this time, intact anthocyanins were detected by HPLC-DAD-MS not only in the plasma (176.4 +/- 50.5 ng/mL, mean +/- SEM) but also in the brain (192.2 +/- 57.5 ng/g). These results demonstrate for the first time that grape pigments can reach the mammalian brain within minutes from their introduction into the stomach.

Extended glucuronidation is another major path of cyanidin 3-O-beta-D-glucopyranoside metabolism in rats

We previously determined that five rather hydrophobic metabolites appeared in blood plasma after oral administration of cyanidin 3-O-beta-D-glucopyranoside, but a group of hydrophilic metabolites still remained unidentified. In the present study, 12 hydrophilic metabolites found were collected from urine and plasma samples by high-performance liquid chromatography (HPLC) and then analyzed by tandem MS spectrometry. From the MS spectra, four metabolites out of 12 were assigned as glucuronides of cyanidin 3-O-beta-D-glucopyranoside and six out of 12 were glucuronides of the primary metabolites of cyanidin 3-O-beta-D-glucopyranoside (O-methyl cyanidin 3-O-beta-D-glucopyranoside). Extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and O-methyl cyanidin 3-O-beta-D-glucopyranoside showed their maximum plasma concentrations at 15 and 60 min (or 30 min) after oral administration, respectively. Their maximum plasma concentrations ranged from 15 to 70 nM. From the profile of urinary-excreted anthocyanins after intravenous administration, it was deduced that extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and O-methyl cyanidin 3-O-beta-D-glucopyranoside were mainly produced in the liver rather than by intestinal flora. The area under the plasma concentration curve was 0.25 micromol min/L for extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and 0.14 micromol min/L for O-methyl cyanidin 3-O-beta-D-glucopyranoside, respectively, when evaluated as cyanidin 3-O-beta-D-glucopyranoside equivalent, indicating that extended glucuronidation is a critical pathway in cyanidin 3-O-beta-D-glucopyranoside metabolism in rats.

Plasma and urine responses are lower for acylated vs nonacylated anthocyanins from raw and cooked purple carrots

The bioavailability of acylated vs nonacylated anthocyanins and the effect of cooking and dose on the comparative bioavailability were investigated in a clinical feeding study using purple carrots as the anthocyanin source. Treatments were purple carrots as follows: 250 g raw (463 micromol of anthocyanins: 400 micromol acylated, 63 micromol nonacylated), 250 g cooked (357 micromol of anthocyanins: 308.5 micromol acylated, 48.5 micromol nonacylated), and 500 g cooked (714 micromol of anthocyanins: 617 micromol acylated, 97 micromol nonacylated). Four of the five carrot anthocyanins were found intact in plasma by 30 min after carrot consumption and peaked between 1.5 and 2.5 h. Acylation of anthocyanins resulted in an 11-14-fold decrease in anthocyanin recovery in urine and an 8-10-fold decrease in anthocyanin recovery in plasma. Cooking increased the recovery of nonacylated anthocyanins but not acylated anthocyanins. Large dose size significantly reduced recovery of both acylated and nonacylated anthocyanins, suggesting saturation of absorption mechanisms.

The effects of cranberry juice consumption on antioxidant status and biomarkers relating to heart disease and cancer in healthy human volunteers

BACKGROUND

Consumption of fruit and vegetables is associated with a decreased risk of heart disease and cancer. This has been ascribed in part to antioxidants in these foods inactivating reactive oxygen species involved in initiation or progression of these diseases. Non-nutritive anthocyanins are present in significant amounts in the human diet. However, it is unclear whether they have health benefits in humans.

AIM

To determine whether daily consumption of anthocyanin-rich cranberry juice could alter plasma antioxidant activity and biomarkers of oxidative stress.

METHODS

20 healthy female volunteers aged 18-40 y were recruited. Subjects consumed 750 ml/day of either cranberry juice or a placebo drink for 2 weeks. Fasted blood and urine samples were obtained over 4 weeks. The total phenol, anthocyanin and catechin content of the supplements and plasma were measured. Anthocyanin glycosides were identified by tandem mass spectrometry (MS-MS). Vitamin C, homocysteine (tHcy) and reduced glutathione (GSH) were measured by HPLC. Total antioxidant ability was determined using electron spin resonance (ESR) spectrometry and by the FRAP assay. Plasma total cholesterol, high density lipoprotein (HDL), and low density lipoprotein (LDL) cholesterol and triglycerides (TG) were measured. Glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) activities were measured in erythrocytes. Urine was collected for analysis of malondialdehyde (MDA) by HPLC and 8-oxo-deoxyguanosine (8-oxo-dG) by ELISA. Endogenous and induced DNA damage were measured by single cell gel electrophoresis (SCGE) in lymphocytes.

RESULTS

Vitamin C, total phenol, anthocyanin and catechin concentrations and FRAP and ESR values were significantly higher in the cranberry juice compared with the placebo. Cyanidin and peonidin glycosides comprised the major anthocyanin metabolites [peonidin galactoside (29.2%) > cyanidin arabinoside (26.1%) > cyanidin galactoside (21.7%) > peonidin arabinoside (17.5%) > peonidin glucoside (4.1%) > cyanidin glucoside (1.4 %)]. Plasma vitamin C increased significantly (P<0.01) in volunteers consuming cranberry juice. No anthocyanins (plasma) or catechins (plasma or urine) were detectable and plasma total phenols, tHcy,TC,TG,HDL and LDL were unchanged. The antioxidant potential of the plasma, GSH-Px, CAT and SOD activities, and MDA were similar for both groups. Supplementation with cranberry juice did not affect 8-oxo-deoxyguanosine in urine or endogenous or H(2)O(2)-induced DNA damage in lymphocytes.

CONCLUSIONS

Cranberry juice consumption did not alter blood or cellular antioxidant status or several biomarkers of lipid status pertinent to heart disease. Similarly, cranberry juice had no effect on basal or induced oxidative DNA damage. These results show the importance of distinguishing between the in vitro and in vivo antioxidant activities of dietary anthocyanins in relation to human health.

Effects of blood orange juice intake on antioxidant bioavailability and on different markers related to oxidative stress

Orange juice is a source of antioxidants that might afford in vivo protection from oxidative stress. To test this hypothesis, we carried out a human intervention study with blood orange juice containing high amounts of vitamin C, anthocyanins, and carotenoids. Sixteen healthy female volunteers were enrolled in a crossover study and were given 600 mL/day of blood orange juice or a diet without juice for 21 days. Before and after each intervention period, plasma vitamin C, cyanidin-3-glucoside, and carotenoids were quantified. Furthermore, plasma antioxidant capacity, malondialdehyde concentration in plasma, 11-dehydrotromboxane B(2) urinary excretion, and lymphocyte DNA damage were evaluated as biomarkers of oxidative stress. Blood orange juice consumption determined a significant increase in plasma vitamin C, cyanidin-3-glucoside, beta-cryptoxanthin, and zeaxanthin. Also, lymphocyte DNA resistance to oxidative stress was improved whereas no effect was observed on the other markers that we analyzed. In turn, these results suggest that blood orange juice is a bioavailable source of antioxidants, which might moderately improve the antioxidant defense system; however, the long-term effects of its consumption are to be further investigated.

Metabolic pathway of cyanidin 3-O-beta-D-glucopyranoside in rats

For better understanding of the physiological function of anthocyanins, the absorption and metabolism of cyanidin 3-O-beta-D-glucopyranoside (Cy3G), which is one of the major anthocyanins in colored food materials, were precisely investigated. Combining two modalities newly developed, that is, highly sensitive semi-micro-HPLC and vein cannulation, Cy3G and its four major metabolites (M1-M4) were detected in the blood plasma of rats after oral administration of Cy3G (100 mg/kg of body mass). The plasma concentration of Cy3G reached its maximum at 15 min after the ingestion. Metabolite 2 (M2) and metabolite 3 (M3) showed their maximum plasma levels at 15 and 30 min, respectively, whereas metabolite 1 (M1) and metabolite 4 (M4) showed their maximum levels at 60 and 120 min, respectively. The maximum plasma concentrations of the four metabolites were in the following order: M3 (21 nM) > M4 (20 nM) > M1 (8.5 nM) > M2 (5 nM). When Cy3G was directly injected into the neck vein, only M2 and M3 were detected in the plasma, indicating that both M1 and M4 were produced during absorption from the gastrointestinal tract. Tandem MS analysis of the metabolites showed that M2 and M3 were monomethylated Cy3G, while M1 and M4 were glucuronides of Cy and methylated Cy, respectively. M3 was assigned as peonidin 3-O-beta-D-glucopyranoside (Pn3G) from the comparison of the retention time of authentic Pn3G.

Bioavailability and bioefficacy of polyphenols in humans. I. Review of 97 bioavailability studies

Polyphenols are abundant micronutrients in our diet, and evidence for their role in the prevention of degenerative diseases is emerging. Bioavailability differs greatly from one polyphenol to another, so that the most abundant polyphenols in our diet are not necessarily those leading to the highest concentrations of active metabolites in target tissues. Mean values for the maximal plasma concentration, the time to reach the maximal plasma concentration, the area under the plasma concentration-time curve, the elimination half-life, and the relative urinary excretion were calculated for 18 major polyphenols. We used data from 97 studies that investigated the kinetics and extent of polyphenol absorption among adults, after ingestion of a single dose of polyphenol provided as pure compound, plant extract, or whole food/beverage. The metabolites present in blood, resulting from digestive and hepatic activity, usually differ from the native compounds. The nature of the known metabolites is described when data are available. The plasma concentrations of total metabolites ranged from 0 to 4 mumol/L with an intake of 50 mg aglycone equivalents, and the relative urinary excretion ranged from 0.3% to 43% of the ingested dose, depending on the polyphenol. Gallic acid and isoflavones are the most well-absorbed polyphenols, followed by catechins, flavanones, and quercetin glucosides, but with different kinetics. The least well-absorbed polyphenols are the proanthocyanidins, the galloylated tea catechins, and the anthocyanins. Data are still too limited for assessment of hydroxycinnamic acids and other polyphenols. These data may be useful for the design and interpretation of intervention studies investigating the health effects of polyphenols.

Bioavailability of anthocyanidin-3-glycosides following consumption of elderberry extract and blackcurrant juice

Pharmacokinetic parameters and the bioavailability of several dietary anthocyanins following consumption of blackcurrant juice and elderberry extract were compared exploratorily in 6 healthy volunteers. They were given a single oral dose of either 137 ml of blackcurrant juice (144.8 mg total anthocyanins) or 30 ml of elderberry extract (147.3 mg total anthocyanins). Within 7 hours, the urinary excretion of total anthocyanins (i.e. the sum of all assayed anthocyanidin glycosides) was 0.04% and 0.37% of the administered dose following blackcurrant juice and elderberry extract ingestion, respectively. Pharmacokinetic parameters based on non-compartmental methods for plasma and urine concentrations exhibited higher variability in urinary excretion after ingestion of elderberry extract. Anthocyanin absorption was significantly greater following the intake of elderberry extract than after the intake of blackcurrant juice as shown by the 5.3- and 6.2-fold higher estimates of dose-normalized Cmax and AUC(0-tZ) of total anthocyanins, respectively. The geometric means of t(1/2) were not significantly different following elderberry extract (1.74 h) and blackcurrant juice ingestion (1.73 h, p > 0.05). The urinary excretion rate of intact anthocyanins was fast, appeared to be monoexponential for both blackcurrant juice and elderberry extract. However, in order to evaluate the contribution of anthocyanins to the health-protecting effects of blackcurrant juice and elderberry extract it will be necessary to perform further studies on the unchanged glycosides and their in vivo metabolites in human plasma and urine.

Anthocyanins are efficiently absorbed from the small intestine in rats

Anthocyanins are natural pigments that possess antioxidant activities and are implicated in various health effects. Recent studies showed that the stomach is a site of anthocyanin absorption. However, the fate of anthocyanins in the small intestine remains unknown. We therefore investigated anthocyanin absorption after in situ perfusion of the jejunum + ileum in rats. The intestine was perfused for 45 min with a physiological buffer supplemented with various anthocyanins. Purified anthocyanin glycosides (9.2 nmol/min) or blackberry (9.0 nmol/min) or bilberry (45.2 nmol/min) anthocyanins were perfused. A high proportion of anthocyanin glycosides was absorbed through the small intestine after perfusion. The rate of absorption was influenced by the chemical structure of the anthocyanin and varied from 10.7 (malvidin 3-glucoside) to 22.4% (cyanidin 3-glucoside). Regardless of the anthocyanins perfused, only glycosides were recovered in the intestinal lumen. After perfusion of a high amount of blackberry anthocyanins (600 nmol/min), native cyanidin 3-glucoside was recovered in urine and plasma from the aorta and mesenteric vein. Methylated and/or glucuronidated derivatives were also identified. Analysis of bile samples revealed that cyanidin 3-glucoside and its methylated derivatives (peonidin 3-glucoside + peonidin glucuronide) quickly appeared in bile. This study demonstrated that anthocyanin glycosides are rapidly and efficiently absorbed from the small intestine. Furthermore, anthocyanins are quickly metabolized and excreted into bile and urine as intact glycosides as well as methylated forms and glucuronidated derivatives.

Anthocyanin metabolites in human urine and serum

In the present study we investigated the metabolic conversion of cyanidin glycosides in human subjects using solid-phase extraction,HPLC-diode array detector, MS, GC, and enzymic techniques. Volunteers consumed approximately 20 g chokeberry extract containing 1.3 g cyanidin 3-glycosides (899 mg cyanidin 3-galactoside, 321 mg cyanidin 3-arabinoside, 51 mg cyanidin 3-xyloside and 50 mg cyanidin 3-glucoside). Blood samples were drawn at 0, 0.5, 1, and 2 h post-consumption of the extract. Urine samples were also collected at 0, 4-5,and 22-24h. We have confirmed that human subjects have the capacity to metabolise cyanidin 3-glycosides, as we observed at least ten individual anthocyanin metabolites in the urine and serum. Average concentrations of anthocyanins and anthocyanin metabolites in the urine reached levels of 17.9 (range 14.9-20.9) l.mol/l within 5 h post-consumption and persisted in 24h urine samples at levels of 12.1 (range 11.1-13.0) nmol/l. In addition, average total levels of anthocyanins and anthocyanin metabolites detected in the serum were observed at 5917 (range 197.3-986.1) nmol/ within 2h post-consumption. Cyanidin 3-galactoside accounted for 55.4% (9.9(range 7-2-12-6) l.mol/) and 66.0% (390.6 (range 119.4-661-9) nmol V) of the detected anthocyanins in the urine and serum samples,respectively. The metabolites were identified as glucuronide conjugates, as well as methylated and oxidised derivatives of cyanidin 3-galactoside and cyanidin glucuronide. Conjugation probably affects the biological activity of anthocyanins and these metabolic products are likely in part responsible for the reported health benefits associated with the consumption of anthocyanins.

Anthocyanins are efficiently absorbed from the stomach in anesthetized rats

After consumption, anthocyanins are rapidly absorbed as glycosides. Their rapid appearance in plasma could result from absorption through the gastric wall. The aim of this study was to evaluate the fate of anthocyanins in the stomach. Absorption of purified anthocyanins (14 micromol/L) as well as blackberry 14 and 750 micromol/L) and bilberry (88 micromol/L) anthocyanins was compared after in situ gastric administration for 30 min. A high proportion (approximately 25%) of anthocyanin monoglycosides (glucoside or galactoside) was absorbed from the stomach, whereas absorption of cyanidin 3-rutinoside was lower. Bilberry anthocyanins were also efficiently absorbed, but absorption varied greatly (19-37%) according to the anthocyanin structure; delphinidin glycosides were the most absorbed. When a high concentration of blackberry anthocyanins (750 micromol/L) was injected into the gastric lumen, the percentage of cyanidin 3-glucoside (Cy 3-glc) absorption was lower than after administration of a low concentration (14 micromol/L). After administration of this high concentration, blackberry anthocyanins were observed in plasma from gastric vein and aorta, whereas neither aglycones nor metabolites were detected. Analysis of bile samples revealed that Cy 3-glc appeared in bile after as little as 20 min. Peonidin 3-glucoside (the methylated form of Cy 3-glc) as well as unknown anthocyanin metabolites were also observed in bile. Thus, this study demonstrated that anthocyanin glycosides were quickly and efficiently absorbed from the stomach and rapidly excreted into bile as intact and metabolized forms.

Methods of analysis for anthocyanins in plants and biological fluids

Anthocyanins are the largest group of water-soluble pigments in the plant kingdom. They are responsible for most of the red, blue, and purple colors of fruits, vegetables, flowers, and other plant tissues or products. The analysis of anthocyanins is complex as a result of their ability to undergo structural transformations and complexation reactions. In addition, they are difficult to measure independently of other flavonoids, as they have similar structural and reactivity characteristics. Anthocyanins are generally extracted with weakly acidified alcohol-based solvents, followed by concentration (under vacuum), and purification of the pigments. Paper and/or thin-layer chromatography and UV-Vis spectroscopy have traditionally been used for the identification of anthocyanins. Capillary zone electrophoresis, a hybrid of chromatography and electrophoresis, is gaining popularity for the analysis of anthocyanins; however, liquid chromatography (LC) has become the standard method for identification and separation in most laboratories and may be used for both preparative and quantitative analysis. LC with mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy are possibly the most powerful methods for the structural elucidation of anthocyanins available, to date. At present, the most satisfactory method for mixture analysis is the multistep method of separation, isolation, and quantification by LC with peak identification by MS and high-field NMR.

Bioavailability of anthocyanidin-3-glucosides following consumption of red wine and red grape juice

Pharmacokinetic parameters and the bioavailability of several dietary anthocyanins following consumption of red wine and red grape juice were compared in nine healthy volunteers. They were given a single oral dose of either 400 mL of red wine (279.6 mg total anthocyanins) or 400 mL of red grape juice (283.5 mg total anthocyanins). Within 7 h, the urinary excretion of total anthocyanins was 0.23 and 0.18% of the administered dose following red grape juice and red wine ingestion, respectively. Pharmacokinetic parameters derived from plasma and urine concentrations exhibited higher variability after ingestion of red grape juice. Compared to red grape juice anthocyanins, the relative bioavailability of red wine anthocyanins was calculated to be 65.7, 61.3, 61.9, 291.5, 57.1, and 76.3% for the glucosides of cyanidin, delphinidin, malvidin, peonidin, petunidin, and its sum (referred to as total anthocyanins), respectively. Bioequivalence was established for none of the anthocyanins. On a low level, urinary excretion of anthocyanins was fast, and the excretion rates seem to exhibit monoexponential characteristics over time after ingestion of both red grape juice and red wine. Due to low bioavailability, any significant contribution of anthocyanins to health protecting properties of red wine or red grape juice seems questionable, but the clinical relevance of these findings awaits further investigation.

Absorption and excretion of black currant anthocyanins in humans and watanabe heritable hyperlipidemic rabbits

Anthocyanins are thought to protect against cardiovascular diseases. Watanabe heritable hyperlipidemic (WHHL) rabbits are hypercholesterolemic and used as a model of the development of atherosclerosis. To compare the uptake and excretion of anthocyanins in humans and WHHL rabbits, single-dose black currant anthocyanin studies were performed. Procedures for workup and analyses of urine and plasma samples containing anthocyanins were developed with high recoveries (99 and 81%, respectively) and low limits of quantification (> or =6.6 and > or =1.1 nM, respectively). The excretion and absorption of anthocyanins from black currant juice were found to be within the same order of magnitude in the two species regarding urinary excretion within the first 4 h (rabbits, 0.035%; humans, 0.072%) and t(max) (rabbits, approximately 30 min; humans, approximately 45 min). A food matrix effect was detected in rabbits, resulting in the absorption of a higher proportion of the anthocyanins from black currant juice than from an aqueous citric acid matrix. In humans the absorption and urinary excretion of anthocyanins from black currant juice were found to be proportional with dose and not influenced by the ingestion of a rice cake. In both species a larger proportion of the anthocyanin rutinosides than of the glucosides was absorbed, whereas the structure of the aglycon had no influence on the absorption and excretion. The anthocyanins had no effect in rabbits on the antioxidant capacity of plasma measured as Trolox equivalent antioxidant capacity and ferruc reducing ability of plasma.

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

In recent years, numerous studies have shown that the polyphenolics present in fruit and vegetable products exhibit a wide range of biological effects. However, there is little reliable information on the absorption of glycosylated and acylated anthocyanins in humans. In the present study, the absorption of anthocyanins in humans was investigated after the consumption of a high-fat meal with a freeze-dried blueberry powder containing 25 individual anthocyanins including 6 acylated structures. Nineteen of the 25 anthocyanins present in the blueberries were detected in human blood serum. Furthermore, the appearance of total anthocyanins in the serum was directly correlated with an increase in serum antioxidant capacity (ORAC(acetone), P < 0.01). These results show that anthocyanins can be absorbed in their intact glycosylated and possibly acylated forms in human subjects and that consumption of blueberries, a food source with high in vitro antioxidant properties, is associated with a diet-induced increase in ex vivo serum antioxidant status.