Absorption, Metabolism and Excretion of Cranberry (Poly)phenols in Humans: A Dose Response Study and Assessment of Inter-Individual Variability

Food intake biomarkers for berries and grapes

Grapes and berries are two types of widely consumed fruits characterized by a high content in different phytochemicals. However, their accurate dietary assessment is particularly arduous, because of the already wide recognized bias associated with self-reporting methods, combined with the large range of species and cultivars and the fact that these fruits are popularly consumed not only in fresh and frozen forms but also as processed and derived products, including dried and canned fruits, beverages, jams, and jellies. Reporting precise type and/or quantity of grape and berries in FFQ or diaries can obviously be affected by errors. Recently, biomarkers of food intake (BFIs) rose as a promising tool to provide accurate information indicating consumption of certain food items. Protocols for performing systematic reviews in this field, as well as for assessing the validity of candidate BFIs have been developed within the Food Biomarker Alliance (FoodBAll) Project. This paper aims to evaluate the putative BIFs for blueberries, strawberries, raspberries, blackberries, cranberries, blackcurrant, and grapes. Candidate BFIs for grapes were resveratrol metabolites and tartaric acid. The metabolites considered as putative BFI for berries consumption were mostly anthocyanins derivatives together with several metabolites of ellagitannins and some aroma compounds. However, identification of BFIs for single berry types encountered more difficulties. In the absence of highly specific metabolites reported to date, we suggested some multi-metabolite panels that may be further investigated as putative biomarkers for some berry fruits.

Cranberry Polyphenols and Prevention against Urinary Tract Infections: Relevant Considerations

Cranberry (Vaccinium macrocarpon) is a distinctive source of polyphenols as flavonoids and phenolic acids that has been described to display beneficial effects against urinary tract infections (UTIs), the second most common type of infections worldwide. UTIs can lead to significant morbidity, especially in healthy females due to high rates of recurrence and antibiotic resistance. Strategies and therapeutic alternatives to antibiotics for prophylaxis and treatment against UTIs are continuously being sought after. Different to cranberry, which have been widely recommended in traditional medicine for UTIs prophylaxis, probiotics have emerged as a new alternative to the use of antibiotics against these infections and are the subject of new research in this area. Besides uropathogenic Escherichia coli (UPEC), the most common bacteria causing uncomplicated UTIs, other etiological agents, such as Klebsiellapneumoniae or Gram-positive bacteria of Enterococcus and Staphylococcus genera, seem to be more widespread than previously appreciated. Considerable current effort is also devoted to the still-unraveled mechanisms that are behind the UTI-protective effects of cranberry, probiotics and their new combined formulations. All these current topics in the understanding of the protective effects of cranberry against UTIs are reviewed in this paper. Further progresses expected in the coming years in these fields are also discussed.

Polyphenols, the new frontiers of prebiotics

There is a growing interest in the identification of molecules capable to promote health and with a concurrent potential for technological applications. Prebiotics are functional ingredients naturally occurring in some plant and animal foods that since many decades stimulated considerable attention from the pharmaceutical and food industries due to their positive health effects. Together the well-known biomolecules with ascertained prebiotic effect, in last year new molecules were finally recognized as prebiotics, so capable to improve the health of an organism, also through the positive effect exerted on host microbiota. Among the so-called prebiotics, a special mention should be given to polyphenols, probably the most important, or at least among the most important secondary metabolites produced by the vegetal kingdom. This short chapter wants to emphasize polyphenols and, after briefly describing the individual microbiome, to illustrate how polyphenols can, through their influence on the microbiome, have a positive effect on the health of the individual in general, and on some pathologies in particular, for which the role of a bad status of the individual microbiome has been definitively established.

Kinetic profile and urinary excretion of phenyl-γ-valerolactones upon consumption of cranberry: a dose-response relationship

Cranberries are a rich source of poly(phenols), mainly monomeric and oligomeric flavan-3-ols. However, information on the appearance of their main circulating microbial metabolites, namely phenyl-γ-valerolactones and phenylvaleric acid, is lacking despite its relevance to understanding the health effects attributed to cranberries. The aim of this study was to evaluate the absorption, metabolism and urinary excretion of cranberry flavan-3-ols through the targeted analysis of phenyl-γ-valerolactones and their related phenylvaleric acids, considering also their potential as biomarkers of flavan-3-ol intake and inter-individual variability in their appearance in plasma and urine. A six-arm acute crossover, randomized, double-blinded, controlled intervention trial was performed in ten healthy males who consumed a cranberry juice drink (375, 716, 1131, 1396, 1741 mg of total flavan-3-ols) or an isocaloric control drink with one-week washout. Plasma and urine were analyzed by UHPLC-ESI-QqQ-MS/MS and 22 compounds were identified. Glucuronide and sulfate conjugates of 5-(3',4'-dihydroxyphenyl)-γ-valerolactone were the main circulating and excreted metabolites after cranberry juice intake, with glucuronidation appearing to be the most favorable conjugation route. These compounds reached maximum plasma concentration at about 4-6 h. Plasma and urinary concentrations of the sum of the metabolites increased in relation to the amounts of cranberry flavan-3-ols provided by the drink, showing a clear and linear dose-dependent relationship and underscoring their potential as biomarkers of flavan-3-ol intake. A high inter-individual variability in circulating and urinary metabolite levels was observed and, interestingly, some subjects seemed to display a greater efficiency in metabolizing flavan-3-ols and producing phenyl-γ-valerolactones.

Characterization of ethyl acetate and n-butanol extracts of Cymbopogon schoenanthus and Helianthemum lippii and their effect on the smooth muscle of the rat distal colon

ETHNOPHARMACOLOGY RELEVANCE

Cymbopogon schoenanthus (C. schoenanthus) and Helianthemum lippii (H. lippii) are Saharan species found in the South West of Algeria, in the region of Bechar. Both plants are used in traditional medicine to treat gastrointestinal disorders.

OBJECTIVE

The aim of our study was to characterize the composition of the ethyl acetate (EtOAc) and n-Butanol (n-BuOH) extracts of C. schoenanthus and H. lippii, and to elucidate and compare their effect on the reactivity of the rat distal colon.

MAIN METHODS

The plants were macerated in a hydroalcoholic solution. After concentration, the aqueous solutions of the residues were submitted to liquid-liquid extractions to obtain EtOAc and n-BuOH extracts. The phenolic and flavonoid content of the extracts was determined by high performance liquid chromatography coupled with mass spectrometry with a time of flight analyzer (HPLC-TOF/MS). The effect of the extracts was tested on the rat distal colon, namely on the basal tone and on KCl- and Ach-induced precontracted preparations.

RESULTS

HPLC-TOF/MS identified 32 phenols and flavonoids in the extracts. The four extracts relaxed the rat distal colon, the effect being noticed on the basal tone and on the KCl- and Ach-induced precontractions. The EtOAc and the n-BuOH extracts of H. lippii decreased the basal tone of the rat distal colon more markedly than the correspondent extracts of C. schoenanthus. Moreover, the n-BuOH extract of C. schoenanthus decreased the basal tone more markedly than the EtOAc extract of this plant but there was no difference between extracts of H. lippii. The EtOAc extracts of both C. schoenanthus and H. lippii totally reverted both the KCl- and the Ach-induced precontraction of the rat distal colon. However, the n-BuOH extracts of the two plants reverted the Ach-precontracted colon but not the colon that has been precontracted with KCl.

CONCLUSION

Extracts of H. lippii contain a higher level of phenols compared to the extracts of C. schoenanthus. All extracts of C. schoenanthus and H. lippii caused marked relaxation of the isolated rat distal colon, either when applied directly or when tested over KCl- and Ach-induced precontraction. These results give support to the use of C. shoenanthus and H. lippii in traditional medicine, namely for gastrointestinal diseases.

Profiling of Endogenous and Gut Microbial Metabolites to Indicate Metabotype-Specific Dietary Responses: A Systematic Review

Upon dietary exposure, the endogenous metabolism responds to the diet-derived nutrients and bioactive compounds, such as phytochemicals. However, the responses vary remarkably due to the interplay with other dietary components, lifestyle exposures, and intrinsic factors, which lead to differences in endogenous regulatory metabolism. These physiological processes are evidenced as a signature profile composed of various metabolites constituting metabolic phenotypes, or metabotypes. The metabolic profiling of biological samples following dietary intake hence would provide information about diet-that is, as the intake biomarkers and the ongoing physiological reactions triggered by this intake-thereby enable evaluation of the metabolic basis required to distinguish the different metabotypes. The capacity of nontargeted metabolomics to also encompass the unprecedented metabolite species has enabled the profiling of multiple metabolites and the corresponding metabotypes with a single analysis, decoding the complex interplay between diet, other relevant factors, and health. In this systematic review, we screened 345 articles published in English in January 2007-July 2018, which applied the metabolomics approach to profile the changes of endogenous metabolites in the blood related to dietary interventions, either derived by metabolism of gut microbiota or the human host. We excluded all the compounds that were directly derived from diet, and also the dietary interventions focusing on supplementation with individual compounds. After the removal of less relevant studies and assessment of eligibility, 49 articles were included in this review. First, we mention the contribution of individual factors, either modifiable or nonmodifiable factors, in shaping metabolic profile. Then, how different aspects of the diet would affect the metabolic profiles are disentangled. Next, the classes of endogenous metabolites altered following included dietary interventions are listed. We also discuss the current challenges in the field, along with future research opportunities.

Effects of grape seed extract on dyslipidaemia: a systematic review and dose–response meta-analysis of randomised controlled trials

Data on the effect of grape seed extract (GSE) on lipid profiles are inconclusive. We undertook a systematic review and meta-analysis of randomised controlled clinical trials on the effect of GSE on serum lipid profiles. The online databases of PubMed, ISI Web of Science, Scopus, ProQuest, Science Direct and Embase were searched for relevant publications until March 2019, using MeSH and non-MeSH keywords. Study selection, data extraction and quality assessment were completed independently by two investigators. Meta-regression and subgroup analyses were performed to identify the source of heterogeneity. Assessment of study quality was conducted using the Jadad scale. Eleven randomised clinical trials involving 536 participants were included in the present meta-analysis. Combining effect sizes from earlier studies, we found that GSE supplementation significantly decreased serum levels of LDL-cholesterol (−0·17 mmol/l; 95 % CI −0·34, −0·01) and TAG (−0·11 mmol/l; 95 % CI −0·18, −0·05). Although no overall significant effect of GSE supplementation on circulating total- and HDL-cholesterol levels was observed, there were significant reductions in these lipids in studies with <10 weeks of intervention and those that had administered the dosages of <300 mg/d of GSE. In conclusion, GSE supplementation seems to favourably affect serum levels of LDL and TAG concentrations, but it did not affect total- and HDL-cholesterol concentrations.

Modifications of the urinary metabolome in young women after cranberry juice consumption were revealed using the UHPLC-Q-orbitrap-HRMS-based metabolomics approach

The objectives of this research were to investigate urinary metabolome modifications and discover potential intake biomarkers in young women after cranberry juice consumption. Fifteen female college students were given either cranberry juice or apple juice for three days using a cross-over design. Urine samples were collected before and after juice consumption. The metabolome in the urine was analyzed using UHPLC-Q-orbitrap-HRMS-based metabolomics followed by orthogonal partial least squares-discriminant analyses (OPLS-DA). An S-plot was used to identify discriminant metabolites. Validated OPLS-DA analyses showed that cranberry juice consumption significantly altered the urinary metabolome. Compared to the baseline urine or urine after apple juice consumption, cranberry juice consumption increased urinary excretion of both exogenous and endogenous metabolites. The tentatively identified exogenous metabolites included quinic acid, coumaric acid, 4-hydroxy-5-(hydroxyphenyl)-valeric acid-O-sulphate, 5-(dihydroxyphenyl)-γ-valerolactone sulfate, diphenol glucuronide, 3,4-dihydroxyphenyl propionic acid, 3-(hydroxyphenyl) propionic acid, 4-O-methylgallic acid, trihydroxybenzoic acid and 1,3,5-trimethoxybenzene. Modifications of endogenous metabolites after cranberry juice consumption included the increases in homocitric acid, hippuric acid, 3-hydroxy-3-carboxymethyl-adipic acid, (2)3-isopropylmalate, pimelic acid and N-acetyl-l-glutamate 5-semialdehyde. These metabolites may serve as urinary biomarkers of cranberry juice consumption and contribute to the bioactivities of cranberries against urinary tract infection.

Flavonoids and gut health

Flavonoids are dietary non-nutrient bioactives with antioxidant and anti-inflammatory properties. Fruits, vegetables, nuts, legumes, and tea are rich in flavonoids. After consumption, flavonoids are extensively metabolized by the gut microbiota and host tissues. Flavonoid metabolism exhibits extensive variation between individuals. It is plausible that inter-individual differences in flavonoid metabolism impact the immune system. Pre-clinical studies have characterized direct and indirect mechanisms by which flavonoids modulate intestinal immune function. This includes modulation of T cell differentiation, alteration of gut microbiota, and modulation of cytokines. Defining the importance of these mechanisms to human chronic disease will improve dietary recommendations for the anti-inflammatory uses of flavonoids.

Loop engineering of aryl sulfotransferase B for improving catalytic performance in regioselective sulfation

Loop engineering of aryl sulfotransferase B improves catalytic performance in regioselective sulfation.

Phenyl-γ-valerolactones and phenylvaleric acids, the main colonic metabolites of flavan-3-ols: synthesis, analysis, bioavailability, and bioactivity

Covering: 1958 to June 2018 Phenyl-γ-valerolactones (PVLs) and their related phenylvaleric acids (PVAs) are the main metabolites of flavan-3-ols, the major class of flavonoids in the human diet. Despite their presumed importance, these gut microbiota-derived compounds have, to date, in terms of biological activity, been considered subordinate to their parent dietary compounds, the flavan-3-ol monomers and proanthocyanidins. In this review, the role and prospects of PVLs and PVAs as key metabolites in the understanding of the health features of flavan-3-ols have been critically assessed. Among the topics covered, are proposals for a standardised nomenclature for PVLs and PVAs. The formation, bioavailability and pharmacokinetics of PVLs and PVAs from different types of flavan-3-ols are discussed, taking into account in vitro and animal studies, as well as inter-individual differences and the existence of putative flavan-3-ol metabotypes. Synthetic strategies used for the preparation of PVLs are considered and the methodologies for their identification and quantification assessed. Metabolomic approaches unravelling the role of PVLs and PVAs as biomarkers of intake are also described. Finally, the biological activity of these microbial catabolites in different experimental models is summarised. Knowledge gaps and future research are considered in this key area of dietary (poly)phenol research.

Personalised nutrition - phenotypic and genetic variation in response to dietary intervention

Personalised nutrition allows individual differences in dietary, lifestyle, anthropometry, phenotype and/or genomic profile to be used to direct specific dietary advice. For personalised nutrition advice to be effective both sides need to be considered; firstly, that factors influencing variation in response to dietary intervention are identified and appropriate advice can be derived and secondly; that these are then used effectively in the provision of nutrition advice, resulting in a positive dietary and/or lifestyle behaviour change. There is considerable evidence demonstrating genetic and phenotypic influence on the biological response to the consumption of nutrients and bioactives. However, findings are often mixed, with studies often investigating at the level of a single nutrient/bioactive and/or a single genetic/phenotypic variation, meaning the derivation of specific advice at a dietary level in an individual/group of individuals can be complex. Similarly, the impact of using this information to derive personalised advice is also mixed, with some studies demonstrating no effectiveness and others showing a significant impact. The present paper will outline examples of phenotypic and genetic variation influencing response to nutritional interventions, and will consider how they could be used in the provision of personalised nutrition.

Critical and emerging topics in dietary carbohydrates and health

Multiple factors may affect the metabolic fate of carbohydrates. Today, well-standardised and accepted methods may allow for the definitions of the changes in the glucose and insulin curves following the ingestion of either carbohydrate-based and other foods. More debate is still raised on the clinical meaning of these classifications when used at a population level, while emphasis is raised on the approach to carbohydrate metabolism on an individual basis. Within these ranges of applications, other compounds, such as plant polyphenols, may favourably add synergic effects through the modulation of carbohydrate digestion and glucose metabolic steps, resulting in lowering postprandial glucose and insulin levels. Finally, a growing knowledge suggests that the balance of dietary fructose and individual physical activity represent the key point to address the compound towards either positive, energy sparing effects, or a degenerative metabolic burden. The carbohydrate quality within a whole dietary and lifestyle pattern may therefore challenge the individual balance towards health or disease.

Pure Polyphenols and Cranberry Juice High in Anthocyanins Increase Antioxidant Capacity in Animal Organs

Anthocyanins and the broader class of polyphenols are strong antioxidants in vitro. Polyphenols are one of the major antioxidants in plant foods, and the beverages derived from them. There is extensive evidence in the literature that polyphenols are beneficial to health. In order to be bioactive in vivo, they need to be bioavailable and be transported from the circulation to target organs. To date, there have been few studies testing the extent to which polyphenols and especially anthocyanins affect the antioxidant capacity of animal organs. In our first pilot study, we investigated how three pure polyphenols (the flavonoids quercetin, catechin and hesperetin) given to rats by intraperitoneal injection (49 to 63 mg/kg) affected their organ antioxidant capacity. This was followed by a subsequent study that injected one ml of 100% cranberry juice (high in anthocyanins) to hamsters. Antioxidant capacity of animal organs was determined by using the ferric reducing antioxidant power (FRAP) colorimetric assay on methanolic extracts of select rat organs (i.e., liver, kidney, heart, prostate and brain) and in the hamster organs (i.e., liver, kidney, heart, bladder and brain). Overall the results showed that antioxidant capacity was significantly increased (p < 0.05) in experimental vs. control organs. Analysis of organs by high performance liquid chromatography (HPLC) from both animal studies provided evidence of polyphenol metabolites in the organ extracts. Taken together, this study provides data that the administration of anthocyanins and other polyphenols cause an increase in organ antioxidant capacity in two animal models. This result supports the growing evidence for the hypothesis that dietary polyphenols reduce the risk and extent of various chronic disease at the disease site.

Cranberry: A Promising Natural Source of Potential Nutraceuticals with Anticancer Activity

Studies have shown that cranberry and its components may exert anticancer properties. The present study aims to critically summarise the existing experimental studies evaluating the potential effects of cranberry on cancer prevention and treatment. PubMed database was searched to identify relevant studies. Current in vitro studies have indicated that cranberry and/or its components may act as chemopreventive agents, diminishing the risk for cancer by inhibiting cells oxidation and inflammatory-related processes, while they may also exert chemotherapeutic effects by inhibiting cell proliferation and angiogenesis, inducing cell apoptosis and attenuating the ability of tumour cells to invade and metastasis. Limited in vivo studies have further documented potential anticancer activity. Cranberry could be considered as a conglomeration of potential effective anticancer druglike compounds.

Prebiotics from Seaweeds: An Ocean of Opportunity?

Seaweeds are an underexploited and potentially sustainable crop which offer a rich source of bioactive compounds, including novel complex polysaccharides, polyphenols, fatty acids, and carotenoids. The purported efficacies of these phytochemicals have led to potential functional food and nutraceutical applications which aim to protect against cardiometabolic and inflammatory risk factors associated with non-communicable diseases, such as obesity, type 2 diabetes, metabolic syndrome, cardiovascular disease, inflammatory bowel disease, and some cancers. Concurrent understanding that perturbations of gut microbial composition and metabolic function manifest throughout health and disease has led to dietary strategies, such as prebiotics, which exploit the diet-host-microbe paradigm to modulate the gut microbiota, such that host health is maintained or improved. The prebiotic definition was recently updated to "a substrate that is selectively utilised by host microorganisms conferring a health benefit", which, given that previous discussion regarding seaweed prebiotics has focused upon saccharolytic fermentation, an opportunity is presented to explore how non-complex polysaccharide components from seaweeds may be metabolised by host microbial populations to benefit host health. Thus, this review provides an innovative approach to consider how the gut microbiota may utilise seaweed phytochemicals, such as polyphenols, polyunsaturated fatty acids, and carotenoids, and provides an updated discussion regarding the catabolism of seaweed-derived complex polysaccharides with potential prebiotic activity. Additional in vitro screening studies and in vivo animal studies are needed to identify potential prebiotics from seaweeds, alongside untargeted metabolomics to decipher microbial-derived metabolites from seaweeds. Furthermore, controlled human intervention studies with health-related end points to elucidate prebiotic efficacy are required.

Identification of phase-II metabolites from human serum samples after oral intake of a willow bark extract

BACKGROUND

Willow bark (Salicis cortex) is a herbal medicinal drug used to treat fever and pain, such as headaches and lower back pain. Until now, it has not been fully understood which compounds are responsible for the efficacy of the drug.

PURPOSE

Although salicylic acid is known as a metabolite of salicylic alcohol derivatives of willow bark in vivo, it has been shown in previous studies that its concentration is too low to account for the overall efficacy of Salicis cortex. The aim this study was to broaden the knowledge regarding phenolic phase-II metabolites after oral intake of a willow bark extract.

STUDY DESIGN/METHODS

Serum samples of a human pharmacokinetic study (Salicis cortex extract intake corresponding to 240 mg of total salicin, 10 volunteers, 12 h fasting time, controlled diet low in phenolics, and 12 blood withdrawals over a period of 24 h) were analyzed by LC-ESI-MS. A library of 142 possible metabolites associated with salicylic alcohol derivatives, flavonoids, and proanthocyanidins was used to characterize possible metabolization products. Their structures were confirmed by LC-ESI-MS experiments with reference compounds after a cleavage reaction using glucuronidase and sulfatase as well as by LC-MS/MS experiments.

RESULTS

In the serum samples, phase-II metabolites of naringenin (2x glucuronides, 2x sulfates, 2x mixed glucuronide-sulfates), eriodictyol (3x glucuronides, 1x sulfate), taxifolin (1x sulfate), catechin (1x sulfate, 1x mixed glucuronide sulfate), ferulic acid (1x sulfate), hydroxyphenyl-propionic acid (1x sulfate), dihydroxyphenyl-valerolactone (1x sulfate), saligenin (1x glucuronide, 1x sulfate), salicylic acid (1x sulfate, 1x unconjugated, 1x salicyluric acid), and catechol (1x glucuronide, 1x sulfate) were characterized. Because taxifolin, dihydroxyphenyl-valerolactone, ferulic acid, and hydroxyphenyl-propionic acid could not be detected in the willow bark preparation, they could be metabolization products of genuine flavanones and flavan-3-ols as well as coumaric acid or C-ring cleavage products of flavonoids, which were present in the extract. No phase-II metabolites of procyanidins and no genuine flavonoid glycosides were detected in all serum samples.

CONCLUSION

This is the first study to identify human metabolites of flavonoids, proanthocyanidins and salicylic alcohol derivatives of Salicis cortex beside salicylic acid or catechol. For the most characterized metabolites, anti-inflammatory activity has been described in the literature, and the present results are an important step in understanding the anti-inflammatory efficacy of willow bark in vivo.

Potential of 2,4-Dihydroxybenzoic Acid as an Oviposition Stimulant for Mass-Reared Ladybird Beetles

The discovery of inexpensive, readily available bioflavonoids, and their degradation products that boost the reproductive potential of mass-reared predators is the overarching goal of this research. We tested the hypothesis that 2,4-dihydroxybenzoic acid (DHBA), an inexpensive degradation product of morin (a flavonol bioflavonoid), stimulates oviposition by the ladybird beetle Coleomegilla maculata (DeGeer). We also tested the hypothesis that C. maculata females must touch or taste DHBA to stimulate oviposition. We setup bioassays in communal cages (housing 10 females) and solitary cages (housing 1 female). In communal cages, nearly all egg clutches were found in or near the chemical dish with DHBA only. Provisioning cages with a tissue substrate reduced oviposition in the chemical dish. Regardless of oviposition site, egg number per clutch did not increase in communal cages or solitary cages with DHBA only. Affixing DHBA to the base of the chemical dish, then covering it with a nylon screen, reduced oviposition. This study suggests that females must touch or taste DHBA to stimulate oviposition. The physiological mechanism involved in oviposition stimulation requires further study. DHBA could potentially serve as a weak oviposition stimulant for predatory ladybird beetles in some mass-rearing systems.

Some New Findings Regarding the Antiadhesive Activity of Cranberry Phenolic Compounds and Their Microbial-Derived Metabolites against Uropathogenic Bacteria

Findings concerning the antiadhesive activity of cranberry phenolic compounds and their microbial-derived metabolites against Gram-negative ( Escherichia coli ATCC 53503 and DSM 10791) and Gram-positive ( Enterococcus faecalis 04-1) bacteria in T24 cells are reported. A-Type procyanidins (A2 and cinnamtannin B-1) exhibited antiadhesive activity (at concentrations ≥250 μM), a feature that was not observed for B-type procyanidins (B2). The metabolites hippuric acid and α-hydroxyhippuric acid also showed effective results at concentrations ≥250 μM. With regard to conjugated metabolites, sulfation seemed to increase the antiadhesive activity of cranberry-derived metabolites as 3-(3,4-dihydroxyphenyl)propionic acid 3- O-sulfate presented active results, unlike its corresponding nonsulfated form. In contrast, methylation decreased antiadhesive activity as 3,4-dihydroxyphenylacetic acid was found to be active but not its corresponding methylated form (4-hydroxy-3-methoxyphenylacetic acid). As a whole, this work sustains the antiadhesive activity of cranberry-derived metabolites as one of the mechanisms involved in the beneficial effects of cranberries against urinary tract infections.

Anthocyanins: From Sources and Bioavailability to Cardiovascular-Health Benefits and Molecular Mechanisms of Action

Anthocyanins are phytochemicals widely found in plant foods, with berries and fruit-derived beverages as the main dietary sources. Accumulating evidence suggests the positive role of anthocyanins in preserving cardiovascular health. Epidemiological data show an association between anthocyanin intake and lower risk of myocardial infarction and cardiovascular-disease-related mortality. Clinical studies report the beneficial effects of the consumption of different anthocyanin-rich sources on surrogate markers of cardiovascular risk. Animal and in vitro evidence suggest the protective role of anthocyanins in dysfunctions related to the development of cardiovascular diseases. Still, the underlying molecular mechanisms of anthocyanin action seem complex and are not entirely clear. This review aims to give a comprehensive update on anthocyanins and their cardioprotective properties. It provides information on their sources; quantities consumed through diet; absorption; bioavailability; cardiovascular properties; and underlying mechanisms of action, including their effects on gene and protein expression and their interactions with cell-signaling pathways and miRNAs.

Cranberries – potential benefits in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) present many complications that potentially could be linked to increased cardiovascular mortality such as inflammation, oxidative stress, cellular senescence and gut dysbiosis.

Impact of a (poly)phenol-rich extract from the brown algae Ascophyllum nodosum on DNA damage and antioxidant activity in an overweight or obese population: a randomized controlled trial

Background

Epidemiologic evidence suggests that a diet rich in (poly)phenols has beneficial effects on many chronic diseases. Brown seaweed is a rich source of (poly)phenols.

Objective

The aim of this study was to investigate the bioavailability and effect of a brown seaweed (Ascophyllum nodosum) (poly)phenol extract on DNA damage, oxidative stress, and inflammation in vivo.

Design

A randomized, double-blind, placebo-controlled crossover trial was conducted in 80 participants aged 30-65 y with a body mass index (in kg/m2) ≥25. The participants consumed either a 400-mg capsule containing 100 mg seaweed (poly)phenol and 300 mg maltodextrin or a 400-mg maltodextrin placebo control capsule daily for an 8-wk period. Bioactivity was assessed with a panel of blood-based markers including lymphocyte DNA damage, plasma oxidant capacity, C-reactive protein (CRP), and inflammatory cytokines. To explore the bioavailability of seaweed phenolics, an untargeted metabolomics analysis of urine and plasma samples after seaweed consumption was determined by ultra-high-performance liquid chromatography-high-resolution mass spectrometry.

Results

Consumption of the seaweed (poly)phenols resulted in a modest decrease in DNA damage but only in a subset of the total population who were obese. There were no significant changes in CRP, antioxidant status, or inflammatory cytokines. We identified phlorotannin metabolites that are considered potential biomarkers of seaweed consumption including pyrogallol/phloroglucinol-sulfate, hydroxytrifurahol A-glucuronide, dioxinodehydroeckol-glucuronide, diphlorethol sulfates, C-O-C dimer of phloroglucinol sulfate, and C-O-C dimer of phloroglucinol.

Conclusions

To the best of our knowledge, this work represents the first comprehensive study investigating the bioactivity and bioavailability of seaweed (poly)phenolics in human participants. We identified several potential biomarkers of seaweed consumption. Intriguingly, the modest improvements in DNA damage were observed only in the obese subset of the total population. The subgroup analysis should be considered exploratory because it was not preplanned; therefore, it was not powered adequately. Elucidation of the biology underpinning this observation will require participant stratification according to weight in future studies. This trial was registered at clinicaltrials.gov as NCT02295878.

Common gut microbial metabolites of dietary flavonoids exert potent protective activities in β-cells and skeletal muscle cells

Flavonoids are dietary compounds with potential anti-diabetes activities. Many flavonoids have poor bioavailability and thus low circulating concentrations. Unabsorbed flavonoids are metabolized by the gut microbiota to smaller metabolites, which are more bioavailable than their precursors. The activities of these metabolites may be partly responsible for associations between flavonoids and health. However, these activities remain poorly understood. We investigated bioactivities of flavonoid microbial metabolites [hippuric acid (HA), homovanillic acid (HVA), and 5-phenylvaleric acid (5PVA)] in primary skeletal muscle and β-cells compared to a native flavonoid [(-)-epicatechin, EC]. In muscle, EC was the most potent stimulator of glucose oxidation, while 5PVA and HA simulated glucose metabolism at 25 μM, and all compounds preserved mitochondrial function after insult. However, EC and the metabolites did not uncouple mitochonndrial respiration, with the exception of 5PVA at10 μM. In β-cells, all metabolites more potently enhanced glucose-stimulated insulin secretion (GSIS) compared to EC. Unlike EC, the metabolites appear to enhance GSIS without enhancing β-cell mitochondrial respiration or increasing expression of mitochondrial electron transport chain components, and with varying effects on β-cell insulin content. The present results demonstrate the activities of flavonoid microbial metabolites for preservation of β-cell function and glucose utilization. Additionally, our data suggest that metabolites and native compounds may act by distinct mechanisms, suggesting complementary and synergistic activities in vivo which warrant further investigation. This raises the intriguing prospect that bioavailability of native dietary flavonoids may not be as critical of a limiting factor to bioactivity as previously thought.

Cranberries attenuate animal-based diet-induced changes in microbiota composition and functionality: a randomized crossover controlled feeding trial

Cranberries have multiple health effects but their impact on gut microbiota has not been examined in randomized controlled feeding trials. We evaluated the relationship between the microbiota and cranberries in the context of an animal-based diet. In a randomized, double-blind, cross-over, controlled design trial, 11 healthy adults consumed for 5 days each a control diet (animal-based diet plus 30 g/day placebo powder) and a cranberry diet (animal-based diet plus 30 g/day freeze-dried whole cranberry powder). The animal-based diet included meats, dairy products, and simple sugars. Stool, urine, and blood samples were obtained before and after each intervention phase. As compared to the pre-control diet, control diet modified 46 taxonomic clades, including an increase in the abundance of Firmicutes and decrease in Bacteroidetes. Moreover, it increased bacteria-derived deoxycholic acid and decreased acetate and butyrate in stool. As compared to the post-intervention phase of control diet, the cranberry diet modified 9 taxonomic clades, including a decrease in the abundance of Firmicutes and increase in Bacteroidetes. Further, the cranberry diet attenuated control diet-induced increase in secondary bile acids and decrease in short-chain fatty acids (SCFA), and increased urinary anthocyanins and bacterially derived phenolic acids. No changes were found in fecal trimethylamine and plasma cytokines. In conclusion, an animal-based diet altered the microbiota composition to a less favorable profile, increased carcinogenic bile acids, and decreased beneficial SCFA. Cranberries attenuated the impact of the animal-based diet on microbiota composition, bile acids, and SCFA, evidencing their capacity to modulate the gut microbiota.

Two flavonoid metabolites, 3,4-dihydroxyphenylacetic acid and 4-methylcatechol, relax arteries ex vivo and decrease blood pressure in vivo

SCOPE

The flavonoid quercetin reduces arterial blood pressure in animals and humans but the mechanisms remains elusive. The aim of this study was to test the activity of flavonoid microbial metabolites, which can participate on the final vasorelaxant effect.

METHODS AND RESULTS

Both ex vivo (isolated rat thoracic aorta and mesenteric artery) and in vivo (normotensive and spontaneously hypertensive rats) approaches were used in this study. 4-methylcatechol and 3,4-dihydroxyphenylacetic acid (DHPA) had greater vasorelaxant effects on mesenteric artery than 3-(3-hydroxyphenyl)propionic acid, the previously reported metabolite with vasorelaxant effect. In vivo testing confirmed their blood pressure decreasing effect given both as bolus and slow infusion. Their mechanism at molecular level was different.

CONCLUSIONS

This study is the first to show that flavonoid metabolites DHPA and 4-methylcatechol decrease arterial blood pressure and hence a mixture of microbial metabolites formed in the gastrointestinal tract may be responsible for or contribute to the effect of orally ingested quercetin.