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Grape pomace (GP) is a by-product rich in phytochemicals, including extractable polyphenols (EPPs) and non-extractable polyphenols (NEPPs), which have distinct metabolic fates that may affect their biological activities. The benefits of GP have been reported in relation to obesity and its comorbidities, particularly when administered preventively focusing on EPPs. Therefore, the aim of this study was to investigate the effects of EPPs and NEPPs from GP as a treatment for obesity and its associated metabolic alterations. A previous comprehensive characterization of the selected GP revealed the most relevant individual compounds in the EPPs fraction (malvidin hexoside, (-)-epicatechin, quercetin, and procyanidin dimer B2 isomer II), as well as in the NEPPs fraction (hydroxybenzoic acid isomers I-II). The experiment was performed in obese rats with insulin resistance, treated for 8 weeks with EPPs or NEPPs grape pomace fractions (100 mg/kg). After the intervention, the HFFD + EPP group showed a significantly lower weight gain (9.6%) and body mass index (9.7%) compared to the HFFD group. While liver triglyceride levels were only significantly reduced in the HFFD + NEPP group (47%) compared to the HFFD group. Neither treatment resulted in a reduction of insulin resistance. Therefore, the supplementation with grape pomace phenolic fractions to an animal model of obesity exerted differential beneficial effects on body weight and liver lipid accumulation, overall contributing to an amelioration of some the metabolic alterations present in obesity, although not to aspects such as glycemic homeostasis. [ABSTRACT FROM AUTHOR]

Introduction: (Poly)phenols (PPs) are plant secondary metabolites widely distributed in dietary sources, and several evidences show that consumption of PP has a positive impact in human health. However, the correct estimation of food intake and the estimation of PP content of foods are essential to associate PPs intake with health effects. Purpose: This review aimed to gather information from several studies on PP intake in different countries, compare methods used for both assessment of food intake and PP quantification and highlight existing gaps and future directions. Methods: Twenty-four studies of PP intake from thirteen countries were selected for analysis. The selected studies included assessment of all plant food groups contributing to PP intake, total PP content and/or content of major classes (flavonoids or phenolic acids), a large study population and both genders. Results and Conclusion: Most studies presented daily intakes of extractable (poly)phenols. Very few studies have determined intake of non-extractable (poly)phenols, which is a very important fraction of PPs contributing to total PP intake. High heterogeneity was observed among countries regarding the intake of total PP intake and the two main PP classes. This may reflect not only different diet patterns, but also different methods used for collecting food consumption data and estimation of PP content. Thus, criteria of harmonization are suggested regarding assessment of food intake, determination of PP content in foods and validation with biomarkers. [ABSTRACT FROM AUTHOR]

This contribution proposes an enzyme-assisted eco-friendly process for the extraction of non-extractable polyphenols (NEPPs) from black tea leftover (BTLO), an underutilized tea waste. BTLO hydrolyzed with various enzyme formulations was extracted using supercritical carbon dioxide and ethanol as co-solvent (SC-CO + EtOH). A conventional solvent extraction (CSE) was performed using EtOH + HO (80:20, v/ v) for comparison purposes. The results revealed that hydrolysis of BTLO with 2.9% ( w/ w) kemzyme at 45 °C and pH 5.4 for 98 min improved the liberation of NEPPs offering 5-fold higher extract yield (g/100 g) as compared with non-treated BTLO. In vitro antioxidant evaluation and LC-MS characterization of extracts revealed the presence of phenolic acids (mainly caffeic and para-coumaric acid) of high antioxidant value. Scanning electron micrograph of the hydrolyzed BTLO samples indicated noteworthy changes in the ultrastructure of BTLO. Moreover, polyphenol extracts obtained by SC-CO + EtOH extraction were found to be cleaner and richer in polyphenols as compared to CSE. The devised enzyme-assisted SC-CO + EtOH extraction process in the present work can be explored as an effective biotechnological mean for the optimal recovery of antioxidant polyphenols. [ABSTRACT FROM AUTHOR]

Epidemiological and clinical studies show that diets with a high antioxidant capacity, such us those rich in plant food and beverages, are associated with significant decreases in the overall risk of cardiovascular disease or colorectal cancer. Current studies on dietary antioxidants and dietary antioxidant capacity focus exclusively on low molecular weight or soluble antioxidants (vitamins C and E, phenolic compounds and carotenoids), ignoring macromolecular antioxidants. These are polymeric phenolic compounds or polyphenols and carotenoids linked to plant food macromolecules that yield bioavailable metabolites by the action of the microbiota with significant effects either local and/or systemic after absorption. This study determined the antioxidant capacity of the Spanish Mediterranean diet including for the first time both soluble and macromolecular antioxidants. Antioxidant capacity and consumption data of the 54 most consumed plant foods and beverages were used. Results showed that macromolecular antioxidants are the major dietary antioxidants, contributing a 61% to the diet antioxidant capacity (8000 μmol Trolox, determined by ABTS method). The antioxidant capacity data for foods and beverages provided here may be used to estimate the dietary antioxidant capacity in different populations, where similar contributions of macromolecular antioxidants may be expected, and also to design antioxidant-rich diets. Including macromolecular antioxidants in mechanistic, intervention and observational studies on dietary antioxidants may contribute to a better understanding of the role of antioxidants in nutrition and health. [ABSTRACT FROM AUTHOR]