Resveratrol metabolite profiling in clinical nutrition research--from diet to uncovering disease risk biomarkers: epidemiological evidence.

Resveratrol is a bioactive plant compound that has drawn scientific and media attention owing to its protective effects against a wide variety of illnesses, including cardiovascular diseases and cancer. In the last two decades, a plethora of preclinical studies have shown these beneficial effects, and some of them have been supported by clinical trials. However, there are few epidemiological studies assessing these relationships, showing mostly inconsistent results among them. This could be partially due to the difficulty of accurately estimating dietary resveratrol exposure. The development of Phenol-Explorer, a database containing resveratrol food-composition data, will facilitate the estimation of resveratrol intake. Moreover, the discovery and validation of a nutritional biomarker of this exposure, urinary resveratrol metabolite profile, will allow a more accurate assessment of dietary resveratrol exposure. Few epidemiological studies have assessed the potential health effects of resveratrol. Resveratrol was not associated with total mortality, cancer, or cardiovascular events, but it was associated with an improvement of serum glucose and triglyceride levels and a decrease in heart rate. Together, these findings suggest a potential cardioprotective effect of resveratrol in epidemiological studies, although the evidence is still scarce.

High-performance liquid chromatography assay using ultraviolet detection for urinary quantification of milrinone concentrations in cardiac surgery patients undergoing cardiopulmonary bypass.

An analytical assay using liquid-liquid extraction and high-performance liquid chromatography with ultraviolet detection was developed for the quantification of total (conjugated and unconjugated) urinary concentrations of milrinone after the inhalation of a 5 mg dose in 15 cardiac patients undergoing cardiopulmonary bypass. Urine samples (700 µL) were extracted with ethyl-acetate and subsequently underwent acid back-extraction before and after deconjugation by mild acid hydrolysis. Milrinone was separated on a strong cation exchange analytical column. The mobile phase consisted of a constant mixture of acetonitrile:tetrahydrofurane-NaH2 PO4 buffer (40:60 v/v, pH 3.0). Thirteen calibration curves were linear in the concentration range of 31.25-4000 ng/mL, using olprinone as the internal standard (r(2) range 0.9911-0.9999, n = 13). Mean milrinone recovery and accuracy were respectively 85.2 ± 3.1% and ≥93%. Intra- and inter-day precisions (coefficients of variation) were ≤5% and ≤8%, respectively. Over a 24 h collection period, the cumulative urinary milrinone recovered from 15 patients was 26.1 ± 7.7% of the nominal 5 mg dose administered. The relative amount of milrinone glucuronic acid conjugate was negligible in the urine of patients undergoing cardiopulmonary bypass This method proved to be reliable, specific and accurate to determine the cumulative amount of total milrinone recovered in urine after inhalation.

Solid-phase column chromatographic and gas chromatographic-mass spectrometric determination of heptaminol in human urine and related pharmacokinetic profiles.

Heptaminol is an antihypotensive drug and is one of the stimulants banned in sport competitions. When heptaminol was fortified to a drug-free urine sample and subjected to solid-phase extraction, trifluroacetic anhydride derivatization, and gas chromatography-mass spectrometry analysis, the results indicated three chromatographic peaks, with one major peak [peak 1 (P1) as heptaminol-2TFA], appearing at retention time 7.17 min, and two minor peaks [peak 2 (P2) and peak 3 (P3) as heptaminol-TFA], appearing at RT 5.87 and 5.81 min, respectively. The characteristic ions of peak mass spectra were m/z 322, 224, and 140 for P1, m/z 223 (molecular ion), 208, 140, and 110 for P2, and m/z 208, 140, and 110 for P3. The urine samples collected from healthy male volunteers who orally ingested a single dose (100 mg) of heptaminol were similar to the analytical results shown in the heptaminol-spiked control urine samples. This result suggested that the unchanged heptaminol was the sole form found in urine. The unchanged parent compound was completely eliminated in urine within 24 h and an average of approximately 97% of the dose was excreted through the renal pathway.

Large dopamine-secreting pheochromocytoma: case report.

Pheochromocytomas are rare tumors that typically present with catecholamine-stimulated symptoms. Some pheochromocytomas secrete dopamine in addition to or in the absence of other catecholamines. Patients with these tumors are frequently normotensive. We describe a normotensive 26-year-old woman with a large pheochromocytoma that secreted multiple catecholamines, including dopamine.

Noncompetitive immunoassay of small analytes at the femtomolar level by affinity probe capillary electrophoresis: direct analysis of digoxin using a uniform-labeled scFv immunoreagent.

A general method for noncompetitive immunoassay of small analytes using affinity probe capillary electrophoresis (APCE) is demonstrated using digoxin as a model analyte. A uniform immunoreagent was prepared from a single-chain antibody (scFv) gene specific for digoxin. Site-directed mutagenesis introduced a unique cysteine residue for uniform labeling with a thiol-reactive fluorochrome. After expression in E. coli, the scFv was purified by immobilized metal affinity chromatography (IMAC) using an added C-terminal 6-histidine sequence. The protein was renatured and labeled while immobilized on the IMAC resin. After 0.02-microm filtration to remove microaggregates, the resulting reagent was highly uniform and stable at -12 degrees C for at least 1 year. Three formats of APCE using the scFv reagent were explored. A "mix-and-inject" assay optimized for low detection limits demonstrated analysis of 10 pM digoxin in aqueous standard solutions in 10 min. A rapid mix-and-inject format in a short capillary allowed detection of 1 nM digoxin in 1 min. Digoxin samples in serum and urine were injected directly after 10-fold dilution. In combination with solid-phase extraction, 400 fM digoxin was detected in 1 mL of serum. Including solid-phase extraction, reproducibility was within 2.5%, and the linear range was 3 orders of magnitude. The strategy adopted in this paper should be of general use in the low-level analysis of small analytes.

Biotransformation of the novel inotropic agent toborinone (OPC-18790) in rats and dogs. Evidence for the formation of novel glutathione and two cysteine conjugates.

The metabolism of toborinone, (+/-)-6-[3-(3,4-dimethoxybenzylamino)-2-hydroxypropoxy]-2(1H)-quin - olinone, a novel inotropic agent, was studied in rats and dogs after intravenous administration. Chemical structures of the 13 metabolites were characterized by direct-probe FAB/MS and field desorption/MS, LC/FAB/MS, and various NMR measurements. After intravenous dosing of 10 mg/kg [14C]toborinone, fecal and urinary recoveries of the 14C dose were approximately 70% and 26-30%, respectively, in both rats and dogs. The predominant component of radioactivity was the unchanged toborinone in every biological specimen in rats and dogs. Although unchanged toborinone was predominantly observed, toborinone underwent extensive conjugations with glucuronic acid, sulfate, and glutathione, either directly or following phase I reaction. Metabolites resulting from oxidative N-C cleavage were minor both in number and in quantity in every biological specimen in rats and dogs. In rats, toborinone underwent O-demethylation to form M-7 and successive phase it reaction to yield the glucuronide M-1 and the sulfoconjugate M-2, and deconjugation to yield M-7, which was a primary metabolite accounted for 35.67% of the radioactivity excreted in the feces by 48 hr. Conjugates M-1 and M-2 were the major metabolites in rat plasma. In dogs, toborinone was metabolized via mercapturic acid pathway to yield the primary metabolites, cysteine conjugates M-10 and M-11 that accounted for 19.10% and 6.70% of the radioactivity excreted in the feces by 48 hr and that were detected species specifically in dogs. The glutathione conjugate M-13, which was isolated from in vitro incubations using dog liver, led us to consider a possible mercapturic acid pathway from the parent compound to M-10. Metabolites in dog plasma and those in urine in both rats and dogs were minor in quantity. The metabolic pathways of toborinone in rats and dogs are proposed herein.

Assessment of the biotransformation of the cardiotonic agent piroximone by high-performance liquid chromatography and gas chromatography-mass spectrometry.

14C-labelled piroximone was administered to rats at a dose of 10 mg/kg body weight. Of the total radioactivity administered, 74.9 +/- 7.9% (n = 4) and 87.8 +/- 1.7 (n = 3) were recovered in the 8-h urine collection after oral and intravenous administration, respectively. Two major metabolites, M1 and M2, were detected in methanol extracts and accounted for 7.1 +/- 1.2% (n = 4) (M1) and 4.3 +/- 0.4% (n = 4) (M2) in response to oral administration and 5.7 +/- 0.8% (n = 3) (M1) and 6.7 +/- 2.0% (n = 3) (M2) in response to intravenous administration. In addition, three minor metabolites were detected; M3 and M4 in the 8-h urine collection and M5 in the 12-h urine collection. Separation of piroximone and metabolites was achieved by high-performance liquid chromatography on a C18 column by gradient elution with 0.05 M ammonium acetate (pH 7) using 0-60% methanol over 20 min at a flow-rate of 1 ml/min, followed by isocratic elution with 60% methanol for 10 min. M1 and M2 were isolated by fraction collection following the addition of 1 mM tetrabutylammonium acetate in the mobile phase. Between each injection a column re-equilibration time of 45 min was necessary to achieve optimum collection of M1 and M2 fractions. Gas chromatography-mass spectrometry of M1 provided evidence for a molecular structure consistent with isonicotinic acid methyl ester. Corroborative evidence for this identification was obtained by comparison with a synthetic standard. Isonicotinic acid is assumed to be the actual metabolite while esterification with methanol had occurred as a result of the work-up procedure.(ABSTRACT TRUNCATED AT 250 WORDS)