Biomarkers of dietary intake of flavonoids and phenolic acids for studying diet-cancer relationship in humans

Food frequency questionnaire is a valid assessment tool of quercetin and kaempferol intake in Iranian breast cancer patients according to plasma biomarkers

In epidemiological and clinical studies, the most common nutritional tool to assess dietary flavonol intake is the food frequency questionnaire (FFQ), which needs to contain a detailed list of plant-based foods and be previously validated. Our study aimed to assess the accuracy of dietary flavonol (quercetin, kaempferol, and isorhamnetin) intake from a food frequency questionnaire (FFQ) compared to fasting plasma flavonol concentrations, as biomarkers of exposure, in breast cancer patients. In a consecutive case series, newly diagnosed patients with breast cancer (n = 140) were recruited at Nour-Nejat Hospital, Tabriz, Iran. Flavonol intake was assessed using a validated FFQ. Plasma flavonol concentrations were measured using high-performance liquid chromatography-ultraviolet detection. The accuracy of dietary status was evaluated using a receiver operating characteristic (ROC) and area under the ROC curve (AUC). Dietary status was shown in dichotomous using ROC-cutoff point. The plasma concentrations of quercetin were moderately correlated with dietary intake of quercetin (Spearman's correlation coefficient (r_s) = 0.188, P < .05; r_partial= 0.330, P < .01) and plasma concentrations of isorhamnetin (r_s = 0.337, P < .001). A linear correlation between dietary levels and plasma concentrations of kaempferol was attained (r_partial = 0.240, P < .05). Using a ROC-cutoff of 61.9 nmol/L for plasma quercetin (test reference), we were able to differentiate between lower and higher consumers of quercetin with an AUC_{ROC-based reference} =0.65 (P < .01, sensitivity = 61.8%, and specificity = 60.0%). Using a plasma kaempferol concentration of 60.1 nmol/L (ROC-cutoff), it was possible to detect significant differences between higher and lower intakes of kaempferol (AUC_{ROC-based reference} = 0.64, P < .05). The correlations and diagnostic performance with plasma concentrations could present a significant accuracy rate (validity), which seems acceptable for a nutritional questionnaire (FFQ) to assess intakes intake levels of quercetin and kaempferol. An improvement in the accuracy of the flavonol exposure can provide more precise relationship with health outcomes, which may increase their clinical significance.

Correlations between urinary concentrations and dietary intakes of flavonols in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

PURPOSE

In this study, we aimed to study the correlation between acute and habitual intakes of flavonols, their main food sources and their 24-h urinary concentrations in an European population.

METHODS

A 24-h dietary recall (24-HDR) and 24-h urine samples were collected on the same day from a convenience subsample of 475 men and women from four countries (France, Italy, Greece and Germany) of the European Prospective Investigation into Cancer and Nutrition (EPIC) study. A standardized 24-HDR software and a country/centre-specific validated dietary questionnaire (DQ) were used to collect acute and habitual dietary data, respectively. The intake of dietary flavonols was estimated using the Phenol-Explorer database. Urinary flavonols (quercetin, isorhamnetin, and kaempferol) were analysed using tandem mass spectrometry with a previous enzymatic hydrolysis.

RESULTS

Weak partial Spearman correlations between both dietary acute and habitual intake and urinary concentrations of quercetin (both Rpartial ~ 0.3) and total flavonols (both Rpartial ~ 0.2) were observed. No significant correlations were found for kaempferol and isorhamentin. Regarding flavonol-rich foods, weak correlations were found between urinary concentrations of quercetin and total flavonols and the acute intake of onions and garlics, fruits, tea, and herbal tea (all Rpartial ~ 0.2). For habitual intake, statistically significant correlations were only found between urinary quercetin concentration and herbal tea (Rpartial = 0.345) and between urinary total flavonol concentration and tea, and herbal tea consumption (Rpartial ~ 0.2).

CONCLUSIONS

Our results suggest that urinary quercetin level can be used as potential concentration biomarkers of both acute and habitual quercetin intake, while urinary concentrations of flavonols are unlikely to be useful biomarkers of individual flavonol-rich foods.

Urinary flavanone concentrations as biomarkers of dietary flavanone intakes in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

In the present study, the aim was to investigate the correlation between the acute and habitual dietary intake of flavanones, their main food sources and the concentrations of aglycones naringenin and hesperetin in 24 h urine in a European population. A 24-h dietary recall (24-HDR) and a 24-h urine sample were collected the same day from a subsample of 475 people from four different countries of the European Prospective Investigation into Cancer and Nutrition study. Acute and habitual dietary data were captured through a standardised 24-HDR and a country/centre-specific validated dietary questionnaire (DQ). The intake of dietary flavanones was estimated using the Phenol-Explorer database. Urinary flavanones (naringenin and hesperetin) were analysed using tandem MS with a previous enzymatic hydrolysis. Weak partial correlation coefficients were found between urinary flavanone concentrations and both acute and habitual dietary flavanone intakes (Rpartial = 0·14-0·17). Partial correlations were stronger between urinary excretions and acute intakes of citrus fruit and juices (Rpartial ∼ 0·6) than with habitual intakes of citrus fruit and juices (Rpartial ∼ 0·24). In conclusion, according to our results, urinary excretion of flavanones can be considered a good biomarker of acute citrus intake. However, low associations between habitual flavanone intake and urinary excretion suggest a possible inaccurate estimation of their intake or a too sporadic intake. For assessing habitual exposures, multiple urinary collections may be needed. These results show that none of the approaches tested is ideal, and the use of both DQ and biomarkers can be recommended.

Adherence to the Saudi dietary guidelines and its relation to colorectal polyps: A university hospital-based study

Objectives

Colorectal polyps are a known precursor to colorectal cancer (CRC). Using the Saudi dietary guidelines adherence scores, this study evaluated whether dietary intake can lead to the development of colorectal polyps in a Saudi cohort.

Methods

In a cross-sectional study, 101 patients of both sexes, aged 30-86 years (40 patients with colorectal polyps and 61 patients without polyps), were recruited from the endoscopy unit in a Saudi hospital. A questionnaire was administered to collect demographic data, anthropometric data, and information about dietary habits.

Results

Patients with colorectal polyps were significantly older than those without polyps (p = 0.05). The mean body mass index in both patient groups was within the overweight range, with a value of 28.6 ± 6.7 kg/m². We did not find significant differences between patients with and without colorectal polyps. Although there was no difference in the overall scores for adherence to the Saudi dietary guidelines between the two groups, the specific adherence score for vegetables was significantly higher in patients without colorectal polyps (5.0 ± 0.0 vs. 4.9 ± 0.3, p = 0.03).

Conclusion

Ageing and lower vegetable intake, previously reported to be risk factors for CRC, were likewise identified in this study. However, a multi-centre study with a larger sample size, utilising data from this study, is needed.

Prognostic associations of circulating phytoestrogens and biomarker changes in long-term survivors of postmenopausal breast cancer

Lignans are associated with improved postmenopausal breast cancer (BC) survival, but whether these associations, particularly with enterolactone (major lignan metabolite), persist over time is unclear. Little is known about other phytoestrogens on prognosis in long-term survivors. The study examines associations of prognosis with 1) circulating postdiagnosis enterolactone, 2) eight circulating phytoestrogen metabolites, and 3) changes in enterolactone and genistein. In a German cohort of 2,105 postmenopausal BC patients with blood samples collected at recruitment 2002-2005 (baseline) and re-interview in 2009 (follow-up), delay-entry Cox proportional hazards regression was used. Landmark analysis showed that circulating enterolactone (log2) associations with 5-year survival changed over time, with strongest hazard ratios of 0.89 (95% CI, 0.80-0.99) at blood draw (BD) and 0.86 (0.77-0.97) at 2 years post-BD for BC mortality, and 0.87 (0.80-0.95) at BD and 0.84 (0.76-0.92) at 3 years post-BD for all-cause mortality, which attenuated thereafter. In long-term survivors, increasing concentrations of genistein (1.17, 1.01-1.36), resveratrol (1.19, 1.02-1.40), and luteolin (1.96, 1.07-3.58) measured in follow-up blood samples were associated with poorer subsequent prognosis. Neither enterolactone at follow-up nor changes in enterolactone/genistein were associated with prognosis. Large long-term longitudinal studies with multiple phytoestrogen measurements are required to understand long-term effects of phytoestrogens after BC.

Technology and Process Design for Phenols Recovery from Industrial Chicory (Chicorium intybus) Leftovers

Vegetal leftovers from the agro-food industry represent a huge source of primary and secondary metabolites, vitamin, mineral salts and soluble as well as insoluble fibers. Economic reports on the growth in the polyphenol market have driven us to focus our investigation on chicory (Chicorium intybus L.), which is one of the most popular horticultural plants in the world and a rich source of phenolic compounds. Ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and their simultaneous combination, using either ethanol/water or water alone (also sub-critical), have been investigated with the aim of designing a green and efficient extraction process. Higher total-polyphenol yields as well as dramatic reductions in extraction times and solvent consumption have been obtained under these conditions. ANOVA test for analyses of variance followed by the Tukey honestly significant difference (HSD) post-hoc test of multiple comparisons was used in the statistical analysis. MAE experiments performed with sub-critical water, and MW/US experiments with an ethanol solution have shown polyphenol recovery values of up to ~3 g of gallic acid equivalents (GAE) per kg of fresh material in only 15 min, while conventional extraction required 240 min to obtain the same result.

Circulating enterolactone concentrations and prognosis of postmenopausal breast cancer: assessment of mediation by inflammatory markers

Higher lignan exposure has been associated with lower all-cause mortality (ACM) and breast cancer-specific mortality (BCSM) for postmenopausal breast cancer patients. However, the biological mechanisms underpinning these associations are still unclear. We investigated for the first time whether and to what extent the association between enterolactone (ENL), the major lignan metabolite, and postmenopausal breast cancer prognosis is mediated by inflammatory biomarkers. Circulating concentrations of ENL and inflammatory markers were measured in a population-based prospective cohort of 1,743 breast cancer patients recruited between 2002 and 2005 and followed-up until 2009. Hazard ratios (HR) and 95% CIs were estimated using multivariable Cox regression. Mediation analysis was performed to estimate the percentage association between ENL (log2) and ACM, BCSM and distant disease-free survival (DDFS), which is mediated by C-reactive protein (CRP) (log2), as the strongest potential mediator, and also interleukin (IL)-10. Median serum/plasma ENL and CRP concentrations for all patients, including 180 deceased patients, were 23.2 and 17.5 nmol/L, and 3.2 and 6.5 mg/l, respectively. ENL concentrations were significantly inversely associated with ACM, BCSM and DDFS (per doubling of ENL concentrations: HRs 0.93 [0.87, 0.99], 0.91 [0.84, 0.99] and 0.92 [0.87, 0.99]), after adjusting for prognostic factors and BMI. Estimated 18, 14 and 12% of the effects of ENL on ACM, BCSM and DDFS, respectively, were mediated through CRP. No mediational effect of IL-10 was found. We provide first evidence that the proinflammatory marker CRP may partially mediate the association of ENL with postmenopausal breast cancer survival, which supports hormone-independent mechanisms.

Habitual Flavonoid Intake from Fruit and Vegetables during Adolescence and Serum Lipid Levels in Early Adulthood: A Prospective Analysis

Flavonoids have been implicated in the prevention of cardiovascular diseases (CVD). In a prospective approach, we investigated whether habitual flavonoid intake from fruit, vegetables and juices (FlavFVJ) during adolescence is associated with adult levels of serum lipids, one of the main CVD risk factors. This analysis included healthy participants from the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) study, who had provided a fasting blood sample in adulthood (aged 18–39 years), data on FlavFVJ intake during adolescence (females: 9–15 years, males: 10–16 years)—estimated either from multiple 3-day weighed dietary records (n = 257), or from validated biomarker hippuric acid (uHA) excretion from multiple 24-h urine samples (n = 233)—together with information on relevant covariates. In multivariable linear regression analyses, a higher FlavFVJ intake during adolescence was independently associated with higher serum high-density lipoprotein cholesterol (HDL-C) levels among males (P_trend = 0.038); however, the inclusion of adult waist circumference attenuated this association (P_trend = 0.053). FlavFVJ was not associated with triglycerides (TG), total cholesterol (TC) or low-density lipoprotein cholesterol (LDL-C; all P_trend ≥ 0.1), nor was uHA excretion with any serum lipid outcome among males (all P_trend ≥ 0.5). Neither FlavFVJ intake nor uHA excretion was associated with serum lipids among women (all P_trend ≥ 0.1). However, a higher flavonoid intake from fruit and vegetables was independently related to lower LDL-C levels (P_trend = 0.021), while a higher intake from juices was associated with higher LDL-C levels (P_trend = 0.016) among females. In conclusion, a higher flavonoid intake from fruit, vegetables and/or juices during adolescence may be linked to cholesterol levels in early adulthood in a sex- and food source-specific manner.

The urinary phenolic acid profile varies between younger and older adults after a polyphenol-rich meal despite limited differences in in vitro colonic catabolism

PURPOSE

To investigate whether age influences colonic polyphenol metabolism.

METHODS

Healthy participants, younger (n = 8; 23-43 years) and older (n = 13; 51-76 years), followed a 3-day low-polyphenol diet (LPD) and a 3-day high-polyphenol diet (HPD). Urinary phenolic acids (PA), short chain fatty acids (SCFA), pH and gas were monitored, alongside selected colonic bacteria. Human faecal in vitro fermentations of rutin with or without raftiline were used to evaluate the gut microbiota capacity in a subset of both groups.

RESULTS

Total urinary PA were higher in the older group after HPD compared to the younger group (1.5-fold; p = 0.04), with no difference between groups in terms of a change between diets (Δ high-low diet). While 17 PA were detected in all younger participants after HPD, a narrower range (n = 8 to 16 PA) was detected in most (n = 9/13) older participants, with lower level of benzoic acid (19-fold; p = 0.03), vanillic acid (4.5-fold; p = 0.04) but higher hippuric acid (2.7-fold; p = 0.03). Faecal SCFA concentration did not change after HPD within group, with similar differential excretion (Δ high-low diet) between groups. There were no differences between groups for faecal pH, total, faecal bacteria including Flavonifractor plautii, bifidobacteria, and bacteroides. In human in vitro faecal fermentations, seven PAs were detected in both groups after 24 h of rutin fermentation, with no quantitative and modest qualitative differences between groups. Total SCFA in faecal fermentation did not differ between groups, except for butyric acid (twofold higher in the older group; p = 0.009) when rutin was fermented with raftiline over 24 h.

CONCLUSIONS

Urinary phenolic acids were less diverse in older participants despite limited difference in functional capacity of in vitro faecal fermentations.

Impact of red and processed meat and fibre intake on treatment outcomes among patients with chronic inflammatory diseases: protocol for a prospective cohort study of prognostic factors and personalised medicine

INTRODUCTION

Chronic inflammatory diseases (CIDs) are frequently treated with biological medications, specifically tumour necrosis factor inhibitors (TNFi)). These medications inhibit the pro-inflammatory molecule TNF alpha, which has been strongly implicated in the aetiology of these diseases. Up to one-third of patients do not, however, respond to biologics, and lifestyle factors are assumed to affect treatment outcomes. Little is known about the effects of dietary lifestyle as a prognostic factor that may enable personalised medicine. The primary outcome of this multidisciplinary collaborative study will be to identify dietary lifestyle factors that support optimal treatment outcomes.

METHODS AND ANALYSIS

This prospective cohort study will enrol 320 patients with CID who are prescribed a TNFi between June 2017 and March 2019. Included among the patients with CID will be patients with inflammatory bowel disease (Crohn's disease and ulcerative colitis), rheumatic disorders (rheumatoid arthritis, axial spondyloarthritis, psoriatic arthritis), inflammatory skin diseases (psoriasis, hidradenitis suppurativa) and non-infectious uveitis. At baseline (pretreatment), patient characteristics will be assessed using patient-reported outcome measures, clinical assessments of disease activity, quality of life and lifestyle, in addition to registry data on comorbidity and concomitant medication(s). In accordance with current Danish standards, follow-up will be conducted 14-16 weeks after treatment initiation. For each disease, evaluation of successful treatment response will be based on established primary and secondary endpoints, including disease-specific core outcome sets. The major outcome of the analyses will be to detect variability in treatment effectiveness between patients with different lifestyle characteristics.

ETHICS AND DISSEMINATION

The principle goal of this project is to improve the quality of life of patients suffering from CID by providing evidence to support dietary and other lifestyle recommendations that may improve clinical outcomes. The study is approved by the Ethics Committee (S-20160124) and the Danish Data Protecting Agency (2008-58-035). Study findings will be disseminated through peer-reviewed journals, patient associations and presentations at international conferences.

TRIAL REGISTRATION NUMBER

NCT03173144; Pre-results.

Intake of Individual Flavonoids and Risk of Carcinogenesis: Overview of Epidemiological Evidence

Several epidemiological findings have demonstrated that specific flavonoids can be responsible for reduction of the risk of certain cancer types. However, these results are still rather limited, inconclusive and controversial. Therefore, in this comprehensive review article the findings reported to date about the associations between dietary intake of individual flavonoid compounds and cancer incidence are compiled and analyzed. Also, the possible reasons for inconsistencies are brought forth and discussed. As diet is a potentially modifiable factor in our behavioral choices, further large-scale prospective studies with longer follow-up times, different populations, various doses and exposure timing as well as diverse well-controlled confounders are highly needed to confirm or disprove the current epidemiological knowledge about the role of flavonoids on cancer risk. Regarding the promising data to date, more research on bioavailability, metabolism and biological action mechanisms of these plant secondary metabolites is also encouraged.

Association of Polyphenol Biomarkers with Cardiovascular Disease and Mortality Risk: A Systematic Review and Meta-Analysis of Observational Studies

Epidemiologic studies have suggested an inverse association between flavonoids and cardiovascular disease (CVD). However, the results might have been influenced by the use of dietary assessment methods, which are error prone. The aim of this paper was to systematically review and analyse the literature for evidence of associations between polyphenol biomarkers and CVD and mortality risk in observational studies. Eligible studies were identified through PubMed, Web of Science, and reference lists. Multivariable adjusted associations were extracted. Data were log-transformed and pooled using the random effects model. In total, eight studies were included, investigating 16 different polyphenol biomarkers in association with CVD and mortality. Blood and urine were used as biospecimens, and enterolactone, a lignan metabolite, was most often investigated. Three meta-analyses were conducted investigating the association between enterolactone, and all-cause and CVD mortality, and non-fatal myocardial infarction. A 30% and 45% reduced all-cause and CVD mortality risk were revealed at higher enterolactone concentrations. Furthermore, inverse associations were observed between polyphenol biomarkers and all-cause mortality, kaempferol, and acute coronary syndrome. There is evidence to suggest that enterolactone is associated with a lower CVD mortality risk. This emphasises the importance of the role of the microbiota in disease prevention. To strengthen the evidence, more studies are warranted.

Relative validation of 24-h urinary hippuric acid excretion as a biomarker for dietary flavonoid intake from fruit and vegetables in healthy adolescents

PURPOSE

A biomarker for dietary flavonoid intake from fruit and vegetables (FlavFV) is needed to elucidate the relevance of flavonoids from these sources for the prevention of chronic diseases. Urinary hippuric acid (HA)-a major metabolite of flavonoids-is promising in this respect as it was shown to satisfyingly indicate fruit and vegetable consumption in different age groups. Therefore, we validated urinary HA as a biomarker for intake of FlavFV.

METHODS

Analyses included data from 287 healthy adolescents of the DONALD Study (aged 9-16 years) for whom a minimum of two pairs of HA measurements from 24-h urine samples (test method) and FlavFV intake estimated from 3-day weighed dietary records (reference method) existed. Agreement between both methods was assessed by Spearman correlation and cross-classification analyses. Possible confounders of the association were identified by linear regression models. Analyses were performed using a split-sample approach allowing for consecutive exploration (n = 192) and confirmation (n = 95) of results.

RESULTS

Agreement between urinary HA excretion and FlavFV intake was moderate according to correlation analysis in the exploratory sample (r _unadjusted = 0.47, P < 0.0001). Yet, 79 % of the subjects were classified into same/adjacent quartiles, and only 5 % were misclassified into opposite quartiles. These findings were corroborated by analyses in the confirmatory sample (r _unadjusted = 0.64; 88 % in same/adjacent vs. 4 % in opposite quartiles). Body surface area (BSA) was the only relevant covariate in the exploratory sample, and its adjustment improved cross-classification estimates in both subsamples.

CONCLUSIONS

BSA-adjusted 24-h urinary HA excretion represents a suitable biomarker of habitual FlavFV intake in healthy adolescents.

Relevance of fruits, vegetables and flavonoids from fruits and vegetables during early life, mid-childhood and adolescence for levels of insulin-like growth factor (IGF-1) and its binding proteins IGFBP-2 and IGFBP-3 in young adulthood

The growth hormone (GH) insulin-like growth factor (IGF) axis has been linked to insulin metabolism and cancer risk. Experimental evidence indicates that the GH-IGF axis itself can be influenced by dietary flavonoids. As fruit and vegetable (FV) intake is a major source of flavonoid consumption, FV's beneficial health effects may be explained via flavonoids' influence on the GH-IGF axis, but observational evidence is currently rare. We used data from Dortmund Nutritional and Anthropometric Longitudinally Designed Study participants to analyse prospective associations between FV, fruit intake and flavonoid intake from FV (FlavFV) with IGF-1 and its binding proteins IGFBP-2 and IGFBP-3. Subjects needed to provide a fasting blood sample in adulthood (18-39 years) and at least two 3-d weighed dietary records in early life (0·5-2 years, n 191), mid-childhood (3-7 years, n 265) or adolescence (girls: 9-15 years, boys: 10-16 years, n 261). Additional analyses were conducted among those providing at least three 24-h urine samples in adolescence (n 236) to address the predictor urinary hippuric acid (HA), a biomarker of polyphenol intake. Higher fruit intake in mid-childhood and adolescence was related to higher IGFBP-2 in adulthood (P=0·03 and P=0·045). Comparable trends (P=0·045-0·09) were discernable for FV intake (but not FlavFV) in all three time windows. Similarly, higher adolescent HA excretion tended to be related (P=0·06) to higher adult IGFBP-2 levels. Regarding IGFBP-3, a marginal (P=0·08) positive association was observed with FlavFV in mid-childhood only. None of the investigated dietary factors was related to IGF-1. In conclusion, higher fruit and FV intakes during growth may be relevant for adult IGFBP-2, but probably not for IGFBP-3 or IGF-1.

Biomarkers of Dietary Polyphenols in Cancer Studies: Current Evidence and Beyond

Polyphenols, commonly contained in fruits and vegetables, have long been associated with a protective role against multiple diseases and adverse health effects. Generally, in vitro and animal experiments have provided strong positive evidence, whereas evidence from in vivo and human epidemiological studies is not strong enough. Most epidemiological studies to date use food frequency questionnaire based dietary intake estimations, which inevitably incur imprecision. Biomarkers of polyphenol have the potential to complement and enhance current studies. This review performed a literature search of all epidemiological studies or controlled clinical/intervention trials which employed biomarkers of exposure for polyphenols to help assess their anticarcinogenic role, using studies on green tea polyphenols as a study model. Currently, studies on this topic are still limited; breast cancer and prostate cancer were the only widely studied cancer types. Isoflavone is the only widely studied polyphenol. In addition to associations between polyphenols and cancer risks, factors such as host genetic susceptibility, epigenetic modification, and gut microbiome patterns may also impact on the protective roles of polyphenols. More evidence should be collected by utilizing biomarkers of exposure for polyphenols in future epidemiological studies before a clear conclusion can be made.

Phenolic compounds: their journey after intake

Plant foods are rich in phenolic compounds (PCs) that display multifaceted bioactions in health promotion and disease prevention. To exert their bioactivity, they must be delivered to and absorbed in the gastrointestinal (GI) tract, transported in circulation, and reach the target tissues. During the journey from ingestion to target tissues and final excretion, PCs are subjected to modifications by many factors during their absorption, deposition, metabolism and excretion (ADME) and consequently their bioefficacy may be modified. Consistent with all nutrients in foods, PCs must first be released from the food matrix through mechanical, chemical, and enzymatic forces to facilitate absorption along the GI tract, particularly in the upper small intestine section. Further, glycosylation of PCs directs the route of their absorption with glycones being transported through active transportation and aglycones through passive diffusion. After enteral absorption, the majority of PCs are extensively transformed by the detoxification system in enterocytes and liver for excretion in bile, feces, and urine. The journey of PCs from consumption to excretion appears to be comparable to many synthetic medications, but with some dissimilarities in their fate and bioactivity after phase I and II metabolism. The overall bioavailability of PCs is determined mainly by chemical characteristics, bioaccessibility, and ADME. In this review, factors accounting for variation in PCs bioavailability are discussed because this information is crucial for validation of the health benefits of PCs and their mechanism of action.

Nitric oxide and reactive species are modulated in the polyphenol-induced ductus arteriosus constriction in pregnant sheep

OBJECTIVE

Because we have previously demonstrated the relation between polyphenol-rich foods (PRF) consumption and ductus arteriosus constriction, in this work, pregnant sheep were submitted to oral PRF intake for 14 days to understand how this process occurs. Fetal Doppler echocardiography, oxidative and inflammatory biomarkers and total polyphenol excretion were evaluated.

RESULTS

The high polyphenol intake induced ductus arteriosus constriction by 71.6% increase in systolic (P = 0.001) and 57.8% in diastolic velocities (P = 0.002), and 18.9% decrease in pulsatility index (P = 0.033), along with 1.7-fold increase in total polyphenol excretion, 2.3-fold decrease in inflammatory mediator nitric oxide and following redox status changes (mean ± standard deviation): higher protein carbonyls (1.09 ± 0.09 and 1.49 ± 0.31), catalase (0.69 ± 0.39 and 1.44 ± 0.33) and glutathione peroxidase (37.23 ± 11.19 and 62.96 ± 15.03) in addition to lower lipid damage (17.22 ± 2.05 and 12.53 ± 2.11) and nonprotein thiols (0.11 ± 0.04 and 0.04 ± 0.01) found before and after treatment, respectively. Ductal parameters correlated to NOx , catalase, glutathione peroxidase and protein carbonyl.

CONCLUSION

Our results highlight the need to reduce maternal PRF intake in late pregnancy to prevent fetal duct constriction through NO-mediated vasoconstrictive action of polyphenols.

Measuring exposure to the polyphenol metabolome in observational epidemiologic studies: current tools and applications and their limits

Much experimental evidence supports a protective role of dietary polyphenols against chronic diseases such as cardiovascular diseases, diabetes, and cancer. However, results from observational epidemiologic studies are still limited and are often inconsistent. This is largely explained by the difficulties encountered in the estimation of exposure to the polyphenol metabolome, which is composed of ~500 polyphenols distributed across a wide variety of foods and characterized by diverse biological properties. Exposure to the polyphenol metabolome in epidemiologic studies can be assessed by the use of detailed dietary questionnaires or the measurement of biomarkers of polyphenol intake. The questionnaire approach has been greatly facilitated by the use of new databases on polyphenol composition but is limited by bias as a result of self-reporting. The use of polyphenol biomarkers holds much promise for objective estimation of polyphenol exposure in future metabolome-wide association studies. These approaches are reviewed and their advantages and limitations discussed by using examples of epidemiologic studies on polyphenols and cancer. The current improvement in these techniques, along with greater emphasis on the intake of individual polyphenols rather than polyphenols considered collectively, will help unravel the role of these major food bioactive constituents in disease prevention.

Impact of dose on the bioavailability of coffee chlorogenic acids in humans

This article reports an investigation of the effect of dose on the bioavailability of chlorogenic acids in humans based on HPLC-MS²analysis of plasma and urine collected 0–24 h after supplementation.

High concentrations of a urinary biomarker of polyphenol intake are associated with decreased mortality in older adults

Polyphenols might have a role in the prevention of several chronic diseases, but evaluating total dietary polyphenol (TDP) intake from self-reported questionnaires is inaccurate and unreliable. A promising alternative is to use total urinary polyphenol (TUP) concentration as a proxy measure of intake. The current study evaluated the relationship between TUPs and TDPs and all-cause mortality during a 12-y period among older adult participants. The study population included 807 men and women aged 65 y and older from the Invecchiare in Chianti study, a population-based cohort study of older adults living in the Chianti region of Tuscany, Italy. TUP concentrations were measured at enrolment (1998-2000) using the Folin-Ciocalteau assay after a solid-phase extraction. TDPs were also estimated at baseline throughout a validated food frequency questionnaire and using our database based on USDA and Phenol-Explorer databases. We modeled associations using Kaplan-Meier survival and Cox proportional hazards models, with adjustment for potential confounders. During the 12-y follow-up, 274 participants (34%) died. At enrollment, TUP excretion adjusted for age and sex tended to be greater in participants who survived [163 ± 62 mg gallic acid equivalents (GAE)/d)] than in those who died (143 ± 63 mg GAE/d) (P = 0.07). However, no significant differences were observed for TDPs. In the multivariable Cox model, participants in the highest tertile of TUP at enrolment had a lower mortality rate than those in the lowest tertile [HR = 0.70 (95% CI: 0.49-0.99); P-trend = 0.045], whereas no significant associations were found between TDP and overall mortality. TUP is an independent risk factor for mortality among community-dwelling older adults, suggesting that high dietary intake of polyphenols may be associated with longevity.

Estimation of dietary intake and patterns of polyphenol consumption in Polish adult population

PURPOSE

Polyphenols play an important role in the prevention of degenerative diseases, particularly cardiovascular diseases and cancers. The purpose was to estimate dietary polyphenol intake in Polish adults, using own database of food polyphenols, and to establish main dietary sources of polyphenols.

MATERIAL AND METHODS

Polish men and women (6661) aged 20-74 years were randomly selected from the Polish National Multicenter Health Survey (WOBASZ). Subjects` daily food consumption was estimated by the 24-hour recall method and was continued for 3 years. It was determined on this basis, that 96 plant foods and plant food products were consumed. The own dietary database of polyphenol contents in food was used to calculate polyphenol intakes in the subjects. The daily total polyphenol intakes were calculated for both genders in individual age categories: 20-40 years, 41-60 years and 61-74 years.

RESULTS

The average polyphenol consumption for the men was 1172 mg/day, and for the women it made 1031 mg/day. Plant food categories such as beverages, vegetables, fruits and cereals were found to be significant sources of polyphenols, of which tea, coffee, potatoes, apples and white bread were the main contributors.

CONCLUSIONS

The amount of polyphenol consumption in Polish adult population is similar to the polyphenol intake in other countries populations, accounting roughly for 1g of polyphenols for both genders and different age groups. Patterns of polyphenol consumption, however, vary for genders and age groups. Polyphenols are characterized by a spectrum of antioxidant capabilities, therefore future studies should focus on dietary intakes of individual polyphenols.

Associations between flavonoids and cardiovascular disease incidence or mortality in European and US populations

Twenty publications from twelve prospective cohorts have evaluated associations between flavonoid intakes and incidence or mortality from cardiovascular disease (CVD) among adults in Europe and the United States. The most common outcome was coronary heart disease mortality, and four of eight cohort studies reported significant inverse associations for at least one flavonoid class (multivariate adjusted p(trend) < 0.05). Three of seven cohorts reported that greater flavonoid intake was associated with lower risk of incident stroke. Comparisons among the studies were difficult because of variability in the flavonoid classes included, demographic characteristics of the populations, outcomes assessed, and length of follow-up. The most commonly examined flavonoid classes were flavonols and flavones combined (11 studies). Only one study examined all seven flavonoid classes. The flavonol and flavone classes were most strongly associated with lower coronary heart disease mortality. Evidence for protection from other flavonoid classes and CVD outcomes was more limited. The hypothesis that flavonoid intakes are associated with lower CVD incidence and mortality requires further study.

Naringin induces death receptor and mitochondria-mediated apoptosis in human cervical cancer (SiHa) cells

Cervical cancer is the second most common female cancer worldwide, and it remains a challenge to manage preinvasive and invasive lesions. Fruit-based cancer prevention entities, such as flavonoid and their derivatives, have demonstrated a marked ability to inhibit preclinical models of epithelial cancer cell growth and tumor formation. Here, we extend the role of naringin-mediated chemoprevention to that of cervical carcinogenesis. The present study sought to investigate the therapeutic potential effect of naringin on apoptosis in human cervical SiHa cancer cells. Viability of SiHa cells was evaluated by the MTT assay, apoptosis and mitochondrial transmembrane potential by flow cytometry, and pro-apoptotic related genes by Real-time quantitative PCR. Naringin showed a 50% inhibition of SiHa human cervical cancer cells at a concentration of 750μM. SiHa cells exhibited apoptotic cell death, intranucleosomal DNA fragmentation, morphological changes and decline in the mitochondrial transmembrane potential. In addition, administration of naringin increased the expression of caspases, p53 and Bax, Fas death receptor and its adaptor protein FADD. These results suggest that the induction of apoptosis by naringin is through both death-receptor and mitochondrial pathways. Taken together, our results suggest that naringin might be an effective agent to treat human cervical cancer.

Application of dietary phenolic biomarkers in epidemiology: past, present, and future

Phenolics are a large group of plant compounds that have been associated with protective health effects against several chronic diseases due to their potential antioxidant, anti-inflammatory, and anticarcinogenic properties. Consequently, in nutritional epidemiology it is essential to make an accurate assessment of phenolic exposure to evaluate their protective activities against human diseases. Self-reported questionnaires and biomarkers are the two main methods used for estimating dietary phenolics. Despite the limitations of self-reported methods, they are still an acceptable and useful measure. Meanwhile, nutritional biomarkers provide an alternative, more accurate measure, but they are expensive, and to date there are few validated biomarkers of phenolic intake. Nowadays, new analytical techniques, using both targeted and untargeted metabolomic approaches, play an important part in the rapid increase in the understanding of phenolic bioavailability and, consequently, have provided new potential biomarkers in small trials. In the near future, these dietary biomarkers should be tested in large epidemiological studies. Furthermore, the use of two independent measures-questionnaires and biomarkers-together provides a more thorough analysis of true phenolic exposure. Indeed, the challenge in the long term is to combine the information from biomarkers and self-reported questionnaires to clarify the relationship between dietary phenolics and disease.

Flavonoid intakes in the Baltimore Longitudinal Study of Aging

Major sources of flavonoids were identified, and mean intakes over several decades were reported, among 1638 participants (mean age 62.1 +/- 16.0 y), of the Baltimore Longitudinal Study of Aging (BLSA). Dietary data were collected using 7-day diet records during three time periods (1980s, 1990s and 2000-present), and the USDA flavonoid, proanthocyanidin and isoflavone databases were used to estimate dietary flavonoid intakes. Dietary intake data were divided according to decade of visit. Foods were matched with appropriate foods in the USDA databases. Mixed dishes were disaggregated to individual foods and a similar procedure was followed. Total flavonoids and five sub-classes of flavonoids, including flavonols, flavones, flavanones, flavan-3-ols and anthocyanidins, were computed by summing appropriate compounds. The median intakes of flavonoids and the contributions of various foods to intakes were calculated by decade. Age and sex adjusted mean (SE) daily intakes of flavonoids increased from 250 (7.4) in the 1980s to 280 (9.9) mg in the 2000s. Top contributors of flavonoids were tea, apple/pear (and juices), citrus fruits (and juices), peaches, plums, grapes, nectarines (and juices) and chocolate. The data show an increase in the consumption of flavonoids over the three decades, which appears to be related to intake of fruit.

Phenolic compound production by different morphological phenotypes in hairy root cultures of Fagopyrum tataricum Gaertn

Hairy roots were obtained after inoculating sterile young stems of Fagopyrum tataricum with Agrobacterium rhizogenes R1000. The established roots displayed two morphological phenotypes when cultured on hormone-free medium containing Murashige-Skoog salts and vitamins. The thin phenotype had a higher growth rate than the thick phenotype. Further, the phenolic compound content of the thin phenotype was higher than that of the thick phenotype. In terms of their total dry weight, the thin phenotype produced an almost double amount of (-)-epigallocatechin as well as more than 51.5% caffeic acid, 65% chlorogenic acid, and 40% rutin compared to the thick phenotype after 21 days of culture. Therefore, selection of the optimal morphological phenotype of hairy roots of tartary buckwheat is an important factor for improved phenolic compound production.

Towards a unifying, systems biology understanding of large-scale cellular death and destruction caused by poorly liganded iron: Parkinson's, Huntington's, Alzheimer's, prions, bactericides, chemical toxicology and others as examples

Exposure to a variety of toxins and/or infectious agents leads to disease, degeneration and death, often characterised by circumstances in which cells or tissues do not merely die and cease to function but may be more or less entirely obliterated. It is then legitimate to ask the question as to whether, despite the many kinds of agent involved, there may be at least some unifying mechanisms of such cell death and destruction. I summarise the evidence that in a great many cases, one underlying mechanism, providing major stresses of this type, entails continuing and autocatalytic production (based on positive feedback mechanisms) of hydroxyl radicals via Fenton chemistry involving poorly liganded iron, leading to cell death via apoptosis (probably including via pathways induced by changes in the NF-κB system). While every pathway is in some sense connected to every other one, I highlight the literature evidence suggesting that the degenerative effects of many diseases and toxicological insults converge on iron dysregulation. This highlights specifically the role of iron metabolism, and the detailed speciation of iron, in chemical and other toxicology, and has significant implications for the use of iron chelating substances (probably in partnership with appropriate anti-oxidants) as nutritional or therapeutic agents in inhibiting both the progression of these mainly degenerative diseases and the sequelae of both chronic and acute toxin exposure. The complexity of biochemical networks, especially those involving autocatalytic behaviour and positive feedbacks, means that multiple interventions (e.g. of iron chelators plus antioxidants) are likely to prove most effective. A variety of systems biology approaches, that I summarise, can predict both the mechanisms involved in these cell death pathways and the optimal sites of action for nutritional or pharmacological interventions.

Urinary metabolites as biomarkers of polyphenol intake in humans: a systematic review

BACKGROUND

To identify associations between polyphenol intake and health and disease outcomes in cohort studies, it is important to identify biomarkers of intake for the various compounds commonly consumed as part of the diet.

OBJECTIVE

The objective of this systematic review was to assess the usefulness of polyphenol metabolites excreted in urine as biomarkers of polyphenol intake in humans.

DESIGN

The method included a structured search strategy for polyphenol intervention studies on Ovid MEDLINE, EMBASE (Ovid), and Cochrane databases; formal inclusion and exclusion criteria; data extraction into an Access database; validity assessment; and meta-analysis.

RESULTS

One hundred sixty-two controlled intervention studies with polyphenols were included, and mean recovery yield and correlations with the dose ingested were determined for 40 polyphenols. Polyphenols such as daidzein, genistein, glycitein, enterolactone, and hydroxytyrosol showed both a high recovery yield (12-37%) and a high correlation with the dose (Pearson's correlation coefficients: 0.67-0.87), which showed good sensitivity and robustness as biomarkers of intake throughout the different studies. Weaker recovery for anthocyanins (0.06-0.2%) and weaker correlations with dose [Pearson's correlation coefficients: 0.21-0.52 for hesperidin, naringenin, (-)-epicatechin, (-)-epigallocatechin, quercetin, and 3 microbial metabolites of isoflavones (dihydrodaidzein, equol, and O-desmethylangolensin)] suggest that they are currently less suitable as biomarkers of intake.

CONCLUSIONS

These data confirm the value of certain urinary polyphenols as biomarkers of intake. A validation in populations is now needed to evaluate their specificity, sensitivity, and responsiveness to dose under free-living conditions.

Antioxidant mechanisms of Quercetin and Myricetin in the gas phase and in solution--a comparison and validation of semi-empirical methods

Flavonoids have long been recognized for their general health-promoting properties, of which their antioxidant activity may play an important role. In this work we have studied the properties of two flavonols, quercetin and myricetin, using semi-empirical methods in order to validate the application of the recent Parametric Model 6 and to understand the fundamental difference between the two molecules. Their geometries have been optimized and important molecular properties have been calculated. The energetic of the possible antioxidant mechanisms have also been analyzed. The two studied flavonols do not differ significantly in their molecular properties, but the antioxidant mechanisms by which they may act in solution can be rather different. Moreover, we also show that the Parametric Model 6 can produce reliable information for this type of compounds.

Electrospray ionization tandem mass spectrometry fragmentation of protonated flavone and flavonol aglycones: a re-examination

Flavonoids are important phytochemicals which have been intensively studied in the last decades in view of their antioxidant activity, which is of particular importance in the case of flavones and flavonols, that differ in a single 3-OH group. Mass spectrometry has been used to elucidate the structures of many types of flavonoids and their metabolites. The work we present here is focused on the electrospray ionization tandem mass spectrometry (ESI-MS/MS) analysis of flavone and flavonols aglycones. Their fragmentation mechanisms in the positive ion mode are described and compared with previously reported mechanisms. We analyzed flavonoid derivatives produced by reaction of the flavonoids with chemically synthesized hypohalous acids (HOCl, HOBr and HOI) and peroxynitrite, reactive species involved in the inflammatory response. All the proposed pathways have been analyzed using computational chemistry methods in order to seek for possible variations and establish the most plausible ones. We observed that the losses of one and two CO molecules can be useful in terms of antioxidant activity prediction. Losses of one and two C(2)H(2)O groups are also informative in terms of structure and activity predictions. The retro-Diels-Alder fragmentations, and subsequent neutral losses, were reviewed and, according to our calculations, the most plausible structures for the product ions were established. These fingerprints will be of great value for differentiating flavonoids from other compounds in complex biological mixtures and for a thorough structural identification of flavonoid aglycones and their in vivo metabolites.

Introducing N-glycans into natural products through a chemoenzymatic approach

The present study describes an efficient chemoenzymatic method for introducing a core N-glycan of glycoprotein origin into various lipophilic natural products. It was found that the endo-beta-N-acetylglucosaminidase from Arthrobactor protophormiae (Endo-A) had broad substrate specificity and can accommodate a wide range of glucose (Glc)- or N-acetylglucosamine (GlcNAc)-containing natural products as acceptors for transglycosylation, when an N-glycan oxazoline was used as a donor substrate. Using lithocholic acid as a model compound, we have shown that introduction of an N-glycan could be achieved by a two-step approach: chemical glycosylation to introduce a monosaccharide (Glc or GlcNAc) as a handle, and then Endo-A catalyzed transglycosylation to accomplish the site-specific N-glycan attachment. For those natural products that already carry terminal Glc or GlcNAc residues, direct enzymatic transglycosylation using sugar oxazoline as the donor substrate was achievable to introduce an N-glycan. It was also demonstrated that simultaneous double glycosylation could be fulfilled when the natural product contains two Glc residues. This chemoenzymatic method is concise, site-specific, and highly convergent. Because N-glycans of glycoprotein origin can serve as ligands for diverse lectins and cell-surface receptors, introduction of a defined N-glycan into biologically significant natural products may bestow novel properties onto these natural products for drug discovery and development.