Pyranoanthocyanins constitute one of the most important classes of anthocyanin-derived pigments occurring naturally in red wine. Nonetheless, correct assignment of their structures and pathways of ...formation in red wine has been relatively recent—less than two decades. Study of these newly discovered pigments is progressively unfolding the chemical pathways that drive the evolution of red wine colour during ageing. The objective of this paper is to review current knowledge regarding the pathway of formation in red wine of a great variety of pyranoanthocyanin structures, namely carboxypyranoanthocyanins, methylpyranoanthocyanins, pyranoanthocyanin-flavanols, pyranoanthocyanin-phenols, portisins, oxovitisins, and pyranoanthocyanin dimers. The chromatic features of some of the compounds, for example their colour expression and acid–base equilibria in aqueous media, are also discussed.
Bitterness is a major sensory attribute of several common foods and beverages rich in polyphenol compounds. These compounds are reported as very important for health as chemopreventive compounds, but ...they are also known to taste bitter. In this work, the activation of the human bitter taste receptors, TAS2Rs, by six polyphenol compounds was analyzed. The compounds chosen are present in a wide range of plant-derived foods and beverages, namely, red wine, beer, tea, and chocolate. Pentagalloylglucose (PGG) is a hydrolyzable tannin, (−)-epicatechin is a precursor of condensed tannins, procyanidin dimer B3 and trimer C2 belong to the condensed tannins, and malvidin-3-glucoside and cyanidin-3-glucoside are anthocyanins. The results show that the different compounds activate different combinations of the ∼25 TAS2Rs. (−)-Epicatechin activated three receptors, TAS2R4, TAS2R5, and TAS2R39, whereas only two receptors, TAS2R5 and TAS2R39, responded to PGG. In contrast, malvidin-3-glucoside and procyanidin trimer stimulated only one receptor, TAS2R7 and TAS2R5, respectively. Notably, tannins are the first natural agonists found for TAS2R5 that display high potency only toward this receptor. The catechol and/or galloyl groups appear to be important structural determinants that mediate the interaction of these polyphenolic compounds with TAS2R5. Overall, the EC50 values obtained for the different compounds vary 100-fold, with the lowest values for PGG and malvidin-3-glucoside compounds, suggesting that they could be significant polyphenols responsible for the bitterness of fruits, vegetables, and derived products even if they are present in very low concentrations.
Anthocyanins. Plant Pigments and Beyond Santos-Buelga, Celestino; Mateus, Nuno; De Freitas, Victor
Journal of agricultural and food chemistry,
07/2014, Letnik:
62, Številka:
29
Journal Article
Recenzirano
Anthocyanins are plant pigments widespread in nature. They play relevant roles in plant propagation and ecophysiology and plant defense mechanisms and are responsible for the color of fruits and ...vegetables. A large number of novel anthocyanin structures have been identified, including new families such as pyranoanthocyanins or anthocyanin oligomers; their biosynthesis pathways have been elucidated, and new plants with “a la carte” colors have been created by genetic engineering. Furthermore, evidence about their benefits in human health has accumulated, and processes of anthocyanin absorption and biotransformation in the human organism have started to be ascertained. These advances in anthocyanin research were revised in the Seventh International Workshop on Anthocyanins that took place in Porto (Portugal) on September 9–11, 2013. Some selected papers are collected in this special issue, where aspects such as anthocyanin accumulation in plants, relationship with color expression, stability in plants and food, and bioavailability or biological activity are revised.
Phenolic compounds are one of the most widespread classes of compounds in nature, with several beneficial biological effects being associated with their anti-oxidant and anti-carcinogenic activities. ...Their application in the prevention or treatment of numerous chronic diseases have been studied, but a major drawback is still the low bioavailability of these compounds, as well as their instability towards pH, temperature, and light in some cases. Nanotechnology has emerged as an alternative to overcome these limitations, and the use of lipidic encapsulation systems is a promising technique to achieve an efficient drug delivery, protecting molecules from external factors and improving their bioavailability. In this review, solid lipid nanoparticles and nanostructured lipid carriers are highlighted as an important tool for the improvement of the bioavailability and stability of natural phenolic compounds, including their preparation methods and functionalization approaches and the discussion of several applications for putative use in cosmetic and pharmacologic products.
Phenolic compounds are responsible for major organoleptic characteristics of plant-derived food and beverages; these substances have received much attention, given that the major function of these ...compounds is their antioxidant ability. In the context of this study, our major aim was study the binding of several phenolic compounds such as (+)-catechin, (−)-epicatechin, (−)-epicatechin gallate, malvidin-3-glucoside, tannic acid, procyanidin B4, procyanidin B2 gallate, and procyanidin oligomers to different proteins (bovine serum albumin and human α-amylase) by fluorescence quenching of protein intrinsic fluorescence. From the spectra obtained, the Stern−Volmer, the apparent static, and the bimolecular quenching constants were calculated. The structure of polyphenols revealed to significantly affect the binding/quenching process; in general, the binding affinity increased with the molecular weight of polyphenol compounds and in the presence of galloyl groups. For catechin monomer and procyanidin dimer B4, the K SV was 14100 and 13800 M-1, respectively, and for galloyl derivatives, the K SV was 19500 and 21900 M-1, respectively. Tannic acid was shown to be the major quenching molecule for both proteins. However, comparing different proteins, the same polyphenol showed different quenching effects, which are suggested to be related to the three-dimensional structure of the proteins studied. For (+)-catechin and BSA, the K SV was 8700 M-1, and with α-amylase, it was 14100 M-1; for tannic acid, the K SV was 100548 and 110674 M-1, respectively. From the results obtained, besides the main binding analysis performed, we conclude that this technique is more sensitive than thought because we can detect several interactions that have not been proven by other methods, namely, nephelometry. Overall, fluorescence quenching has proven to be a very sensitive technique with many potentialities to analyze the interaction between polyphenols and proteins. Keywords: Polyphenols; bovine serum albumin; human salivary α-amylase; fluorescence quenching
•Phase II methylation of anthocyanins originates new 4′-methyl metabolites.•The catechol and pyrogallol group are metabolised in a different way.•The synthesised metabolites retain antiradicalar and ...reduction power.•All compounds inhibited the proliferation of all cell lines tested.•Dp3glc was the anthocyanin with the better inhibitory activity.
Anthocyanins are major flavonoids in many plant foods and have been related to health promotion. In the human organism anthocyanins are metabolised to different metabolites. One of the most important phase II reactions of flavonoids is the methylation of the catechol group. This feature is expected to have an effect on the antioxidant and antiproliferative properties of flavonoids including anthocyanins. In this work, delphinidin-3-glucoside, cyanidin-3-glucoside and petunidin-3-glucoside methylated metabolites were obtained by enzymatic hemi-synthesis. The compounds were identified as monomethylated products by HPLC–MS and NMR. The methylated metabolites were found to still retain significant radical scavenging activity and reducing activity, suggesting that they could act as potential antioxidants in vivo. The antiproliferative activity of the metabolites in comparison with the parental anthocyanins was also evaluated in three cancer cell lines by sulforhodamine B assay. The conjugation with methyl groups decreased or did not alter the antiproliferative effect of the original anthocyanin.
Condensed tannins are a group of polyphenols that are associated with the astringency sensation, as they readily interact and precipitate salivary proteins. As this interaction is affected by ...carbohydrates, the aim of this work was to study the effect of some carbohydrates used in the food industry arabic gum (AG), pectin, and poligalacturonic acid (PGA) on the salivary proteins/grape seed procyanidins interaction. This was assessed monitoring the salivary proteins that remain soluble in the presence of condensed tannins with the addition of carbohydrates (HPLC) and analysis of the respective precipitates (SDS-PAGE). The results show that pectin was the most efficient in inhibiting protein/tannin precipitation, followed by AG and PGA. The results suggest that pectin and PGA exert their effect by formation of a ternary complex protein/polyphenol/carbohydrate, while AG competes with proteins for tannin binding (competition mechanism). The results also point out that both hydrophilic and hydrophobic interactions are important for the carbohydrate effects.
Pyranoanthocyanins are anthocyanin-derived compounds found in nature that present a vast palette of colours ranging from yellow to turquoise blue. Studies in aqueous solutions of these pigments by ...UV–Visible spectroscopy revealed their higher colour stability when compared to their anthocyanin precursors. Through Nuclear Magnetic Resonance (NMR) techniques it was possible to confirm the absence of hydration reactions in pyranoanthocyanins, contrarily to anthocyanins, which helps explaining their higher colour stability with the increase of the pH.
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•Pyranoanthocyanin pigments equilibrium forms studies in aqueous solution are reviwed.•Pyranoanthocyanins present higher colour stabilization with the increase of pH when compared to the anthocyanin precursors.•The absence of hydration reactions in pyranoanthocyanins were confirmed using NMR techniques.
The altered expression and subcellular distribution of tight junction (TJ) proteins, leading to a dysfunctional intestinal barrier, is a key mechanistic feature of inflammatory bowel disease (IBD). ...Therefore, increasing the integrity of the intestinal barrier by manipulating the TJ may constitute an innovative and effective therapeutic strategy in IBD. In this context, recent studies showed that dietary polyphenols are able to protect the intestinal TJ barrier integrity. Here, using a cellular model of intestinal inflammation, consisting of cytokine-stimulated HT-29 colon epithelial cells, we show that a polyphenolic extract obtained from Portuguese red wine (RWE) decreased the paracellular permeability across the cell monolayer compared with the control cells, even in the presence of pro-inflammatory cytokines. The beneficial effect of RWE was exerted at three complementary levels: (1) by promoting a significant increase of the mRNA of key barrier-forming TJ proteins, including occludin, claudin-5 and zonnula occludens (ZO)-1 above the levels observed in the control cells; (2) by preventing the decrease in the expression of these proteins under inflammatory conditions and (3) by averting the increase in claudin-2 mRNA, a channel-forming TJ protein induced by pro-inflammatory cytokines. Taken together, these results strongly suggest that polyphenols presented and consumed in red wine as a mixture can reinforce and protect the intestinal barrier against inflammatory stimulus by affecting the TJ protein expression and, thus, without the need for purifying individual compounds, might represent a readily available therapeutic intervention against IBD and intestinal inflammation.
We evaluated how the taxonomic, phylogenetic and functional diversities of butterflies and their community-weighted traits are affected by urbanization in the southeastern Brazilian Atlantic Forest. ...For this purpose, a dataset of Nymphalidae species distributed across 15 urban, semiurban, and rural fragments was analyzed. Urbanization was defined by a set of environmental variables. Furthermore, the total area of each fragment was also considered in the analyses but did not influence the results, in which disturbance level and patch connectivity drove the environmental variation across the urban matrix. Species diversity increased towards the more connected fragments, while phylogenetic and functional diversity did not vary in relation to urbanization. A high forewing:hindwing ratio and the frequency of tiger-like wings were positively related to the urban fragments, while a low forewing:hindwing ratio and iridescent wings were related to the semiurban and rural fragments. The suitability of highly interconnected rural habitats for the maintenance of butterfly diversity was corroborated as expected. Nonetheless, our results also showed that semiurban fragments preserved the ecologically relevant traits of butterflies related to forested habitats, expressed in butterfly groups possibly linked with dispersal capability to avoid predation. Careful management of semiurban fragments and urban landscaping, including highly structured and native vegetation outside urban parks, may increase the functional and taxonomic diversities or at least maintain the current levels of functionality in the urban matrix. Thus, it is possible to preserve the biological diversity of native fauna and flora and recover relevant ecosystem services, ensuring the conservation of Neotropical urban centers.
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