Oligomeric Flavanols Research Articles

The Effect of the Light Intensity on the Growth and Accumulation of Monomeric and Oligomeric Flavanols in Callus Cultures of Camellia sinensis L.

The Effect of the Light Intensity on the Growth and Accumulation of Monomeric and Oligomeric Flavanols in Callus Cultures of Camellia sinensis L.

Higher Habitual Dietary Intakes of Flavanols and Anthocyanins Differentially Associate with Lower Incidence of Ischemic Stroke Subtypes—A Follow-Up Analysis

BackgroundWe previously reported that habitual consumption of dietary flavanol oligomers + polymers and anthocyanins is associated with a lower risk of ischemic stroke. However, no studies have investigated their relationship with ischemic stroke subtypes. ObjectivesIn this follow-up analysis, we aimed to examine the association of flavanol oligomers + polymers and anthocyanin intake with ischemic stroke subtypes, including the following: 1) large-artery atherosclerosis, 2) cardioembolism, 3) small-vessel occlusion, 4) other determined etiology, and 5) undetermined etiology. MethodsParticipants (n = 55,094) from the Danish Diet, Cancer, and Health Study were followed up for <16 y for first-time ischemic stroke events, which were classified according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. Intakes of flavanol oligomers + polymers and anthocyanins were calculated from food frequency questionnaires using the Phenol-Explorer database, and their relationships with ischemic stroke subtypes were investigated using restricted cubic splines within Cox proportional hazards models. After multivariable adjustment, higher habitual intakes (quintile 5 compared with quintile 1) of flavanol oligomers + polymers and anthocyanins were associated with a lower risk of specific ischemic stroke subtypes, including large-artery atherosclerosis [flavanol oligomers + polymers, hazard ratio {HR} (95% confidence interval {CI}): 0.64 (0.47, 0.87)], cardioembolism [anthocyanins, HR (95% CI): 0.45 (0.25, 0.82)], and small-vessel occlusion [flavanol oligomers + polymers, HR (95% CI): 0.65 (0.54, 0.80); anthocyanins, HR (95% CI): 0.79 (0.64, 0.97)], but not stroke of other determined or undetermined etiology. ConclusionsHigher habitual intakes of flavanols and anthocyanins are differentially associated with a lower risk of ischemic stroke from atherosclerosis and/or cardioembolism but not with other subtypes.

Effect of FLAVAnols on bone turnover markers in type 2 diabetes mellitus–post hoc analysis from a 3-month randomized placebo-controlled trial

BACKGROUND: Individuals with type 2 diabetes mellitus (T2DM) have increased fracture risk with high bone mineral density, possibly related to advanced glycation end products (AGEs) accumulation in bone. Flavanol supplementation in postmenopausal women reduced AGEs formation and decreased bone resorption markers. However, to date, these effects have not been investigated in T2DM. OBJECTIVE: We used a post hoc secondary analysis to determine the effect of monomeric and oligomeric flavanols supplementation on bone turnover markers (BTMs) in individuals with T2DM. METHODS: Eighty-three individuals with T2DM, aged 40–85 years, with microalbuminuria were enrolled from 4 trial centers in Rotterdam, the Netherlands, into a randomized, double-blind, placebo-controlled trial with renal vascular health as the primary outcome. Participants were randomized (1:1) to receive either a placebo or 200 mg of monomeric and oligomeric flavanols as intervention for three months. Serum alkaline phosphatase (ALP), type I collagen crosslinked beta C-telopeptide (β-CTx), and type I procollagen-N-propeptide (P1NP) were measured at baseline and three months. ANCOVA was performed on rank transformed BTMs at three months as the outcome, adjusting for baseline BTMs, group, age, sex, and BMI. RESULTS: Baseline characteristics did not differ between the two arms. The adjusted mean change in BTMs at three months was not different between the placebo vs. intervention arm: ALP –0.059 (–0.262–0.145) vs. 0.060 (–0.135–0.356), p = 0.41; β-CTx 0.013 (–0.205–0.231) vs. 0.100 (–0.109–0.310), p = 0.53 and P1NP 0.091 (–0.080–0.262) vs. 0.030 (–0.134–0.195), p = 0.61. There was no significant within-group change in BTMs after three months in both study arms. CONCLUSION: Supplementation with daily 200 mg of flavanols during three months, on top of usual care in individuals with T2DM, did not result in changes in BTMs compared to placebo. Future studies are needed to show whether long-term supplementation in higher dosages may positively affect BTMs in individuals with T2DM.

Novel ADM Ceylon Standardized Extract With Antioxidant and Antimicrobial Effects Evaluated in Caenorhabditis elegans Model

ObjectivesThe main objective is to develop a novel powdered extract from Ceylon tea, standardized to gallic acid, flavanols and xanthines, and to evaluate “in vivo” its functional properties. MethodsCeylon tea leaves and corresponding powdered extracts were obtained at laboratory and industrial scales. To analyze individual antioxidants, High Performance Liquid Chromatography (J. Chromatogr. A, 2000,881, 439–447) and Gas Chromatography (ACS Food Sci. Technol., 2021, 1, 4,596–604). Oxidative stress resistance (J. Agric. Food Chem., 2011, 59,2077–2085). C. elegans nematodes were egg-synchronized in NGM plates (control medium) and NGM plates containing Ceylon extract (0.1 to 2 mg/mL). Nematode viability was assessed after oxidative stress (2 mM H2O2). Vitamin C (10 μg/mL) was used as positive control. Experiments were carried out in duplicate. Infection assays (Antioxidants 2021, 10,536). Nematodes were age-synchronized by recovering the eggs from adults in agar plates, already seeded with E. coli OP50 (NGM), and NGM plates containing three different doses of Ceylon (0.1 to 1 mg/mL). The pathogen strain Staphylococcus aureus (ATCC25923) was used for infections. Nematodes were incubated at 25 °C and scored for survival during 5–10 days. ResultsChromatographic analyses Industrial scale Ceylon extracts was standardized to gallic acid (1.8 ± 0.0%), monomeric, oligomeric flavanols and methyl xanthines, respectively 2.1 ± 0.1%, 0.2 ± 0.0%, & 4.2 ± 0.1%. The volatile composition showed characteristic profile of Camellia sinensis, with higher relative proportion of trans-2-hexenal (1.9 ± 0.1%), linalool (3.1 ± 0.3%) and benzaldehyde (3.5 ± 0.2%), together with limonene (12.0 ± 1.3%) and eugenol (13.0 ± 0.0%). Antioxidant activity and pathogen protection ADM® Ceylon extract showed significant protection both upon acute oxidative stress and S. aureus infection in the model of C. elegans. Thus, nematodes feeding 1 mg/mL of Ceylon extract, significantly increased their survival compared with control fed population (48% versus 28%). The extract (1 mg/mL) increased 20% survival vs control infected population. ConclusionsADM® Ceylon powdered extract is a novel standardized functional extract with potential antioxidant and protective effects against pathogens. Funding SourcesThanks to ADM® for funding this research work.

Chemometric Classification of Colombian Cacao Crops: Effects of Different Genotypes and Origins in Different Years of Harvest on Levels of Flavonoid and Methylxanthine Metabolites in Raw Cacao Beans.

The aim of this study was to evaluate the levels of chemical markers in raw cacao beans in two clones (introduced and regional) in Colombia over several years. Multivariate statistical methods were used to analyze the flavanol monomers (epicatechin and catechin), flavanol oligomers (procyanidins) and methylxanthine alkaloids (caffeine and theobromine) of cocoa samples. The results identified genotype as the main factor contributing to cacao chemistry, although significant differences were not observed between universal and regional clones in PCA. The univariate analysis allowed us to establish that EET-96 had the highest contents of both flavanol monomers (13.12 ± 2.30 mg/g) and procyanidins (7.56 ± 4.59 mg/g). In addition, the geographic origin, the harvest conditions of each region and the year of harvest may contribute to major discrepancies between results. Turbo cocoa samples are notable for their higher flavanol monomer content, Chigorodó cocoa samples for the presence of both types of polyphenol (monomer and procyanidin contents) and the Northeast cocoa samples for the higher methylxanthine content. We hope that knowledge of the heterogeneity of the metabolites of interest in each clone will contribute to the generation of added value in the cocoa production chain and its sustainability.

The effect of monomeric and oligomeric FLAVAnols in patients with type 2 diabetes and microalbuminuria (FLAVA-trial): A double-blind randomized controlled trial

Microalbuminuria is an early sign of vascular complications of type 2 diabetes and predicts cardiovascular disease and mortality. Monomeric and oligomeric flavanols (MOFs) are linked to improved vascular health. The aim of this study was to assess the effect of 3 months MOFs on albuminuria and endothelial function markers in patients with type 2 diabetes and microalbuminuria. We conducted a double-blind, placebo-controlled trial among patients with type 2 diabetes and microalbuminuria. Patients with type 2 diabetes received either 200mg MOFs or placebo daily on top of their habitual diet and medication. The primary endpoint was the between-group difference of the change in 24-h Albumin Excretion Rate (AER) over three months. Secondary endpoints were the between-group differences of the change in plasma levels of different markers of endothelial dysfunction. Mixed-modelling was applied for the longitudinal analyses. Participants (n=97) were 63.0±9.5 years old; diabetes-duration was 15.7±8.5 years. Median baseline AER was 60 (IQR 20-120) mg/24h. There was no within-group difference in median change of AER from baseline to 3 months in the intervention (0 (-35-21) mg/24h, p=0.41) or the control group (0 (-20-10) mg/24h, p=0.91). There was no between-group difference in the course of AER over three months (log-transformed data: β=-0.02 (95%CI -0.23-0.20), p=0.88), nor in the plasma levels of the endothelial dysfunction markers. Daily 200mg MOFs for three months on top of habitual diet and usual care did not reduce AER and plasma markers of endothelial dysfunction compared to placebo, in patients with long-term type 2 diabetes and microalbuminuria. NTR4669, www.trialregister.nl.

Effect of different yeast mannoproteins on the interaction between wine flavanols and salivary proteins

Unbalanced wine astringency, caused by a gap between phenolic and technological grape maturities, is one of the consequences of the global climate change in the vitiviniculture. To resolve it, potential strategies are being currently used, like the addition of commercial yeast mannoproteins (MPs) to wines. In this work, the main interactions responsible for the wine astringent sensation, namely, interactions between human salivary proteins and wine flavanols have been studied by Dynamic Light Scattering (DLS) and liquid chromatography coupled to DAD and MS detectors (HPLC–DAD–MS), in presence or absence of two MPs with different saccharide/protein ratio. The results indicate that there are differences on the substrate specificity for each mannoprotein and that its action mechanism could change not only depending on the mannoprotein composition but also on the flavanol structure. MPs with elevated carbohydrate content could act thought the stabilization of soluble aggregates with human salivary proteins and flavanols, mainly non-galloylated flavanol oligomers, whereas MPs with higher protein percentage mostly could precipitate flavanols (mainly non-galloylated ones with low degree of polymerization) which partially prevents the formation of insoluble flavanol–salivary protein aggregates.

Use of flavanols in type 2 diabetes mellitus with microalbuminuria (FLAVA-TRIAL): A randomized controlled multicenter trial

Rationale: In patients with type 2 diabetes mellitus (T2DM), microalbuminuria is a good proxy of endothelial dysfunction and strongly associated with unfavorable outcome. Monomeric and oligomeric flavanols (MOF) isolated from grape seeds (Vitis vinifera) have been linked to improved endothelial function and vascular health. The aim of this study was to determine the effect of daily MOF supplementation on albuminuria and endothelial function in patients with T2DM and microalbuminuria.

Effects of Monomeric and Oligomeric Flavanols on Kidney Function, Inflammation and Oxidative Stress in Runners: A Randomized Double-Blind Pilot Study.

Nonsteroidal anti-inflammatory drugs are frequently used by athletes in order to prevent musculoskeletal pain and improve performance. In combination with strenuous exercise, they can contribute to a reduction of renal blood flow and promote development of kidney damage. We aimed to investigate whether monomeric and oligomeric flavanols (MOF) could reduce the severity of kidney injuries associated with the intake of 400-mg ibuprofen followed by the completion of a half-marathon in recreational athletes. In this double-blind, randomized study, the original MOF blend of extracts from grape seeds (Vitis vinifera L.) and pine bark (Pinus pinaster L.) or placebo were taken for 14 days preceding the ibuprofen/half-marathon. Urine samples were collected before and after the ibuprofen/half-marathon, and biomarkers of kidney injury, inflammation and oxidative stress were assessed. Intake of MOF significantly reduced the incidence of post-race hematuria (p = 0.0004) and lowered concentrations of interleukin (IL)-6 in the urine (p = 0.032). Urinary neutrophil-associated lipocalin, creatine, albumin, IL-8 and malondialdehyde tended to decrease. The supplementation with MOF in recreational runners appears to safely preserve kidney function, reduce inflammation and promote antioxidant defense during strenuous exercise and intake of a single dose of ibuprofen.

(−)-Epicatechin metabolites promote vascular health through epigenetic reprogramming of endothelial-immune cell signaling and reversing systemic low-grade inflammation

Ingestion of (−)-epicatechin flavanols reverses endothelial dysfunction by increasing flow mediated dilation and by reducing vascular inflammation and oxidative stress, monocyte-endothelial cell adhesion and transendothelial monocyte migration in vitro and in vivo. This involves multiple changes in gene expression and epigenetic DNA methylation by poorly understood mechanisms. By in silico docking and molecular modeling we demonstrate favorable binding of different glucuronidated, sulfated or methylated (−)-epicatechin metabolites to different DNA methyltransferases (DNMT1/DNMT3A). In favor of this model, genome-wide DNA methylation profiling of endothelial cells treated with TNF and different (−)-epicatechin metabolites revealed specific DNA methylation changes in gene networks controlling cell adhesion-extravasation endothelial hyperpermeability as well as gamma-aminobutyric acid, renin-angiotensin and nitric oxide hypertension pathways. Remarkably, blood epigenetic profiles of an 8 weeks intervention with monomeric and oligomeric flavanols (MOF) including (−)-epicatechin in male smokers revealed individual epigenetic gene changes targeting similar pathways as the in vitro exposure experiments in endothelial cells. Furthermore, epigenetic changes following MOF diet intervention oppose atherosclerosis associated epigenetic changes. In line with biological data, the individual epigenetic response to a MOF diet is associated with different vascular health parameters (glutathione peroxidase 1 and endothelin-1 expression, acetylcholine-mediated microvascular response), in part involving systemic shifts in blood immune cell types which reduce the neutrophil–lymphocyte ratio (NLR). Altogether, our study suggests that different (−)-epicatechin metabolites promote vascular health in part via epigenetic reprogramming of endothelial-immune cell signaling and reversing systemic low-grade inflammation.

The Effect of Cocoa Flavanols and Metabolites on β‐cell Proliferation and Survival

Currently, an estimated 30.3 million Americans have diabetes, and experts predict 54.9 million Americans will have diabetes by 2030. The increasing prevalence of Type 2 diabetes (T2D) accounts for much of this expected growth. T2D is characterized by insulin resistance, which eventually leads to a reduction in functional β‐cell mass. Thus, treatments that increase β‐cell proliferation, survival, and function have the potential to reverse the effects of diabetes. One treatment that has shown promise is the use of dietary cocoa flavanols. These compounds have shown the ability to prevent the onset of diabetes in mice. Furthermore, a recent study conducted by our lab demonstrated that monomeric cocoa flavanols improved insulin secretion by increasing mitochondrial respiration. In addition to stimulating insulin secretion, we hypothesize that cocoa flavanols may also confer antidiabetic effects by promoting β‐cell proliferation and protecting β‐cells from lipotoxicity‐mediated cell death. To that end, we present data that shows the effect of epicatechin (monomeric flavanol), oligomeric, and polymeric cocoa flavanols on β‐cell proliferation and survival. Our results demonstrated that epicatechin enhances β‐cell proliferation. This finding is important because only monomeric flavanols have been found at significant levels in circulation. Notably, several gut bacteria‐derived cocoa metabolites have also been observed and identified. Consequently, we tested the effects of several cocoa metabolites on β‐cell proliferation and survival as well. We found that the cocoa metabolite hippuric acid, also enhances β‐cell proliferation. Additionally, we suggest a mechanism for the observed increase in proliferation caused by epicatechin and hippuric acid. These findings strengthen the growing body of evidence that dietary cocoa flavanols can ameliorate the effects of T2D.Support or Funding InformationDiabetes Action Research and Education Foundation grant #475 to JSTThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Lack of acute or chronic effects of epicatechin-rich and procyanidin-rich apple extracts on blood pressure and cardiometabolic biomarkers in adults with moderately elevated blood pressure: a randomized, placebo-controlled crossover trial

The reported effects of flavanol-rich foods such as cocoa, dark chocolate, and apples on blood pressure and endothelial function may be due to the monomeric flavanols [mainly (-)-epicatechin (EC)], the oligomeric flavanols [procyanidins (PCs)], or other components. Reports of well-controlled intervention studies that test the effects of isolated oligomeric flavanols on biomarkers of cardiovascular health are lacking. We studied the acute and chronic effects of an EC-rich apple flavanol extract and isolated apple PCs on systolic blood pressure (BP) and other cardiometabolic biomarkers. Forty-two healthy men and women with moderately elevated BP completed this randomized, double-blind, placebo-controlled, 4-arm crossover trial. Participants ingested a single dose of an apple flavanol extract (70 mg monomeric flavanols, 65 mg PCs), a double dose of this extract (140 mg monomeric flavanols, 130 mg PCs), an apple PC extract (130 mg PCs, 6.5 mg monomeric flavanols), or placebo capsules once daily for 4 wk, in random order. Biomarkers of cardiovascular disease risk and vascular function were measured before and 2 h after ingestion of the first dose and after the 4-wk intervention. Compared with placebo, none of the isolated flavanol treatments significantly (P<0.05) changed systolic or diastolic BP (peripheral and aortic), plasma nitric oxide (NO) reaction products, or measures of arterial stiffness (carotid femoral pulse-wave velocity, brachial-ankle pulse-wave velocity, or Augmentation Index) after 2 h or 4 wk of the intervention. There were no changes in plasma endogenous metabolite profiles or circulating NO; endothelin 1; total, HDL, or LDL cholesterol; triglycerides; fasting glucose; fructosamine; or insulin after 4 wk of the intervention. Our data suggest that, in isolation, neither monomeric flavanols nor PCs affect BP, blood lipid profiles, endothelial function, or glucose control in individuals with moderately elevated BP. The reported benefits of consuming flavanol-rich cocoa, chocolate, and apple products appear to be dependent on other components, which may work in combination with monomeric flavanols and PCs. This trial was registered at www.clinicaltrials.gov as NCT02013856.

Use of monomeric and oligomeric flavanols in the dietary management of patients with type 2 diabetes mellitus and microalbuminuria (FLAVA trial): study protocol for a randomized controlled trial

BackgroundPatients with type 2 diabetes mellitus (T2D) are prone to micro- and macro-vascular complications. Monomeric and oligomeric flavanols (MOF) isolated from grape seeds (Vitis vinifera) have been linked to improved endothelial function and vascular health. The aim of this study is to determine the effect of a daily supplementation of 200 mg MOF on renal endothelial function of patients with T2D and microalbuminuria.Methods/designFor this double-blind, placebo-controlled, randomized, multicenter trial 96 individuals (ages 40–85 years) with T2D and microalbuminuria will be recruited. Participants will be randomly assigned to the intervention group, receiving 200 mg of MOF daily for 3 months, or to the control group, receiving a placebo. The primary endpoint is the evolution over time in albumin excretion rate (AER) until 3 months of intervention as compared with placebo. Secondary endpoints are the evolution over time in established plasma markers of renal endothelial function—asymmetric dimethylarginine (ADMA), soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular cell adhesion molecule-1 (sICAM-1), interleukin-6 (IL-6), and von Willebrand Factor (vWF)—until 3 months of intervention as compared with placebo. Mixed modeling will be applied for the statistical analysis of the data.DiscussionWe hypothesize that T2D patients with microalbuminuria have a medically determined requirement for MOF and that fulfilling this requirement will result in a decrease in AER and related endothelial biomarkers. If confirmed, this may lead to new insights in the dietary management of patients with T2D.Trial registrationNederlands Trial Register, NTR4669, registered on 7 July 2014.

Monomeric and oligomeric flavanols maintain the endogenous glucocorticoid response in human macrophages in pro-oxidant conditions in vitro

Chronic inflammation and oxidative stress are (sub)cellular processes that enhance each other and contribute to the genesis of many systemic pathologies. The endogenous glucocorticoid cortisol plays an important role in the physiological termination of a pro-inflammatory immune response. However, in conditions of pronounced oxidative stress the anti-inflammatory action of cortisol is impaired. Since grape seed-derived monomeric and oligomeric flavan-3-ols (MOF) have been shown to attenuate both inflammation and oxidative stress in vitro and in humans, we hypothesized that these compounds are able to maintain the anti-inflammatory activity of cortisol in immune cells in a pro-oxidant environment.In a glucocorticoid resistance model using human monocytes (THP-1 cell line) differentiated into macrophage-like cells we observed that exposure to 1 mM tertiary butyl hydroperoxide (t-BuOOH) for 4 h significantly hampered the anti-inflammatory action of cortisol assessed as attenuation of the interleukin (IL)-8 production.Under these conditions, the effects of MOF were assessed on pro-inflammatory cytokines expression, cortisol's anti-inflammatory action and on the expression of 11β-hydroxysteroid dehydrogenase (11β-HSD) 1, which catalyzes intracellular conversion of cortisone to cortisol.MOF attenuated the gene expression of pro-inflammatory cytokines and prevented the decline of the anti-inflammatory effect of cortisol in the presence of t-BuOOH. MOF also maintained the activity of histone deacetylase in the cell nucleus which is essential for cortisol's molecular action to terminate the transcription of pro-inflammatory genes. Moreover, MOF prevented the down-regulation of 11β-HSD1 gene expression in this pro-oxidant cellular environment.Taken together our data suggest that MOF contribute to maintain the anti-inflammatory action of cortisol under pro-oxidant conditions via preservation of the intracellular availability of bioactive cortisol and cortisol-mediated termination of pro-inflammatory gene transcription. These findings provide novel insights in how MOF may enhance the ability to adapt, which is of particular relevance for their rational use as dietary supplement to maintain health.

Phenolic compounds and antioxidant activity of lingonberry (Vaccinium vitis-idaea L.) leaf, stem and fruit at different harvest periods

Fruits and aerial parts of lingonberry could be better developed as dietary supplements if the composition in bioactive phenolic compounds and the best period for collection were known. UPLC/MS analysis revealed the predominant presence of arbutin in leaf and that of flavanols in stems harvested in May, July and September. Anthocyanins, flavanols and benzoic acid derivatives were equally present in fruits. Stem and leaf are highly homologous with (+)-catechin, A- and B-type dimers/trimers, and two quercetin glycosides as major contributors. No or only weak seasonal variations were highlighted for all phenolic classes. Additionally, flavanol oligomers showed a lower mDP for fruit (3–4) than for stem and leaf (4–6). The rate of A-type linkage was 3–5% with A-type subunits in extension mainly. Finally, the content in phenolic compounds (UPLC) correlated well with TPC and the DPPH radical scavenging activity although leaf and stem constituents reacted differently in both antioxidant tests.

Monomeric cocoa catechins enhance β-cell function by increasing mitochondrial respiration

A hallmark of type 2 diabetes (T2D) is β-cell dysfunction and the eventual loss of functional β-cell mass. Therefore, mechanisms that improve or preserve β-cell function could be used to improve the quality of life of individuals with T2D. Studies have shown that monomeric, oligomeric and polymeric cocoa flavanols have different effects on obesity, insulin resistance and glucose tolerance. We hypothesized that these cocoa flavanols may have beneficial effects on β-cell function. INS-1 832/13-derived β-cells and primary rat islets cultured with a monomeric catechin-rich cocoa flavanol fraction demonstrated enhanced glucose-stimulated insulin secretion, while cells cultured with total cocoa extract and with oligomeric or polymeric procyanidin-rich fraction demonstrated no improvement. The increased glucose-stimulated insulin secretion in the presence of the monomeric catechin-rich fraction corresponded with enhanced mitochondrial respiration, suggesting improvements in β-cell fuel utilization. Mitochondrial complex III, IV and V components are up-regulated after culture with the monomer-rich fraction, corresponding with increased cellular ATP production. The monomer-rich fraction improved cellular redox state and increased glutathione concentration, which corresponds with nuclear factor, erythroid 2 like 2 (Nrf2) nuclear localization and expression of Nrf2 target genes including nuclear respiratory factor 1 (Nrf1) and GA binding protein transcription factor alpha subunit (GABPA), essential genes for increasing mitochondrial function. We propose a model by which monomeric cocoa catechins improve the cellular redox state, resulting in Nrf2 nuclear migration and up-regulation of genes critical for mitochondrial respiration, glucose-stimulated insulin secretion and ultimately improved β-cell function. These results suggest a mechanism by which monomeric cocoa catechins exert their effects as an effective complementary strategy to benefit T2D patients.

Application of enzyme preparations for extraction of berry skin phenolics in withered winegrapes

Postharvest withering of grapes strongly affects the content and extractability of phenolic compounds in the production of sfursat, fortified and passito wines. This work evaluated the effectiveness of enzymes applied individually and/or in multi-enzyme blends, on the extraction of anthocyanins, oligomeric flavanols and polymeric flavanols from withered grape skins during simulated maceration. The study was performed on Vitis vinifera L. cv. Nebbiolo and Barbera because of their different skin phenolic profile and cell wall composition. Our findings highlight that the relationship between skin mechanical properties (berry skin break force and energy) and extraction yield of phenolic compounds is variety dependent. Significant correlations were found between the skin softening associated with cell wall degradation and the extraction of anthocyanins and flavanols in Nebbiolo, for which polygalacturonase, individually or in multi-enzyme blends, plays an important role. In Barbera, the extractability of phenolic compounds was not affected by the presence of exogenous enzymes.

Development, validation and evaluation of an analytical method for the determination of monomeric and oligomeric procyanidins in apple extracts

There is a lack of data for individual oligomeric procyanidins in apples and apple extracts. Our aim was to develop, validate and evaluate an analytical method for the separation, identification and quantification of monomeric and oligomeric flavanols in apple extracts. To achieve this, we prepared two types of flavanol extracts from freeze-dried apples; one was an epicatechin-rich extract containing ∼30% (w/w) monomeric (−)-epicatechin which also contained oligomeric procyanidins (Extract A), the second was an oligomeric procyanidin-rich extract depleted of epicatechin (Extract B). The parameters considered for method optimisation were HPLC columns and conditions, sample heating, mass of extract and dilution volumes. The performance characteristics considered for method validation included standard linearity, method sensitivity, precision and trueness. Eight laboratories participated in the method evaluation. Chromatographic separation of the analytes was best achieved utilizing a Hilic column with a binary mobile phase consisting of acidic acetonitrile and acidic aqueous methanol. The final method showed linearity for epicatechin in the range 5–100μg/mL with a correlation co-efficient >0.999. Intra-day and inter-day precision of the analytes ranged from 2 to 6% and 2 to 13% respectively. Up to dp3, trueness of the method was >95% but decreased with increasing dp. Within laboratory precision showed RSD values <5 and 10% for monomers and oligomers, respectively. Between laboratory precision was 4 and 15% (Extract A) and 7 and 30% (Extract B) for monomers and oligomers, respectively. An analytical method for the separation, identification and quantification of procyanidins in an apple extract was developed, validated and assessed. The results of the inter-laboratory evaluation indicate that the method is reliable and reproducible.

Pre-fermentative cold maceration, saignée, and various thermal treatments as options for modulating volatile aroma and phenol profiles of red wine.

The effects of six maceration treatments on volatile aroma and phenol composition of Teran red wine were studied: standard maceration (control C), cold pre-fermentation maceration (CPM), saignée (S), pre-fermentation heating with extended maceration (PHT) or juice fermentation (PHP), and post-fermentation heating (POH). PHP wine contained the highest amounts of esters, fatty acids and anthocyanins, and the lowest content of other phenols. Alternative treatments decreased higher alcohols in relation to control C. CPM treatment lowered the extraction of seed tannins, exhibited the highest acetaldehyde, ethyl acetate and C6-compounds levels, and had increased ester levels in relation to control C. POH wine contained the highest concentration of total phenols, flavonoids, monomeric, oligomeric and polymeric flavanols, and color intensity and hue. S and PHT wines contained lower amount of total phenols, but higher than in C and CPM wines. The calculated Odor Activity Values were used to establish significant differences between the treatments.

Sustainable recovery of grape skins for use in an apple beverage with antiglycation properties

SummaryAn apple puree formulated with red grape skins was developed on pilot scale as a new beverage with antiglycation properties. The addition level of grape skins was selected by a liking test with 70 consumers. The selected formulation was a fibre‐rich source and delivered grape anthocyanins, flavonols and flavanols resulting in ~ twofold higher antiglycation activity than the apple puree. Pasteurisation (3‐D in the target microorganism Alicyclobacillus acidoterrestris) did not affect the antiglycation activity, which decreased by 30% upon sterilisation. Storage for 1 month in the temperature range 15–35 °C affected the contents of anthocyanins, monomeric, dimeric and oligomeric flavanols, while chlorogenic acid, flavonols and dihydrochalcones were stable. About 90% antiglycation activity was retained after one‐month storage at 15 °C. The use of red grape skin as ingredient could represent an opportunity for the apple processing industry to develop a value‐added product.