SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Polyphenol

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Resveratrol is a bioactive polyphenol enriched in red wine that exhibits many beneficial health effects via multiple mechanisms. However, it is unclear whether resveratrol is beneficial for the prevention of food allergy. This study investigated whether resveratrol inhibited the development of food allergy by using a mouse model of the disease.

Concepts: Human, Nutrition, Allergy, Mouse, Resveratrol, Wine, Polyphenol, French Paradox

171

(-)-Epigallocatechin gallate (EGCG) is a major polyphenol component of green tea that has antioxidant activities. Lipopolysaccharide (LPS) induces inflammatory cytokine production and impairs blood-brain barrier (BBB) integrity. We examined the effect of EGCG on LPS-induced expression of the inflammatory cytokines in human cerebral microvascular endothelial cells (hCMECs) and BBB permeability.

Concepts: Inflammation, Cytokine, Antioxidant, Tea, Catechin, Green tea, Polyphenol, Epigallocatechin gallate

170

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a polyphenol found in various plants, especially in the skin of red grapes. The effect of resveratrol on human health is the topic of numerous studies. In fact this molecule has shown anti-cancer, anti-inflammatory, blood-sugar-lowering ability and beneficial cardiovascular effects. However, for many polyphenol compounds of natural origin bioavailability is limited by low solubility in biological fluids, as well as by rapid metabolization in vivo. Therefore, appropriate carriers are required to obtain efficient therapeutics along with low administration doses.Liposomes are excellent candidates for drug delivery purposes, due to their biocompatibility, wide choice of physico-chemical properties and easy preparation.In this paper liposome formulations made by a saturated phosphatidyl-choline (DPPC) and cholesterol (or its positively charged derivative DC-CHOL) were chosen to optimize the loading of a rigid hydrophobic molecule such as resveratrol.Plain and resveratrol loaded liposomes were characterized for size, surface charge and structural details by complementary techniques, i.e. Dynamic Light Scattering (DLS), Zeta potential and Small Angle X-ray Scattering (SAXS). Nuclear and Electron Spin magnetic resonances (NMR and ESR, respectively) were also used to gain information at the molecular scale.The obtained results allowed to give an account of loaded liposomes in which resveratrol interacted with the bilayer, being more deeply inserted in cationic liposomes than in zwitterionic liposomes. Relevant properties such as the mean size and the presence of oligolamellar structures were influenced by the loading of RESV guest molecules.The toxicity of all these systems was tested on stabilized cell lines (mouse fibroblast NIH-3T3 and human astrocytes U373-MG), showing that cell viability was not affected by the administration of liposomial resveratrol.

Concepts: Electron, Electric charge, Molecule, Scattering, Resveratrol, Polyphenol antioxidant, Polyphenol, Dynamic light scattering

166

The most common technique used to detect ochratoxin A (OTA) in food matrices is based on extraction, clean-up, and chromatography detection. Different clean-up cartridges, such as immunoaffinity columns (IAC), molecular imprinting polymers (MIP), Mycosep™ 229, Mycospin™, and Oasis® HLB (Hydrophilic Lipophilic balance) as solid phase extraction were tested to optimize the purification for red wine, beer, roasted coffee and chili. Recovery, reproducibility, reproducibility, limit of detection (LOD) and limit of quantification (LOQ) were calculated for each clean-up method. IAC demonstrated to be suitable for OTA analysis in wine and beer with recovery rate >90%, as well as Mycosep™ for wine and chili. On the contrary, MIP columns were the most appropriate to clean up coffee. A total of 120 samples (30 wines, 30 beers, 30 roasted coffee, 30 chili) marketed in Italy were analyzed, by applying the developed clean-up methods. Twenty-seven out of 120 samples analyzed (22.7%: two wines, five beers, eight coffees, and 12 chili) resulted positive to OTA. A higher incidence of OTA was found in chili (40.0%) more than wine (6.6%), beers (16.6%) and coffee (26.6%). Moreover, OTA concentration in chili was the highest detected, reaching 47.8 µg/kg. Furthermore, three samples (2.5%), two wines and one chili, exceeded the European threshold.

Concepts: Measurement, Analytical chemistry, Detection limit, Harshad number, Wine, Oenology, Alcoholic beverage, Polyphenol

163

Flavonoids are a significant group of secondary metabolites in plants. Many of these compounds are potent antioxidants, being an important part in food products derived from the plants. The current status of research on flavonoid compounds in the fruit of Saskatoon berries (Amelanchier alnifolia Nutt.) and their health promoting effects, including recommended utilization, are reviewed. The major classes of flavonoids in the fruit are flavonols (quercetin and rutin), flavanes (proanthocyanidin compounds ranging from dimers through to heptamers and even higher polymers) and finally anthocyanins. The flavonoids represented the group of polyphenols that mostly contributed to the antioxidant activity of Saskatoon berries. High content of the flavoinoids antioxidants in the fruit is responsible for the observed anti-inflammatory, antidiadiabetic and chemo-protective effects.

Concepts: Nutrition, Antioxidant, Flavonoid, Resveratrol, Polyphenol, Flavonols, Rutin, Amelanchier alnifolia

30

Aim: The therapeutic potential of epigallocatechin-3-gallate (EGCG), a green tea polyphenol with anticancer properties, is limited by its inability to specifically reach tumors following intravenous administration. The purpose of this study was to determine whether a tumor-targeted vesicular formulation of EGCG would suppress the growth of A431 epidermoid carcinoma and B16-F10 melanoma in vitro and in vivo. Materials & methods: Transferrin-bearing vesicles encapsulating EGCG were administered intravenously to mice bearing subcutaneous A431 and B16-F10 tumors. Results: The intravenous administration of EGCG encapsulated in transferrin-bearing vesicles resulted in tumor suppression in 40% of A431 and B16-F10 tumors. Animal survival was improved by more than 20 days compared with controls. Conclusion: Encapsulation of EGCG in transferrin-bearing vesicles is a promising therapeutic strategy. Original submitted 28 November 2011; Revised submitted 11 May 2012; Published online 14 August 2012.

Concepts: Cancer, Oncology, Intravenous therapy, Catechin, Green tea, Polyphenol, Epigallocatechin gallate, Theaflavin

29

Tea leaves contain varying amounts of polyphenols of which the majority are catechins. There has been a sizable amount of research on the potential effect of green tea catechins for cancer risk, cardiovascular disease risk and weight loss; all conditions that are relevant to mid-life health. The aim was to produce an overview of the evidence for green tea for these three important health conditions.

Concepts: Medicine, Tea, Catechin, Camellia sinensis, Green tea, Tannin, Polyphenol, Epigallocatechin gallate

28

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. So, 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 hydrolysable 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.

Concepts: Antioxidant, Taste, Tea, Catechin, Resveratrol, Tannin, Polyphenol, Taste receptor

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The binding sites of antioxidant polyphenols resveratrol, genistein and curcumin are located with milk α- and β-caseins in aqueous solution. FTIR, CD and fluorescence spectroscopic methods and molecular modeling were used to analyse polyphenol binding sites, the binding constant and the effects of complexation on casein stability and conformation. Structural analysis showed that polyphenols bind casein via hydrophilic and hydrophobic interactions with the number of bound polyphenol molecules (n) 1.20 for resveratrol, 1.4 for genistein and 1.4 for curcumin with α-casein and 1.2 for resveratrol, 1.3 for genistein and 1.3 for curcumin with β-casein. The overall binding constants of the complexes formed are Kres-α-casein = 1.9 (± 0.6) x 104 M-1, Kgen-α-casein = 1.8 (± 0.4) x 104 M-1 , Kcur-α-casein = 2.8 (± 0.8) x 104 M-1 with α-casein and Kres-β-casein = 2.3 (± 0.3) x 104 M-1, Kgen-β-casein = 3.0 (± 0.5) x 104 M-1 and Kcur-β-casein = 3.1 (± 0.5) x 104 M-1 for β-casein. Molecular modeling showed the participation of several amino acids in polyphenol-protein complexes, which were stabilized by hydrogen bonding network with the free binding energy of -11.56 (resveratrol-α-casein), -12.35 (resveratrol-β-casein), -9.68 (genistein-α-casein, -9.97 (genistein-β-casein), -8.89 (curcumin-α-casein) and -10.70 kcal/mol (curcumin-β-casein). The binding sites of polyphenols are different with α- and β-caseins. Polyphenol binding altered casein conformation with reduction of α-helix indicating a partial protein destabilization. Caseins might act as carriers to transport polyphenol in vitro.

Concepts: Protein, Antioxidant, Molecule, Chemistry, Atom, Resveratrol, Polyphenol antioxidant, Polyphenol

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Different dehydrated waste grape skins from the juice industry were added into aged and young red wines as an innovative way of compensating for colour loss before bottling. After addition of grape skins, colour intensity of wines increased a mean 11% and a maximum of 31% with predominance of the red component. Total polyphenols mean increase was 10% with a maximum value of 20%. Analysis of low molecular weight phenolic compounds by HPLC-DAD showed a significant (p<0.05) content increase of the bioactive compounds gallic acid, (+)-catechin, (-)-epicatechin, and (E)-resveratrol. Anthocyanins content also increased at an average of 50mg/l. The volatile profile of wines analysed by SBSE-GC-MS was only moderately influenced by the treatments. Mixtures of dehydrated waste grape skins were useful to improve the colour and polyphenol profile of red wines, considering them a useful tool for correcting colour loss before bottling.

Concepts: Catechin, Resveratrol, Wine, Tannin, Polyphenol, Fermentation, Anthocyanin, Polyphenols