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Stryphnodendron pulcherrimum is a plant found in the Brazilian Amazon and contains high content of catechin/(epi)catechin (flavan-3-ol) derivatives. The polymerization of this kind of flavan-3-ol generates condensed tannins, often associated to plant-based diets and gut microbiota. Thus, the discovery of condensed tannins from plants is a valuable approach once it enhances their availability from natural sources. Herein, we described a tetrameric condensed tannin (Molecular Mass 1,170 a.m.u.) tentatively identified for the first time in the barks from S. pulcherrimum. Condensed tannins-derived (flavan-3-ols units) are likely degraded in the gut, and their degradation products such as 3-hydroxyphenylacetic acid (OPAC), 3,4-dihydroxyphenylacetic acid (DHAA), 3-(3,4-dihydroxyphenyl)-propionic acid (DHPA), and 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone (DHPV) could present benefits to gut microbiome metabolism. Therefore, this observational study represents a new insight into S. pulcherrimum, its molecules, and their potential benefits to avoid different diseases and gut well-functional.

This study aimed to determine structure–function relationships of monomeric and oligomeric flavan-3-ols (procyanidins) with respect to their antimicrobial activity and their inhibition of digestive enzymes. Monomeric flacan-3-ols were purchased as reference compounds; oligomeric procyanidins were extracted from grape seeds, separated by high-performance counter-current chromatography and characterized by LC-MS/MS. The antimicrobial activity against a broad range of intestinal microorganisms increased in the order catechin = epicatechin > epigallocatechin and oligomeric procyanidins > epigallocatechin gallate. Facultative anaerobes were highly resistant while strict anaerobes including Allobaculum sp. and Ruminococcus gnavus were 10 – 100 times more sensitive. The inhibition of digestive enzymes from the rat small intestine increased in the order catechin

Flavan-3-ols are the most abundant flavonoids in diet and the analysis and quantification of flavan-3-ol metabolites could report valuable information to assess their absorption mechanisms and bioavailability. In our research, we have studied the feasibility of the determination of three flavan-3-ols metabolites (3-hydroxyphenylacetic acid, 4-hydroxyphenylacetic acid and syringic acid) in urine samples using parallel factor analysis of fluorescence excitation emission matrices. In the optimised conditions, urine samples were directed analysed after diluting in water, centrifuged and filtered. The procedure was successfully applied to quantify the concentration of the selected flavan-3-ols catabolites in urine samples with recoveries ranging between 85 and 93%. For instance, multivariate analytical figures of merit show low sensitivity and selectivity and LOD between 39 μg/L and 53 μg/L. The proposed procedure is fast, simple, reliable and cheap method to quantify flavan-3-ols metabolites in urine and constitutes a powerful tool for screening their abundance in different food matrices after consumption.

Evidence supports an inverse association between nut consumption and cardiovascular disease (CVD) risk and (poly)phenols have been identified as potential co-mediators of these beneficial effects. This study investigated the acute absorption and the bioavailability of (poly)phenols of a hazelnut skin drink in healthy subjects and assessed its acute impact on vascular/endothelial function. A single-blind, non-randomised unilateral cross-over trial involved 41 healthy adults. Blood and urine were collected resulting in the detection of ten plasma and twenty-four urine metabolites. Bioavailability was estimated about 27%. The acute ingestion of the test drink did not show any statistically significant changes to vascular/endothelial function, although a trend was observed with high-producers of certain secondary metabolites. These results indicate that the hazelnut skin drink contains an important fraction of bioavailable bioactive compounds. However, no significant acute effects of the test drink on vascular/endothelial function were observed. The study has been registered on http://www.isrctn.com.

Markets of different countries have proposed guava tea infusions as a drink that can modulate the glycaemic index in blood. This property has been attributed to the phenolic compounds contained in guava leaves. However, phenolic profile of guava leaves is still not well-known. Based on this information, different ethanol/water mixtures were used to extract the phenolic compounds in guava leaves. Phenolic identification was carried out by HPLC-ESI-QTOF-MS in guava leaves from pomifera and pyrifera varieties; moreover, the antioxidant activities of the ethanolic extracts were determined by TEAC and FRAP methods. To sum up, seventy-two phenolic compounds were identified. To our knowledge, twelve of them were determined for the first time in guava leaves. The highest amount of phenolic compounds was found in EtOH/H2O 80:20 (v/v) mixture. Furthermore, pyrifera var. showed higher concentration of phenolic compounds than pomifera var. (113.34 vs. 86.12 mg/g leaf d.w.) and also greater antioxidant capacity.

Total phenolic, flavonoid and anthocyanin contents of dichloromethane, ethyl acetate, ethanol, and aqueous extracts of branches, leaves and fruits from Prunus spinosa were quantified by spectrophotometrical methods and the results showed solvent and botanical organ dependence. In order to detect antioxidant activity, a method based on the reduction of DPPH was carried out. Activity of ethanol, ethyl acetate and aqueous extracts of branches demonstrated a higher scavenging capacity compared to other analysed extracts. Phytochemical analysis allowed detecting flavonoids, coumarins, phenolic acids and flavan-3-ols. Ethanolic extract of branches was subjected to an in vitro digestion. Buccal and gastric digestion had no substantial effect on any of the phenolic compounds. However, these compounds were significantly altered during intestinal digestion. The results showed that a significant proportion of these compounds would be transformed into other unknown and/or undetected structural forms. Furthermore, three phenolic acids, two coumarins, fourteen flavan-3-ols, and six flavonols were identified using HPLC-DAD-ESI-MS.

[Display omitted] • A tetrameric condensed tannin of (epi)catechin-(epi)gallocatechin was described for the first time in the barks from Stryphnodendron pulcherrimum. • Condensed tannins have many potentials to avoid human diseases. • Metabolized products (e.g., OPAC, DHAA, DHPA, and DHPV) from condensed tannins could be associated with the gut well-functional. Stryphnodendron pulcherrimum is a plant found in the Brazilian Amazon and contains high content of catechin/(epi)catechin (flavan-3-ol) derivatives. The polymerization of this kind of flavan-3-ol generates condensed tannins, often associated to plant-based diets and gut microbiota. Thus, the discovery of condensed tannins from plants is a valuable approach once it enhances their availability from natural sources. Herein, we described a tetrameric condensed tannin (Molecular Mass 1,170 a.m.u.) tentatively identified for the first time in the barks from S. pulcherrimum. Condensed tannins-derived (flavan-3-ols units) are likely degraded in the gut, and their degradation products such as 3-hydroxyphenylacetic acid (OPAC), 3,4-dihydroxyphenylacetic acid (DHAA), 3-(3,4-dihydroxyphenyl)-propionic acid (DHPA), and 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone (DHPV) could present benefits to gut microbiome metabolism. Therefore, this observational study represents a new insight into S. pulcherrimum , its molecules, and their potential benefits to avoid different diseases and gut well-functional. [ABSTRACT FROM AUTHOR]

Catechin and epicatechin are the health beneficial flavan-3-ols in tea and many fruits. However, their extreme hydrophilicity renders drawbacks for them to pass through the bio-membranes. We prepared lipophilic flavan-3-ol derivatives by acetylation or by acetone-conjugation. The structures of these derivatives were determined based on their NMR and MS spectra. The 3,5- and 3,7-diacetyl derivatives showed radical scavenging activity slightly weaker than catechin and epicatechin, but showed significantly enhanced capacity to penetrate into living cells. Moreover, the diacetyl derivatives released flavan-3-ols inside cells, while catechin or epicatechin themselves could not penetrate into the cells. The acetone conjugates showed strong antioxidant activity and were able to enter into living cells in the intact form. The acetylated and acetone-conjugated derivatives protected H2O2-induced erythrocyte hemolysis more effectively than catechin and epicatechin. These results indicated that acetylated and acetone-conjugated flavan-3-ols are promising compounds with less hydrophilicity and better bioactivities in biological systems.

Flavan-3-ols are the most abundant flavonoids in diet and the analysis and quantification of flavan-3-ol metabolites could report valuable information to assess their absorption mechanisms and bioavailability. In our research, we have studied the feasibility of the determination of three flavan-3-ols metabolites (3-hydroxyphenylacetic acid, 4-hydroxyphenylacetic acid and syringic acid) in urine samples using parallel factor analysis of fluorescence excitation emission matrices. In the optimised conditions, urine samples were directed analysed after diluting in water, centrifuged and filtered. The procedure was successfully applied to quantify the concentration of the selected flavan-3-ols catabolites in urine samples with recoveries ranging between 85 and 93%. For instance, multivariate analytical figures of merit show low sensitivity and selectivity and LOD between 39 μg/L and 53 μg/L. The proposed procedure is fast, simple, reliable and cheap method to quantify flavan-3-ols metabolites in urine and constitutes a powerful tool for screening their abundance in different food matrices after consumption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Procyanidins were extracted from grape seeds and purified by HSCCC. • The antimicrobial activity of flavan- 3 -ols was highly selective. • Activity increased in the order EC < EGC, oligomeric procyanidins < EGCG. • Strict anaerobes were 10 – 100 times more sensitive than facultative anaerobes. • Inhibition of intestinal amylases increased in the order EC, oligomers < EGC < EGCG. This study aimed to determine structure–function relationships of monomeric and oligomeric flavan- 3 -ols (procyanidins) with respect to their antimicrobial activity and their inhibition of digestive enzymes. Monomeric flacan- 3- ols were purchased as reference compounds; oligomeric procyanidins were extracted from grape seeds, separated by high-performance counter-current chromatography and characterized by LC-MS/MS. The antimicrobial activity against a broad range of intestinal microorganisms increased in the order catechin = epicatechin > epigallocatechin and oligomeric procyanidins > epigallocatechin gallate. Facultative anaerobes were highly resistant while strict anaerobes including Allobaculum sp. and Ruminococcus gnavus were 10 – 100 times more sensitive. The inhibition of digestive enzymes from the rat small intestine increased in the order catechin < epicatechin and oligomeric procyanidins < epigallocatechin < epigallocatechin gallate. Trimeric and polymeric procyanidins were more inhibitory than dimeric procyanidins. Both the antimicrobial and enzyme-inhibitory activities of procyanidins and flavan- 3- ols likely relate to their microbiome-modulating and health beneficial properties. [ABSTRACT FROM AUTHOR]

Markets of different countries have proposed guava tea infusions as a drink that can modulate the glycaemic index in blood. This property has been attributed to the phenolic compounds contained in guava leaves. However, phenolic profile of guava leaves is still not well-known. Based on this information, different ethanol/water mixtures were used to extract the phenolic compounds in guava leaves. Phenolic identification was carried out by HPLC-ESI-QTOF-MS in guava leaves from pomifera and pyrifera varieties; moreover, the antioxidant activities of the ethanolic extracts were determined by TEAC and FRAP methods. To sum up, seventy-two phenolic compounds were identified. To our knowledge, twelve of them were determined for the first time in guava leaves. The highest amount of phenolic compounds was found in EtOH/H 2 O 80:20 (v/v) mixture. Furthermore, pyrifera var. showed higher concentration of phenolic compounds than pomifera var. (113.34 vs. 86.12 mg/g leaf d.w.) and also greater antioxidant capacity. [ABSTRACT FROM AUTHOR]

Total phenolic, flavonoid and anthocyanin contents of dichloromethane, ethyl acetate, ethanol, and aqueous extracts of branches, leaves and fruits from Prunus spinosa were quantified by spectrophotometrical methods and the results showed solvent and botanical organ dependence. In order to detect antioxidant activity, a method based on the reduction of DPPH was carried out. Activity of ethanol, ethyl acetate and aqueous extracts of branches demonstrated a higher scavenging capacity compared to other analysed extracts. Phytochemical analysis allowed detecting flavonoids, coumarins, phenolic acids and flavan-3-ols. Ethanolic extract of branches was subjected to an in vitro digestion. Buccal and gastric digestion had no substantial effect on any of the phenolic compounds. However, these compounds were significantly altered during intestinal digestion. The results showed that a significant proportion of these compounds would be transformed into other unknown and/or undetected structural forms. Furthermore, three phenolic acids, two coumarins, fourteen flavan-3-ols, and six flavonols were identified using HPLC-DAD-ESI-MS. [ABSTRACT FROM AUTHOR]

Catechin and epicatechin are the health beneficial flavan-3-ols in tea and many fruits. However, their extreme hydrophilicity renders drawbacks for them to pass through the bio-membranes. We prepared lipophilic flavan-3-ol derivatives by acetylation or by acetone-conjugation. The structures of these derivatives were determined based on their NMR and MS spectra. The 3,5- and 3,7-diacetyl derivatives showed radical scavenging activity slightly weaker than catechin and epicatechin, but showed significantly enhanced capacity to penetrate into living cells. Moreover, the diacetyl derivatives released flavan-3-ols inside cells, while catechin or epicatechin themselves could not penetrate into the cells. The acetone conjugates showed strong antioxidant activity and were able to enter into living cells in the intact form. The acetylated and acetone-conjugated derivatives protected H 2 O 2 -induced erythrocyte hemolysis more effectively than catechin and epicatechin. These results indicated that acetylated and acetone-conjugated flavan-3-ols are promising compounds with less hydrophilicity and better bioactivities in biological systems. [ABSTRACT FROM AUTHOR]

• A hazelnut skin drink was tested in a single-blind, non-randomised unilateral cross-over trial. • Ten plasma and twenty-four urine hazelnut phenolic metabolites were identified and quantified. • Hazelnut skin phenolics were highly bioavailable. • No acute beneficial effect of the test drink on endothelial function was observed. Evidence supports an inverse association between nut consumption and cardiovascular disease (CVD) risk and (poly)phenols have been identified as potential co-mediators of these beneficial effects. This study investigated the acute absorption and the bioavailability of (poly)phenols of a hazelnut skin drink in healthy subjects and assessed its acute impact on vascular/endothelial function. A single-blind, non-randomised unilateral cross-over trial involved 41 healthy adults. Blood and urine were collected resulting in the detection of ten plasma and twenty-four urine metabolites. Bioavailability was estimated about 27%. The acute ingestion of the test drink did not show any statistically significant changes to vascular/endothelial function, although a trend was observed with high-producers of certain secondary metabolites. These results indicate that the hazelnut skin drink contains an important fraction of bioavailable bioactive compounds. However, no significant acute effects of the test drink on vascular/endothelial function were observed. The study has been registered on http://www.isrctn.com. [ABSTRACT FROM AUTHOR]