Phenolic sulfates as new and highly abundant metabolites in human plasma after ingestion of a mixed berry fruit purée.

Bioavailability studies are vital to assess the potential impact of bioactive compounds on human health. Although conjugated phenolic metabolites derived from colonic metabolism have been identified in the urine, the quantification and appearance of these compounds in plasma is less well studied. In this regard, it is important to further assess their potential biological activity in vivo. To address this gap, a cross-over intervention study with a mixed fruit purée (blueberry, blackberry, raspberry, strawberry tree fruit and Portuguese crowberry) and a standard polyphenol-free meal was conducted in thirteen volunteers (ten females and three males), who received each test meal once, and plasma metabolites were identified by HPLC-MS/MS. Sulfated compounds were chemically synthesised and used as standards to facilitate quantification. Gallic and caffeic acid conjugates were absorbed rapidly, reaching a maximum concentration between 1 and 2 h. The concentrations of sulfated metabolites resulting from the colonic degradation of more complex polyphenols increased in plasma from 4 h, and pyrogallol sulfate and catechol sulfate reached concentrations ranging from 5 to 20 µm at 6 h. In conclusion, phenolic sulfates reached high concentrations in plasma, as opposed to their undetected parent compounds. These compounds have potential use as biomarkers of polyphenol intake, and their biological activities need to be considered.

Identification of compounds in the essential oil of nutmeg seeds (Myristica fragrans Houtt.) that inhibit locomotor activity in mice.

The present study was designed to evaluate the inhibitory effect of nutmeg (Myristica fragrans Houtt.) seed essential oil on the locomotor activity of mice in a wheel cage. Active compounds in the essential oil were identified by off-line solid phase extraction (SPE-C18) and GC/MS analysis. The essential oil was administered by inhalation at doses of 0.1, 0.3, and 0.5 mL/cage. The results showed that inhalation of nutmeg seed essential oil at a dose of 0.5 mL/cage decreased locomotion by 68.62%; and inhalation of 0.1 and 0.3 mL/cage inhibited locomotion by 62.81% and 65.33%, respectively. Generally, larger doses and longer administrations of nutmeg seed essential oil exhibited greater locomotor inhibition. Subsequently, the plasma concentrations of essential oil compounds were measured. The most concentrated compound in the plasma was myristicin. Half an hour after the addition of 1 mL/cage of nutmeg seed oil, the plasma concentration of myristicin was 3.7 µg/mL; one and two hours after the addition, the blood levels of myristicin were 5.2 µg/mL and 7.1 µg/mL, respectively. Other essential oil compounds identified in plasma were safrole (two-hour inhalation: 1.28 µg/mL), 4-terpineol (half-hour inhalation: 1.49 µg/mL, one-hour inhalation: 2.95 µg/mL, two-hour inhalation: 6.28 µg/mL) and fatty esters. The concentrations of the essential oil compounds in the blood plasma were relatively low (µg/mL or ppm). In conclusion, the volatile compounds of nutmeg seed essential oil identified in the blood plasma may correlate with the locomotor-inhibiting properties of the oil when administered by inhalation.

Antioxidant effects of a cinnamon extract in people with impaired fasting glucose that are overweight or obese.

OBJECTIVE: To determine the effects of a dried aqueous extract of cinnamon on antioxidant status of people with impaired fasting glucose that are overweight or obese. METHODS: Twenty-two subjects, with impaired fasting blood glucose with BMI ranging from 25 to 45, were enrolled in a double-blind placebo-controlled trial. Subjects were given capsules containing either a placebo or 250 mg of an aqueous extract of cinnamon (Cinnulin PF) two times per day for 12 weeks. Plasma malondialdehyde (MDA) concentrations were assessed using high performance liquid chromatography and plasma antioxidant status was evaluated using ferric reducing antioxidant power (FRAP) assay. Erythrocyte Cu-Zn superoxide (Cu-Zn SOD) activity was measured after hemoglobin precipitation by monitoring the auto-oxidation of pyrogallol and erythrocyte glutathione peroxidase (GPx) activity by established methods. RESULTS: FRAP and plasma thiol (SH) groups increased, while plasma MDA levels decreased in subjects receiving the cinnamon extract. Effects were larger after 12 than 6 weeks. There was also a positive correlation (r = 0.74; p = 0.014) between MDA and plasma glucose. CONCLUSION: This study supports the hypothesis that the inclusion of water soluble cinnamon compounds in the diet could reduce risk factors associated with diabetes and cardiovascular disease.

Syringol metabolites as new biomarkers for smoked meat intake.

BACKGROUND: Processed meat intake is associated with a higher risk of colorectal and stomach cancers, coronary artery disease, and type 2 diabetes and with higher mortality, but the estimation of intake of different processed meat products in this heterogeneous food group in epidemiological studies remains challenging. OBJECTIVE: This work aimed at identifying novel biomarkers for processed meat intake using metabolomics. METHODS: An untargeted, multi-tiered metabolomics approach based on LC-MS was applied to 33 meat products digested in vitro and secondly to urine and plasma samples from a randomized crossover dietary intervention in which 12 volunteers consumed successively 3 processed meat products (bacon, salami, and hot dog) and 2 other foods used as controls, over 3 consecutive days. The putative biomarkers were then measured in urine from 474 subjects from the European Prospective Investigation into Cancer and Nutrition (EPIC) cross-sectional study for which detailed 24-h dietary recalls and FFQs were available. RESULTS: Syringol and 4 derivatives of syringol were found to be characteristic of in vitro digests of smoked meat products. The same compounds present as sulfate esters in urine increased at 2 and 12 h after consumption of smoked meat products (hot dog, bacon) in the intervention study. The same syringol sulfates were also positively associated with recent or habitual consumption of smoked meat products in urine samples from participants of the EPIC cross-sectional study. These compounds showed good discriminative ability for smoked meat intake with receiver operator characteristic areas under the curve ranging from 0.78 to 0.86 and 0.74 to 0.79 for short-term and habitual intake, respectively. CONCLUSIONS: Four novel syringol sulfates were identified as potential biomarkers of smoked meat intake and may be used to improve assessment of smoked meat intake in epidemiological studies. This trial was registered at clinicaltrials.gov as NCT03354130.

Antioxidant capacity of human blood plasma and human urine: simultaneous evaluation of the ORAC index and ascorbic acid concentration employing pyrogallol red as probe.

The oxygen radical absorbance capacity (ORAC) methodology has been employed to estimate the antioxidant capacity of human blood plasma and human urine using pyrogallol red (ORAC-PGR) as target molecule. Uric acid, reduced glutathione, human serum albumin, and ascorbic acid (ASC) inhibited the consumption of pyrogallol red, but only ASC generated an induction time. Human blood plasma and human urine protected efficiently pyrogallol red. In these assays, both biological fluids generated neat induction times that were removed by ascorbate oxidase. From these results, ORAC-PGR method could be proposed as a simple alternative to evaluate an ORAC index and, simultaneously, to estimate the concentration of ascorbic acid in human blood plasma or human urine.

Processing 'Ataulfo' Mango into Juice Preserves the Bioavailability and Antioxidant Capacity of Its Phenolic Compounds.

The health-promoting effects of phenolic compounds depend on their bioaccessibility from the food matrix and their consequent bioavailability. We carried out a randomized crossover pilot clinical trial to evaluate the matrix effect (raw flesh and juice) of 'Ataulfo' mango on the bioavailability of its phenolic compounds. Twelve healthy male subjects consumed a dose of mango flesh or juice. Blood was collected for six hours after consumption, and urine for 24 h. Plasma and urine phenolics were analyzed by electrochemical detection coupled to high performance liquid chromatography (HPLC-ECD). Five compounds were identified and quantified in plasma. Six phenolic compounds, plus a microbial metabolite (pyrogallol) were quantified in urine, suggesting colonic metabolism. The maximum plasma concentration (Cmax) occurred 2-4 h after consumption; excretion rates were maximum at 8-24 h. Mango flesh contributed to greater protocatechuic acid absorption (49%), mango juice contributed to higher chlorogenic acid absorption (62%). Our data suggests that the bioavailability and antioxidant capacity of mango phenolics is preserved, and may be increased when the flesh is processed into juice.

Method for analysis of tannic acid and its metabolites in biological samples: application to tannic acid metabolism in the rat.

A new analytical method for measuring tannic acid (TA) using tannase was developed and applied to the investigation of TA metabolism in the rat following oral administration at a dose of 1.0 g/kg. The proposed method for TA determination was based on the enzymatic hydrolysis of TA to gallic acid (GA) and subsequent determination by HPLC. TA metabolites were determined by HPLC. 4-O-Methylgallic acid (4-OMGA), pyrogallol (PY), and resorcinol (RE) were detected in serum. TA was excreted into urine as GA (0.01%), 4-OMGA (0.10%), PY (0.24%), and RE (2.06%) and into feces as TA (62.74%), GA (0.19%), PY (0.02%), and RE (0.76%) within 54 h after oral administration. It was suggested that >60% of TA remained unchanged but that some was hydrolyzed to GA by tannase in the intestine and further metabolized to 4-OMGA, PY, and RE.

Determination of gallic acid and its metabolites in human plasma and urine by high-performance liquid chromatography.

Gallic acid occurs naturally in plants and has been found to be pharmacologically active as antioxidant, antimutagenic and anticarcinogenic agent. In this work, the metabolism of gallic acid in the human body was investigated. Two methods were developed for the identification and determination of gallic acid and its phenolic metabolites in human plasma and urine by reversed-phase high-performance liquid chromatography using UV detection and involving isocratic elution. One of these methods enables the simultaneous separation and determination of gallic acid (GA), 4-O-methylgallic acid (4OMGA), pyrogallol (PY), 2-O-methylpyrogallol (2OMPY) and resorcinol (RE) in biological fluids. This method is of interest because it allows the separation of a large number of phenolic compounds by isocratic elution using a solution of 4.4 x 10(-3) M phosphoric acid in water as mobile phase. The analysis time for this method, however, is not optimal (57 min). After oral administration of 50 mg GA, 4OMGA rapidly appeared in the plasma and urine besides unchanged GA. Other phenolic compounds, PY, 2OMPY and RE, were not detected. The second method was developed to determine GA and 4OMGA with a short analysis time (25 min).