Metabolome biomarkers linking dietary fibre intake with cardiometabolic effects: results from the Danish Diet, Cancer and Health-Next Generations MAX study.

Biomarkers associated with dietary fibre intake, as complements to traditional dietary assessment tools, may improve the understanding of its role in human health. Our aim was to discover metabolite biomarkers related to dietary fibre intake and investigate their association with cardiometabolic risk factors. We used data and samples from the Danish Diet Cancer and Health Next Generation (DCH-NG) MAX-study, a one-year observational study with evaluations at baseline, six and 12 months (n = 624, 55% female, mean age: 43 years, 1353 observations). Direct associations between fibre intake and plasma concentrations of 2,6-dihydroxybenzoic acid (2,6-DHBA) and indolepropionic acid were observed at the three time-points. Both metabolites showed an intraclass-correlation coefficient (ICC) > 0.50 and were associated with the self-reported intake of wholegrain cereals, and of fruits and vegetables, respectively. Other metabolites associated with dietary fibre intake were linolenoyl carnitine, 2-aminophenol, 3,4-DHBA, and proline betaine. Based on the metabolites associated with dietary fibre intake we calculated predicted values of fibre intake using a multivariate, machine-learning algorithm. Metabolomics-based predicted fibre, but not self-reported fibre values, showed negative associations with cardiometabolic risk factors (i.e. high sensitivity C-reactive protein, systolic and diastolic blood pressure, all FDR-adjusted p-values <0.05). Furthermore, different correlations with gut microbiota composition were observed. In conclusion, 2,6-DHBA and indolepropionic acid in plasma may better link dietary fibre intake with its metabolic effects than self-reported values. These metabolites may represent a novel class of biomarkers reflecting both dietary exposure and host and/or gut microbiota characteristics providing a read-out that is differentially related to cardiometabolic risk.

Intake of the Total, Classes, and Subclasses of (Poly)Phenols and Risk of Prostate Cancer: A Prospective Analysis of the EPIC Study.

Existing epidemiological evidence regarding the potential role of (poly)phenol intake in prostate cancer (PCa) risk is scarce and, in the case of flavonoids, it has been suggested that their intake may increase PCa risk. We investigated the associations between the intake of the total and individual classes and subclasses of (poly)phenols and the risk of PCa, including clinically relevant subtypes. The European Prospective Investigation into Cancer and Nutrition (EPIC) cohort included 131,425 adult men from seven European countries. (Poly)phenol intake at baseline was assessed by combining validated center/country-specific dietary questionnaires and the Phenol-Explorer database. Multivariable-adjusted Cox proportional hazards models were used to estimate the hazard ratios (HR) and 95% confidence intervals (CI). In total, 6939 incident PCa cases (including 3501 low-grade and 710 high-grade, 2446 localized and 1268 advanced, and 914 fatal Pca cases) were identified during a mean follow-up of 14 years. No associations were observed between the total intake of (poly)phenols and the risk of PCa, either overall (HRlog2 = 0.99, 95% CI 0.94-1.04) or according to PCa subtype. Null associations were also found between all classes (phenolic acids, flavonoids, lignans, and stilbenes) and subclasses of (poly)phenol intake and the risk of PCa, overall and according to PCa subtype. The results of the current large prospective cohort study do not support any association between (poly)phenol intake and PCa incidence.

Total carotene plasma concentrations are inversely associated with atherosclerotic plaque burden: A post-hoc analysis of the DIABIMCAP cohort.

BACKGROUND AND AIMS: Atherosclerosis is the major risk factor for cardiovascular disease (CVD), the first cause of death worldwide. Chronic low-grade inflammation and a sustained oxidative milieu are causatively related to atherosclerosis onset and progression, and therefore, dietary patterns rich in bioactive compounds with anti-inflammatory and antioxidant activities might likely contribute to revert or slowing the progression of atherosclerosis. The aim of this study is to analyse the association between fruit and vegetables intake, quantitatively measured through carotene plasma concentrations, and atherosclerotic burden, as a surrogate biomarker of CVD, in free-living subjects from the DIABIMCAP cohort study. METHODS: The 204 participants of the DIABIMCAP Study cohort (Carotid Atherosclerosis in Newly Diagnosed Type 2 Diabetic Individuals, ClinicalTrials.gov Identifier: NCT01898572), were included in this cross-sectional study. Total, α-, and ß-carotenes were quantified by HPLC-MS/MS. Lipoprotein analysis in serum was performed by 2D- 1H NMR- DOSY, and atherosclerosis and intima media thickness (IMT) were measured through standardized bilateral carotid artery ultrasound imaging. RESULTS: Subjects with atherosclerosis (n = 134) had lower levels of large HDL particles than subjects without atherosclerosis. Positive associations were found between α-carotene and both large and medium HDL particles, and inverse associations were found between ß- and total carotene, and VLDL and its medium/small particles. Subjects with atherosclerosis presented significantly lower plasma concentrations of total carotene compared with subjects without atherosclerosis. Plasma concentrations of carotene decreased as the number of atherosclerotic plaques increased, although after multivariate adjustment, the inverse association between ß- and total carotene with plaque burden remained significant only in women. CONCLUSIONS: A diet rich in fruit and vegetables results in higher plasmatic carotene concentrations, which are associated with a lesser atherosclerotic plaque burden.

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

This study aimed to develop and validate a liquid chromatography/electrospray ionization-linear ion trap quadrupole-Orbitrap-high-resolution mass spectrometry (HPLC/ESI-LTQ-Orbitrap-HRMS) method to identify and quantify urinary microbial phenolic metabolites (MPM), as well as to explore the relationship between MPM and dietary (poly)phenols in Spanish adolescents. A total of 601 spot urine samples of adolescents aged 12.02 ± 0.41 years were analyzed. The quantitative method was validated for linearity, limit of detection, limit of quantification, recovery, intra- and inter-day accuracy and precision, as well as postpreparative stability according to the criteria established by the Association of Official Agricultural Chemists International. A total of 17 aglycones and 37 phase II MPM were identified and quantified in 601 spot urine samples. Phenolic acids were the most abundant urinary MPM, whereas stilbenes, hydroxytyrosol, and enterodiol were the least abundant. Urinary hydroxycoumarin acids (urolithins) were positively correlated with flavonoid and total (poly)phenol intake. An HPLC-ESI-LTQ-Orbitrap-HRMS method was developed and fully validated to quantify MPM. The new method was performed accurately and is suitable for MPM quantification in large epidemiological studies. Urinary lignans and urolithins are proposed as potential biomarkers of grain and nut intake in an adolescent population.

Moderate Consumption of Beer (with and without Ethanol) and Menopausal Symptoms: Results from a Parallel Clinical Trial in Postmenopausal Women.

The menopausal transition can be a challenging period for women's health and a trigger of uncomfortable symptoms. Beer is the main food source of isoxanthohumol, a precursor of 8-prenylnaringenin, the strongest phytoestrogen identified to date. As phytoestrogens are reported to reduce perimenopausal symptoms, we evaluated if a daily moderate consumption of beer with (AB) and without alcohol (NAB) could improve menopausal symptoms and modify cardiovascular risk factors. A total of 37 postmenopausal women were enrolled in a parallel controlled intervention trial and assigned to three study groups: 16 were administered AB (330 mL/day), 7 NAB (660 mL/day), and 14 were in the control group. After a 6-month follow-up of the 34 participants who finished the trial, both interventions (AB and NAB) significantly reduced the severity of the menopause-related symptoms (p-value AB vs. Control: 0.009; p-value NAB vs. Control: 0.033). Moreover, AB had a beneficial net effect on psychological menopausal discomforts compared to the control group. As the sex hormone profile did not differ significantly between the study groups, the effects of both types of beers (AB and NAB) are attributed to the non-alcoholic fraction of beer. Furthermore, moderate NAB consumption improved the lipid profile and decreased blood pressure in postmenopausal women.

Effect of physiological factors, pathologies, and acquired habits on the sweet taste threshold: A systematic review and meta-analysis.

Sweet taste perception is a key factor in the establishment of the food pattern with nonstatic thresholds. Indeed, taste sensitivity can be influenced by physiological factors (age and sex), pathologies (obesity and type 2 diabetes mellitus), and acquired habits (tobacco and alcohol consumption). In order to elucidate how these variables influence the sucrose detection threshold (DT) and recognition threshold (RT), a systematic review and meta-analysis of the relevant literature were performed. After a comprehensive search in the PubMed and Scopus databases, a total of 48 studies were qualitatively considered, and 44 were meta-analyzed. The factors of aging (standard mean difference [SMD]: -0.46; 95% confidence interval (CI), -0.74 to -0.19; I2 : 73%; Tau2 : 0.18) and type 2 diabetes mellitus (SMD: 0.30; 95% CI, 0.06 to 0.55; I2 : 0%; Tau2 : 0.00) were found to significantly increase the sucrose RT, whereas the DT only increased in subjects with a higher body mass index (SMD: 0.58; 95% CI, 0.35 to 0.82; I2 : 0%; Tau2 : 0.00). No effects of sex and tobacco smoking were found, and associations with alcohol consumption could not be assessed, as it was included as a variable in only one study. Feasible mechanisms underlying changes in sucrose thresholds include the modulation of hormones involved in energy and body weight homeostasis, taste bud abundance, taste brain signaling, and the gut-brain axis. The present work provides insights into the variables that should be considered when assessing sweet taste sensitivity, discusses the mechanisms underlying differences in sweet taste, and highlights the need for further research in the field of personalized nutrition.

Potential association of plasma lysophosphatidic acid (LPA) species with cognitive impairment in abstinent alcohol use disorders outpatients.

Lysophosphatidic acid (LPA) species are bioactive lipids participating in neurodevelopmental processes. The aim was to investigate whether the relevant species of LPA were associated with clinical features of alcohol addiction. A total of 55 abstinent alcohol use disorder (AUD) patients were compared with 34 age/sex/body mass index-matched controls. Concentrations of total LPA and 16:0-LPA, 18:0-LPA, 18:1-LPA, 18:2-LPA and 20:4-LPA species were quantified and correlated with neuroplasticity-associated growth factors including brain derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1) and IGF-2, and neurotrophin-3 (NT-3). AUD patients showed dysexecutive syndrome (22.4%) and memory impairment (32.6%). Total LPA, 16:0-LPA, 18:0-LPA and 18:1-LPA concentrations, were decreased in the AUD group compared to control group. Total LPA, 16:0-LPA, 18:2-LPA and 20:4-LPA concentrations were decreased in men compared to women. Frontal lobe functions correlated with plasma LPA species. Alcohol-cognitive impairments could be related with the deregulation of the LPA species, especially in 16:0-LPA, 18:1-LPA and 20:4-LPA. Concentrations of BDNF correlated with total LPA, 18:2-LPA and 20:4-LPA species. The relation between LPA species and BDNF is interesting in plasticity and neurogenesis functions, their involvement in AUD might serve as a biomarker of cognitive impairment.

Beer Phenolic Composition of Simple Phenols, Prenylated Flavonoids and Alkylresorcinols.

Beer is a fermented beverage with beneficial phenolic compounds and is widely consumed worldwide. The current study aimed to describe the content of three families of phenolic compounds with relevant biological activities: prenylated flavonoids (from hops), simple phenolic alcohols (from fermentation) and alkylresorcinols (from cereals) in a large sample of beers (n = 45). The prenylated flavonoids analyzed were xanthohumol, isoxanthohumol, 6- and 8-prenylnaringenin. The total prenylated flavonoids present in beer ranged from 0.0 to 9.5 mg/L. The simple phenolic alcohols analyzed were tyrosol and hydroxytyrosol, ranging from 0.2 to 44.4 and 0.0 to 0.1 mg/L, respectively. Our study describes, for the first time, the presence of low amounts of alkylresorcinols in beer, in concentrations ranging from 0.02 to 11.0 µg/L. The results in non-alcoholic beer and the differences observed in the phenolic composition among different beer types and styles highlight the importance of the starting materials and the brewing process (especially fermentation) on the final phenolic composition of beer. In conclusion, beer represents a source of phenolic compounds in the diet that could act synergistically, triggering beneficial health effects in the context of its moderate consumption.

5-cis-, Trans- and Total Lycopene Plasma Concentrations Inversely Relate to Atherosclerotic Plaque Burden in Newly Diagnosed Type 2 Diabetes Subjects.

Diabetic subjects are at increased risk of cardiovascular disease. Atherosclerosis, the common soil of most of the cardiovascular complications, is more prevalent and extensive in this population due not only to hyperglycemia, insulin resistance, and dyslipidemia, but also to inflammation and oxidative stress. Lycopenes are bioactive compounds with antioxidant and anti-inflammatory activities mostly supplied by tomato and tomato byproducts. We investigated the association between circulating lycopenes and carotid plaque burden in diabetic patients, in a cross-sectional study in 105 newly diagnosed diabetic subjects. Atheroma plaque (wall thickness ≥ 1.5 mm), number of plaques, and plaque burden (sum of maximum heights of all plaques) were assessed by sonographic evaluation of carotid arteries. Plasma lycopenes (5-cis-, 9-cis-, 13-cis-, and trans-lycopene) were quantified by high performance liquid chromatography-mass spectrometry HPLC-MS. Atheroma plaque was observed in 75 participants, from which 38 presented one plaque and 37 two or more carotid plaques. No differences were observed in the plasmatic concentrations of lycopenes between subjects with and without atherosclerotic plaque presence. However, plaque burden was inversely associated with 5-cis-lycopene, all cis-lycopene isomers, trans-lycopene, and total lycopene isomers (all, p < 0.05). High plasma levels of lycopenes inversely relate to atherosclerotic burden. We provide novel evidence that suggests that the consumption of compounds found in tomato and tomato byproducts might be beneficial for the prevention of atherosclerosis.

Ethnobotanical, nutritional and medicinal properties of Mexican drylands Cactaceae Fruits: Recent findings and research opportunities.

The Mexican drylands possess enormous biotic and cultural wealth, representing 65% of the national territory. Approximately 50% of Mexican dryland flora is endemic and accompanied by ample local and traditional knowledge. There are certain types of cactus fruits that are being technologically produced. However, there are other cactus fruit that are underutilized and understudied that could be promoted for their sustainable use. Evidence indicates that the genera of Escontria, Myrtilocactus, Hylocereus, and Stenocereus contain bioactive compounds such as betalains and phenols. Opuntia, the most abundant cactus in Mexico, produces fruit known as prickly pears with bioactive compounds that are associated with health benefits. The purpose of this review is to compile the nutritional and functional properties of selected cactus fruits from the Mexican drylands, as well as their use in the health, food, cosmetic, and agricultural industries in order to establish knowledge gaps and well-supported future research directions.

Microbial Phenolic Metabolites: Which Molecules Actually Have an Effect on Human Health?

The role of gut microbiota in human health has been investigated extensively in recent years. The association of dysbiosis, detrimental changes in the colonic population, with several health conditions has led to the development of pro-, pre- and symbiotic foods. If not absorbed in the small intestine or secreted in bile, polyphenols and other food components can reach the large intestine where they are susceptible to modification by the microbial population, resulting in molecules with potentially beneficial health effects. This review provides an overview of studies that have detected and/or quantified microbial phenolic metabolites using high-performance liquid chromatography as the separation technique, followed by detection through mass spectrometry. Both in vitro experimental studies and human clinical trials are covered. Although many of the microbial phenolic metabolites (MPM) reported in in vitro studies were identified in human samples, further research is needed to associate them with clinical health outcomes.

Extra Virgin Olive Oil Minor Compounds Modulate Mitogenic Action of Oleic Acid on Colon Cancer Cell Line.

Experimental and clinical findings suggest that olive oil has a protective effect, whereas oleic acid consumption induces colorectal cancer (CRC). Considering this apparent contradiction and that olive oil is a complex mix of fatty acids, mainly oleic acid and minor compounds such as phenolic compounds, lignans, hydrocarbons, and triterpenes, we study its effects on intestinal epithelial cell growth. Our results show that oleic acid (1-100 µM) but not elaidic acid induced DNA synthesis and Caco-2 cell growth (2-fold higher than cells without growth factors, p < 0.05). These effects were inhibited by 5-lipoxygenase inhibitors as well as the leukotriene antagonist (p < 0.05), suggesting the implication of this pathway in this mitogenic action. Hydroxytyrosol, oleuropein, pinoresinol, squalene, and maslinic acid (0.1-10 µM) reverted DNA synthesis and Caco-2 cell growth induced by oleic acid. These effects were not the consequence of the cell cycle arrest or the impairment of cell viability with the exception of hydroxytyrosol and maslinic acid that induced cell detachment and apoptosis (35.6 ± 2.3 and 43.2 ± 2.4%, respectively) at the higher concentration assayed. Oleuropein effects can be related with hydroxytyrosol release as a consequence of oleuropein hydrolysis by Caco-2 cells (up to 25%). Furthermore, hydroxytyrosol modulates the arachidonic acid cascade, and this event can be associated with its antimitogenic action. In conclusion, oleic acid and oleic acid in the presence of olive oil representative minor components have opposite effects, suggesting that the consumption of seed oils, high oleic acid seed oils, or olive oil will probably have different effects on CRC.

Characterisation of bioactive compounds and assessment of antioxidant activity of different traditional Lycopersicum esculentum L. varieties: chemometric analysis.

Eight different Serbian genotypes were analysed for their polyphenol, carotenoid, vitamin C content and evaluated for their antioxidant properties. The highest content of biologically important carotenoids such as lutein (4.58 mg/10 g), lycopene (160.64 mg/10 g) and ß-carotene (189.64 mg/10 g) were detected in the genotype S606. Rutin was the most abundant phenolic compound in all tastes samples, but its content is highest in the genotype S615 (1424.30 µg/100 g dw). All tomato samples were the great source of vitamin C, where the sample S615 stood out (68.54 mg AA g-1 of dw). Their content of antioxidant compounds suggested that genotypes S606 and S615 showed the best antioxidant potential. Principal component analysis (PCA) and Partial least squares (PLS) were applied to analyse results. The results obtained in the present study could be of considerable interest for breeding programmes wishing to select tomato genotypes with high biological and nutritional properties.

Acute Effect of a Single Dose of Tomato Sofrito on Plasmatic Inflammatory Biomarkers in Healthy Men.

Sofrito is a Mediterranean tomato-based sauce that typically also contains olive oil, onion, and garlic. The preparation of sofrito modifies the bioactive compounds (carotenoids and polyphenols) in the ingredients to more bioavailable forms, promoting cis-lycopene formation and polyphenol bioaccessibility. To evaluate the health benefits of this cooking technique, the effect of consuming an acute dose of sofrito on the inflammatory status was studied. In a clinical trial, 22 healthy male subjects consumed a single dose of sofrito (240 g/70 kg) after three days without ingesting any tomato products and following a low-antioxidant diet the day before the intervention. Plasma carotenoids and total polyphenol excretion (TPE) were evaluated, as well as the inflammatory biomarkers C-reactive protein (CRP), interleukin-6 (IL-6), interleukin 1ß (IL-1ß) and tumor necrosis factor-α (TNF-α). After the sofrito intake, a significant decrease in CRP (p = 0.010) and TNF-α (p = 0.011) was observed, but only TNF-α was inversely correlated with an increase in TPE and plasma ß-carotene (not the major carotenoid, lycopene). The positive health effects of this tomato-based product may be attributed not only to lycopene, but to the bioactive compounds of all the ingredients.

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.

Identification of phenolic metabolites in human urine after the intake of a functional food made from grape extract by a high resolution LTQ-Orbitrap-MS approach.

Grape pomace (GP) is known to be a rich source of polyphenols with biological activity which may be used as functional ingredients for the development of new health-promoting products. Numerous studies have reported that bioactive compounds may act through multiple mechanisms. In order to verify the oral absorption and metabolism of grape polyphenols, we performed a prospective, randomised and cross-over acute study in 12 volunteers with two interventions: 500mL of a functional beverage enriched with 200mL of GP and 500mL of a control beverage without GP. In this work, liquid chromatography coupled with an electrospray ionization hybrid linear ion trap quadrupole-Orbitrap-mass spectrometry (LC/ESI-LTQ-Orbitrap-MS) technique has been used to accurately identify phenolics in GP and human urine. In GP, 41 phenolic compounds were identified mainly procyanidins, phenolic acids and flavonols, and in human urine over 70 metabolites of phenolic compounds including microbiota metabolites, glucuronides and sulfate derivatives were detected. Overall, high resolution mass spectrometry (HR-MS) enhances the identification of a large variety of polyphenols and their metabolites with great mass accuracies for all molecular ions.

Modulation of Nrf2 by Olive Oil and Wine Polyphenols and Neuroprotection.

Strong adherence to a Mediterranean diet is associated with improved cognitive function and a lower prevalence of mild cognitive impairment. Olive oil and red wine are rich sources of polyphenols which are responsible in part for the beneficial effects on cognitive functioning. Polyphenols induce endogenous antioxidant defense mechanisms by modulating transcription factors such as the nuclear factor (erythroid-derived 2)-like 2 (Nrf2). This review discusses the scientific data supporting the modulating effect of olive oil and red wine polyphenols on Nrf2 expression, and the potential health benefits associated with cognitive functioning.

Home cooking and ingredient synergism improve lycopene isomer production in Sofrito.

There has been increasing interest in tomato products rich in lycopene Z-isomers since these carotenoids present greater bioavailability and antioxidant capacity than the all-E lycopene form. Intrinsic food properties as well as processing and the interaction between dietary components can all influence the content, type and bioavailability of carotenoids. The aim of this study was to evaluate whether carotenoid content and isomerization in tomato-based Mediterranean sofrito is affected by the process of home cooking and the presence of other ingredients such as extra virgin olive oil, onion and garlic. We used a full factorial design to clarify the contribution of each ingredient to the carotenoid composition of sofrito and to determine whether this can be improved by the cooking time and ingredient synergism. Cooking time and onion content were associated with a higher production of 5-Z-lycopene, 9-Z-lycopene and 13-Z-lycopene in sofrito. Onion proved to be the most interesting ingredient in the sofrito formulation due to their enhancing effect on lycopene isomerization. The use of onion combined with an adequate processing time may improve the bioavailability of lycopene in tomato products.

trans-Lycopene from tomato juice attenuates inflammatory biomarkers in human plasma samples: An intervention trial.

SCOPE: The effect of carotenoids from tomato juice (TJ) on inflammatory biomarkers was evaluated by performing a 4-week dose-response nutritional trial in a population at high cardiovascular risk. METHODS AND RESULTS: An open, prospective, randomized, cross-over, and controlled clinical trial was carried out with 28 volunteers (mean age 69.7 ± 3.1 years; mean BMI 31.5 ± 3.6 kg/m2 ) at high cardiovascular risk, which were assigned to consume daily for 4 weeks in random order: 200 mL (LD) or 400 mL (HD) of TJ, or water as a control (C), with a 21-day wash-out period between each intervention. Blood samples were collected at baseline (B) and after each intervention. Endpoints included significant changes in plasmatic carotenoids, and adhesion molecules ICAM-1, and VCAM-1, as well as a tendency to decrease the chemokine IL-8. Compared to C, concentration of ICAM-1, and VCAM-1 were significantly lower (p ˂ 0.001), after each TJ intervention. Decreases were correlated remarkably with the trans-lycopene, while the other carotenoids present in TJ have presented a minor association or no association with changes in these molecules. CONCLUSION: trans-Lycopene from TJ may attenuate the risk of cardiovascular disease by reducing the concentration of important inflammatory molecules related to atherosclerosis.

Is enzymatic hydrolysis a reliable analytical strategy to quantify glucuronidated and sulfated polyphenol metabolites in human fluids?

Phenolic compounds are present in human fluids (plasma and urine) mainly as glucuronidated and sulfated metabolites. Up to now, due to the unavailability of standards, enzymatic hydrolysis has been the method of choice in analytical chemistry to quantify these phase II phenolic metabolites. Enzymatic hydrolysis procedures vary in enzyme concentration, pH and temperature; however, there is a lack of knowledge about the stability of polyphenols in their free form during the process. In this study, we evaluated the stability of 7 phenolic acids, 2 flavonoids and 3 prenylflavanoids in urine during enzymatic hydrolysis to assess the suitability of this analytical procedure, using three different concentrations of ß-glucuronidase/sulfatase enzymes from Helix pomatia. The results indicate that enzymatic hydrolysis negatively affected the recovery of the precursor and free-form polyphenols present in the sample. Thus, enzymatic hydrolysis does not seem an ideal analytical strategy to quantify glucuronidated and sulfated polyphenol metabolites.