Procyanidin Research Articles

Proanthocyanidins and Their Contribution to Sensory Attributes of Black Currant Juices.

Black currant juices from five different cultivars were analyzed for composition, content, and mean degree of polymerization (mDP) of proanthocyanidins (PA) by UPLC-MS/MS. Juices contained both procyanidins (PC) and prodelphinidins (PD), but the PC-% varied significantly, from 28 to 82% of the total PA. In addition, high PD-% was related to high mDP and total PA content. Enzyme-assisted processing increased significantly total PA (5-14-fold), PD-% (12-65%), and mDP (1.8-6.2-fold) in the juices of all cultivars. Enzymatic treatment increased the contents of large PAs more than those of small PAs. The contents of PA and mDP were positively associated with the mouth-drying and puckering astringent characteristics. However, the PA content did not contribute to the bitter taste. Juices from the most bitter cultivars had the lowest contents of proanthocyanidins regardless of the processing method. This finding indicates the existence of other bitter compounds in black currants in addition to PA.

Crosslinking of decellularized heart valve by procyanidins in the acidic buffer solution: Compliance, anti-calcification and biological compatibility

Crosslinking of decellularized heart valve by procyanidins in the acidic buffer solution: Compliance, anti-calcification and biological compatibility

Procyanidins-crosslinked aortic elastin scaffolds with distinctive anti-calcification and biological properties

Elastin, a main component of decellularized extracellular matrices and elastin-containing materials, has been used for tissue engineering applications due to their excellent biocompatibility. However, elastin is easily calcified, leading to the decrease of life span for elastin-based substitutes. How to inhibit the calcification of elastin-based scaffolds, but maintain their good biocompatibility, still remains significantly challenging. Procyanidins (PC) are a type of natural polyphenols with crosslinking ability. To investigate whether pure elastin could be crosslinked by PC with anti-calcification effect, PC was first used to crosslink aortic elastin. Results show that PC can crosslink elastin and effectively inhibit elastin-initiated calcification. Further experiments reveal the possible mechanisms for the anti-calcification of PC crosslinking including (1) inhibiting inflammation cell attachment, and secretion of inflammatory factors such as MMPs and TNF-α, (2) preventing elastin degradation by elastase, and (3) direct inhibition of mineral nucleation in elastin. Moreover, the PC-crosslinked aortic elastin maintains natural structure with high pore volume (1111μL/g), large pore size (10–300μm) and high porosity (75.1%) which facilitates recellularization of scaffolds in vivo, and displays excellent hemocompatibility, anti-thrombus and anti-inflammatory potential. The advantages of PC-crosslinked porous aortic elastin suggested that it can serve as a promising scaffold for tissue engineering.

Effect of post-veraison source limitation on the accumulation of sugar, anthocyanins and seed tannins inVitis viniferacv. Sangiovese berries

Background and Aims Climate change can alter the synchronous accumulation of sugar and other main berry compounds during ripening. The aim of this study was to determine whether post-veraison trimming could delay sugar accumulation and influence the production of anthocyanins and seed tannins in Sangiovese grapes. Methods and Results Shoots were trimmed in 2009, 2010 and 2011 when the berry total soluble solids (TSS) reached 15–17°Brix, leaving eight nodes on each main shoot. The accumulation of TSS, anthocyanins and seed tannins was measured during ripening, and yield parameters were recorded at harvest. Grapes from trimmed vines contained a lower TSS in 2009 and 2010, but there was no impact on the concentration of anthocyanins and seed tannins. In 2011, leaf area limitation was insufficient to reduce TSS accumulation, because yield constraints were observed and the leaf area/yield ratio was within the optimal range. Conclusions The lower rate of TSS accumulation in berries had no impact on the concentration of anthocyanins and seed tannins, suggesting that this approach could produce grapes with a lower TSS at harvest or delay harvest. In low-vigour vines suffering from water deficit, the post-veraison trimming repeated over the years could reduce yield, which may be responsible for the lack of TSS reduction compared with that of control vines. Significance of the Study Our study provides insight into the relationship between TSS accumulation and the production of anthocyanins and seed tannins in the berry in response to post-veraison leaf area reduction.

Systemic absorption and metabolism of dietary procyanidin B4 in pigs.

Procyanidins (PCs) are among the most abundant polyphenols in the human diet and they are reported to exhibit several beneficial health effects. However, the knowledge about their metabolic fate is rather limited. To investigate the systemic absorption and metabolism of dietary PC B4, a kinetic study using pigs as model system has been performed. After oral application of a single dose of 10 mg/kg body weight PC B4, urine and plasma were collected over a period of 48 h. PC B4 and its possible metabolites were analyzed in physiological samples using HPLC-MS/MS and GC-MS. PC B4 was detected as intact molecule in urine as well as in plasma. Maximum reached plasma concentration of PC B4 (cmax ) was 2.13 ng/mL (3.68 nM) and mean total urinary excretion related to the administered dose was 0.008 ± 0.003%. In addition to that the monomeric structural units catechin and epicatechin were determined as degradation products. Furthermore, methylated and conjugated monomeric metabolites were identified. Monomeric metabolites were identified to be the major fraction occurring in the systemic circulation. The analysis of phenolic acids did not show an increase of these possible further metabolites. After oral administration, PC B4 is absorbed as intact molecule and it is excreted in urine. In addition, it is degraded to the monomeric subunits that are then further metabolized to methylated and glucuronidated conjugates in pigs.

Procyanidins protects against oxidative damage and cognitive deficits after traumatic brain injury

Primary objective: Oxidative stress is the principal factor in traumatic brain injury (TBI) that initiates the events that result in protracted neuronal dysfunction and remodeling. Importantly, antioxidants can protect the brain against oxidative damage and modulate the capacity of the brain to cope with synaptic dysfunction and cognitive impairment.Research design: To date, however, no studies have investigated the effects of procyanidins (PC) on cognitive deficits after TBI. Methods and Procedures: In the present study, rats with controlled cortical impact (CCI) were used to investigate the protective effects of procyanidins.Main outcomes and results: The results showed that procyanidins reduced the level of malondialdehyde (MDA) and elevated the level of glutathione (GSH) and the activity of superoxide dismutase (SOD). In addition, treatment with procyanidins, which elevated the levels of brain-derived neurotropic factor (BDNF), phosphorylation-cAMP-response element binding protein (pCREB), total CREB, and cyclic AMP (cAMP), improved cognitive performance in the Morris water maze after TBI.Conclusions: These results suggest that procyanidins appear to counteract oxidative damage and behavioral dysfunction after TBI through antioxidant activity and the up-regulation of cAMP/CREB signaling.

Superior antioxidant polymer films created through the incorporation of grape tannins in ethyl cellulose

Agro-wastes represent an abundant and economical source of antioxidant compounds. Extraction and incorporation of antioxidants from these compounds into ethyl cellulose films provides the basis for an active packaging material. Grape tannin extract (GT) incorporation into ethyl cellulose results in hydrogen bonding between polyphenols and ethyl cellulose strands, which allows for the polyphenols to remain active and to be securely incorporated. Incorporation of 0.5 % GT in ethyl cellulose produced a significant increase (p < 0.01) in antioxidant activity while not altering physical or mechanical properties. A higher loading of GT at 3.0 % into ethyl cellulose resulted in further improvement in antioxidant activity (12-fold), while a slight decrease in the tensile properties was noted due to the plasticizing effect of GT as a consequence of disruption of the intermolecular hydrogen bonding.

In vivo interactions between procyanidins and human saliva proteins: effect of repeated exposures to procyanidins solution.

The general accepted mechanism for astringency arises from the interaction between tannins and salivary proteins (SP) resulting in (in)soluble aggregates. By HPLC analysis, it was observed that repeated sips of procyanidins (PC) solution practically depleted aPRPs (∼14%) and statherin (∼2%), and significantly reduced the amount of gPRPs. On the other hand, bPRPs were not significantly affected. In the analysis performed after the last exposure to PC solution, it was seen a significant recovering of the chromatographic peaks corresponding especially to aPRPs (∼74%) and statherin (∼80%). In vitro interaction between SP and PC results in the decrease of the chromatographic peaks of aPRPs and statherin, suggesting that these proteins were involved in the formation of a significant quantity of insoluble complexes. In general, the results suggest that the different families of SP can be involved in different stages of the development of astringency sensation.

A new generation of topical chronic wound treatments containing specific MMP inhibitors

A new generation of topical chronic wound treatments containing specific MMP inhibitors Ravi Shrivastava, Nathalie Cucuat, Monika Rousse, Thomas Weigand, Pedro Neto, Claire Janicot, Christiane Shrivastava VITROBIO Research Institute, Issoire, France Purpose: Incidence of chronic wounds is constantly rising worldwide, but all currently available treatments are intended either to provide symptomatic relief or to assist cicatrization to some extent, but not to directly stimulate cellular growth. Physiologically, chronic wound healing simply requires cell growth to fill the injured cavity. To grow, our cells need to attach onto a cushion, called extracellular matrix (ECM), secreted by the mother cells and composed of multiple proteins. Recent scientific works prove that the concentration of certain matrix metalloproteinases (MMPs) is extremely high in all chronic wounds and, because of their proteolytic nature, some MMPs completely degrade the ECM, hindering cell attachment and cell growth. The aim of this study was to identify, neutralize, and eliminate these MMPs from the wound surface so as to design an effective treatment for chronic wounds. Methods: Acute and chronic models of human epithelial and fibroblast cells were prepared on a defined ECM cushion in vitro and MMPs were added in the culture medium to identify the MMPs causing ECM disintegration for each cell type. ECM-degrading MMPs were then incubated with selected procyanidin-rich plant extracts (PCDs) and cell growth was reanalyzed. Results: It was observed that: 1) multiple MMPs are involved in cellular matrix destruction; 2) ECM-destroying MMPs are specific with respect to cell type; and 3) specific PCDs may bind and neutralize selected MMPs. Conclusion: Topical application of specific plant PCDs to selectively neutralize ECM-destroying MMPs in acute and chronic wounds represents a novel approach for the treatment of superficial and deep skin wounds. Keywords: extra cellular matrix (ECM), matrix metalloproteinases, procyanidins (PCDs), tannins, ulcers

Molecular analysis of proanthocyanidins related to pigmentation in brown cotton fibre (Gossypium hirsutum L.).

The structural characteristics and component differences of proanthocyanidins in brown and white cotton fibres were identified by nuclear magnetic resonance (NMR) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) analyses. Proanthocyanidins in brown and white cotton fibres were found to contain mainly procyanidin (PC) and prodelphidin (PD) units with 2, 3-cis form (epigallocatechin and epicatechin). However, part of the proanthocyanidins in the white cotton fibres were modified by acylation and were constitutively different from the proanthocyanidins in brown cotton fibres. The relative amount of PD was similar to that of PC in white cotton fibres, while proanthocyanidins in brown cotton fibres consisted mainly of PD units with a relative ratio of 9:1. In brown cotton fibres, the proanthocyanidin monomeric composition was consistent with the expression profiles of proanthocyanidin synthase genes, suggesting that anthocyanidin reductase represented the major flow of the proanthocyanidin biosynthesis pathway. In addition, the structural characteristics and component differences of proanthocanidins in brown and white cotton fibres suggested that quinones, the oxidation products of proanthocyanidins, were the direct contributors to colour development in brown cotton fibre. This was demonstrated by vanillin-HCl staining and Borntrager's test. Collectively, these data demonstrated that the biosynthesis of proanthocyanidins is a crucial pigmentation process in brown cotton fibre, and that quinones may represent the main pigments contributing to formation of the the brown colour. This study revealed the molecular basis of pigmentation in brown cotton fibres, and provided important insights for genetic manipulation of pigment production in cotton fibres.

Protein-Precipitable Tannin in Wines from Vitis vinifera and Interspecific Hybrid Grapes (Vitis ssp.): Differences in Concentration, Extractability, and Cell Wall Binding

Although they possess significant viticultural advantages, interspecific hybrid grapes (Vitis spp.) are reported to produce wine with lower tannin concentrations than European wine varieties (Vitis vinifera). However, extensive quantitative data on this phenomenon as well as mechanistic explanations for these differences are lacking. A survey of primarily commercial wines from the Finger Lakes American Viticultural Area (New York) using a protein precipitation method determined that hybrid-based wines had >4-fold lower tannin concentrations than vinifera wines. To elucidate factors responsible for differences in wine tannin, 24 wines were produced from both red hybrid and vinifera cultivars under identical conditions. Lower wine tannin in French-American hybrid- than vinifera-based wines could be partially explained by lower grape tannin. However, experiments in which cell wall material was incubated with tannin indicated that cell wall binding may be of equal or greater importance in explaining lower wine tannin concentrations in hybrid-based wines. Subsequent characterization of cell wall material revealed that protein in flesh cell walls and, to a lesser extent, pectin in skin cell walls were correlated with cell wall binding.

GENETIC ANALYSIS OF WINE GRAPE HIGH-QUALITY RIPENING IN THE 'MONASTRELL' × 'SYRAH' PROGENY

The technological (sugar/acid balance) and the phenolic ripening (accumula-tion and extractability of grape anthocyanins and tannins) have great relevance to wine quality. In order to find genes involved in high-quality wine grape ripening, we are carrying out a genetic analysis in a F1 progeny segregating for these traits, consisting of 230 hybrids from a cross between the cultivars ?Monastrell? and ?Syrah?. ?Monastrell? is a variety widely grown and used in the Murcia Region (southeast of Spain), and is very well adapted to the dry conditions of the Mediterranean climate. ?Syrah? is used in the same region blended with ?Monastrell?. We genotyped the 230 offspring for 138 SNP markers and 104 SSR markers scattered over 19 linkage groups (LGs). The consensus map contained 229 markers covering 1,180.79 cM, with an average distance between loci of 5.16 cM. The female and male genetic maps covered a total length of 1,039.66 and 1,027.20 cM, respectively. Grape quality traits and phenological parameters were evaluated for two years. QTL analyses are being carried out using a Multiple- QTL Mapping (MQM) method focused on QTLs previously detected during the two seasons via simple interval mapping (SIM analysis). Both genome-wide and linkage-group-wide LOD thresholds corresponding to a=0.20 were used as minimum values for QTL detection. QTLs for sprouting time with LOD value higher than the genome-wide threshold (significant QTLs) were consistently detected on LGs 1 and 8, explaining between 14% and 18% of total variance. Other QTLs for veraison time, fertility and berry weight were also found.

Pre-fermentation addition of grape tannin increases the varietal thiols content in wine

The recent finding that grape tannin may contain significant amount of S-glutathionylated (GSH-3MH) and S-cysteinylated (Cys-3MH) precursors of the varietal thiols 3-mercapto-1-hexanol and 3-mercaptohexyl acetate, characteristic of Sauvignon blanc wines, offers new opportunities for enhancing the tropical aroma in fermented beverages. In this study this new hypothesis was investigated: Müller Thurgau (17 samples) and Sauvignon blanc (15 samples) grapes were fermented with and without addition of a selected grape tannin. As expected, the tannin-added juices were higher in precursors, and they produced wines with increased free thiols. Preliminary informal sensory tests confirmed that in particular the Sauvignon wines produced with the tannin addition were often richer with increased “fruity/green” notes than the corresponding reference wines. This outcome confirms that grape tannin addition prior to fermentation can fortify the level of these compounds.

Low molecular weight procyanidins from grape seeds enhance the impact of 5-Fluorouracil chemotherapy on Caco-2 human colon cancer cells.

ObjectiveGrape seed procyanidins (PC) are flavan-3-ol oligomers and polymers known for their biological activity in the gut. Grape seed extract (GSE) have been reported to reduce intestinal injury in a rat model of mucositis. We sought to investigate effects of purified PC fractions differing in mean degree of polymerization (mDP) combined with 5-Fluorouracil (5-FU) chemotherapy on the viability of colon cancer cells (Caco-2).DesignSixPC fractions (F1-F6) were isolated from Cabernet Sauvignon seeds at two ripeness stages: pre-veraison unripe (immature) and ripe (mature), utilizing step gradient, low-pressure chromatography on a Sephadex LH-20 resin. Fractions were tested on Caco-2 cells, alone and in combination with 5-FU. Eluted fractions were characterized by phloroglucinolysis and gel permeation chromatography. Cell viability was determined by the 3-(4,5-Dimethylthiazol-2yl)-2,5-diphenyl-tetrazolium bromide) (MTT) assay.ResultsAll isolated fractions significantly reduced Caco-2 cell viability compared to the control (P<0.05), but F2 and F3 (mDP 2–6) were the most active fractions (immature F2 = 32% mDP 2.4, F3 = 35% mDP 5.8 and mature F2 = 13% mDP 3.6 and F3 = 17% mDP 5.9; percentage of viable cells remaining) on Caco-2 cells. When combined with 5-FU, immature fractions F1-F3 enhanced the cell toxicity effects of 5-FU by 27–73% (P<0.05). Mature seed PC fractions (F1–F4) significantly enhanced the toxicity of 5-FU by 60–83% against Caco-2 cells (P<0.05). Moreover, some fractions alone were more potent at decreasing viability in Caco-2 cells (P<0.05; immature fractions = 65–68% and mature fractions = 83–87%) compared to 5-FU alone (37%).ConclusionsPCs of mDP 2–6 (immature F1-F3 and mature F1 and F4)not only enhanced the impact of 5-FU in killing Caco-2 cells, but also surpassed standard 5-FU chemotherapy as an anti-cancer agent.The bioactivity of PC is therefore attributed primarily to lower molecular weight PCs.

Computational study of the structure–free radical scavenging relationship of procyanidins

Procyanidins (PCs) are effective free radical scavengers, however, their antioxidant ability is variable because they have different degrees of polymerisation, are composed by distinct types of subunits and are very susceptible to changes in conformation. In this work the structure–free radical scavenging relationship of monomers, dimers and trimers of PCs was studied through the hydrogen atom transfer (HAT), sequential proton-loss electron-transfer (SPLET) and single electron transfer followed by proton transfer (SET-PT) mechanisms in aqueous phase, employing the Density Functional Theory (DFT) computational method. The structure–free radical scavenging relationship of PCs showed a very similar behaviour in HAT and SET-PT mechanisms, but very different in the SPLET mechanism. The structural factor that showed more effects on the ability of PCs to scavenge free radicals in aqueous phase was the conformation.

Crosslinking of saphenous vein ECM by procyanidins for small diameter blood vessel replacement

Xenogenic decellularized vessels, mainly composed of extracellular matrices (ECMs), are thought to be one of the alternative resources of small-diameter blood vessels due to abundant source, tubular configuration, vascular microstructure, and good cytocompatibility. However, the main shortcomings of ECM vessels are their low chemical stability, easy calcification, immunogenicity, and high risk of thrombogenicity. Previous studies have shown that, glutaraldehyde (GA), as a crosslinking agent, led to significant calcification and cytotoxicity for the prepared ECM substitutes. To overcome the drawbacks of pure and GA-crosslinked vascular alternatives of small-diameter blood vessels, procyanidins (PC), a naturally derived polyphenol with anti-inflammatory and platelet aggregation inhibiting bioactivities, was applied to crosslink the decellularized bovine saphenous vein ECM (svECM). After crosslinking, the obtained svECM substitutes exhibited natural tubular configuration with significantly improved mechanical properties, proper resistance to proteolysis, high chemical stability, and excellent anticalcification property. The PC-crosslinked svECM substitutes were cytocompatible for cells adhesion and proliferation, and blood compatible for erythrocytes with far less hemolysis than that of safety standard. Furthermore, the PC-crosslinked svECM substitutes showed distinct antithrombosis and anti-immunogenicity potential. With these advantages, it is suggested that the PC-crosslinked svECM may be used as a practical substitutes of small diameter blood vessels.

Toward Unraveling Grape Tannin Composition: Application of Online Hydrophilic Interaction Chromatography × Reversed-Phase Liquid Chromatography–Time-of-Flight Mass Spectrometry for Grape Seed Analysis

Despite the significant importance of tannins in viticulture and enology, relatively little is known about the detailed chemical composition of these molecules. This is due to challenges associated with the accurate analytical determination of the highly structurally diverse proanthocyanidins which comprise tannins. In this contribution, we address this limitation by demonstrating how online comprehensive two-dimensional liquid chromatography (LC × LC) coupled to high resolution mass spectrometry (HR-MS) can be exploited as a powerful analytical approach for the detailed characterization of grape seed tannins. Hydrophilic interaction chromatography (HILIC) and reversed-phase liquid chromatography (RP-LC) were employed in the two dimensions to provide complementary information in terms of separation according to hydrophilicity and hydrophobicity, respectively. Online coupling of HILIC × RP-LC with fluorescence detection and electrospray ionization MS delivered high resolution analysis in a practical analysis time, while allowing selective detection and facilitating compound identification. Time-of-flight (TOF) MS provided high acquisition rates and sensitivity coupled to accurate mass information, which allowed detection of procyanidins up to a degree of polymerization (DP) of 16 and a degree of galloylation up to 8 in a red grape seed extract. This analytical methodology promises to shed new light on these important grape constituents and potentially on their evolution during wine production.

Effects of Fruit By-product Extracts Supplementation on Growth Performance and Nutrient Digestibility in Growing Pigs

ABSTRACT A total of 96 pigs [(Landrace × Yorkshire) × Duroc] with an initial BW of 27.94 ± 0.92 kg were used in a 6-week experiment to determine the effects of dietary supplementation with fruit by-product extracts on growth performance and nutrient digestibility in growing pigs. Pigs were randomly allotted to four treatments : 1) CON (basal diet), 2) PRO (CON + 0.5% procyanidin), 3) HES (CON + 0.5% hesperidin), 4) TAN (CON + 0.5% tannin). There were six replications per treatment with four pigs per pen. Supplementation had no effect ( p >0.05) on average daily gain, average daily feed intake, and G/F. The apparent total tract digestibility (ATTD) of dry matter and nitrogen was increased ( p <0.05) in the HES treatment relative to the PRO treatment. Pigs fed the HES and TAN diets had greater ( p <0.05) ATTD of energy than pigs fed PRO diet. The ATTD of ash was greatest( p <0.05) in HES treatments. In addition, the ATTD of calcium was greater ( p <0.05) in HES treatments than in CON and PRO treatments. Overall, the results of this study indicated that dietary supplementation with 0.5% fruit by-products did not affect growth performance, but inclusion of 0.5% hesperidin increased nutrient digestibility in growing pigs.(

Effects of Fruit By-product Extracts on Blood Characteristics, Antioxidant Activity, and Immune Response in Pigs

This experiment was conducted to determine the effects of extracts from fruit by-products on the blood characteristics, antioxidant activities, and immune response to Escherichia coli lipopolysaccharide (LPS) in growing pigs. A total of 96 pigs [(Landrace <TEX>${\times}$</TEX> Yorkshire) <TEX>${\times}$</TEX> Duroc] with an initial BW of <TEX>$27.94{\pm}0.92kg$</TEX> were used in a 6-week feeding trial. The pigs were randomly placed into one of four treatment groups with six replications (four pigs per replication) per treatment according to their initial BW. Treatments were: 1) CON (basal diet), 2) PRO (CON + 0.5% procyanidin), 3) HES (CON + 0.5% hesperetin), 4) TAN (CON + 0.5% tannin). At the end of the sixth week, five pigs (total 20 pigs, <TEX>$BW=27.94{\pm}0.92kg$</TEX>) were selected from each treatment and injected with LPS (<TEX>$100{\mu}g/kg$</TEX> of BW). Blood samples were collected 3 h after LPS injection to assess anti-oxidative and inflammatory responses. After the LPS challenge, the concentration of serum cholesterol decreased with fruit by-product treatment compared with CON (p<0.05). The administration of TAN increased the concentration of blood total protein compared with the CON group 3 h after LPS challenge (p<0.05). The albumin concentration was also higher with PRO treatment compared to HES treatment (p<0.05). The concentration of IgM was increased by fruit by-product supplementation at 0 and 3 h (p<0.05). In addition, IgG concentration was higher in PRO, HES, and TAN treatments compared to CON treatment at 0 h, and IgG concentrations were also higher in the HES group compared to the CON group at 3 h (p<0.05). The concentration of IgA also increased with fruit by-product treatments at 3 h (p<0.05). In conclusion, dietary supplementation with fruit by-products may moderate the immune response after a LPS challenge in growing pigs.

Transepithelial Permeability Studies of Flavan-3-ol-C-glucosides and Procyanidin Dimers and Trimers across the Caco-2 Cell Monolayer

In this study the permeability of two flavanol-C-glucosides (FCglcs) and five dimeric and trimeric flavan-3-ols, namely, procyanidins (PCs), was investigated with the human colon carcinoma cell line (Caco-2) model. These compounds can be found especially in cocoa, and they are of great interest due to their assumed beneficial health effects. Transepithelial electrical resistance (TEER) and capacitance were measured online with a CellZscope device prior to and during the whole experiment to guarantee the maintenance of the barrier properties. The transport experiments with pure, single compounds (50-300 μM) from apical to basolateral side showed slight permeation of PCs A2, B2, and B5 and cinnamtannin B1 (CB1) as well as (-)-catechin-6-C-glucoside (C6Cglc) and (-)-catechin-8-C-glucoside (C8Cglc) of about 0.02-0.2% after 24 h. Transport of PC C1 could not be detected. Inhibition of P-glycoprotein (Pgp) increased the permeation of PC B2 and CB1 to the basolateral side, which indicates that Pgp counteracts the transport of these compounds. Metabolites (epicatechin, 3'- and 4'-O-epicatechin) in very small amounts were detectable only for PC B2. These are the first data concerning the permeability of flavan-3-ol-C-glucosides across the Caco-2 cell monolayer.