Identification and Quantification of Urinary Microbial Phenolic Metabolites by HPLC-ESI-LTQ-Orbitrap-HRMS and Their Relationship with Dietary Polyphenols in Adolescents

Enterolignans: from natural origins to cardiometabolic significance, including chemistry, dietary sources, bioavailability, and activity

The enterolignans, enterolactone and enterodiol, the main metabolites produced from plant lignans by the gut microbiota, have enhanced bioavailability and activity compared to their precursors, with beneficial effects on metabolic and cardiovascular health. Although extensively studied, the biosynthesis, cardiometabolic effects, and other therapeutic implications of mammalian lignans are still incompletely understood. The aim of this review is to provide a comprehensive overview of these phytoestrogen metabolites based on up-to-date information reported in studies from a wide range of disciplines. Established and novel synthetic strategies are described, as are the various lignan precursors, their dietary sources, and a proposed metabolic pathway for their conversion to enterolignans. The methodologies used for enterolignan analysis and the available data on pharmacokinetics and bioavailability are summarized and their cardiometabolic bioactivity is explored in detail. The special focus given to research on the health benefits of microbial-derived lignan metabolites underscores the critical role of lignan-rich diets in promoting cardiovascular health.

Novel insights into enzymes inhibitory responses and metabolomic profile of supercritical fluid extract from chestnut shells upon intestinal permeability

The health benefits of chestnut (Castanea sativa) shells (CSs) have been ascribed to phytochemicals, mainly phenolic compounds. Nevertheless, an exhaustive assessment of their intestinal absorption is vital considering a possible nutraceutical application. This study evaluated the bioactivity of CSs extract prepared by Supercritical Fluid Extraction and untargeted metabolomic profile upon in-vitro intestinal permeation across a Caco-2/HT29-MTX co-culture model. The results demonstrated the neuroprotective, hypoglycemic, and hypolipidemic properties of CSs extract by inhibition of acetylcholinesterase, α-amylase, and lipase activities. The untargeted metabolic profiling by LC-ESI-LTQ-Orbitrap-MS unveiled almost 60 % of lipids and 30 % of phenolic compounds, with 29 metabolic pathways indicated by enrichment analysis. Among phenolics, mostly phenolic acids, flavonoids, and coumarins permeated the intestinal barrier with most metabolites arising from phase I reactions (reduction, hydrolysis, and hydrogenation) and a minor fraction from phase II reactions (methylation). The permeation rates enhanced in the following order: ellagic acid < o-coumaric acid < p-coumaric acid < ferulaldehyde ≤ hydroxyferulic acid ≤ dihydroferulic acid < ferulic acid < trans-caffeic acid < trans-cinnamic acid < dihydrocaffeic acid, with better outcomes for 1000 µg/mL of extract concentration and after 4 h of permeation. Taken together, these findings sustained a considerable in-vitro intestinal absorption of phenolic compounds from CSs extract, enabling them to reach target sites and exert their biological effects.

Dietary Antioxidants and Cardiovascular Health-Editorial Comments and Summary

The influence of dietary antioxidants on health is supported by a large body of evidence [...].

Metabolomic insights into phenolics-rich chestnut shells extract as a nutraceutical ingredient - A comprehensive evaluation of its impacts on oxidative stress biomarkers by an in-vivo study

The present study attempted for the first time to explore the effects of the daily oral intake of a phenolics-rich extract from chestnut shells (CS) on the metabolomic profiling of rat tissues by liquid chromatography coupled to Orbitrap-mass spectrometry (LC-ESI-LTQ-Orbitrap-MS) targeted to polyphenolics and their metabolites and screen potential oxidative stress biomarkers, validating its use as a promising nutraceutical ingredient with outstanding antioxidant properties for the prevention and co-therapy of lifestyle-related diseases triggered by oxidative stress. The results demonstrated new insights into the metabolomic fingerprinting of polyphenols from CS, confirming their absorption and biotransformation by phase I (hydrogenation) and II (glucuronidation, methylation, and sulfation) enzymes. Phenolic acids were the main polyphenolic class, followed by hydrolyzable tannins, flavanols, and lignans. In contrast to the liver, sulfated conjugates were the principal metabolites reaching the kidneys. The multivariate data analysis predicted an exceptional contribution of polyphenols and their microbial and phase II metabolites to the in-vivo antioxidant response of the CS extract in rats, recommending its use as an appealing source of anti-aging molecules for nutraceuticals. This is the first study that explored the relation between metabolomic profiling of rat tissues and in-vivo antioxidant effects after oral treatment with a phenolics-rich CS extract.

UHPLC-HRMS Spectrometric Analysis: Method Validation and Plasma and Urinary Metabolite Identification after Mango Pulp Intake

After an acute intake of 300 g of mango purée by 10 subjects, 0 and 24 h urine and plasma samples were analyzed by high-performance liquid chromatography-high-resolution mass spectrometry. The method was first validated for 44 reference polyphenols in terms of linearity, specificity, limits of detection and quantification, intra-day and inter-day precision, recovery, and matrix effects in two biological matrices. After method validation, a total of 94 microbial-derived phenolic catabolites, including 15 cinnamic acids, 3 phenylhydracrylic acids, 14 phenylpropanoic acids, 12 phenylacetic acids, 28 benzoic acids, 2 mandelic acids, 15 hydroxybenzenes, and 5 hippuric acid derivatives, were identified or tentatively identified in urine and/or plasma. These results establish the value of the UHPLC-HRMS protocol and the use of authentic standards to obtain a detailed and accurate picture of mango polyphenol metabolites, together with their phase II conjugated metabolites, in human bioavailability studies.

Fatty acid composition of cholesterol esters reflects dietary fat intake after dietary interventions in a multinational population

BACKGROUND

The effects of different dietary fatty acids (FA) on cardiovascular risk still needs clarification. Plasma lipids composition may be a biomarker of FA dietary intake.

PURPOSE

To evaluate in a composite population the relationships between changes in dietary fat intake and changes in FA levels in serum cholesterol esters.

METHODS

In a multinational, parallel-design, dietary intervention (KANWU study), dietary intakes (3-day food record) and FA composition of serum cholesterol esters (gas-liquid chromatography) were evaluated at baseline and after 3 months in 162 healthy individuals, randomly assigned to a diet containing a high proportion of saturated (SFA) or monounsaturated (MUFA) fat, with a second random assignment to fish oil or placebo supplements.

RESULTS

Main differences in serum lipid composition after the two diets included saturated (especially myristic, C14:0, and pentadecanoic, C15:0) and monounsaturated (oleic acid, C18:1 n-9) FA. C14:0 and C15:0 were related to SFA intake, while C18:1 n-9 was associated with MUFA intake. Fish oil supplementation induced a marked increase in eicosapentaenoic (C20:5 n-3) and docosahexaenoic (C22:6 n-3) acids. After the 3-month intervention, Δ-9 desaturase activity, calculated as palmitoleic acid/palmitic acid (C16:1/C16:0) ratio, was more reduced after the MUFA (0.31±0.10 vs 0.25±0.09, p<0.0001) than SFA diet (0.31±0.09 vs 0.29±0.08, p=0.006), with a statistically significant difference between the two groups (p<0.0001).

CONCLUSIONS

This study shows that serum cholesterol ester FA composition can be used during randomized controlled trials as an objective indicator of adherence to experimental diets based on saturated and monounsaturated fat modifications, as well as fish oil supplementation.

Urinary metabolomics of phenolic compounds reveals biomarkers of type-2 diabetes within the PREDIMED trial

BACKGROUND

Phenolic compounds have been associated with protective effects against type-2 diabetes (T2D). We used a metabolomics approach to determine urinary phenolic metabolites associated with T2D and fasting plasma glucose.

METHODS

This case-control study within the PREDIMED trial included 200 participants at high cardiovascular risk, 102 of whom were diagnosed with T2D. A panel of urinary phenolic compounds were analysed using a novel method based on liquid chromatography coupled to mass spectrometry. Multivariate statistics and adjusted logistic regressions were applied to determine the most discriminant compounds and their association with T2D. The relationship between the discriminant phenolic compounds and plasma glucose was assessed using multivariable linear regressions.

RESULTS

A total of 41 phenolic compounds were modeled in the orthogonal projection to latent structures discriminant analysis, and after applying adjusted logistic regressions two were selected as discriminant: dihydrocaffeic acid (OR = 0.22 (CI 95 %: 0.09; 0.52) per 1-SD, p-value = 0.021) and genistein diglucuronide (OR = 0.72 (CI 95%: 0.59; 0.88) per 1-SD, p-value = 0.021). Both metabolites were associated with a lower risk of suffering from T2D, but only dihydrocaffeic acid was inversely associated with plasma glucose (β = -17.12 (95 % CI: -29.92; -4.32) mg/dL per 1-SD, p-value = 0.009).

CONCLUSIONS

A novel method using a metabolomics approach was developed to analyse a panel of urinary phenolic compounds for potential associations with T2D, and two metabolites, dihydrocaffeic acid and genistein diglucuronide, were found to be associated with a lower risk of this condition.

Urinary Phenolic Metabolites Associated with Peanut Consumption May Have a Beneficial Impact on Vascular Health Biomarkers

Phenolic compounds in peanuts may moderate inflammation and endothelial function. Thus, the aim of this study was to evaluate the association of urinary phenolic metabolites (UPMs) with vascular biomarkers after peanut product consumption. A three-arm parallel-group randomized controlled trial was conducted in 63 healthy young adults who consumed 25 g/day of skin roasted peanuts (SRP), 32 g/day of peanut butter (PB), or 32 g/day of a control butter for six months. UPMs were analyzed by liquid chromatography coupled to mass spectrometry. Additionally, urinary eicosanoids, prostacyclin I2 (PGI2), and thromboxane A2 (TXA2) were determined using two competitive enzyme-linked immunosorbent assay kits. Consumers of SRP and PB presented significantly higher excretion of UPMs (enterodiol glucuronide (p = 0.018 and p = 0.031), 3-hydroxybenzoic acid (p = 0.002 and p < 0.001), vanillic acid sulfate (p = 0.048 and p = 0.006), p-coumaric acid (p = 0.046 and p = 0.016), coumaric acid glucuronide I (p = 0.001 and p = 0.030) and II (p = 0.003 and p = 0.036), and isoferulic acid (p = 0.013 and p = 0.015) in comparison with the control group. An improvement in PGI2 (p = 0.037) levels and the TXA2:PGI2 ratio (p = 0.008) was also observed after the peanut interventions compared to the control. Interestingly, UPMs with significantly higher post-intervention levels were correlated with an improvement in vascular biomarkers, lower TXA2 (r from −0.25 to −0.48, p < 0.050) and TXA2:PGI2 ratio (r from −0.25 to −0.43, p < 0.050) and higher PGI2 (r from 0.24 to 0.36, p < 0.050). These findings suggest that the UPMs with higher excretion after peanut product consumption could have a positive impact on vascular health.

Association of microbiota polyphenols with cardiovascular health in the context of a Mediterranean diet

BACKGROUND AND AIMS

The Mediterranean diet (MedDiet) is rich in polyphenols, phytochemicals that are beneficial for cardiovascular health. Phenolic compounds have poor bioavailability but they are extensively metabolized by the gut microbiota. Therefore, we aimed to assess the association of microbial phenolic metabolites (MPM) with adherence to the MedDiet, and their relationship with ideal cardiovascular health (ICVH) and cardiovascular risk factors.

METHODS AND RESULTS

This cross-sectional substudy within the PREDIMED trial included 200 participants from the Barcelona-Clinic recruitment center. Five MPM were identified and quantified using a novel method based on liquid chromatography coupled to mass spectrometry: protocatechuic acid (PCA), enterodiol glucuronide (EDG), enterolactone glucuronide (ELG), vanillic acid glucuronide (VAG) and urolithin B glucuronide (UBG). Multivariable-adjusted regressions were used to evaluate the associations between MPM and MedDiet adherence, ICVH score, biochemical parameters, and blood pressure. Additionally, an MPM score was calculated as the weighted sum of MedDiet adherence and ICVH and found to be directly associated. Among individual polyphenols, UBG was inversely associated with LDL-cholesterol.

CONCLUSIONS

A score of urinary MPM was associated with higher adherence to the MedDiet and ICVH, and individual MPM were related to better cardiovascular health. These findings suggest that the MedDiet may affect gut microbiota, whose metabolites are linked with cardiovascular health.

One-Year Changes in Urinary Microbial Phenolic Metabolites and the Risk of Type 2 Diabetes-A Case-Control Study

The intake of polyphenols has been associated with a risk reduction of type 2 diabetes. Nevertheless, to the best of our knowledge, the molecules that might be metabolically active after ingestion are only starting to be investigated regarding this metabolic disease. To investigate the association between one-year changes in urinary microbial phenolic metabolites (MPM) and the incidence of type 2 diabetes, we performed a case-control study using data and samples of the PREDIMED trial including 46 incident type 2 diabetes cases of 172 randomly selected participants. Eight urinary MPMs were quantified in urine by liquid chromatography coupled to mass spectrometry and used to assess their associations with type 2 diabetes risk by multivariable logistic regression models. Compared to participants in the lowest tertile of one-year changes in hydroxybenzoic acid glucuronide, those in the highest tertile had a significantly lowered probability of developing type 2 diabetes (OR [95% CI], 0.39 [0.23−0.64]; p < 0.001 for trend). However, when additionally adjusting for fasting plasma glucose, the statistical significance was lost. Changes in the dietary pattern can increase the concentrations of this compound, derived from many (poly)phenol-rich foods, and might be changing the gut microbial population as well, promoting the production of the metabolite.

Purified recombinant enzymes efficiently hydrolyze conjugated urinary (poly)phenol metabolites

Purified recombinant enzymes are efficient at hydrolyzing microbial (poly)phenol metabolite phase II conjugates, and hence, can be used to accurately quantify them using unconjugated analytical standards.