Gut and microbial resveratrol metabolite profiling after moderate long-term consumption of red wine versus dealcoholized red wine in humans by an optimized ultra-high-pressure liquid chromatography tandem mass spectrometry method

Microbiota and Resveratrol: How Are They Linked to Osteoporosis?

Osteoporosis (OP), which is characterized by a decrease in bone density and increased susceptibility to fractures, is closely linked to the gut microbiota (GM). It is increasingly realized that the GM plays a key role in the maintenance of the functioning of multiple organs, including bone, by producing bioactive metabolites such as short-chain fatty acids (SCFA). Consequently, imbalances in the GM, referred to as dysbiosis, have been identified with a significant reduction in beneficial metabolites, such as decreased SCFA associated with increased chronic inflammatory processes, including the activation of NF-κB at the epigenetic level, which is recognized as the main cause of many chronic diseases, including OP. Furthermore, regular or long-term medications such as antibiotics and many non-antibiotics such as proton pump inhibitors, chemotherapy, and NSAIDs, have been found to contribute to the development of dysbiosis, highlighting an urgent need for new treatment approaches. A promising preventive and adjuvant approach is to combat dysbiosis with natural polyphenols such as resveratrol, which have prebiotic functions and ensure an optimal microenvironment for beneficial GM. Resveratrol offers a range of benefits, including anti-inflammatory, anti-oxidant, analgesic, and prebiotic effects. In particular, the GM has been shown to convert resveratrol, into highly metabolically active molecules with even more potent beneficial properties, supporting a synergistic polyphenol-GM axis. This review addresses the question of how the GM can enhance the effects of resveratrol and how resveratrol, as an epigenetic modulator, can promote the growth and diversity of beneficial GM, thus providing important insights for the prevention and co-treatment of OP.

From the gut to the brain: the long journey of phenolic compounds with neurocognitive effects

The human gut microbiota is a complex community of micro-organisms that play a crucial role in maintaining overall health. Recent research has shown that gut microbes also have a profound impact on brain function and cognition, leading to the concept of the gut-brain axis. One way in which the gut microbiota can influence the brain is through the bioconversion of polyphenols to other bioactive molecules. Phenolic compounds are a group of natural plant metabolites widely available in the human diet, which have anti-inflammatory and other positive effects on health. Recent studies have also suggested that some gut microbiota-derived phenolic metabolites may have neurocognitive effects, such as improving memory and cognitive function. The specific mechanisms involved are still being studied, but it is believed that phenolic metabolites may modulate neurotransmitter signaling, reduce inflammation, and enhance neural plasticity. Therefore, to exert a protective effect on neurocognition, dietary polyphenols or their metabolites must reach the brain, or act indirectly by producing an increase in bioactive molecules such as neurotransmitters. Once ingested, phenolic compounds are subjected to various processes (eg, metabolization by gut microbiota, absorption, distribution) before they cross the blood-brain barrier, perhaps the most challenging stage of their trajectory. Understanding the role of phenolic compounds in the gut-brain axis has important implications for the development of new therapeutic strategies for neurological and psychiatric disorders. By targeting the gut microbiota and its production of phenolic metabolites, it may be possible to improve brain function and prevent cognitive decline. In this article, the current state of knowledge on the endogenous generation of phenolic metabolites by the gut microbiota and how these compounds can reach the brain and exert neurocognitive effects was reviewed.

Exploring Human Metabolome after Wine Intake-A Review

Wine has a rich history dating back to 2200 BC, originally recognized for its medicinal properties. Today, with the aid of advanced technologies like metabolomics and sophisticated analytical techniques, we have gained remarkable insights into the molecular-level changes induced by wine consumption in the human organism. This review embarks on a comprehensive exploration of the alterations in human metabolome associated with wine consumption. A great number of 51 studies from the last 25 years were reviewed; these studies systematically investigated shifts in metabolic profiles within blood, urine, and feces samples, encompassing both short-term and long-term studies of the consumption of wine and wine derivatives. Significant metabolic alterations were observed in a wide variety of metabolites belonging to different compound classes, such as phenolic compounds, lipids, organic acids, and amino acids, among others. Within these classes, both endogenous metabolites as well as diet-related metabolites that exhibited up-regulation or down-regulation following wine consumption were included. The up-regulation of short-chain fatty acids and the down-regulation of sphingomyelins after wine intake, as well as the up-regulation of gut microbial fermentation metabolites like vanillic and syringic acid are some of the most important findings reported in the reviewed literature. Our results confirm the intact passage of certain wine compounds, such as tartaric acid and other wine acids, to the human organism. In an era where the health effects of wine consumption are of growing interest, this review offers a holistic perspective on the metabolic underpinnings of this centuries-old tradition.

Biomarkers of moderate alcohol intake and alcoholic beverages: a systematic literature review

The predominant source of alcohol in the diet is alcoholic beverages, including beer, wine, spirits and liquors, sweet wine, and ciders. Self-reported alcohol intakes are likely to be influenced by measurement error, thus affecting the accuracy and precision of currently established epidemiological associations between alcohol itself, alcoholic beverage consumption, and health or disease. Therefore, a more objective assessment of alcohol intake would be very valuable, which may be established through biomarkers of food intake (BFIs). Several direct and indirect alcohol intake biomarkers have been proposed in forensic and clinical contexts to assess recent or longer-term intakes. 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. The aim of this systematic review is to list and validate biomarkers of ethanol intake per se excluding markers of abuse, but including biomarkers related to common categories of alcoholic beverages. Validation of the proposed candidate biomarker(s) for alcohol itself and for each alcoholic beverage was done according to the published guideline for biomarker reviews. In conclusion, common biomarkers of alcohol intake, e.g., as ethyl glucuronide, ethyl sulfate, fatty acid ethyl esters, and phosphatidyl ethanol, show considerable inter-individual response, especially at low to moderate intakes, and need further development and improved validation, while BFIs for beer and wine are highly promising and may help in more accurate intake assessments for these specific beverages.

Targeting microbiota-host interactions with resveratrol on cancer: Effects and potential mechanisms of action

Resveratrol (RSV) is a natural polyphenolic compound detected in grapes, berries, and red wine. The anticancer activities of RSV have been observed in vivo and in vitro studies. However, the pharmacology mechanism of RSV is confusing due to its low bioavailability. According to studies of the metabolic characteristics of RSV, the gut intestine is a crucial site of its health benefits. Dietary RSV exhibits a profound effect on the gut microbiota structure and metabolic function. In addition, emerging evidence demonstrates a protective effect of RSV metabolites against carcinogenesis. Therefore, to better understand the anticancer mechanisms of dietary RSV, it is vital to evaluate the role of RSV-microbiota-host interactions in cancer therapy. In this review, we summarized significant findings on the anticancer activities of RSV based on epidemiological, experimental and clinical studies involved in investigating the metabolic characteristics and the traditional anticancer mechanisms of RSV. Special attention is given to the putative mechanisms involving microbiota-host interactions, such as the modulation of gut microecology and the anticancer effects of RSV metabolites. The changes in microbiota-host interactions after RSV supplementation play vital roles in cancer prevention and thus offering a new perspective on nutritional interventions to treat cancer.

Phenol Biological Metabolites as Food Intake Biomarkers, a Pending Signature for a Complete Understanding of the Beneficial Effects of the Mediterranean Diet

The Mediterranean diet (MD) has become a dietary pattern of reference due to its preventive effects against chronic diseases, especially relevant in cardiovascular diseases (CVD). Establishing an objective tool to determine the degree of adherence to the MD is a pending task and deserves consideration. The central axis that distinguishes the MD from other dietary patterns is the choice and modality of food consumption. Identification of intake biomarkers of commonly consumed foods is a key strategy for estimating the degree of adherence to the MD and understanding the protective mechanisms that lead to a positive impact on health. Throughout this review we propose potential candidates to be validated as MD adherence biomarkers, with particular focus on the metabolites derived from the phenolic compounds that are associated with the consumption of typical Mediterranean plant foods. Certain phenolic metabolites are good indicators of the intake of specific foods, but others denote the intake of a wide-range of foods. For this, it is important to emphasise the need to increase the number of dietary interventions with specific foods in order to validate the biomarkers of MD adherence. Moreover, the identification and quantification of food phenolic intake biomarkers encouraging scientific research focuses on the study of the biological mechanisms in which polyphenols are involved.

Polyphenols as adjunctive treatments in psychiatric and neurodegenerative disorders: Efficacy, mechanisms of action, and factors influencing inter-individual response

The pathophysiology of psychiatric and neurodegenerative disorders is complex and multifactorial. Polyphenols possess a range of potentially beneficial mechanisms of action that relate to the implicated pathways in psychiatric and neurodegenerative disorders. The aim of this review is to highlight the emerging clinical trial and preclinical efficacy data regarding the role of polyphenols in mental and brain health, elucidate novel mechanisms of action including the gut microbiome and gene expression, and discuss the factors that may be responsible for the mixed clinical results; namely, the role of interindividual differences in treatment response and the potentially pro-oxidant effects of some polyphenols. Further clarification as part of larger, well conducted randomized controlled trials that incorporate precision medicine methods are required to inform clinical efficacy and optimal dosing regimens.

Role of dietary polyphenols on gut microbiota, their metabolites and health benefits

The beneficial health roles of dietary polyphenols in preventing oxidative stress related chronic diseases have been subjected to intense investigation over the last two decades. As our understanding of the role of gut microbiota advances our knowledge of the antioxidant and anti-inflammatory functions of polyphenols accumulates, there emerges a need to examine the prebiotic role of dietary polyphenols. This review focused onthe role of different types and sources of dietary polyphenols on the modulation of the gut microbiota, their metabolites and how they impact on host health benefits. Inter-dependence between the gut microbiota and polyphenol metabolites and the vital balance between the two in maintaining the host gut homeostasis were discussed with reference to different types and sources of dietary polyphenols. Similarly, the mechanisms behind the health benefits by various polyphenolic metabolites bio-transformed by gut microbiota were also explained. However, further research should focus on the importance of human trials and profound links of polyphenols-gut microbiota-nerve-brain as they provide the key to unlock the mechanisms behind the observed benefits of dietary polyphenols found in vitro and in vivo studies.

Quantitative Assessment of Dietary (Poly)phenol Intake: A High-Throughput Targeted Metabolomics Method for Blood and Urine Samples

Many studies have associated the consumption of (poly)phenol-rich diets with health benefits. However, accurate high-throughput quantitative methods for estimating exposure covering a broad spectrum of (poly)phenols are lacking. We have developed and validated a high-throughput method for the simultaneous quantification of 119 (poly)phenol metabolites in plasma and urine using ultra high-performance liquid chromatography coupled with triple quadrupole mass spectrometry, with a very fast sample treatment and a single run time of 16 min. This method is highly sensitive, precise, accurate, and shows good linearity for all compounds (R² > 0.992). This novel method will allow a quantitative assessment of habitual (poly)phenol intake in large epidemiological studies as well as clinical studies investigating the health benefits of dietary (poly)phenols.

Relationship between Wine Consumption, Diet and Microbiome Modulation in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder leading to the most common form of dementia in elderly people. Modifiable dietary and lifestyle factors could either accelerate or ameliorate the aging process and the risk of developing AD and other age-related morbidities. Emerging evidence also reports a potential link between oral and gut microbiota alterations and AD. Dietary polyphenols, in particular wine polyphenols, are a major diver of oral and gut microbiota composition and function. Consequently, wine polyphenols health effects, mediated as a function of the individual's oral and gut microbiome are considered one of the recent greatest challenges in the field of neurodegenerative diseases as a promising strategy to prevent or slow down AD progression. This review highlights current knowledge on the link of oral and intestinal microbiome and the interaction between wine polyphenols and microbiota in the context of AD. Furthermore, the extent to which mechanisms bacteria and polyphenols and its microbial metabolites exert their action on communication pathways between the brain and the microbiota, as well as the impact of the molecular mediators to these interactions on AD patients, are described.

Resveratrol Metabolites Are Able to Reduce Steatosis in Cultured Hepatocytes

Steatosis is characterized primarily by excessive lipid accumulation in the form of triglycerides in the liver. Although resveratrol shows a low bioavailability, it has significant positive effects on steatosis. The aim of this study was to analyze whether some phase II and microbial resveratrol metabolites (trans-resveratrol-4'-O-glucuronide (R-4G); trans-resveratrol-3-O-glucuronide (R-3G); trans-resveratrol-3-O-sulfate (R-S) and dihydro-resveratrol (DH-R) were effective in reducing hepatocyte fat accumulation. An in vitro model mimicking the hepatocyte situation in fatty liver was developed by incubating mouse AML12 hepatocytes with palmitic acid (PA). For cell treatments, hepatocytes were incubated with 1, 10, or 25 µM resveratrol or its metabolites. Triglycerides and cell viability were assessed using commercial kits. Protein expression of enzymes and transporters involved in triglyceride metabolism were analyzed by western blot. We show for the first time that resveratrol and all the tested metabolites, at 1 µM, partially prevented lipid accumulation induced by the saturated fatty acid PA in AML12 hepatocytes. This effect was mainly due to the inhibition of de novo lipogenesis. This demonstrates that the low bioavailability of resveratrol is not as big a problem as it was thought to be, because resveratrol metabolites contribute to the delipidating effects of the parent compound.

Characterization of the Human Exposome by a Comprehensive and Quantitative Large-Scale Multianalyte Metabolomics Platform

The exposome, defined as the cumulative measure of external exposures and associated biological responses throughout the lifespan, has emerged in recent years as a cornerstone in biomedical sciences. Metabolomics stands out here as one of the most powerful tools for investigating the interplay between the genetic background, exogenous, and endogenous factors within human health. However, to address the complexity of the exposome, novel methods are needed to characterize the human metabolome. In this work, we have optimized and validated a multianalyte metabolomics platform for large-scale quantitative exposome research in plasma and urine samples, based on the use of simple extraction methods and high-throughput metabolomic fingerprinting. The methodology enables, for the first time, the simultaneous characterization of the endogenous metabolome, food-related metabolites, pharmaceuticals, household chemicals, environmental pollutants, and microbiota derivatives, comprising more than 1000 metabolites in total. This comprehensive and quantitative investigation of the exposome is achieved in short run times, through simple extraction methods requiring small-sample volumes, and using integrated quality control procedures for ensuring data quality. This metabolomics approach was satisfactorily validated in terms of linearity, recovery, matrix effects, specificity, limits of quantification, intraday and interday precision, and carryover. Furthermore, the clinical potential of the methodology was demonstrated in a dietary intervention trial as a case study. In summary, this study describes the optimization, validation, and application of a multimetabolite platform for comprehensive and quantitative metabolomics-based exposome research with great utility in large-scale epidemiological studies.

Quantifying the human diet in the crosstalk between nutrition and health by multi-targeted metabolomics of food and microbiota-derived metabolites

BACKGROUND

Metabolomics is a powerful tool for investigating the association between nutrition and health status. Although urine is commonly employed for studying the metabolism and transformation of food components, the use of blood samples could be preferable to gain new insights into the bioavailability of diet-derived compounds and their involvement in health. However, the chemical complexity of blood samples hinders the analysis of this biological fluid considerably, which makes the development of novel and comprehensive analytical methods mandatory.

METHODS

In this work, we optimized a multi-targeted metabolomics platform for the quantitative and simultaneous analysis of 450 food-derived metabolites by ultra-high performance liquid chromatography coupled to tandem mass spectrometry. To handle the chemical complexity of blood samples, three complementary extraction methods were assayed and compared in terms of recovery, sensitivity, precision and matrix effects with the aim of maximizing metabolomics coverage: protein precipitation, reversed solid-phase extraction, and hybrid protein precipitation with solid-phase extraction-mediated phospholipid removal.

RESULTS

After careful optimization of the extraction conditions, protein precipitation enabled the most efficient and high-throughput extraction of the food metabolome in plasma, although solid-phase extraction-based protocols provided complementary performance for the analysis of specific polyphenol classes. The developed method yielded accurate recovery rates with negligible matrix effects, and good linearity, as well as high sensitivity and precision for most of the analyzed metabolites.

CONCLUSIONS

The multi-targeted metabolomics platform optimized in this work enables the simultaneous detection and quantitation of 450 dietary metabolites in short-run times using small volumes of biological sample, which facilitates its application to epidemiological studies.

Effects of resveratrol and its derivative pterostilbene on brown adipose tissue thermogenic activation and on white adipose tissue browning process

The main function of brown adipose tissue (BAT) is thermogenesis, a process mediated by uncoupling protein 1 (UCP1), which is located in the inner mitochondrial membrane and acts uncoupling oxidative phosphorylation from ATP production, thereby dissipating energy as heat. White adipose tissue can also express UCP1 positive cells due to a process known as browning. This phenomenon could also increase the thermogenic effect in the classical brown adipose depots. BAT thermogenesis depends, among other factors on both, nutritional conditions and food availability. Indeed, some studies have found that BAT recruitment and function are enhanced by some food components. The present study focuses on the effects of resveratrol and pterostilbene, two phenolic compounds belonging to the stilbene group, on BAT thermogenic activation and white adipose tissue browning process. The reported studies, carried out in cell cultures and animal models, show that both resveratrol and pterostilbene induce thermogenic capacity in interscapular BAT by increasing mitochondriogenesis, as well as enhancing fatty acid oxidation and glucose disposal. In addition, resveratrol seems to promote browning by activating peroxisome proliferator-activated receptor (PPAR), while the lack of changes in mitochondrial biogenesis suggests that probably the browning process occurs by direct resveratrol-mediated upregulation of ucp1 mRNA expression.

Quantitative Dietary Fingerprinting (QDF)-A Novel Tool for Comprehensive Dietary Assessment Based on Urinary Nutrimetabolomics

Accurate dietary assessment is a challenge in nutritional research, needing powerful and robust tools for reliable measurement of food intake biomarkers. In this work, we have developed a novel quantitative dietary fingerprinting (QDF) approach, which enables for the first time the simultaneous quantitation of about 350 urinary food-derived metabolites, including (poly)phenolic aglycones, phase II metabolites, and microbial-transformed compounds, as well as other compounds (e.g., glucosinolates, amino acid derivatives, methylxanthines, alkaloids, and markers of alcohol and tobacco consumption). This method was fully validated for 220 metabolites, yielding good linearity, high sensitivity and precision, accurate recovery rates, and negligible matrix effects. Furthermore, 127 additional phase II metabolites were also included in this method after identification in urines collected from acute dietary interventions with various foods. Thus, this metabolomic approach represents one-step further toward precision nutrition and the objective of improving the accurateness and comprehensiveness in the assessment of dietary patterns and lifestyles.

The Bidirectional Interactions between Resveratrol and Gut Microbiota: An Insight into Oxidative Stress and Inflammatory Bowel Disease Therapy

Dysbiosis and oxidative stress in the gut have contributed to the progression of intestinal inflammatory bowel disease (IBD). The current study has reported that enteric bacteria mediate redox homeostasis through the regulation of reactive oxygen species (ROS) production. Resveratrol, one of the most abundant polyphenols, with poor oral bioavailability, is considered as a scavenger of ROS and other free radicals. Recent studies have shown that resveratrol effectively enhances the growth of Lactococcus lactis and inhibits the growth of Enterococcus faecalis. (1) In terms of the two-way relationship between gut microbiota and resveratrol, resveratrol modulates gut microbiota; (2) in terms of resveratrol biotransformation by gut microbiota, we speculate that gut microbiota could be a target of resveratrol to maintain gut homeostasis. Here, we reviewed the current researches about the cellular signaling pathways in intestinal epithelial cells triggered by gut microbiota in response to oxidative stress. These results suggest that the modulation of the gut microbiota through resveratrol supplementation appears as a promising potential approach for the therapy of inflammatory bowel disease.

Endothelial Cells Deconjugate Resveratrol Metabolites to Free Resveratrol: A Possible Role in Tissue Factor Modulation

SCOPE

The antithrombotic effects of resveratrol (RV) and its derivatives remain unknown. The objective is to evaluate the modulatory effects of RV, its glucoside form, piceid, and its biological metabolites (RV-3-O-β-d-glucuronide, RV-4'-O-d-glucuronide, and RV-3-O-sulfate) on tissue factor (TF). Moreover, the endothelial metabolism of RV is assessed.

METHODS AND RESULTS

Human aortic endothelial cells (HAECs) are incubated with trans-piceid, trans-RV, or their biological metabolites and stimulated with tumor necrosis factor-α (TNF-α). TF activity, protein levels, and mRNA expression are determined in cell lysates. Moreover, RV conjugation (phase-II-metabolism) to its sulfated or glucuronidated metabolites and their deconjugation to their parent compound (free RV) are also assessed in cell lysates and culture media. RV decreased TF activity, protein levels, and mRNA expression, whereas piceid and RV metabolites (RVmet) had no effects. RV-3-O-sulfate was the main metabolite generated in the endothelium, while RVmet are deconjugated to free RV. Isomerization of trans-RV and its trans-metabolites to their cis-forms is observed.

CONCLUSIONS

RV exerts antithrombotic effects by modulating TF. RVmet and piceid does not exert this effect. However, the capacity of endothelial cells to deconjugate RVmet to free RV indicates that RVmet function as an endothelial reservoir for RV regeneration, thus, contributing to the antithrombotic effects of RV.

Health Effects of Resveratrol: Results from Human Intervention Trials

The effect of resveratrol (RV) intake has been reviewed in several studies performed in humans with different health status. The purpose of this review is to summarize the results of clinical trials of the last decade, in which RV was determined in biological samples such as human plasma, urine, and feces. The topics covered include RV bioavailability, pharmacokinetics, effects on cardiovascular diseases, cognitive diseases, cancer, type 2 diabetes (T2D), oxidative stress, and inflammation states. The overview of the recent research reveals a clear tendency to identify RV in plasma, showing that its supplementation is safe. Furthermore, RV bioavailability depends on several factors such as dose, associated food matrix, or time of ingestion. Notably, enterohepatic recirculation of RV has been observed, and RV is largely excreted in the urine within the first four hours after consumption. Much of the research on RV in the last 10 years has focused on its effects on pathologies related to oxidative stress, inflammatory biomarkers, T2D, cardiovascular diseases, and neurological diseases.

Resveratrol, Metabolic Syndrome, and Gut Microbiota

Resveratrol is a polyphenol which has been shown to have beneficial effects on metabolic syndrome-related alterations in experimental animals, including glucose and lipid homeostasis improvement and a reduction in fat mass, blood pressure, low-grade inflammation, and oxidative stress. Clinical trials have been carried out to address its potential; however, results are still inconclusive. Even though resveratrol is partly metabolized by gut microbiota, the relevance of this “forgotten organ” had not been widely considered. However, in the past few years, data has emerged suggesting that the therapeutic potential of this compound may be due to its interaction with gut microbiota, reporting changes in bacterial composition associated with beneficial metabolic outcomes. Even though data is still scarce and for the most part observational, it is promising nevertheless, suggesting that resveratrol supplementation could be a useful tool for the treatment of metabolic syndrome and its associated conditions.

Wine and Olive Oil Phenolic Compounds Interaction in Humans

Extra virgin olive oil (EVOO) and red wine (RW) are two basic elements that form part of the so-called Mediterranean diet. Both stand out because of their high phenolic compound content and their potential related health benefits. The present study is focused on the metabolic disposition of resveratrol (RESV), tyrosol (TYR), and hydroxytyrosol (HT) following the consumption of EVOO, RW, and a combination of both. In this study, 12 healthy volunteers consumed a single dose of 25 mL of EVOO, 150 mL of RW, and a combination of both in a crossover randomized clinical trial. Urinary recovery of RESV, TYR, and HT was analysed in urine samples collected over a 6-h period following the intake of each treatment. Higher HT levels were observed following EVOO compared to RW (3788 ± 1751 nmols and 2308 ± 847 nmols respectively). After the combination of EVOO and RW, the recovery of TYR and HT metabolites increased statistically compared to their separate consumption (4925 ± 1751 nmols of TYR and 6286 ± 3198 nmols of HT). EVOO triggered an increase in glucuronide conjugates, while RW intake raised sulfate metabolites. Marginal effects were observed in RESV increased bioavailability after the combination of RW with the fat matrix provided by EVOO.

The effects of grape and red wine polyphenols on gut microbiota - A systematic review

There is a growing body of evidence implicating the gut 'microbiome' role in overall human health. Bacterial species belonging to the genera Lactobacillus and Bifidobacterium are generally considered to be beneficial and are commonly used in probiotic applications, whereas increases in some genera including Clostridum, Eubacterium and Bacteroides are implicated in negative health outcomes. Dietary polyphenols are bioactive compounds that have been found to increase the numbers of beneficial bacteria and antimicrobial actions against pathogenic bacteria, however most studies have been conducted in animal models or in-vitro colonic models. The aim of this systematic review was to provide an overview of recent trials on the effect of dietary grape and red wine polyphenols on the gut microbiota in humans. Following PRISMA guidelines, a systematic review was conducted of electronic databases (PubMed, CINAHL, Cochrane Library, Wed of Science and Scopus) to identify human intervention trials examining the effect of grape or wine polyphenols on gut microbiota. Seven trials met the inclusion criteria. One study looked at changes in gut microbiota following the ingestion of de-alcoholised red wine or red wine, and six studies referred to gut microbiota as intermediates in formation of phenolic metabolites. All studies confirmed that ingested polyphenols from grape and red wine, were modulated by gut microbiota, increasing numbers of polyphenolic metabolites which were found in blood, urine, ileal fluid and faeces. Intake of polyphenols derived from grape and red wine can modulate gut microbiota and contribute to beneficial microbial ecology that can enhance human health benefits. Additionally, grape and red wine polyphenols were modulated by the gut microbiota and there is a potential for a two-way relationship between the gut microbiota and polyphenolic compounds. Nevertheless, additional research is required to fully understand the complex relationship between gut microbiota and dietary polyphenols before any health claims can be made in relation to human health.

Cardiovascular and Antiobesity Effects of Resveratrol Mediated through the Gut Microbiota

Encouraging scientific research into the health effects of dietary bioactive resveratrol has been confounded by its rapid first-pass metabolism, which leads to low in vivo bioavailability. Preliminary studies have shown that resveratrol can modulate gut microbiota composition, undergo biotransformation to active metabolites via the intestinal microbiota, or affect gut barrier function. In rodents, resveratrol can modify the relative Bacteroidetes:Firmicutes ratio and reverse the gut microbial dysbiosis caused by a high-fat diet. By upregulating the expression of genes involved in maintaining tight junctions between intestinal cells, resveratrol contributes to gut barrier integrity. The composition of the gut microbiome and rapid metabolism of resveratrol determines the production of resveratrol metabolites, which are found at greater concentrations in humans after ingestion than their parent molecule and can have similar biological effects. Resveratrol may affect cardiovascular risk factors such as elevated blood cholesterol or trimethylamine N-oxide concentrations. Modulating the composition of the gut microbiota by resveratrol may affect central energy metabolism and modify concentrations of satiety hormones to produce antiobesity effects. Encouraging research from animal models could be tested in humans.

Resveratrol in the foodomics era: 1:25,000

Resveratrol is probably the most investigated plant secondary metabolite ever. An epidemiological study known as the French paradox showed a correlation between red wine intake and low mortality due to coronary heart diseases, and the red wine substance resveratrol was claimed to play a key role. Since then, several hundred resveratrol studies have been conducted to demonstrate its antioxidant and other beneficial properties. In the foodomics era, considering a complex foodome including over 25,000 substances that make up the human diet, it appears to be outdated to pursue the hunt for biological activities one function/compound at a time. First, nature is multivariate, and the effect of any one molecule will have to be modulated by its carrying matrix, its bioavailability, and synergies with other molecules. Second, a large number of targeted studies have the tendency to become biased, as they tend to retain only the data that the researchers think are relevant and thus increase the chances of spurious correlations. In this concise review, we retrace the research toward a more inductive, holistic, and multivariate path.

A Focused Multiple Reaction Monitoring (MRM) Quantitative Method for Bioactive Grapevine Stilbenes by Ultra-High-Performance Liquid Chromatography Coupled to Triple-Quadrupole Mass Spectrometry (UHPLC-QqQ)

Grapevine stilbenes are a family of polyphenols which derive from trans-resveratrol having antifungal and antimicrobial properties, thus being considered as phytoalexins. In addition to their diverse bioactive properties in animal models, they highlight a strong potential in human health maintenance and promotion. Due to this relevance, highly-specific qualitative and quantitative methods of analysis are necessary to accurately analyze stilbenes in different matrices derived from grapevine. Here, we developed a rapid, sensitive, and specific analysis method using ultra-high-performance liquid chromatography coupled to triple-quadrupole mass spectrometry (UHPLC-QqQ) in MRM mode to detect and quantify five grapevine stilbenes, trans-resveratrol, trans-piceid, trans-piceatannol, trans-pterostilbene, and trans-ε-viniferin, whose interest in relation to human health is continuously growing. The method was optimized to minimize in-source fragmentation of piceid and to avoid co-elution of cis-piceid and trans-resveratrol, as both are detected with resveratrol transitions. The applicability of the developed method of stilbene analysis was tested successfully in different complex matrices including cellular extracts of Vitis vinifera cell cultures, reaction media of biotransformation assays, and red wine.

Challenges in Analyzing the Biological Effects of Resveratrol

The suggested health effects (e.g., disease prevention) of dietary bioactive compounds such as resveratrol are challenging to prove in comparison to man-made drugs developed for therapeutic purposes. Dietary bioactive compounds have multiple cellular targets and therefore have a variety of biological effects. Extrapolating the biological effects of dietary compounds from in vitro and in vivo animal experiments to humans may lead to over- or under-estimation of the effect and role of these compounds. The present paper will discuss a few of these challenges and suggest directions for future research. Questions we address include: (1) Is the combinatorial effect of resveratrol and other compounds real? (2) What are the real and relevant doses of resveratrol after administration? and (3) Is it possible to estimate the preventive effect of resveratrol by clinical trials using standard experimental designs? The examples concerning resveratrol taken from the scientific literature are mainly from 2010 and later. The challenges pointed out in this review are similar to most naturally occurring bioactive compounds.

Metabolic fingerprint after acute and under sustained consumption of a functional beverage based on grape skin extract in healthy human subjects

Grape-derived polyphenols are considered to be one of the most promising ingredients for functional foods due to their health-promoting activities. We applied a HPLC-MS-based untargeted metabolomic approach in order to evaluate the impact of a functional food based on grape skin polyphenols on the urinary metabolome of healthy subjects. Thirty-one volunteers participated in two dietary crossover randomized intervention studies: with a single-dose intake (187 mL) and with a 15-day sustained consumption (twice per day, 187 mL per day in total) of a functional beverage (FB). Postprandial (4-hour) and 24-hour urine samples collected after acute consumption and on the last day of sustained FB consumption, respectively, were analysed using an untargeted HPLC-qTOF-MS approach. Multivariate modelling with subsequent application of an S-plot revealed differential mass features related to acute and prolonged consumption of FB. More than half of the mass features were shared between the two types of samples, among which several phase II metabolites of grape-derived polyphenols were identified at confidence level II. Prolonged consumption of FB was specifically reflected in urine metabolome by the presence of first-stage microbial metabolites of flavanols: hydroxyvaleric acid and hydroxyvalerolactone derivatives. Overall, several epicatechin and phenolic acid metabolites both of tissular and microbiota origin were the most representative markers of FB consumption. To our knowledge, this is one of the first studies where an untargeted LC-MS metabolomic approach has been applied in nutrition research on a grape-derived FB.

Metabolic faecal fingerprinting of trans-resveratrol and quercetin following a high-fat sucrose dietary model using liquid chromatography coupled to high-resolution mass spectrometry

Faecal non-targeted metabolomics deciphers metabolic end-products resulting from the interactions among food, host genetics, and gut microbiota. Faeces from Wistar rats fed a high-fat sucrose (HFS) diet supplemented with trans-resveratrol and quercetin (separately or combined) were analysed by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). Metabolomics in faeces are categorised into four clusters based on the type of treatment. Tentative identification of significantly differing metabolites highlighted the presence of carbohydrate derivatives or conjugates (3-phenylpropyl glucosinolate and dTDP-D-mycaminose) in the quercetin group. The trans-resveratrol group was differentiated by compounds related to nucleotides (uridine monophosphate and 2,4-dioxotetrahydropyrimidine D-ribonucleotide). Marked associations between bacterial species (Clostridium genus) and the amount of some metabolites were identified. Moreover, trans-resveratrol and resveratrol-derived microbial metabolites (dihydroresveratrol and lunularin) were also identified. Accordingly, this study confirms the usefulness of omics-based techniques to discriminate individuals depending on the physiological effect of food constituents and represents an interesting tool to assess the impact of future personalized therapies.

Towards the fecal metabolome derived from moderate red wine intake

Dietary polyphenols, including red wine phenolic compounds, are extensively metabolized during their passage through the gastrointestinal tract; and their biological effects at the gut level (i.e., anti-inflammatory activity, microbiota modulation, interaction with cells, among others) seem to be due more to their microbial-derived metabolites rather than to the original forms found in food. In an effort to improve our understanding of the biological effects that phenolic compounds exert at the gut level, this paper summarizes the changes observed in the human fecal metabolome after an intervention study consisting of a daily consumption of 250 mL of wine during four weeks by healthy volunteers (n = 33). It assembles data from two analytical approaches: (1) UPLC-ESI-MS/MS analysis of phenolic metabolites in fecal solutions (targeted analysis); and (2) UHPLC-TOF MS analysis of the fecal solutions (non-targeted analysis). Both approaches revealed statistically-significant changes in the concentration of several metabolites as a consequence of the wine intake. Similarity and complementarity between targeted and non-targeted approaches in the analysis of the fecal metabolome are discussed. Both strategies allowed the definition of a complex metabolic profile derived from wine intake. Likewise, the identification of endogenous markers could lead to new hypotheses to unravel the relationship between moderate wine consumption and the metabolic functionality of gut microbiota.

Bioavailability, bioactivity and impact on health of dietary flavonoids and related compounds: an update

There is substantial interest in the role of plant secondary metabolites as protective dietary agents. In particular, the involvement of flavonoids and related compounds has become a major topic in human nutrition research. Evidence from epidemiological and human intervention studies is emerging regarding the protective effects of various (poly)phenol-rich foods against several chronic diseases, including neurodegeneration, cancer and cardiovascular diseases. In recent years, the use of HPLC-MS for the analysis of flavonoids and related compounds in foods and biological samples has significantly enhanced our understanding of (poly)phenol bioavailability. These advancements have also led to improvements in the available food composition and metabolomic databases, and consequently in the development of biomarkers of (poly)phenol intake to use in epidemiological studies. Efforts to create adequate standardised materials and well-matched controls to use in randomised controlled trials have also improved the quality of the available data. In vitro investigations using physiologically achievable concentrations of (poly)phenol metabolites and catabolites with appropriate model test systems have provided new and interesting insights on potential mechanisms of actions. This article will summarise recent findings on the bioavailability and biological activity of (poly)phenols, focusing on the epidemiological and clinical evidence of beneficial effects of flavonoids and related compounds on urinary tract infections, cognitive function and age-related cognitive decline, cancer and cardiovascular disease.

Investigation of liquid chromatography quadrupole time-of-flight mass spectrometry performance for identification and determination of hydroxylated stilbene antioxidants in wine

The performance of liquid chromatography (LC) followed by quadrupole time-of-flight (QTOF) mass spectrometry (MS) for the determination of hydroxylated stilbene compounds in red and white wine samples is assessed. When combined with a solid-phase extraction step, LC-QTOF-MS allowed the selective determination of five target compounds (trans- and cis-resveratrol, trans-piceatannol, trans-piceid and trans-pterostilbene) attaining limits of quantification between 3 and 20ngmL(-1) and providing linear responses up to 4000ngmL(-1). Recoveries, established against standards prepared in methanol, varied between 93% and 115%. The distribution of the above species in wine is illustrated with the analysis of 15 samples. Trans-pterostilbene remained undetected in samples, whereas trans-piceid and trans-resveratrol maximum concentrations exceed the 6000ngmL(-1) level. Values for trans-piceatannol and cis-resveratrol ranged from non detected to 600ngmL(-1), and from 11 to more than 3200ngmL(-1), respectively. Accurate MS and MS/MS scan spectra were used to investigate the existence of reduced (dihydro) and oxidized (dehydro) forms of resveratrol and picetannol in the processed samples. Dihydro derivatives appeared, as free compounds, in 100% (dihydro-piceatannol) and 40% (dihydro-resveratrol) of the samples. On the other hand, dehydro derivatives were noticed as conjugated (glycosylated) species, with detection frequencies of 100% and 47% for dehydro-glucosyl-resveratrol and dehydro-glucosyl-piceatannol, respectively. Above findings confirm the suitability of LC-QTOF-MS for the comprehensive study of hydroxylated stilbene antioxidants in wine samples.

Profiling of microbial-derived phenolic metabolites in human feces after moderate red wine intake

A controlled and randomized trial study involving 41 healthy volunteers (33 intervention and 8 control subjects) was performed in order to establish changes in the microbial-derived phenolic metabolite profile of feces after moderate consumption of red wine (250 mL/day, 4 weeks). Out of the 35 phenolic metabolites identified, 10 compounds (mainly benzoic and 4-hydroxyvaleric acids) showed statistically significant increases (P < 0.05) after the wine intake. Also, the total phenolic metabolites content was significantly (P < 0.05) higher in the samples after the wine intake (625 ± 380 μg/g feces) in comparison to the samples before (358 ± 270 μg/g feces), and a tentative distribution of the volunteers into three groups could be established: <500, 500-1000, and >1000 μg/g feces. These results suggest that a different gut microbial capacity to metabolize wine polyphenols exists among the human population, as observed for polyphenols from other sources.

Microbial metabolomic fingerprinting in urine after regular dealcoholized red wine consumption in humans

The regular consumption of dealcoholized red wine (DRW) has demonstrated benefits in cardiovascular risk factors. The analysis of phenolic metabolites formed in the organism, especially those that could come from microbiota metabolism, would help to understand these benefits. The aim of this study was to determine the widest urinary metabolomic fingerprinting of phenolics and microbial-derived phenolic acids (n = 61) after regular intake of DRW in men at high cardiovascular risk by UPLC-MS/MS using a targeted approach. Up to 49 metabolites, including phase II and microbial phenolic metabolites, increased after DRW consumption compared to baseline (P < 0.05). The highest percentage of increase was found for microbial metabolites from anthocyanin degradation such as syringic, p-coumaric, gallic acids and pyrogallol and from flavan-3-ols degradation such as hydroxyphenylvalerolactones and (epi)catechins. These findings provide the most complete metabolic fingerprinting after wine consumption, amplifying the spectrum of microbial derived metabolites and their potential bioactivity related with health benefits.

The combination of resveratrol and conjugated linoleic acid attenuates the individual effects of these molecules on triacylglycerol metabolism in adipose tissue

PURPOSE

The combination of resveratrol + conjugated linoleic acid (RSV + CLA) did not show the body fat-lowering effect exhibited by these molecules when administered separately. This study aimed to find metabolic explanations for this situation in an experimental model of diet-induced obesity.

METHODS

Thirty-six male Wistar rats were divided into four groups: rats treated with saline (control), resveratrol (RSV), conjugated linoleic acid (CLA) and a combination of these molecules (RSV + CLA).

RESULTS

Rats treated with RSV + CLA did not show the reduction in heparin-releasable lipoprotein lipase (HR-LPL) and fatty acid synthase activities observed in RSV group or the increased HSL expression found in RSV and CLA groups. These animals showed reduced sirtuin 1 expression and CLA isomer amounts in adipose tissue. Finally, intracellular Ca(2+) concentration was increased.

CONCLUSION

The attenuation of the effects induced in adipose tissue triacylglycerol metabolism by RSV and CLA separately, such as the decrease in lipogenesis and fatty acid uptake and the increase in lipolysis, contributes to explain the lack of body fat-lowering effect of the combination RSV + CLA.

Comparative study of microbial-derived phenolic metabolites in human feces after intake of gin, red wine, and dealcoholized red wine

The analysis of microbial phenolic metabolites in fecal samples from in vivo studies is crucial to understanding the potential modulatory effects derived from polyphenol consumption and its overall health effects, particularly at the gut level. In this study, the composition of microbial phenolic metabolites in human feces collected after regular consumption of either red wine, dealcoholized red wine, or gin was analyzed by UPLC-ESI-MS/MS. Red wine interventions produce a change in the content of eight phenolic acids, which are probably derived from the catabolism of flavan-3-ols and anthocyanins, the main flavonoids in red wine. Moreover, alcohol seemed not to influence the formation of phenolic metabolites by the gut microbiota. A principal component analysis revealed large interindividual differences in the formation of microbial metabolites after each red wine polyphenol intervention, but not after the gin intervention, indicating differences in the gut microbial composition among subjects.

Resveratrol administration or SIRT1 overexpression does not increase LXR signaling and macrophage-to-feces reverse cholesterol transport in vivo

The natural polyphenol resveratrol has cardiometabolic protective properties. Resveratrol has been reported to be an activator of NAD+-dependent deacetylase sirtuin 1 (SIRT1), which may regulate liver X receptor (LXR) activity, thereby upregulating the expression of genes crucial in reverse cholesterol transport (RCT). In the present study, the effects of resveratrol and SIRT1 overexpression on RCT from macrophages-to-feces in vivo in C57BL/6 mice were determined. [³H]cholesterol-labeled mouse macrophages were injected intraperitoneally into mice treated with intragastric doses of the well-known LXR agonist T0901317, resveratrol, or a vehicle solution, and radioactivity was determined in plasma, liver, and feces. T0901317-treated mice presented increased [³H]cholesterol in plasma and HDL 48 h after the label injection. Treatment with T0901317 also increased liver ABCA1, G1, and G5 gene expression and reduced intestinal cholesterol absorption which were changes that were associated with a 2.8-fold increase in macrophage-derived [³H]cholesterol in feces. In contrast, resveratrol treatment had no effect on liver LXR signaling or fecal [³H]cholesterol excretion. A separate experiment was conducted in SIRT1 transgenic mice. Liver LXR-target gene expression and magnitude of macrophage-derived [³H]cholesterol in plasma, liver, and feces of SIRT1 transgenic mice did not differ from those of wild-type mice. We conclude that neither resveratrol administration nor SIRT1 overexpression upregulate liver LXR-target genes and macrophage-to-feces RCT in vivo.

Comparative analysis of sample preparation methods to handle the complexity of the blood fluid metabolome: when less is more

Blood sample preparation before LC-MS metabolomic fingerprinting is one of the most challenging and error-prone parts of the analytical procedure. Besides proteins, phospholipids contained in blood fluids are known to cause matrix effects and ion suppression phenomena, thus masking biological variation. Nevertheless, the commonly used sample preparation techniques do not consider their removal prior to analysis. Pooled plasma and serum samples were used as biological material, partly as raw samples and partly spiked with distinct concentrations of a metabolite mix (1-5 μg/mL). Prior to LC-ESI-qToF-MS-driven metabolomic analysis, samples were subjected to different preparation methods consisting of three extractions with organic solvents (acetonitrile, methanol, and methanol/ethanol), a membrane-based solvent-free technique, and a hybrid method combining solvent extraction and SPE-mediated removal of phospholipids. The comparative analysis among sample preparation procedures was based on the capacity to detect endogenous compounds in raw samples, differentiate raw versus spiked samples, and reveal real-life metabolomic changes, following a dietary intervention. Method speed, minimum sample handling, compatibility to automation, and applicability to large-scale metabolomic studies were also considered. The combination of solvent deproteinization and the selective removal of phospholipids was revealed to be the most suitable method, in terms of improvement of nonlipid metabolite coverage, extraction reproducibility, quickness, and compatibility with automation, the minimization of matrix effects being among the most probable causes for the good extraction performance associated with the removal of phospholipid species. The main advantage of conventional solvent extraction procedures was the metabolite information coverage for lipid low-molecular-weight species, and extraction with acetonitrile was generally the second choice for sample preparation. Ultrafiltration was the least effective method for plasma and serum preparation; thus, its use without a previous solvent extraction step of the samples should be discarded. According to the presented data, there is no apparent reason to believe that sacrificing information on lipid compounds is too high of a price to pay in order to gain more information on nonlipid LMW metabolites.