Stability of the flavan-3-ols epicatechin and catechin and related dimeric procyanidins derived from cocoa

In Vitro Antioxidant, Anti-Inflammatory Activity and Bioaccessibility of Ethanolic Extracts from Mexican Moringa oleifera Leaf

This study aimed to assess the antioxidant and anti-inflammatory properties, and bioaccessibility of Moringa oleifera ethanolic extracts using pressurized liquid extraction with varying ethanol concentrations (0%, 30%, 50%, 70%, and 100%) in water-ethanol mixtures. Quercetin derivatives and neochlorogenic acid were identified as major compounds via high-performance liquid chromatography with diode array detection. The 70% ethanol extract displayed the highest antioxidant activity and phenolic content, highlighting a strong correlation between phenolics and antioxidant potential. Extracts prepared with 50% and 70% ethanol (30 μg/mL) significantly inhibited TNF-α, IL-1β, and IL-6 cytokine secretion, with the 70% ethanol extract demonstrating robust anti-inflammatory effects. During in vitro digestion (oral, gastric, and intestinal phases), minimal changes were noted in most phenolic compounds' post-oral phase, but reductions occurred after the gastric phase. Substantial decreases in major compounds and antioxidant activity were observed in post-gastric and intestinal phases. Overall, ethanolic extracts of Moringa oleifera, particularly those with 70% ethanol, exhibit promising antioxidant and anti-inflammatory properties, suggesting potential for developing therapeutic agents against oxidative stress and inflammation-related disorders. However, it is essential to protect these compounds to prevent their degradation during digestion.

Determination of the variations in the metabolic profiles and bacterial communities during traditional craftsmanship Liupao tea processing

In this study, the metabolic profiles of traditional craftsmanship (TC) Liupao tea presented great changes at different processing stages. The contents of flavonoids and their glycosides generally exhibited a continuing downward trend, resulting in the sensory quality of TC-Liupao tea gradually improved. However, the taste of TC-Liupao tea faded when piling exceeded 12 h, as a result of the excessive degradation of some key flavor substances. Therefore, it could be deduced that piling for 10 h might be optimum for the quality formation of TC-Liupao tea. Sphingomonas, Acrobacter, Microbacterium, and Methylobacterium were the dominant bacteria during piling. The correlation analysis between differential metabolites and bacteria showed that only Sphingomonas and Massilia were significantly correlated to metabolites, demonstrating that the bacteria had less effect on the transformation of metabolites. Thus, the metabolic structure change during the process of TC-Liupao tea might be mainly attributed to the high temperature and humidity environment.

Optimisation of Polyphenols Extraction from Wild Bilberry Leaves-Antimicrobial Properties and Stability Studies

Polyphenolic extracts from natural sources have received great interest due to their beneficial properties for human health. A method to reduce their variability is to use the design of experiments which allows a limited number of experiments to be performed while exploring the experimental space. Firstly, a 23-full factorial model was used to investigate the polyphenols extraction from wild bilberry leaves. Spectrophotometric data (the content of polyphenols, flavonoids, chlorophyll and radical scavenger activity) and extraction yield were used as responses, and six statistical models were determined depending on the two numerical factors (temperature and alcohol % of ethanol-water mixture) being significant (p < 0.05) in all cases. Numerical optimisation performed by Design Expert 13 software correlates well with the chemical profile determined by high-performance liquid chromatography and the amount of the polyphenol. Afterwards, under the optimised conditions, an extract was prepared in three extraction steps for which composition, chemical stability and antimicrobial properties were evaluated. The antimicrobial potential of the extract was compared with that of the standard compounds (rutin and chlorogenic acid), and the results supported a synergistic effect of the extract components.

Activation of transient receptor potential channels is involved in reactive oxygen species (ROS)-dependent regulation of blood flow by (-)-epicatechin tetramer cinnamtannin A2

Intervention trials confirmed that blood flow-mediated dilatation increases significantly after intake of astringent (-)-epicatechin (EC) oligomers (procyanidins)-rich foods, but the mechanism remains unclear. We have previously found that procyanidins can activate the sympathetic nervous and subsequently increase blood flow. Here, we examined whether procyanidin-derived reactive oxygen species (ROS) activate transient receptor potential (TRP) channels in gastrointestinal sensory nerves and consequently induce sympathoexcitation. We evaluated the redox properties of EC and its tetramer cinntamtannin A2 (A2) at pH 5 or 7, mimicking plant vacuole or oral cavity/small intestine using a luminescent probe. At pH 5, A2 or EC showed O₂^･- scavenging ability, but they promoted O₂^･- generation at pH 7. We observed blood flow in rat cremaster arterioles using laser Doppler, a single oral dose of 10 µg/kg A2 markedly increased blood flow, while EC showed little activity. This change with A2 was significantly dampened by co-administration of adrenaline blocker, ROS scavenger N-acetyl-L-cysteine (NAC), TRP vanilloid 1, or ankyrin 1 antagonist. We also performed a docking simulation of EC or A2 with the binding site of a typical ligand for each TRP channel and calculated the respective binding affinities. The binding energies were notably higher for A2 than typical ligands, suggesting that A2 is less likely to bind to these sites. ROS produced at neutral pH following the orally administered A2 to the gastrointestinal tract could activate TRP channels, triggering sympathetic hyperactivation and causing hemodynamic changes.

In Vitro Bioaccessibility Assessment of Phenolic Compounds from Encapsulated Grape Pomace Extract by Ionic Gelation

Grape pomace is a by-product of winemaking characterized by a rich chemical composition from which phenolics stand out. Phenolics are health-promoting agents, and their beneficial effects depend on their bioaccessibility, which is influenced by gastrointestinal digestion. The effect of encapsulating phenol-rich grape pomace extract (PRE) with sodium alginate (SA), a mixture of SA with gelatin (SA-GEL), and SA with chitosan (SA-CHIT) on the bioaccessibility index (BI) of phenolics during simulated digestion in vitro was studied. A total of 27 individual phenolic compounds (IPCs) were quantified by UHPLC. The addition of a second coating to SA improved the encapsulation efficiency (EE), and the highest EE was obtained for SA-CHIT microbeads (56.25%). Encapsulation affected the physicochemical properties (size, shape and texture, morphology, crystallinity) of the produced microbeads, which influenced the delivery of phenolics to the intestine and their BI. Thus, SA-GEL microbeads had the largest size parameters, as confirmed by scanning electron microscopy (SEM), and the highest BI for total phenolic compounds and IPCs (gallic acid, 3,4-dihydroxybenzoic acid and o-coumaric acid, epicatechin, and gallocatechin gallate) ranged from 96.20 to 1011.3%. The results suggest that encapsulated PRE has great potential to be used as a functional ingredient in products for oral administration.

The Utilization of Physiologically Active Molecular Components of Grape Seeds and Grape Marc

Nutritional interventions may highly contribute to the maintenance or restoration of human health. Grapes (Vitis vinifera) are one of the oldest known beneficial nutritional components of the human diet. Their high polyphenol content has been proven to enhance human health beyond doubt in statistics-based public health studies, especially in the prevention of cardiovascular disease and cancer. The current review concentrates on presenting and classifying polyphenol bioactive molecules (resveratrol, quercetin, catechin/epicatechin, etc.) available in high quantities in Vitis vinifera grapes or their byproducts. The molecular pathways and cellular signaling cascades involved in the effects of these polyphenol molecules are also presented in this review, which summarizes currently available in vitro and in vivo experimental literature data on their biological activities mostly in easily accessible tabular form. New molecules for different therapeutic purposes can also be synthesized based on existing polyphenol compound classes available in high quantities in grape, wine, and grape marc. Therefore an overview of these molecular structures is provided. Novel possibilities as dendrimer nanobioconjugates are reviewed, too. Currently available in vitro and in vivo experimental literature data on polyphenol biological activities are presented in easily accessible tabular form. The scope of the review details the antidiabetic, anticarcinogenic, antiviral, vasoprotective, and neuroprotective roles of grape-origin flavonoids. The novelty of the study lies in the description of the processing of agricultural by-products (grape seeds and skins) of industrial relevance, and the detailed description of the molecular mechanisms of action. In addition, the review of the clinical therapeutic applications of polyphenols is unique as no summary study has yet been done.

Formation and stabilization of multiple w/o/w emulsions encapsulating catechin, by mechanical and microfluidic methods using a single pH-sensitive copolymer: effect of copolymer/drug interaction

Multiple w/o/w emulsions (MEs) are promising systems for protecting fragile hydrophilic drugs and controlling their release. We explore the capacity of a single pH-sensitive copolymer, PDMS₆₀-b-PDMAEMA₅₀, and salts, to form and stabilize MEs loaded with sucrose or catechin by a one-step mechanical process or a microfluidic method. ME cytotoxicity was evaluated in various conditions of pH. Using the mechanical process, the most stable emulsions were obtained with Miglyol®812N and isopropyl myristate in a final pH range of 8-12 and [0.3 M-1 M] NaCl concentrations. Conversely, with the microfluidic method, isopropyl myristate at pH 3 without salt was more efficient. Catechin strongly affected the formation of droplets by the mechanical process but did not modify the conditions of stability of MEs obtained by the microfluidic method. The antioxidant power of catechin was preserved in the inner droplets, even in emulsions prepared by the mechanical method at pH 8. An incomplete release of sucrose and catechin from the emulsions was observed and attributed to the interaction of molecules with the copolymer through hydrogen bonding. This study highlights some of the barriers to break to formulate multiple emulsions stabilized by a PDMS-b-PDMAEMA copolymer or other polymers which can form hydrogen bonds interaction with encapsulated drugs.

Impact of Eutectic Solvents Utilization in the Microwave Assisted Extraction of Proanthocyanidins from Grape Pomace

The extraction of proanthocyanidins (PACs), despite being an important and limiting aspect of their industrial application, is still largely unexplored. Herein, the possibility of combining eutectic solvents (ESs) with microwave assisted extraction (MAE) in the extraction of PACs from grape pomace (GP) is explored, aiming to improve not only the extraction yield but also the mean degree of polymerization (mDP). The combination of choline chloride with lactic acid was shown to be the most effective combination for PACs extraction yield (135 mg_PAC/g_GP) and, despite the occurrence of some depolymerization, also enabled us to achieve the highest mDP (7.13). Additionally, the combination with MAE enabled the process to be completed in 3.56 min, resulting in a considerably reduced extraction time.

Unveiling structure-activity relationships of proanthocyanidins with dentin collagen

OBJECTIVE

To elucidate the structure-activity relationships (SARs) of proanthocyanidins (PACs) with type I collagen using sixteen chemically defined PACs with degree of polymerization (DP) 2-6.

METHODS

Under a dentin model, the biomimicry of PACs with type I collagen was investigated by dynamic mechanical analysis (DMA) and infrared spectroscopy. The dentin matrix was modified with PACs from Pinus massoniana [monomers (Mon-1 and Mon-2), dimers (Dim-1-Dim-4), trimers (Tri-1-Tri-4), tetramers (Tet-1-Tet-5), and hexamer (Hex-1)]. A strain sweep method in a 3-point bending submersion clamp was used to assess the viscoelastic properties [storage (E'), loss (E"), and complex moduli (E*) and tan δ] of the dentin matrix before and after biomodification. Biochemical analysis of the dentin matrix was assessed with FTIR spectroscopy. Data were statistically analyzed using one-way ANOVA and post-hoc tests (α = 0.05).

RESULTS

DP had a significant effect on modified dentin moduli (tetramers ≈ trimers > hexamers ≈ dimers > monomers ≈ control, p < 0.001). Trimers and tetramers yielded 6- to 8-fold increase in the mechanical properties of modified dentin and induced conformational changes to the secondary structure of collagen. Modifications to the tertiary structure of collagen was shown in all PAC modified-dentin matrices.

SIGNIFICANCE

Findings establish three key SARs: (i) increasing DP generally enhances biomimicry potential of PACs in modulating the mechanical and chemical properties of dentin (ii) the secondary structure of dentin collagen is affected by the position of B-type inter-flavanyl linkages (4β → 6 and 4β → 8); and (iii) the terminal monomeric flavan-3-ol unit plays a modulatory role in the viscoelasticity of dentin.

Changes in Antioxidant Properties and Amounts of Bioactive Compounds during Simulated In Vitro Digestion of Wheat Bread Enriched with Plant Extracts

Cereal preparation can be an excellent source of substances with proven health-promoting properties. Unfortunately, some types of bread, such as white flour bread, are devoid of many valuable nutrients. Therefore, it is necessary to look for ways to increase its density and nutritional value. The aim of the study was to investigate the effect of stabilized plant extracts on the quality of bread, its antioxidant activity and polyphenol content, and to evaluate the stability of bioactive compounds and antioxidant activity during in vitro digestion. The research material was the wheat bread baked with spray dried microcapsules of hawthorn bark, soybeans and onion husks in maltodextrin or inulin carriers. The addition of plant extracts resulted in the presence of phenolic compounds in the wheat bread, and its antioxidant activity significantly increased. There was no significant difference in antioxidant activity between breads containing microcapsules with different carriers. During in vitro digestion, procyanidins and isoflavones in bread were more resistant to the digestive processes than other compounds. The antioxidant activity during simulated digestion was the highest at the stage of gastric digestion, and its value depended on the extract used and the analytical method applied.

Characterization of Oligomeric Proanthocyanidin-Enriched Fractions from Aronia melanocarpa (Michx.) Elliott via High-Resolution Mass Spectrometry and Investigations on Their Inhibitory Potential on Human Topoisomerases

Aronia melanocarpa (MICHX.) ELLIOTT, which belongs to the Rosaceae family, has increasingly come into focus of research due to the high content of polyphenols. In addition to antioxidative properties, further health-promoting effects of these polyphenols are still of interest. Especially, the proanthocyanidins offer thereby huge opportunities due to their high structural heterogeneity. Therefore, the present study focuses on the topoisomerase inhibiting effects of oligomeric proanthocyanidins (PACs), which are potentially depended on their degree of polymerization. The investigated PACs isolated from Aronia berries were characterized by chromatographic techniques and liquid chromatography-high-resolution mass spectrometry. Four PAC enriched fractions were obtained from Aronia pomace containing 47 PACs with a degree of polymerization from three to six. Due to the low yield of hexamers, the potential inhibiting effects against human topoisomerase were investigated for the trimer to pentamer fractions. The relaxation and decatenation assays were performed to examine the inhibiting effect on topoisomerases under cell-free conditions. Moreover, rapid isolation of topoisomerase cleavage complexes in human colon carcinoma HT29 cells was performed to evaluate the effect on topoisomerases in a cell-based system. The fractions demonstrated inhibitory potential on topoisomerases I and II. In sum, an increasing effect strength depending on the degree of polymerization was shown.

Elucidation of Interaction between Whey Proteins and Proanthocyanidins and Its Protective Effects on Proanthocyanidins during In-Vitro Digestion and Storage

Whey proteins and oligomeric proanthocyanidins have nutritional value and are widely used in combination as food supplements. However, the effect of the interactions between proanthocyanidins and whey proteins on their stability has not been studied in depth. In this work, we aimed to characterize the interactions between β-Lactoglobulin (β-LG) and α-lactalbumin (α-LA) and oligomeric proanthocyanidins, including A1, A2, B1, B2, B3, and C1, using multi-spectroscopic and molecular docking methods. Fluorescence spectroscopic data revealed that all of the oligomeric proanthocyanidins quenched the intrinsic fluorescence of β-LG or α-LA by binding-related fluorescence quenching. Among the six oligomeric proanthocyanidins, A1 showed the strongest affinity for β-LG (K_a = 2.951 (±0.447) × 10⁴ L∙mol⁻¹) and α-LA (K_a = 1.472 (±0.236) × 10⁵ L∙mol⁻¹) at 297 K. β-LG/α-LA and proanthocyanidins can spontaneously form complexes, which are mainly induced by hydrophobic interactions, hydrogen bonds, and van der Waals forces. Fourier-transform infrared spectroscopy (FTIR) and circular dichroism spectroscopy showed that the secondary structures of the proteins were rearranged after binding to oligomeric proanthocyanidins. During in vitro gastrointestinal digestion, the recovery rate of A1 and A2 increased with the addition of WPI by 11.90% and 38.43%, respectively. The addition of WPI (molar ratio of 1:1) increased the retention rate of proanthocyanidins A1, A2, B1, B2, B3, and C1 during storage at room temperature by 14.01%, 23.14%, 30.09%, 62.67%, 47.92%, and 60.56%, respectively. These results are helpful for the promotion of protein–proanthocyanidin complexes as functional food ingredients in the food industry.

HPLC-MS-based design of experiments approach on cocoa roasting

Modern statistical methods, such as the design of experiments and response surface methodology, are widely used to describe changes in multiparameter processes during the processing of food in both science and technology contexts. However, these approaches are described to a lesser degree in the case of cocoa roasting than other foods and processes. Our study aimed to use the design of experiments to establish a model of cocoa roasting for relevant flavor-related constituents. We have used HPLC-MS techniques to link standard process parameters with chemical compounds changing in concentration during cocoa roasting. Influence of time, temperature, the addition of water, acid, and base, on relative concentrations of procyanidin monomers, dimers, and trimers, an Amadori compound, and a peptide, was shown. High-quality models for each compound were established and validated, displaying good prediction accuracy. Such an approach could be used to optimize processing conditions for cocoa roasting in order to influence the concentration of certain chemical compounds, and in turn, improving the flavor of chocolate products.

Modification of Natural Proanthocyanidin Oligomers and Polymers Via Chemical Oxidation under Alkaline Conditions

We tested the susceptibility of 102 proanthocyanidin (PA)-rich plant extracts to oxidation under alkaline conditions and the possibility to produce chemically modified PAs via oxidation. Both the nonoxidized and the oxidized extracts were analyzed using group-specific ultrahigh-performance liquid chromatography-diode array detection-tandem mass spectrometry (UHPLC-DAD-MS/MS) methods capable of detecting procyanidin (PC) and prodelphinidin (PD) moieties along the two-dimensional (2D) chromatographic fingerprints of plant PAs. The results indicated different reactivities for PCs and PDs. When detected by UHPLC-DAD only, most of the PC-rich samples exhibited only a subtle change in their PA content, but the UHPLC-MS/MS quantitation showed that the decrease in the PC content varied by 0-100%. The main reaction route was concluded to be intramolecular. The PD-rich and galloylated PAs showed a different pattern with high reductions in the original PA content by both ultraviolet (UV) and MS/MS quantitation, accompanied by the shifted retention times of the chromatographic PA humps. In these samples, both intra- and intermolecular reactions were indicated.

Pharmacokinetic Differences of Grape Seed Procyanidins According to the Gavage Administration Between Normal Rats and Alzheimer's Disease Rats

Background:

Grape Seed Procyanidins (GSP) refers to a type of natural polyphenols that have to roust antioxidant capacity. Studies have shed light on the fact that GSP significantly impacts the alleviation of Alzheimer's Disease (AD).

Objective:

This study aimed at investigating whether there exists a pharmacokinetics difference in GSP between normal and AD rats, a rapid UPLC-MS/MS methodology, for the detection of its content in plasma samples was put forward. We carried out an analysis of the plasma concentrations of procyanidin B2, procyanidin B3, catechin and epicatechin in normal and AD rats over time for determining the plasma concentration of GSP.

Methods:

We made use of 400 μL of methanol for the protein precipitation solvent in the plasma treatment. The chromatographic separation was carried out on a C18 column at a temperature of 20 °C. The mobile phase was a gradient of 0.1% formic acid in water and methanol within 15 min.

Results:

: In the current research work, the plasma concentrations of procyanidin B2, procyanidin B3, catechin and epicatechin in AD rats were significantly higher as compared with those in normal rats (P < 0.05) and the content of epicatechin constituted the highest as compared with catechin, procyanidin B2 and procyanidin B3 following the administration of GSP.

Conclusion:

We discovered the better absorptions of these analytes in the AD group as compared with that in the normal group, providing an analytical basis for treating the AD with procyanidins.

Insight into Polyphenol and Gut Microbiota Crosstalk: Are Their Metabolites the Key to Understand Protective Effects against Metabolic Disorders?

Lifestyle factors, especially diet and nutrition, are currently regarded as essential avenues to decrease modern-day cardiometabolic disorders (CMD), including obesity, metabolic syndrome, type 2 diabetes, and atherosclerosis. Many groups around the world attribute these trends, at least partially, to bioactive plant polyphenols given their anti-oxidant and anti-inflammatory actions. In fact, polyphenols can prevent or reverse the progression of disease processes through many distinct mechanisms. In particular, the crosstalk between polyphenols and gut microbiota, recently unveiled thanks to DNA-based tools and next generation sequencing, unravelled the central regulatory role of dietary polyphenols and their intestinal micro-ecology metabolites on the host energy metabolism and related illnesses. The objectives of this review are to: (1) provide an understanding of classification, structure, and bioavailability of dietary polyphenols; (2) underline their metabolism by gut microbiota; (3) highlight their prebiotic effects on microflora; (4) discuss the multifaceted roles of their metabolites in CMD while shedding light on the mechanisms of action; and (5) underscore their ability to initiate host epigenetic regulation. In sum, the review clearly documents whether dietary polyphenols and micro-ecology favorably interact to promote multiple physiological functions on human organism.

Evaluation of polyphenol bioaccessibility and kinetic of starch digestion of spaghetti with persimmon (Dyospyros kaki) flours coproducts during in vitro gastrointestinal digestion

The aim was to study the in vitro starch digestibility, the free and bound polyphenol profile and their bioaccessibility and antioxidant activity during in vitro gastrointestinal digestion of durum wheat semolina spaghetti added with two types of persimmon flour concentrates ("Rojo Brillante" flour and "Triumph" flour) at two concentrations (3 and 6%). Results obtained showed that persimmon flour improves the polyphenol profile of spaghetti by addition gallic acid and coumaric acid-o-hexoside, and increasing 2-fold and around 3-fold its content in spaghetti with 3% and 6% persimmon flours, respectively. Cooked process and digestion affected more to free polyphenol content than bound. Furthermore, 3% persimmon flour enriched spaghetti reduce kinetic of starch digestion, while 6% enriched spaghetti increased it. In conclusion, persimmon flours (Rojo Brillante and Triumph) at low concentrations could be used to develop spaghetti with more polyphenol content and less starch digestibility than traditional spaghetti.

Proanthocyanidins: Components, Pharmacokinetics and Biomedical Properties

Proanthocyanidins (PAs) are a group of polyphenols enriched in plant and human food. In recent decades, epidemiological studies have upheld the direct relationship between PA consumption and health benefits; therefore, studies on PAs have become a research hotspot. Although the oral bioavailability of PAs is quite low, pharmacokinetics data revealed that some small molecules and colonic microbial metabolites of PAs could be absorbed and exert their health beneficial effects. The pharmacological effects of PAs mainly include anti-oxidant, anticancer, anti-inflammation, antimicrobial, cardiovascular protection, neuroprotection, and metabolism-regulation behaviors. Moreover, current toxicological studies show that PAs have no observable toxicity to humans. This review summarizes the resources, extraction, structures, pharmacokinetics, pharmacology, and toxicology of PAs and discusses the limitations of current studies. Areas for further research are also proposed.

Functional changes induced by extrusion during cocoa alkalization

Polyphenols, a group of secondary metabolites, have well-known relevant effects on human health. During traditional alkalization, this content dramatically lowers. We aimed to evaluate an alternative alkalization method based on extrusion on cocoa functional characteristics. The results showed that the antioxidant capacity and total phenolic values increased as alkali concentration and temperature did, and these values doubled under less extreme conditions. Comparing the functional properties between extruded and traditionally produced powders revealed that catechin, epicatechin and dimers B1 and B2 contents were 43%, 33%, 54% and 34% lower in the extruded samples, respectively. However, this reduction was partially balanced by increased clovamide content up to 50%. Thus the total phenol content and antioxidant capacity of the extruded samples were statistically above those of the commercial one. Hence extrusion alkalization should be considered a new processing alternative to avoid markedly reducing functional properties.

Anthelmintic A-Type Procyanidins and Further Characterization of the Phenolic Composition of a Root Extract from Paullinia pinnata

Extracts from the roots of Paullinia pinnata L. are used in West Africa as traditional remedies for a variety of diseases including infestations with soil-transmitted helminths. Based on the results of an ethnopharmacological survey in Ghana, an aqueous acetone (70%) extract was investigated for its anthelmintic and phytochemical properties. Partitioning of the crude extract followed by several fractionation steps of the ethyl acetate phase using Sephadex® LH-20, fast centrifugal partition chromatography, RP-18-MPLC and HPLC led to isolation of six oligomeric A-type procyanidins (1 to 6). To determine the anthelmintic activity, the crude extract, fractions and isolated compounds were tested in vitro against the model organism Caenorhabditis elegans. A significantly better activity was observed for the trimeric A-type procyanidin (1) compared to a B-type trimer. However, this effect could not be generalized for the tetrameric procyanidins, for which the type of the interflavan-linkage (4→6 vs. 4→8) had the greatest impact on the bioactivity. Besides the procyanidins, three novel compounds, isofraxidin-7-O-α-l-rhamnopyranosyl-(1″→6')-β-d-glucopyranoside (17), 4-methoxycatechol-2-O-(5''-O-vanilloyl-β-apiofuranosyl)-(1''→2')-β-glucopyranoside (18) and a 6-(3-methoxy-4-hydroxyphenyl)-hexane-2,4-diol-2-O-hexoside (19) were isolated together with further ten known compounds (7 to 16), mainly coumarins and coumarinolignans. Except for 3-β-d-glucopyranosyloxy-4-methyl-2(5H)-furanone (15), none of the isolated compounds has previously been described for P. pinnata. The anthelmintic activity was attributed to the presence of procyanidins, but not to any of the other compound classes. In summary, the findings rationalize the traditional use of P. pinnata root extracts as anthelmintic remedies.

In Vitro Digestion of Apple Tissue Using a Dynamic Stomach Model: Grinding and Crushing Effects on Polyphenol Bioaccessibility

Food structure is a key determinant for the release of phenolic compounds during gastric and intestinal digestion. We evaluated the bioaccessibility of polyphenols from apple tissue during gastric digestion in vitro from bio-mechanical perspectives including the effects of gastric juice and mucin on the apple tissue matrix under simulated stomach peristalsis. The gastric model system was effective in releasing polyphenols because of simultaneous compression and extrusion, with 3 times higher release from coarse than from fine particles. However, bioaccessibility of polyphenols was reduced up to 44% in the presence of both cell walls and gastric mucin. Most individual phenolic molecules were gradually released and were stable in the gastric environment, except for procyanidin B2. The study suggests that the bioaccessibility of polyphenols from apples in the upper digestive tract is dependent on mechanical disintegration and the residual matrix present in the swallowed bolus.

The Polyphenols as Potential Agents in Prevention and Therapy of Prostate Diseases

In recent years, the progress of science and medicine greatly has influenced human life span and health. However, lifestyle habits, like physical activity, smoking cessation, moderate alcohol consumption, diet, and maintaining a normal body weight represent measures that greatly reduce the risk of various diseases. The type of diet is very important for disease development. Numerous epidemiological clinical data confirm that longevity is linked to predominantly plant-based diets and it is related to a long life; whereas the western diet, rich in red meat and fats, increases the risk of oxidative stress and thus the risk of developing various diseases and pre-aging. This review is focused on the bioavailability of polyphenols and the use of polyphenols for the prevention of prostate diseases. Special focus in this paper is placed on the isoflavonoids and flavan-3-ols, subgroups of polyphenols, and their protective effects against the development of prostate diseases.

Oligomer Procyanidins from Lotus Seedpod Regulate Lipid Homeostasis Partially by Modifying Fat Emulsification and Digestion

Dietary polyphenols have shown hypolipidemic effects by reducing triglyceride absorption. The mechanisms may involve modifying fat emulsion during digestion in the gastrointestinal tract and suppressing lipase during hydrolysis in the small intestine. In an in vivo study, lotus seedpod oligomeric procyanidin (LSOPC) decreased total serum triglyceride and total cholesterol and elevated the high-density lipoprotein level in the hyperlipidemic rat model. In addition, LSOPC suppressed de novo lipogenesis-related gene expressions. In an in vitro study, the LSOPC-enriched emulsion decreased the mean droplet size from 0.36 to 0.33 μm and increased the viscosity of the emulsion. Moreover, the LSOPC-enriched emulsion improved the antioxidant properties. A digestion model was developed and showed that the particle size of the LSOPC-enriched emulsion increased in the oral cavity. However, an increase and then a significant drop of the particle size was measured in the stomach and small intestine. The free fatty acid release rate was decreased in the LSOPC-enriched emulsion partly ascribed to the inhibition of lipase by LSOPC.

Effects of simulated digestion on the phenolic composition and antioxidant activity of different cultivars of lychee pericarp

Background

Lychee pericarp is rich in phenolic and has good antioxidant activity. The effects of simulated gastric (SGF) and intestinal fluid (SIF) digestion on the contents, composition, and antioxidant activities of the phenolic substances in the pericarp of different lychee cultivars (cv Jizui, Lizhiwang, Guiwei, Yuhe, Nuomici and Guihong) were investigated.

Results

Compared with distilled water (DW) treatment, the total phenolic content (TPC) and total flavonoid content (TFC) in the pericarp of different lychee cultivars decreased after SGF digestion; especially, the TFC in "Lizhiwang" decreased by 41.5%. The TPC and TFC of lychee pericarp also decreased after SIF digestion. However, the TPC in "Jizui", "Guiwei" and "Yuhe" increased. The SGF and SIF also had different effects on the FRAP and ABTS antioxidant activities of different lychee cultivars. The SGF digestion decreased the ABTS antioxidant capacity of lychee pericarp but enhanced the FRAP value of some lychee cultivars. However, the SIF digestion decreased the FRAP antioxidant activity of different lychee cultivar pericarps but enhanced the ABTS antioxidant capacity of lychee. The HPLC results showed that lychee pericarp had relatively high contents of procyanidin B2 and procyanidin A2. After SIF digestion, caffeic acid and isoquercitrin could not be detected in any of the lychee varieties. However, quercetin-3-rutinose-7-rhamnoside and isoquercitrin were increased after SGF digestion.

Conclusions

Lychee pericarp could be used as an inexpensive functional food ingredient.

Insight of Stability of Procyanidins in Free and Liposomal Form under an in Vitro Digestion Model: Study of Bioaccessibility, Kinetic Release Profile, Degradation, and Antioxidant Activity

Small unilamellar and multilayered liposomes loaded with polymeric (epi)catechins up to pentamers were produced. The bioaccessibility, kinetic release profile, and degradation under in vitro gastrointestinal conditions were monitored by UHPLC-DAD-QTOF-MS/MS. The results show that all of the procyanidins underwent depolymerization and epimerization into small molecular oligomers and mainly to (epi)catechin subunits. Moreover, all of the liposome formulations presented higher bioaccessibility and antioxidant activity in comparison to their respective counterparts in non-encapsulated form. Similar results were obtained with procyanidins from cocoa extract-loaded liposomes. Namely, the bioaccessibility of dimer, trimer, and tetramer fractions from cocoa-loaded liposomes were 4.5-, 2.1-, and 9.3-fold higher than those from the non-encapsulated cocoa extract. Overall, the procyanidin release profile was dependent on their chemical structure and physicochemical interaction with the lipid carrier. These results confirmed that liposomes are efficient carriers to stabilize and transport procyanidins with the aim of enhancing their bioaccessibility at a controlled release rate.

Cocoa and Dark Chocolate Polyphenols: From Biology to Clinical Applications

It is well known that cocoa and dark chocolate possess polyphenols as major constituents whose dietary consumption has been associated to beneficial effects. In fact, cocoa and dark chocolate polyphenols exert antioxidant and anti-inflammatory activities switching on some important signaling pathways such as toll-like receptor 4/nuclear factor κB/signal transducer and activator of transcription. In particular, cocoa polyphenols induce release of nitric oxide (NO) through activation of endothelial NO synthase which, in turn, accounts for vasodilation and cardioprotective effects. In the light of the above described properties, a number of clinical trials based on the consumption of cocoa and dark chocolate have been conducted in healthy subjects as well as in different categories of patients, such as those affected by cardiovascular, neurological, intestinal, and metabolic pathologies. Even if data are not always concordant, modifications of biomarkers of disease are frequently associated to improvement of clinical manifestations. Quite interestingly, following cocoa and dark chocolate ingestion, cocoa polyphenols also modulate intestinal microbiota, thus leading to the growth of bacteria that trigger a tolerogenic anti-inflammatory pathway in the host. Finally, many evidences encourage the consumption of cocoa and dark chocolate by aged people for the recovery of the neurovascular unit.

Bioactive polyphenols and cardiovascular disease: chemical antagonists, pharmacological agents or xenobiotics that drive an adaptive response?

Polyphenols are widely regarded to have a wide range of health-promoting qualities, including beneficial effects on cardiovascular disease. Historically, the benefits have been linked to their well-recognized powerful antioxidant activity. However, the concept that the beneficial effects are attributable to direct antioxidant activity in vivo does not pay sufficient heed to the fact that polyphenols degrade rapidly, are poorly absorbed and rapidly metabolized, resulting in very low bioavailability. This review explores alternative mechanisms by which polyphenols, or their metabolites, exert biological activity via mechanisms that can be activated by physiologically relevant concentrations. Evidence is presented to support the action of phenolic derivatives on receptors and signalling pathways to induce adaptive responses that drive changes in endogenous antioxidant, antiplatelet, vasodilatory and anti-inflammatory effects. The implications are that in vitro antioxidant measures as predictors of polyphenol protective activity in vivo hold little relevance and that closer attention needs to be paid to bioavailable metabolites to understand the mode of action of these diet-derived components.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

The absorption, distribution, metabolism and excretion of procyanidins

Procyanidins (PAs) are polyphenols in plant food that have many health benefits, including cancer prevention, cardiovascular protection and diabetes prevention. PAs have been known to have low oral bioavailability. In this review, we summarize the published results on the ADME (absorption, distribution, metabolism and excretion) of PAs in vivo and in vitro. After oral administration, in the stomach the decomposition of PAs is highly dependent on the pH value of gastric juice, which is also affected by food intake. In the small intestine, PA polymers and oligomers with DP > 4 are not directly absorbed in vivo, but minor PA monomers and dimers could be detected in the plasma. Methylated and glucuronidated PA dimers and monomers are the main metabolites of PAs in plasma. In the colon, PAs are catabolized by colonic microflora into a series of low molecular weight phenolic acids, such as phenyl valerolactone, phenylacetic acids and phenylpropionic acids. We reviewed the degradation of PAs in gastric digestion, the absorption of PAs in the small intestine and the metabolic pathway of PAs by colonic microflora. To clearly explain the in vivo pharmacokinetics of PAs, a systematic comparative analysis on previously published data on PAs was conducted.

Pinus massoniana Bark Extract: Structure-Activity Relationship and Biomedical Potentials

Proanthocyanidins (PAs) belong to the condensed tannin subfamily of natural flavonoids. Recent studies have shown that the main bioactive compounds of Pinus massoniana bark extract (PMBE) are PAs, especially the proanthocyanidins B series, which play important roles in cell cycle arrest, apoptosis induction and migration inhibition of cancer cells in vivo and in vitro. PA-Bs are mixtures of oligomers and polymers composed of flavan-3-ol, and the relationship between their structure and corresponding biomedical potentials is summarized in this paper. The hydroxyl at certain positions or the linkage between different carbon atoms of different rings determines or affects their anti-oxidant and free radical scavenging bioactivities. The degree of polymerization and the water solubility of the reaction system also influence their biomedical potential. Taken together, PMBE has a promising future in clinical drug development as a candidate anticancer drug and as a food additive to prevent tumorigenesis. We hope this review will encourage interested researchers to conduct further preclinical and clinical studies to evaluate the anticancer activities of PMBE, its active constituents and their derivatives.

High-molecular-weight cocoa procyanidins possess enhanced insulin-enhancing and insulin mimetic activities in human primary skeletal muscle cells compared to smaller procyanidins

Dysregulation of glucose metabolism is a primary hallmark of metabolic disease (i.e., diabetes, obesity, etc.). Complementary nonpharmaceutical strategies are needed to prevent and/or ameliorate dysregulation of glucose metabolism and prevent progression from normoglycemia to prediabetes and type 2 diabetes across the lifespan. Cocoa compounds, particularly the procyanidins, have shown promise for improving insulin sensitivity and blood glucose homeostasis. However, the molecular mechanisms by which cocoa procyanidins exert these functions remain poorly understood. Furthermore, cocoa procyanidins exhibit size diversity, and evidence suggests that procyanidin bioactivity and size may be related. Here, we show that a procyanidin-rich cocoa extract elicits an antidiabetic effect by stimulating glycogen synthesis and glucose uptake, independent of insulin. Cocoa procyanidins did not appear to act via stimulation of AMPK or CaMKII activities. Additionally, in the presence of insulin, glycogen synthesis and AKT phosphorylation were affected. These mechanisms of action are most pronounced in response to oligomeric and polymeric procyanidins. These results demonstrate (1) specific mechanisms by which cocoa procyanidins improve glucose utilization in skeletal muscle and (2) that larger procyanidins appear to possess enhanced activities. These mechanistic insights suggest specific strategies and biological contexts that may be exploited to maximize the antidiabetic benefits of cocoa procyanidins.

Deodorization of Garlic Breath by Foods, and the Role of Polyphenol Oxidase and Phenolic Compounds

Garlic causes a strong garlic breath that may persist for almost a day. Therefore, it is important to study deodorization techniques for garlic breath. The volatiles responsible for garlic breath include diallyl disulfide, allyl mercaptan, allyl methyl disulfide, and allyl methyl sulfide. After eating garlic, water (control), raw, juiced or heated apple, raw or heated lettuce, raw or juiced mint leaves, or green tea were consumed immediately. The levels of the garlic volatiles on the breath were analyzed from 1 to 60 min by selected ion flow tube mass spectrometry (SIFT-MS). Garlic was also blended with water (control), polyphenol oxidase (PPO), rosemarinic acid, quercetin or catechin, and the volatiles in the headspace analyzed from 3 to 40 min by SIFT-MS. Raw apple, raw lettuce, and mint leaves significantly decreased all of the garlic breath volatiles in vivo. The proposed mechanism is enzymatic deodorization where volatiles react with phenolic compounds. Apple juice and mint juice also had a deodorizing effect on most of the garlic volatiles but were generally not as effective as the raw food, probably because the juice had enzymatic activity but the phenolic compounds had already polymerized. Both heated apple and heated lettuce produced a significant reduction of diallyl disulfide and allyl mercaptan. The presence of phenolic compounds that react with the volatile compounds even in the absence of enzymes is the most likely mechanism. Green tea had no deodorizing effect on the garlic volatile compounds. Rosmarinic acid, catechin, quercetin, and PPO significantly decreased all garlic breath volatiles in vitro. Rosmarinic acid was the most effective at deodorization.

Stability of polyphenols and carotenoids in strawberry and peach yoghurt throughout in vitro gastrointestinal digestion

The aim of this research was to evaluate the influence of in vitro gastrointestinal digestion on the stability and bio-accessibility of phenolic compounds and carotenoids, as well as on the antioxidant activity in strawberry and peach enriched yoghurt. The radical scavenging capacity of strawberry and peach yoghurt was 480 and 550% higher, respectively, at the level of the intestine than in fruit yoghurt not subjected to digestion. In strawberry the amount of bio-accessible anthocyanins increased during gastric digestion and the transition to the intestinal compartment produced a decrease in all the analyzed classes of polyphenols, being more pronounced in pelargonidin-3-glucoside (65%) and pelargonidin-3-rutinoside (58%). In peach the (+)-catechin content strongly decreased (80%), and neochlorogenic, chlorogenic acid, rutin and the carotenoid zeaxanthin decreased at lower levels, between 32-45%, while β-carotene was rather stable under gastric conditions (increased by 12%) during intestinal digestion. Despite the decrease in the concentration of these bioactive compounds after being subjected to in vitro gastrointestinal digestion, results suggest that fruit yoghurt is an important source of bio-accessible polyphenols and carotenoids and that despite some losses induced by digestion conditions, it still releases relevant amounts at the level of the intestine to be absorbed and to promote health benefits.

Cancer Chemopreventive Potential of Procyanidin

Chemoprevention entails the use of synthetic agents or naturally occurring dietary phytochemicals to prevent cancer development and progression. One promising chemopreventive agent, procyanidin, is a naturally occurring polyphenol that exhibits beneficial health effects including anti-inflammatory, antiproliferative, and antitumor activities. Currently, many preclinical reports suggest procyanidin as a promising lead compound for cancer prevention and treatment. As a potential anticancer agent, procyanidin has been shown to inhibit the proliferation of various cancer cells in “in vitro and in vivo”. Procyanidin has numerous targets, many of which are components of intracellular signaling pathways, including proinflammatory mediators, regulators of cell survival and apoptosis, and angiogenic and metastatic mediators, and modulates a set of upstream kinases, transcription factors, and their regulators. Although remarkable progress characterizing the molecular mechanisms and targets underlying the anticancer properties of procyanidin has been made in the past decade, the chemopreventive targets or biomarkers of procyanidin action have not been completely elucidated. This review focuses on the apoptosis and tumor inhibitory effects of procyanidin with respect to its bioavailability.

In vitro evaluation of the effects of protein-polyphenol-polysaccharide interactions on (+)-catechin and cyanidin-3-glucoside bioaccessibility

The bioaccessibility of cyanidin-3-glucoside and (+)-catechin in model solutions when β-lactoglobulin (β-LG) and pectin/chitosan are present was investigated using an in vitro model simulating gastrointestinal conditions. In the mouth, the free cyanidin content increased (+) 90 and 14% while the (+)-catechin content decreased (-) 23 and 13%, respectively for mixtures with -pectin and -β-LG-pectin. Under gastric conditions, the cyanidin content decreased 85 and 28% for mixtures with -pectin and -β-LG-pectin. On the contrary, after gastric digestion, (+)-catechin bioaccessibility increased and exhibited values similar to the original samples for all the systems tested. The transition to the intestinal environment induced a significant alteration on both polyphenols and this effect was more marked for cyanidin. Systems with pectin allowed obtaining a higher content of bioaccessible cyanidin. The gastric conditions promoted an increase in the antioxidant capacity, followed by a decrease of it in the intestine. The free (+)-catechin and cyanidin-3-glucoside contents decreased when exposed to the gastrointestinal tract conditions. However, when incorporated in food matrix components, the gastrointestinal tract may act positively on the extraction of polyphenols, since they are progressively released from protein and polysaccharide bonds, being available for the absorption and to exert their biological effects.