[Show abstract][Hide abstract] ABSTRACT: This study investigated and compared the absorption, metabolism, and subsequently, the
tissue distribution and excretion of hydroxytyrosol (HT) administered either in its free form
or through its naturally occurring esterified precursors, namely oleuropein (OLE) and its aglycone
forms known as secoiridoids (SEC). Here, rats were fed a diet supplemented with the
equivalent of 5 mg phenol/kg/day for 21 days and the HT metabolites in the gastrointestinal
digesta (stomach, small intestine and caecum), plasma, urine and metabolic tissues (liver
and kidney) were analysed. Compared to HT and SEC, OLE showed greater stability during
digestion, and, consequently, the bioavailability based on the urine excretion of HT metabolites
was higher. OLE, as a glycoside molecule, reached the colon unaltered generating
more diverse microbial metabolites. In terms of bioavailability, findings suggest that OLE
might be the most suitable precursor of HT for incorporation into foods or nutraceutical
[Show abstract][Hide abstract] ABSTRACT: In the present study, simultaneous extraction of natural antioxidants (phenols and carotenoids) in complex matrices, such as tomato sauces, is presented. The tomato sauce antioxidant compounds studied were the phenolics hydroxytyrosol, from virgin olive oil, quercetin and its derivatives, from onions, and quercetin-rutinoside as well as the carotenoid, lycopene (cis and trans), from tomatoes. These antioxidant compounds were extracted simultaneously with n-hexane/acetone/ethanol (50/25/25, v/v/v). The phenolics were analysed by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS), and lycopene (cis- and trans-forms) was analysed using high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD). After studying the parameters of these methods, they were applied to the analysis of virgin olive oil, fresh onion, tomato concentrate and tomato powder, and commercial five tomato sauces. Subsequently, the results obtained in our laboratory were compared with those from the Gallina Blanca Star Group laboratory.
[Show abstract][Hide abstract] ABSTRACT: An understanding of causal relations between phenol intake and its beneficial effects on health is hindered by the lack of robust biological markers of its exposure. This is particularly relevant in mid/long-term nutritional intervention studies. An analytical methodology based on UPLC-MS/MS has been developed to determine the metabolites of the phenolic compounds from olive oil and thyme in biological fluids after a sustained intake of two phenol-enriched olive oils for their further use as compliance biomarkers. In a randomized, double-blind, controlled, cross-over trial, 33 hypercholesterolemic volunteers received during 3 weeks 25 mL/day of (1) raw Virgin Olive Oil with a low phenolic content as a control (80 mg total phenols / kg oil; VOO), (2) Functional Virgin Olive Oil enriched with its own phenolics (500 mg total phenols / kg oil; FVOO), and (3) Functional Virgin Olive Oil enriched with its own phenolics plus complementary phenolics from Thyme (500 mg total phenols / kg oil, 50% from olive oil and 50% from thyme respectively; FVOOT). Plasma and 24 h-urine samples were collected. The results showed that some hydroxytyrosol (HT) metabolites presented low specificity as biomarkers of intake. However, hydroxytyrosol sulfate and hydroxytyrosol acetate sulfate appeared to be suitable biomarkers for monitoring compliance with olive oil intake as their values in plasma or/and 24-h urine were significantly higher after FVOO compared to baseline pre-intervention concentrations. They were also significantly correlated with the monitored level of compliance. On the other hand, metabolites derived from thyme were more specific, thymol sulfate and hydroxyphenylpropionic acid sulfate being the metabolites with the largest increase in both plasma and 24-h urine, whereas urinary p-cymene-diol glucuronide presented the greatest increase post-treatment. Their urinary excretion values also displayed significant correlations with the level of compliance and they were defined as FVOOT compliance biomarkers. This study enabled robust quantitative and qualitative compliance biomarkers after the ingestion of two phenol-enriched olive oils to be determined and provided a thorough analysis of the true phenolic exposure after a sustained consumption that could be further related to expected biological effects.
Full-text · Article · Nov 2014 · Food Research International
[Show abstract][Hide abstract] ABSTRACT: Olive oil phenolic compounds are extensively metabolized into methylated and glucurono- and sulpho-conjugates of hydroxytyrosol (HT), the detected circulating forms in plasma. However, these conjugates are considered to be pharmacologically inactive and their in situ deconjugation in certain sites appears to be an absolute requirement to exert their beneficial effects. In the present study, red blood cells (RBCs) were analysed in rats after an oral administration of an olive phenolic extract and their in vivo deconjugation capacity of hydroxytyrosol phase II metabolites was assessed. A decreasing trend of the conjugated forms of HT and a parallel free HT increasing in concentration up to 6 h was observed in RBCs, indicating that HT conjugates might be hydrolysed intracellularly in RBCs. Our results suggest that RBCs could play a pivotal role in the distribution and bioavailability of circulating phenols and their metabolites and also in protection against oxidative damage to cells.
[Show abstract][Hide abstract] ABSTRACT: Olive oils flavoured with edible herbs have grown in popularity because of their added value and potential health benefits. However, the combined presence of different phytochemicals from olive oil and herbs requires study of their possible interactions during intestinal transport and metabolism. The aim of this study was firstly to evaluate the effect on bioaccessibility of the co-occurring bioactive compounds from olive oil and thyme through an in vitro digestion model of three extracts: olive extract (OE), thyme extract (TE) and a combination of both (OTE). The bioaccessible fractions were exposed to Caco-2 and HepG-2 cell models, as well as to a co-culture of both of these. Results indicated that the bioaccessibility of hydroxytyrosol was enhanced when OTE was digested. After Caco-2 cells exposure, no significant differences were observed in hydroxytyrosol transport, whereas the main flavonoids from thyme seemed to undergo an enhanced basolateral permeation when both phenolic sources where exposed.
[Show abstract][Hide abstract] ABSTRACT: The growing interest in β-glucans and the dietary recommendations of an exact daily intake will require rapid and accurate quantification methods of β-glucans that can be used routinely by the food industry. The objective of the present study was to adapt the standard enzymatic procedure (Megazyme method) to quantify (1-3)(1-4)-β-D-glucans to micro-plate format and further application to analyze cereal based samples with a wide range of (1-3)(1-4)-β-D-glucan content (from 0,27 to 75%). The samples used in this study included two breads (wheat and barley/wheat), barley flours (4% and 8% β-glucans) and two samples of oat bran (28% and 75% β-glucans). Results showed that there was no significant differences in the quantification of β-(1,3)(1,4)-D-glucans in different samples by using the Megazyme method or the micro-method. The methodology developed was also compared in terms of sensitivity and reproducibility with the results obtained by the Megazyme kit method and no differences were observed. In conclusion, the developed method allows the β-glucan quantification (specifically for mixed-linkage [(1-3)(1-4)]-β-D-glucan) to be conducted rapidly and by an efficient and sensitive micro-method in a wide range of concentrations.
No preview · Article · Mar 2014 · Journal of Cereal Science
[Show abstract][Hide abstract] ABSTRACT: The aim of this work was to examine whether bioactives in thyme could enhance the antioxidant capacity of phenolics in virgin olive oil and their bioavailability in Wistar rats. After acute oral administration of extracts from olive cake (OE), thyme (TE) or their combination (OTE), blood samples were collected from 0 to 360 min. Plasma antioxidant status was analyzed by DPPH and FRAP in plasma and by SOD, CAT and GPx activities in erythrocytes. Plasma pharmacokinetics of the main metabolites of bioactives in olive oil and thyme were characterized. Plasma non-enzymatic antioxidant capacity was significantly modulated by OE, TE, and OTE in a time-, assay, and extract-dependent manner. OE, TE, and OTE all significantly decreased superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity and catalase (CAT) activity was increased. Pharmacokinetic results showed that plasma concentration (Cmax) of the main olive phenolic metabolites in rats fed with OTE were similar to those of OE. These results indicate that an enhanced bioavailability of olive phenolic compounds could occur in the presence of thyme, although any synergistic effect was observed in the antioxidant status when both phenolic extracts were administered. Antioxidant protection by phenolics from olive and thyme against oxidative stress occurs primarily through a direct antioxidant effect and may be related to the phenolic plasmatic metabolites.
[Show abstract][Hide abstract] ABSTRACT: Spices, like vegetables, fruit, and medicinal herbs, are known to possess a variety of antioxidant effects and other biological activities. Phenolic compounds in these plant materials are closely associated with their antioxidant activity, which is mainly due to their redox properties and their capacity to block the production of reactive oxygen species. More recently, their ability to interfere with signal transduction pathways involving various transcription factors, protein kinases, phosphatases, and other metabolic enzymes has also been demonstrated. Many of the spice-derived compounds which are potent antioxidants are of great interest to biologists and clinicians because they may help protect the human body against oxidative stress and inflammatory processes. It is important to study the bioactive compounds that can modulate target functions related to defence against oxidative stress, and that might be used to achieve health benefits individually. In the present review, an attempt has been made to summarize the most current scientific evidence about the in vitro and in vivo effects of the bioactive compounds derived from herbs and spices, focused on anti-inflammatory and antioxidant effects, in order to provide science-based evidence for the traditional uses and develop either functional foods or nutraceuticals.
Full-text · Article · Jun 2013 · Critical reviews in food science and nutrition
[Show abstract][Hide abstract] ABSTRACT: Three different functional phenol-enriched virgin olive oils (FVOO) were prepared with a phenolic content of 250 (L-FVOO), 500 (M-FVOO), and 750mg (H-FVOO) total phenols/kg. In a randomised, cross-over study with 12 healthy volunteers, the pharmacokinetics of phenolic biological metabolites was assessed. An increasing linear trend was observed for hydroxytyrosol sulfate, the main phenolic metabolite quantified in plasma, with C(max) values of 1.35, 3.32, and 4.09μmol/l, and AUC mean values of 263.7, 581.4, and 724.4μmol/min for L-FVOO, M-FVOO, and H-FVOO, respectively. From our data an acute intake of phenol-enriched olive oils promotes a dose-dependent response of phenol conjugate metabolites in human plasma. Also, we point out for the first time hydroxytyrosol acetate sulfate as a main biological metabolite of hydroxytyrosol from olive oil ingestion.
[Show abstract][Hide abstract] ABSTRACT: We report progress in the study of olive oil phenolic metabolites in humans and identify a new hydroxytyrosol metabolite called hydroxytyrosol acetate sulphate, which was determined using tandem MS, after ingestion of 30ml of olive oil with a high phenolic content (500mg/kg oil), reaching a maximum concentration of 1.63μM. In order to understand and explain the generation of this metabolite, two different pathways are proposed.
[Show abstract][Hide abstract] ABSTRACT: Epidemiological data suggest that plant-derived phenolics beneficial effects include an inhibition of LDL oxidation. After applying a screening method based on 2,4-dinitrophenyl hydrazine- protein carbonyl reaction to 21 different plant-derived phenolic acids, we selected the most antioxidant ones. Their effect was assessed in 5 different oxidation systems, as well as in other model proteins. Mass-spectrometry was then used, evidencing a heterogeneous effect on the accumulation of the structurally characterized protein carbonyl glutamic and aminoadipic semialdehydes as well as for malondialdehyde-lysine in LDL apoprotein. After TOF based lipidomics, we identified the most abundant differential lipids in Cu(++)-incubated LDL as 1-palmitoyllysophosphatidylcholine and 1-stearoyl-sn-glycero-3-phosphocholine. Most of selected phenolic compounds prevented the accumulation of those phospholipids and the cellular impairment induced by oxidized LDL. Finally, to validate these effects in vivo, we evaluated the effect of the intake of a phenolic-enriched extract in plasma protein and lipid modifications in a well-established model of atherosclerosis (diet-induced hypercholesterolemia in hamsters). This showed that a dietary supplement with a phenolic-enriched extract diminished plasma protein oxidative and lipid damage. Globally, these data show structural basis of antioxidant properties of plant-derived phenolic acids in protein oxidation that may be relevant for the health-promoting effects of its dietary intake.
[Show abstract][Hide abstract] ABSTRACT: In the present study, a selective and sensitive method, based on microelution solid-phase extraction (μSPE) plate and ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) was validated and applied to determine the plasma metabolites of the bioactive compounds of thyme. For validation process, standards of the more representative components of the phenolic and monoterpene fractions of thyme were spiked in plasma samples and then the quality parameters of the method were studied. Extraction recoveries (%R) of the studied compounds were higher than 75%, and the matrix effect (%ME) was lower than 18%. The LODs ranged from 1 to 65μg/L, except for the thymol sulfate metabolite, which was 240μg/L. This method was then applied for the analysis of rat plasma obtained at different times, from 0 to 6h, after an acute intake of thyme extract (5g/kg body weight). Different thyme metabolites were identified and were mainly derived from rosmarinic acid (coumaric acid sulfate, caffeic acid sulfate, ferulic acid sulfate, hydroxyphenylpropionic acid sulfate, dihydroxyphenylpropionic acid sulfate and hydroxybenzoic acid) and thymol (thymol sulfate and thymol glucuronide). The most abundant thyme metabolites generated were hydroxyphenylpropionic acid sulfate and thymol sulfate, their respective concentrations in plasma being 446 and 8464μM 1h after the intake of the thyme extract.
Full-text · Article · Aug 2012 · Journal of chromatography. B, Analytical technologies in the biomedical and life sciences
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Procyanidins are extensively metabolized via phase-II and microbial enzymes. However, their distribution in the body is not well characterized. AIM: This study investigates the distribution of procyanidins (monomers and dimers) and their phase-II metabolites in plasma and tissues (thymus, heart, liver, testicle, lung, kidney, spleen and brain). METHODS: Wistar rats were fed with 1 g of cocoa cream (CC), 50 mg of procyanidin hazelnut skin extract (PE) and 50 mg PE in 1 g CC (PECC). The rats were killed at 0, 1, 1.5, 2, 3, 4 and 18 h after gavage, and the plasma and tissues were analyzed by UPLC-MS/MS. RESULTS: Epicatechin-glucuronide was the main metabolite in the plasma after the CC intake, with C (max) at 423 nM and t (max) at 2 h, and methyl catechin-glucuronide (301 nM, 2 h) was the main metabolite in the plasma after the PE intake. As a result of the PECC enrichment, epicatechin-glucuronide (452 nM, 1.5 h) and catechin-glucuronide (297 nM, 2 h) were the main metabolites in the plasma. Methyl catechin-glucuronide was found in the liver after PE (8 nmol/g tissue, 4 h) and PECC (8 nmol/g, 1.5 h). The kidney was found to contain a high concentration of phase-II metabolites of procyanidins and is therefore thought to be the main site of metabolism of the compounds. Methyl catechin-sulfate (6.4 nmol/g, 4 h) was only quantified in the brain and after PE intake. Catechin metabolites were not found in the spleen or heart. Phenolic acids were detected in all tissues. CONCLUSIONS: The formulation of a product enriched or fortified with procyanidins is a way to increase their bioavailability, with clear effects on the plasmatic pharmacokinetics, and a greater accumulation of phenolic metabolites in such tissues as the liver, kidney, lung and brain.
Full-text · Article · Jul 2012 · European Journal of Nutrition
[Show abstract][Hide abstract] ABSTRACT: An improved method, based on ultra-performance liquid chromatography (UPLC) coupled to tandem mass spectrometry (MS/MS), has been developed to determine the bioactive dipeptides carnosine (CAR) and anserine (ANS) in chicken broth. These analytes are hydrophilic (polar) and in order to improve their retention, the chromatographic mode used was hydrophilic interaction chromatography (HILIC) (1.7 μm particle size). In order to remove the salt before the chromatographic analysis of the chicken broth (0.8%, w/w), an exhaustive sample pre-treatment strategy was necessary since the salt is not volatilized and could block the ionization source and lead to signal suppression. The chicken broth was firstly centrifuged to remove the fat and chicken proteins, and then was pretreated by off-line solid-phase extraction (SPE), using traditional cartridges, or off-line μElution plate (μSPE), using microplates, and the results were compared. Due to the high polar character of the dipeptides studied and the sample matrix, these compounds were not retained in the sorbent hydrophilic-lipophilic balanced (HLB) and were eluted in the load step, whereas the salt was retained in the sorbent. This fact was observed by the addition of silver nitrate in the chicken broth extract, where before the SPE or μSPE a white precipitate (silver chloride) was formed and after the SPE or μSPE this precipitate was not observed. By using these sample pre-treatment strategies, the extraction recoveries were higher than 80%, and the matrix effect was lower than 12%. Once the improved method was developed, the quality parameters of the method were studied. The LODs and LOQs of the CAR and ANS were lower than 6 and 1.8 μg/l, respectively. Then, the method was applied to analyse a commercial chicken broth. This improved method allowed determining CAR and ANS between 6 and 10mg dipeptide/l chicken broth in 10 min (sample pre-treatment and chromatographic analysis). Therefore, the proposed improved method is concluded to be rapid, sensitive and selective for the determination of polar compounds by MS in samples that contain salt.
[Show abstract][Hide abstract] ABSTRACT: Besides affecting the oil's sensorial characteristics, the presence of herbs and spices has an impact on the nutritional value of the flavored oils. The aim of the study was to develop a new product based on the phenol-enrichment of a virgin olive oil with both its own phenolic compounds (secoiridoid derivatives) plus additional complementary phenols from thyme (flavonoids). We studied the effect of the addition of phenolic extracts (olive cake and thyme) on phenolic composition, oxidative stability, antioxidant activity, and bitter sensory attribute of olive oils. Results showed that flavonoids from thyme appeared to have higher transference ratios (average 89.7%) from the phenolic extract to oil, whereas secoiridoids from olive presented lower transference ratios (average 35.3%). The bitter sensory attribute of the phenol-enriched oils diminished with an increase of the concentration of phenols from thyme, which might denote an improvement in the consumer acceptance.
Full-text · Article · Mar 2012 · Journal of Agricultural and Food Chemistry
[Show abstract][Hide abstract] ABSTRACT: The distribution and accumulation of olive oil phenolic compounds in the body are topics lacked of information. The aim of this study was to evaluate the bioavailability, metabolism and distribution of phenolic compounds from olive cake.
The metabolism and distribution of phenolic compounds were examined by UPLC-MS/MS after an acute intake of a phenolic extract from olive cake, analyzing plasma and tissues (heart, brain, liver, kidney, spleen, testicle and thymus) 1, 2 and 4 h after ingestion using Wistar rats as the in vivo model. The results showed a wide distribution of phenolic compounds and their metabolites in the tissues, with a main detoxification route through the kidneys. Highlighting the quantification of the free forms of some phenolic compounds, such as oleuropein derivative in plasma (Cmax 4 h: 24 nmol/L) and brain (Cmax 2 h: 2.8 nmol/g), luteolin in kidney (Cmax 1 h: 0.04 nmol/g), testicle (Cmax 2 h: 0.07 nmol/g) and heart (Cmax 1 h: 0.47 nmol/g); and hydroxytyrosol in plasma (Cmax 2 h: 5.2 nmol/L), kidney (Cmax 4 h: 3.8 nmol/g) and testicle (Cmax 2 h: 2.7 nmol/g).
After a single ingestion of olive oil phenolic compounds, these were absorbed, metabolized and distributed through the blood stream to practically all parts of the body, even across the blood-brain barrier.
No preview · Article · Mar 2012 · Molecular Nutrition & Food Research
[Show abstract][Hide abstract] ABSTRACT: Flavonoids are metabolized by the gut microflora giving rise to a wide range of phenolic acids that may exert systemic effects in the body. Nevertheless, the colonic metabolism pathways and the function of the metabolites formed are poorly studied. In the present study, the individual colonic metabolism of three subclasses of flavonoids (flavonols, flavones and flavanones) and phenolic acids was evaluated. For this, seven standards of flavonoids (quercetin, quercetin–rhamnoside, quercetin–rutinoside, myricetin, luteolin, naringenin and kaempferol–rutinoside) and two phenolic acids (protocatechuic acid and gallic acid) were submitted to an in vitro fermentation model using rat colonic microflora. Simultaneously, a nuts–cocoa cream enriched with these standards of flavonoids was incubated and the colonic metabolism of these compounds was evaluated. The results showed that the greatest number of colonic metabolites came from the fermentation of quercetin and quercetin–rhamnoside, and the maximum concentration of fermentation products was observed after 48 h of fermentation. On the other hand, a smaller number of fermentation products were observed after the colonic fermentation of kaempferol–rutinoside, naringenin, luteolin and myricetin. The phenolic acids were slightly metabolized by the colonic microflora.
[Show abstract][Hide abstract] ABSTRACT: Procyanidins are present in a wide range of dietary foods and their metabolism is well known. Nevertheless, the biological target and their distribution are topics lacking information. The purpose of the present work was to study the metabolism and distribution of procyanidins and their metabolites in rat plasma and different tissues, such as liver, brain, lung, kidney, intestine, testicle, spleen, heart and thymus, after 2 h of an acute intake of hazelnut extract rich in procyanidins (5 g kg(-1) of rat body weight). The interest of an acute intake of procyanidins instead of repeated low doses from daily ingestion of is to achieve a concentration of metabolites in the tissues that allows their detection and quantification. The results showed that catechin and epicatechin-glucuronide, methyl catechin and epicatechin-glucuronide and methyl catechin and epicatechin-sulphate were detected in plasma samples at the μmol level. On the other hand, catechin-glucuronide, methyl catechin-glucuronide and methyl catechin-sulphate were identified in some tissues, such as thymus, intestine, lung, kidney, spleen and testicle at the nmol level. Procyanidins with a low grade of polymerization (dimers and trimers) were detected in plasma samples and the intestine. Additionally, a wide range of simple aromatic acids from fermentation by the colonic microflora was detected in all tissues studied.
[Show abstract][Hide abstract] ABSTRACT: Phenolic compounds are one of the main reasons behind the healthy properties of virgin olive oil (VOO). However, their daily intake from VOO is low compared with that obtained from other phenolic sources. Therefore, the intake of VOO enriched with its own phenolic compounds could be of interest to increase the daily dose of these beneficial compounds. To evaluate the effectiveness of enrichment on their bioavailability, the concentration of phenolic compounds and their metabolites in human plasma (0, 60, 120, 240 and 300 min) from thirteen healthy volunteers (seven men and six women, aged 25 and 69 years) was determined after the ingestion of a single dose (30 ml) of either enriched virgin olive oil (EVOO) (961·17 mg/kg oil) or control VOO (288·89 mg/kg oil) in a cross-over study. Compared with VOO, EVOO increased plasma concentration of the phenol metabolites, particularly hydroxytyrosol sulphate and vanillin sulphate (P < 0·05). After the consumption of VOO, the maximum concentration of these peaks was reached at 60 min, while EVOO shifted this maximum to 120 min. Despite these differences, the wide variability of results indicates that the absorption and metabolism of olive oil phenols are highly dependent on the individual.
Full-text · Article · Jun 2011 · The British journal of nutrition