Characteristics of (+)-catechin and (-)-epicatechin transport across pig intestinal brush border membranes

Low Plasma Appearance of (+)-Catechin and (-)-Catechin Compared with Epicatechin after Consumption of Beverages Prepared from Nonalkalized or Alkalized Cocoa-A Randomized, Double-Blind Trial

Flavan-3-ols are claimed to be responsible for the cardioprotective effects of cocoa. Alkalized cocoa powder (ALC), commonly used for many non-confectionary products, including beverages, provides less (+)-catechin, (−)-epicatechin, and procyanidins and more (−)-catechin than nonalkalized cocoa powder (NALC). This may affect the plasma appearance of monomeric flavan-3-ol stereoisomers after consumption of NALC vs. ALC. Within a randomized, crossover trial, 12 healthy nonsmokers ingested a milk-based cocoa beverage providing either NALC or ALC. Blood was collected before and within 6 h postconsumption. (+)-Catechin, (−)-catechin, and epicatechin were analyzed in plasma by HPLC as sum of free and glucuronidated metabolites. Pharmacokinetic parameters were obtained by a one-compartment model with nonlinear regression methods. For epicatechin in plasma, total area under the curve within 6 h postconsumption (AUC_0–6h) and incremental AUC_0–6h were additionally calculated by using the linear trapezoidal method. After consumption of NALC and ALC, (+)-catechin and (−)-catechin were mostly not detectable in plasma, in contrast to epicatechin. For epicatechin, total AUC_0–6h was different between both treatments, but not incremental AUC_0–6h. Most kinetic parameters were similar for both treatments, but they varied strongly between individuals. Thus, epicatechin is the main monomeric flavan-3-ol in plasma after cocoa consumption. Whether NALC should be preferred against ALC due to its higher (−)-epicatechin content remains unclear with regard to the results on incremental AUC_0–6h. Future studies should investigate epicatechin metabolites in plasma for a period up to 24 h in a larger sample size, taking into account genetic polymorphisms in epicatechin metabolism and should consider all metabolites to understand inter-individual differences after cocoa intake.

Flavocoxid attenuates airway inflammation in ovalbumin-induced mouse asthma model

Asthma is a common airways inflammatory disease. This study provides evidence on the efficacy of flavocoxid against ovalbumin (OVA)-induced allergic airways inflammation in a mouse model of asthma. Airway inflammation was induced by intrapеritonеal injection of 10 mg ovalbumin (OVA) on day zero and day 7 followed by OVA challenge starting from 14th day to 16th day. Beclomethasone; a standard anti-inflammatory agent was selected as a drug in asthma. Flavocoxid (20 mg/kg, i. p.) was administered on day zero till 16th day followed by OVA challenge. At the end of the study, lung weight index, bronchoalveolar lavage fluid (BALF) content of total and differential WBCs, interleukin-13(IL-13), in addition to lung tissue nitrate/nitrite (NO) and oxidative stress biomarkers were measured. Also, histological and immunohistochemical analysis were conducted. Daily i. p. injection of flavocoxid (20 mg/kg) significantly improved airway inflammation. Inflammatory cells in BALF, malondialdehyde (MDA), NO and IL-13 significantly declined with concomitant increase in superoxide dismutase (SOD) activity. Histopathological examination and immunohistochеmical staining of mast cells were correlated with observed biochemical improvements. Collectively, these results demonstrate that flavocoxid mitigates the allergic airway inflammation induced by ovalbumin through attenuation of IL-13, NO expressions and oxidative stress.

Systemic Absorption of Catechins after Intraruminal or Intraduodenal Application of a Green Tea Extract in Cows

Green tea catechins have various potential health benefits in humans including anti-inflammatory, anti-oxidative and hepato-protective effects. If present in the circulation, they might have similar effects in ruminants, which are exposed to oxidative stress and fatty liver disease such as dairy cows during the periparturient phase. However, the bioavailability of a substance is a prerequisite for any post absorptive effect in vivo. This study aimed to investigate the appearance of catechins from a green tea extract (GTE) in cattle plasma after intraruminal and intraduodenal administration because absorption is of major importance regarding the bioavailability of catechins. The studies were performed in 5 rumen-fistulated non-lactating heifers and 6 duodenally fistulated lactating dairy cows, respectively, equipped with indwelling catheters placed in a jugular vein. The GTE was applied intraruminally (10 and 50 mg/kg BW, heifers) or duodenally (10, 20 and 30 mg/kg BW, dairy cows) in a cross-over design with a 2 d washout period between different dosages. Blood samples were drawn following the GTE administration at various pre-defined time intervals. The concentration of the major GTE catechins (gallocatechin, epigallocatechin, catechin, epicatechin, epigallocatechin-gallate, epicatechin-gallate) in plasma samples were analysed by HPLC with electrochemical detection. Irrespective of the dose, almost none of the catechins originally contained in the GTE were detected in plasma samples after intraruminal application. In contrast, intraduodenal administration of GTE resulted in increased plasma concentrations of epicatechin, epigallocatechin, epigallocatechin gallate in a dose-dependent manner. Thus, we can conclude that intraruminally or orally administered catechins are intensively metabolized by ruminal microorganisms.

Wine consumption and intestinal redox homeostasis

Regular consumption of moderate doses of wine is an integral part of the Mediterranean diet, which has long been considered to provide remarkable health benefits. Wine's beneficial effect has been attributed principally to its non-alcoholic portion, which has antioxidant properties, and contains a wide variety of phenolics, generally called polyphenols. Wine phenolics may prevent or delay the progression of intestinal diseases characterized by oxidative stress and inflammation, especially because they reach higher concentrations in the gut than in other tissues. They act as both free radical scavengers and modulators of specific inflammation-related genes involved in cellular redox signaling. In addition, the importance of wine polyphenols has recently been stressed for their ability to act as prebiotics and antimicrobial agents. Wine components have been proposed as an alternative natural approach to prevent or treat inflammatory bowel diseases. The difficulty remains to distinguish whether these positive properties are due only to polyphenols in wine or also to the alcohol intake, since many studies have reported ethanol to possess various beneficial effects. Our knowledge of the use of wine components in managing human intestinal inflammatory diseases is still quite limited, and further clinical studies may afford more solid evidence of their beneficial effects.

Target-based selection of flavonoids for neurodegenerative disorders

Habitual consumption of dietary flavonoids known to improve mitochondrial bioenergetics and inhibit various secondary sources of reactive oxygen species (ROS) reduces the risk for neurodegenerative disorders such as Parkinson's disease (PD), stroke, and Alzheimer's disease (AD). Combining specific dietary flavonoids selected on the basis of oral bioavailability, brain penetration, and the inhibition of multiple processes responsible for excessive ROS production may be a viable approach for the prevention and treatment of neurodegenerative disorders. Inclusion of flavonoids that raise cAMP levels in the brain may be of additional benefit by reducing the production of proinflammatory mediators and stimulating the transcriptional machinery necessary for mitochondrial biosynthesis. Preclinical models suggest that flavonoids reduce hearing loss resulting from treatment with the chemotherapeutic drug cisplatin by opposing the excessive production of ROS and proinflammatory mediators implicated in PD, stroke, and AD. Flavonoid combinations optimized for efficacy in models of cisplatin-induced hearing loss (CIHL) may therefore have therapeutic utility for neurodegenerative disorders.

Bioavailability of wine-derived phenolic compounds in humans: a review

Phenolic compounds are produced in the seeds and skins of grapes, and are transferred into wine during the fermentation process. Phenolic compounds can also be imparted into wine from maturation and storage in oak wood barrels after fermentation. The consumption of wine, an alcoholic beverage, has been observed in epidemiological studies to reduce the risk of cardiovascular disease and certain cancers, as well as diabetes and dementia, in a J-shaped relationship between amount consumed and level of risk. The bioactivity of wine primarily observed in vitro and ex vivo, may result from wine's relatively high content of phenolic compounds, which is similar to that observed in fruits and vegetables; a Mediterranean fruit and vegetable rich-diet is also associated with a reduced risk of cardiovascular disease and cancers. If the wine-derived phenolic compounds or their active metabolites are not absorbed in sufficient amounts and in a readily available form for cells, however, then they are less likely to have any significant in vivo activity. This review considers and discusses the available data to date on the bioavailability of the different wine-derived phenolic compounds in humans.

Epicatechin ingested via cocoa products reduces blood pressure in humans: a nonlinear regression model with a Bayesian approach

BACKGROUND

Four meta-analyses of randomized controlled trials (RCTs) based on the classical random-effects model showed that cocoa consumption can reduce systolic blood pressure (SBP) and diastolic blood pressure (DBP). Because epicatechin is suggested to be responsible for the treatment effect, changes in blood pressure should depend on the dose of ingested epicatechin, which may explain the between-study differences.

OBJECTIVE

The objective was to quantify the effect of epicatechin ingested via cocoa products on changes in SBP and DBP.

DESIGN

A nonlinear meta-regression model was chosen to investigate the impact of the epicatechin dose on changes in SBP and DBP. A Bayesian approach using Markov chain Monte Carlo methods was applied for an appropriate treatment of the nonlinearity.

RESULTS

Data from 16 RCTs on SBP and 15 RCTs on DBP were included. The dose of epicatechin ingested via cocoa products influenced the changes in SBP and DBP. The asymptotic limit for the reduction was estimated at -4.6 mm Hg (95% CI: -5.4, -3.9 mm Hg) for SBP and at -2.1 mm Hg (95% CI: -2.7, -1.6 mm Hg) for DBP. An intake of 25 mg epicatechin/d led to a mean reduction of -4.1 mm Hg (95% CI: -4.6, -3.6 mm Hg) in SBP and of -2.0 mm Hg (95% CI: -2.4, -1.5 mm Hg) in DBP.

CONCLUSIONS

Blood pressure reduction by consumption of cocoa products depends on the dose of ingested epicatechin, which explains most of the between-study differences in classical meta-analyses. Similar effects may be achieved by consumption of other foods that are also rich in epicatechin.

Insights into the putative catechin and epicatechin transport across blood-brain barrier

The identification of mechanisms associated with phenolic neuroprotection is delayed due to a lack of information regarding the ability of phenolic compounds to enter the central nervous system (CNS). The aim of this work was to evaluate the transmembrane transport of catechin and epicatechin across blood-brain barrier (BBB). Two BBB cell lines, RBE-4 cells (immortalized cell line of rat capillary cerebral endothelial cells) and hCMEC/D3 (immortalized human cerebral microvessel endothelial cell line), were used. HPLC-DAD/MS was used to detect these compounds and their metabolites in the studied samples. The metabolites of the tested flavan-3-ols were synthesized to be used as standards. Catechin and epicatechin could cross both cells in a time-dependent manner. This transport was stereoselective (epicatechin ≫ catechin), involving one or more stereoselective entities. Additionally, these cells were capable of metabolizing these compounds, particularly by conjugation with glucuronic acid, since this metabolite was detected in the basolateral media. Several studies suggest that blood levels of catechin and epicatechin are far below the levels used in this study and that these compounds appeared mainly as methyl, sulfate and glucuronide metabolites. Nevertheless, the information obtained by this study is valuable for the new insights about flavan-3-ols transport.

IN CONCLUSION

(i) catechin and epicatechin are capable of crossing the BBB; (ii) a stereoselective process was involved in the passage of these compounds across BBB cells; (iii) these endothelial cells have enzymes capable of metabolizing these compounds.

Metabolites are key to understanding health effects of wine polyphenolics

Phenolic compounds in grapes and wine are grouped within the following major classes: stilbenes, phenolic acids, ellagitannins, flavan-3-ols, anthocyanins, flavonols, and proanthocyanidins. Consumption of foods containing phenolic substances has been linked to beneficial effects toward chronic diseases such as coronary heart disease and colorectal cancer. However, such correlations need to be supported by in vivo testing and bioavailability studies are the first step in establishing cause and effect. Class members from all phenolic groups can be glucuronidated, sulfated, and/or methylated and detected at low concentrations in the bloodstream and in urine. But the majority of phenolic compounds from grapes and wine are metabolized in the gastrointestinal tract, where they are broken down by gut microflora. This typically involves deglycosylation, followed by breakdown of ring structures to produce phenolic acids and aldehydes. These metabolites can be detected in bloodstream, urine, and fecal samples by using sophisticated instrumentation methods for quantitation and identification at low concentrations. The health effects related to grape and wine consumption may well be due to these poorly understood phenolic acid metabolites. This review discusses the known metabolism of each major class of wine and grape phenolics, the means to measure them, and ideas for future investigations.