Phenolic Metabolites in Plasma and Thigh Meat of Chickens Supplemented with Grape Byproducts.

Grape byproducts are rich sources of polyphenols with powerful antioxidant and health-promoting effects. The impact of supplementing chicken diets with grape byproducts on plasma and thigh meat concentrations of phenolic metabolites was evaluated by analyzing samples by high-performance liquid chromatography quadrupole time of flight mass spectrometry. Chickens were fed three experimental diets: Control diet, Control+8% grape pomace, and Control+0.1% grape seed extract. In plasma, 32 phenolic metabolites were identified, some of which were conjugated catechin/epicatechin metabolites exclusively identified in chickens fed diets enriched in grape byproducts. Also, these chickens showed significantly higher plasmatic concentrations of 21 phenolic metabolites. In thigh meat, 14 phenolic metabolites were identified, but no differences were found between diets. Higher plasmatic tocopherol was found when supplementing diets with grape byproducts, while no changes were observed in meat. Thus, supplementing chicken diets with grape byproducts leads to a significant increase in the circulation of phenolic metabolites and tocopherol.

Influence of diabetes on plasma pharmacokinetics and brain bioavailability of grape polyphenols and their phase II metabolites in the Zucker diabetic fatty rat.

SCOPE: The effect of diabetes on the pharmacokinetics, bioavailability and brain distribution of grape polyphenols and select metabolites was studied in the Zucker diabetic fatty (ZDF) rat model. METHODS AND RESULTS: (ZDF) rats and their lean controls (LN) were dosed with a Standardized Grape Polyphenol (SGP) Mixture consisting of grape seed extract, Concord grape juice and resveratrol (RES) by oral gavage for 10 days. An 8-h pharmacokinetic study was performed. After 24 h, a second dose of SGP was administered and 1 h later animals were sacrificed and brain tissue was harvested. Plasma, urine, and brain tissue were analyzed for grape polyphenols. ZDF rats exhibited significantly diminished Cmax for all catechin, epicatechin, quercetin and resveratrol conjugated metabolites. Bioavailability was significantly lower in ZDF rats for methylated flavan-3-ol, RES, and quercetin metabolites. Significantly lower levels of metabolites of RES, quercetin, and flavan-3-ols were found in brains of ZDF rats. There was no significant difference between ZDF and LN in anthocyanins in plasma and no anthocyanins were detectable in brain extracts. ZDF rats showed significantly higher urinary excretion for all polyphenols. CONCLUSION: Diabetes may alter the overall bioavailability of some polyphenols in plasma and brain in part due to higher urinary clearance.

Potentiation of the bioavailability of blueberry phenolic compounds by co-ingested grape phenolic compounds in mice, revealed by targeted metabolomic profiling in plasma and feces.

The low bioavailability of dietary phenolic compounds, resulting from poor absorption and high rates of metabolism and excretion, is a concern as it can limit their potential beneficial effects on health. Targeted metabolomic profiling in plasma and feces of mice supplemented for 15 days with a blueberry extract, a grape extract or their combination revealed significantly increased plasma concentrations (3-5 fold) of blueberry phenolic metabolites in the presence of a co-ingested grape extract, associated with an equivalent decrease in their appearance in feces. Additionally, the repeated daily administration of the blueberry-grape combination significantly increased plasma phenolic concentrations (2-3-fold) compared to animals receiving only a single acute dose, with no such increase being observed with individual extracts. These findings highlight a positive interaction between blueberry and grape constituents, in which the grape extract enhanced the absorption of blueberry phenolic compounds. This study provides for the first time in vivo evidence of such an interaction occurring between co-ingested phenolic compounds from fruit extracts leading to their improved bioavailability.

Quantitative combination of natural anti-oxidants prevents metabolic syndrome by reducing oxidative stress.

Insulin resistance and abdominal obesity are present in the majority of people with the metabolic syndrome. Antioxidant therapy might be a useful strategy for type 2 diabetes and other insulin-resistant states. The combination of vitamin C (Vc) and vitamin E has synthetic scavenging effect on free radicals and inhibition effect on lipid peroxidation. However, there are few studies about how to define the best combination of more than three anti-oxidants as it is difficult or impossible to test the anti-oxidant effect of the combination of every concentration of each ingredient experimentally. Here we present a math model, which is based on the classical Hill equation to determine the best combination, called Fixed Dose Combination (FDC), of several natural anti-oxidants, including Vc, green tea polyphenols (GTP) and grape seed extract proanthocyanidin (GSEP). Then we investigated the effects of FDC on oxidative stress, blood glucose and serum lipid levels in cultured 3T3-L1 adipocytes, high fat diet (HFD)-fed rats which serve as obesity model, and KK-ay mice as diabetic model. The level of serum malondialdehyde (MDA) in the treated rats was studied and Hematoxylin-Eosin (HE) staining or Oil red slices of liver and adipose tissue in the rats were examined as well. FDC shows excellent antioxidant and anti-glycation activity by attenuating lipid peroxidation. FDC determined in this investigation can become a potential solution to reduce obesity, to improve insulin sensitivity and be beneficial for the treatment of fat and diabetic patients. It is the first time to use the math model to determine the best ratio of three anti-oxidants, which can save much more time and chemical materials than traditional experimental method. This quantitative method represents a potentially new and useful strategy to screen all possible combinations of many natural anti-oxidants, therefore may help develop novel therapeutics with the potential to ameliorate the worldwide metabolic abnormalities.

Role of intestinal microbiota in the generation of polyphenol-derived phenolic acid mediated attenuation of Alzheimer's disease ß-amyloid oligomerization.

SCOPE: Grape seed polyphenol extract (GSPE) is receiving increasing attention for its potential preventative and therapeutic roles in Alzheimer's disease (AD) and other age-related neurodegenerative disorders. The intestinal microbiota is known to actively convert many dietary polyphenols, including GSPE, to phenolic acids. There is limited information on the bioavailability and bioactivity of GSPE-derived phenolic acid in the brain. METHODS AND RESULTS: We orally administered GSPE to rats and investigated the bioavailability of 12 phenolic acids known to be generated by microbiota metabolism of anthocyanidins. GSPE treatment significantly increased the content of two of the phenolic acids in the brain: 3-hydroxybenzoic acid and 3-(3´-hydroxyphenyl)propionic acid, resulting in the brain accumulations of the two phenolic acids at micromolar concentrations. We also provided evidence that 3-hydroxybenzoic acid and 3-(3´-hydroxyphenyl)propionic acid potently interfere with the assembly of ß-amyloid peptides into neurotoxic ß-amyloid aggregates that play key roles in AD pathogenesis. CONCLUSION: Our observation suggests important contribution of the intestinal microbiota to the protective activities of GSPE (as well as other polyphenol preparations) in AD. Outcomes from our studies support future preclinical and clinical investigations exploring the potential contributions of the intestinal microbiota in protecting against the onset/progression of AD and other neurodegenerative conditions.

Synthesis and quantitative analysis of plasma-targeted metabolites of catechin and epicatechin.

Grape seed polyphenolic extract (GSPE) rich in the flavan-3-ols (+)-catechin and (-)-epicatechin beneficially modulates Alzheimer's Disease phenotypes in animal models. The parent molecules in the extract are converted to a series of methylated and glucuronidated derivatives. To fully characterize these metabolites and establish a robust quantitative assay of their levels in biological fluids, we have implemented a partial synthetic approach utilizing chemical methylation followed by enzymatic glucuronidation. Liquid chromatography/time-of-flight mass spectrometry (LC-TOF-MS) and nuclear magnetic resonance (NMR) spectroscopy were used to assign unequivocal structures to the compounds. An analytical method using solid-phase extraction and LC-MS/MS in selective reaction monitoring mode (SRM) was validated for their quantitation in plasma. These studies provide a basis for improvements in future work on the bioavailability, metabolism, and mechanism of action of metabolites derived from dietary flavan-3-ols in a range of interventions.

Flavanol metabolites distribute in visceral adipose depots after a long-term intake of grape seed proanthocyanidin extract in rats.

A considerable number of epidemiological investigations and intervention studies have supported an association between the intake of flavanol- and proanthocyanidin-containing foods and a decreased risk of metabolic diseases. Nonetheless, less is know about the capacity of tissues to accumulate flavanols and/or their metabolites. The main objective of the present study was to determine (n 20) plasma bioavailability and disposition in the liver, muscle, brown adipose tissue (BAT) and white adipose tissues (mesenteric and perirenal) in rats after a long-term consumption of three doses of grape seed phenolic extract (5, 25 and 50 mg/kg body weight) for 21 d in order to determine whether there is a dose-response relationship. Glucuronidated conjugates (total glucuronidated conjugates: C(5 mg/kg) 1·9; C(25 mg/kg) 6·4; C(50 mg/kg) 27·7 µmol/l plasma) followed by methyl glucuronidated conjugates (total methyl glucuronidated conjugates: C(5 mg/kg) 1·98; C(25 mg/kg) 4·48; C(50 mg/kg) 12·5 µmol/l plasma) were the main flavanol metabolites quantified in plasma, also detecting a dimer in its free form (C(25 mg/kg) 0·74; C(50 mg/kg) 0·79 µmol/l plasma). Each of the studied organs has a particular behaviour of accumulation and response to the assayed grape seed extract doses, with an exponential bioavailability-dose relationship in BAT, in which flavanols could play an important role in the reduction or prevention of obesity, modulating the functionality of that tissue.