Associations of metabolomic profiles with circulating vitamin E and urinary vitamin E metabolites in middle-aged individuals.

Vitamin E (α-tocopherol [α-TOH]) is transported in lipoprotein particles in blood, but little is known about the transportation of its oxidized metabolites. In the Netherlands Epidemiology of Obesity Study, we aimed to investigate the associations of 147 circulating metabolomic measures obtained through targeted nuclear magnetic resonance with serum α-TOH and its urinary enzymatic (α-CEHC) and oxidized (α-TLHQ) metabolites from 24-h urine quantified by liquid chromatography with tandem mass spectrometry. Multivariable linear regression analyses, in which multiple testing was taken into account, were performed to assess associations between metabolomic measures (determinants; standardized to mean = 0, SD = 1) and vitamin E metabolites (outcomes), adjusted for demographic factors. We analyzed 474 individuals (55% women, 45% men) with a mean (SD) age of 55.7 (6.0) y. Out of 147 metabolomic measures, 106 were associated (P < 1.34 × 10-3) with serum α-TOH (median ß [interquartile range] = 0.416 [0.383-0.466]), predominantly lipoproteins associated with higher α-TOH. The associations of metabolomic measures with urinary α-CEHC have directions similar to those with α-TOH, but effect sizes were smaller and non-significant (median ß [interquartile range] = 0.065 [0.047-0.084]). However, associations of metabolomic measures with urinary α-TLHQ were markedly different from those with both serum α-TOH and urinary α-CEHC, with negative and small-to-null relations to most very-low-density lipoproteins and amino acids. Therefore, our results highlight the differences in the lipoproteins involved in the transportation of circulating α-TOH and oxidized vitamin E metabolites. This indicates that circulating α-TOH may be representative of the enzymatic but not the antioxidative function of vitamin E.

Determination of vitamin E and its metabolites in equine urine using liquid chromatography-mass spectrometry.

Equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) is a hereditary, deteriorating central nervous disease in horses. Currently, the only way to confirm eNAD/EDM is through a postmortem histological evaluation of the central nervous system. Vitamin E, specifically the isoform alpha-tocopherol (α-TP), is known to protect eNAD/EDM susceptible horses from developing the clinical phenotype. While vitamin E is an essential nutrient in the diet of horses, there are no diagnostic tests able to quantitate vitamin E and its metabolites in urine. An ultra-performance liquid chromatography-atmospheric-pressure chemical ionization mass spectrometry (UPLC-APCI-MS/MS) method was developed and validated following acidic hydrolysis and solid phase extraction to quantitate vitamin E and its metabolites in equine urine. A blank control horse urine matrix was used and spiked with different concentrations of analytes to form a standard curve using either alpha-tocopherol-d6 or chlorpropamide as the internal standard. Inter-day and intra-day statistics were performed to evaluate the method for accuracy (90% to 116%) and precision (0.75% to 14%). Matrix effects, percent recovery, and stability were also assessed. The method successfully analyzed alpha-carboxyethyl hydroxychroman (α-CEHC), alpha-carboxymethylbutyl hydroxychromans (α-CMBHC), gamma-carboxyethyl hydroxychroman γ-CEHC, and α-TP concentrations in urine to determine a baseline levels of analytes in healthy horses, and can be used to determine concentrations of vitamin E metabolites in equine urine allowing for its evaluation as a diagnostic approach in the treatment of eNAD/EDM.

Urinary conjugated α-tocopheronolactone--a biomarker of oxidative stress in children with type 1 diabetes.

Increased oxidative stress has been implicated in both the onset and the progression of diabetes mellitus and its complications. The development of easy to measure biomarkers of oxidative stress would, therefore, help in determining in a prospective manner the impact of glycemic control on oxidative stress and macrovascular disease in patients with diabetes. We report the development and validation of a novel method to directly measure the urinary concentrations of the conjugated metabolites of vitamin E (α-tocopherol) and investigate whether the oxidized metabolite α-tocopheronolactone (α-TL) could be used as a biomarker of oxidative stress in children with type 1 diabetes. A novel method using liquid chromatography-tandem mass spectrometry was developed and used to measure directly and rapidly the urinary concentrations of the glucuronidated and sulfated metabolites of α-tocopherol in 32 young patients with type 1 diabetes and age-matched controls. The mean concentrations of the glucuronidated and sulfated conjugates of α-TL were all highly significantly increased in the children with type 1 diabetes (p<0.001). The results suggest that the measurement of the urinary concentrations of α-TL conjugates may provide a useful biomarker of oxidative stress in diabetes and possibly in other clinical conditions in which oxidative stress has been implicated.

[Characteristics of nutrition and vitamin supply in girls with metabolic syndrome].

Assessment of actual nutrition in girls with metabolic syndrome revealed excess dietary energy value due to the higher intake of fat and carbohydrates (mono- and disaccharides in particular) and the low intake of vitamin E. The vitamin status of the majority of girls with metabolic syndrome showed varying blood and urinary vitamin E, C, and B, deficiencies.

Urinary excretion rates of 8-oxoGua and 8-oxodG and antioxidant vitamins level as a measure of oxidative status in healthy, full-term newborns.

The aim of the present study was to evaluate the oxidative status in healthy full-term children and piglets. Urinary excretion of 8-oxoGua (8-oxoguanine) and 8-oxodG (8-oxo-2'-deoxyguanosine) were determined using HPLC/GS/MS methodology and concentrations of vitamins A, C and E with HPLC technique. The levels of 8-oxoGua in urine samples were about 7-8 times higher in newborn children and piglets when compared with the level of adult subjects, while in the case of 8-oxodG the difference was about 2.5 times. The levels of vitamin C and E in umbilical cord blood of newborn children significantly depend on the concentration of these compounds in their mother's blood. However, the values of vitamin C in human's cord blood were about 2-times higher than in respective mother blood, while the level of vitamin E showed an opposite trend. The results suggest that: (i) healthy, full-term newborns are under potential oxidative stress; (ii) urinary excretion of 8-oxoGua and 8-oxodG may be a good marker of oxidative stress in newborns; and (iii) antioxidant vitamins, especially vitamin C, play an important role in protecting newborns against oxidative stress.

A feasibility study quantifying in vivo human alpha-tocopherol metabolism.

BACKGROUND: Quantitation of human vitamin E metabolism is incomplete, so we quantified RRR- and all-rac-alpha-tocopherol metabolism in an adult. OBJECTIVE: The objective of the study was to quantify and interpret in vivo human vitamin E metabolism. DESIGN: A man was given an oral dose of 0.001821 micromol [5-14CH3]RRR-alpha-tocopheryl acetate (with 101.5 nCi 14C), and its fate in plasma, plasma lipoproteins, urine, and feces was measured over time. Data were analyzed and interpreted by using kinetic modeling. The protocol was repeated later with 0.001667 micromol [5-14CH3]all-rac-alpha-tocopheryl acetate (with 99.98 nCi 14C). RESULTS: RRR-alpha-tocopheryl acetate and all-rac-alpha-tocopheryl acetate were absorbed equally well (fractional absorption: approximately 0.775). The main route of elimination was urine, and approximately 90% of the absorbed dose was alpha-2(2'-carboxyethyl)-6-hydroxychroman. Whereas 93.8% of RRR-alpha-tocopherol flow to liver kinetic pool B from plasma was returned to plasma, only 80% of the flow of all-rac-alpha-tocopherol returned to plasma; the difference (14%) was degraded and eliminated. Thus, for newly digested alpha-tocopherol, the all-rac form is preferentially degraded and eliminated over the RRR form. Respective residence times in liver kinetic pool A and plasma for RRR-alpha-tocopherol were 1.16 and 2.19 times as long as those for all-rac-alpha-tocopherol. Model-estimated distributions of plasma alpha-tocopherol, extrahepatic tissue alpha-tocopherol, and liver kinetic pool B for RRR-alpha-tocopherol were, respectively, 6.77, 2.71, and 3.91 times as great as those for all-rac-alpha-tocopherol. Of the lipoproteins, HDL had the lowest 14C enrichment. Liver had 2 kinetically distinct alpha-tocopherol pools. CONCLUSIONS: Both isomers were well absorbed; all-rac-alpha-tocopherol was preferentially degraded and eliminated in urine, the major route. RRR-alpha-tocopherol had a longer residence time and larger distribution than did all-rac-alpha-tocopherol. Liver had 2 distinct alpha-tocopherol pools. The model is a hypothesis, its estimates are model-dependent, and it encourages further testing.

The effect of gamma-tocopherol administration on alpha-tocopherol levels and metabolism in humans.

BACKGROUND: The bioavailability of gamma-tocopherol and metabolites of vitamin E after gamma-tocopherol administration is not well understood. We investigated the effect of gamma-tocopherol administration on the levels and metabolism of alpha- and gamma-tocopherol in healthy volunteers. METHODS: We measured two metabolites of vitamin E (2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman (alpha-CEHC) and 2,7,8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman (gamma-CEHC)) in plasma and urine by high-performance liquid chromatography with electrochemical detection (HPLC-ECD) during administration of gamma-tocopherol. Two groups of volunteers were enrolled. The gamma-tocopherol group received two gamma-tocopherol capsules (each containing 186.4 mg of gamma-tocopherol and 5 mg of alpha-tocopherol) for 28 days, while the control group received d-alpha-tocopherol at 5 mg/day, which was the same dose as that given to the gamma-tocopherol group. Blood and urine samples were obtained on days 0, 14, 28, 35, 42, and 56 after the initiation of gamma-tocopherol administration. RESULTS: The plasma gamma-tocopherol concentration increased markedly during administration of gamma-tocopherol and the plasma gamma-CEHC concentration increased along with that of gamma-tocopherol. The plasma alpha-tocopherol concentration decreased significantly during gamma-tocopherol administration. The plasma concentration of alpha-CEHC decreased significantly and urinary excretion of alpha-CEHC tended to increase in the gamma-tocopherol group. Urinary sodium secretion was significantly increased at 1 week after the cessation of gamma-tocopherol administration, but there was no significant difference of urine volume between the two groups. CONCLUSION: Metabolism of alpha-tocopherol is accelerated and the plasma alpha-tocopherol concentration is decreased during gamma-tocopherol administration.

The impact of vitamins and/or mineral supplementation on blood pressure in type 2 diabetes.

OBJECTIVE: The present study designed to assess the effect of Mg+Zn, vitamin C+E, and combination of these micronutrients on blood pressure in type 2 diabetic patients. MATERIALS AND METHODS: In a randomized, double-blind, placebo controlled clinical trial, 69 type 2 diabetic patients were randomly divided into four groups, each group receiving one of the following daily supplement for three months; group M: 200 mg Mg and 30 mg Zn (n = 16), group V: 200 mg vitamin C and 150 mg vitamin E (n = 18), group MV: minerals plus vitamins (n = 17), group P: placebo (n = 18). Blood pressure was measured at the beginning and at the end of the trial. Treatment effects were analyzed by general linear modeling. RESULTS: Results indicate that after three months of supplementation levels of systolic, diastolic and mean blood pressure decreased significantly in the MV group by 8 mmHg (122 +/- 16 vs. 130 +/- 19 mmHg), 6 mmHg (77 +/- 9 vs. 83 +/- 11 mmHg), and 7 mmHg (92 +/- 9 vs. 99 +/- 13 mmHg), respectively (p < 0.05). Also combination of vitamin and mineral supplementation had significantly effects in increasing serum potassium (p < 0.05) and in decreasing serum malondialdehyde (p < 0.05). There was no significant change in the levels of these parameters in the other three groups. CONCLUSION: The results of the present study indicated that in type 2 diabetic patients a combination of vitamins and minerals, rather than vitamin C and E or Mg and Zn, might decrease blood pressure.

Urine 8-isoprostane F2alpha concentrations in patients with neurogenic bladder due to spinal cord injury.

BACKGROUND: Isoprostanes are prostaglandin-like end products of arachidonic acid peroxidation that are produced by a free radical-catalyzed mechanism. Considering its free radical-dependent formation and potent contractor effect, it is postulated that isoprostane 8-iso PGF2alpha may play an important role in oxidative stress-related smooth muscle dysfunction. These substances may also influence bladder activity directly by effects on the smooth muscle. The present study was designed to measure traditional biochemical parameters (MDA, TAS, vitamin E) in plasma and 8-iso PGF2alpha concentrations in urine of patients with spinal cord injury and to evaluate the relation of urinary isoprostane concentrations to the bladder function. METHODS: All spinal cord patients underwent urodynamic evaluations. The biochemical tests were performed in both hyperreflexic bladder group (n = 23) and areflexic bladder group (n = 10), and the findings were compared to those of the patients with normally functioning bladder (controls, n = 19). RESULTS: Urine 8-iso PGF2alpha concentrations were significantly increased in hyperreflexic group (median value 0.89 pg/mg creatinine) compared to both control (0.52 pg/mg creatinine) and areflexic groups (p < 0.001). The lowest concentrations of urinary 8-iso PGF2alpha were observed in the areflexic group (0.22 pg/mg creatinine), and these were positively correlated to the plasma MDA concentrations in areflexic patients (p = 0.05; r = 0.684). CONCLUSION: Isoprostanes may be involved in the pathogenesis of neurogenic bladder dysfunction. It may be of value to determine the urinary concentrations of 8-iso PGF2alpha in order to distinguish areflexic bladders from the hyperreflectics.

Lipid peroxidation and urinary excretion of vitamin E in rats submitted to an immunological inflammatory process.

Inflammation is a protective physiologic response, generally controlled by the organism at the injury site. Vitamin E is the most important antioxidant in the lipid phase present in nature and acts by interrupting the chain reaction produced by free radicals. The objective of this study was to evaluate the effect of inflammation on vitamin E levels and lipid peroxidation in rats. Forty Wistar rats (four groups of 10 rats each) were studied over a period of 15 days. Two substances inducing the inflammatory process were parenterally administered, anti-rat basement membrane serum (ABMG) and Freund's complete adjuvant (FAG). Lipid peroxidation levels in hepatic and renal tissue and in plasma and urine were analyzed and compared with the control (CG). Vitamin E was determined by HPLC and lipid peroxidation by quantification of thiobarbituric acid reactive substances (TBARS). ABMG produced more (p < 0.05) TBARS in renal and hepatic tissues (0.7 +/- 0.11 and 1.28 +/- 0.27 nmol/g protein, respectively) compared to CG (0.65 +/- 0.81 and 0.69 +/- 0.13 nmol/g protein). Analysis of TBARS in urine did not show statistically significant differences between the experimental groups and the control. Vitamin E levels in the hepatic tissue of ABMG and FAG (40.7 +/- 10.04 and 44.26 +/- 20.24 micrograms/g tissue) were higher than in CG (22.37 +/- 8.20 micrograms/g tissue) while in kidney tissue and plasma these values were lower (P < 0.05). Renal excretion was increased (P < 0.05) in the group that received anti-rat basement membrane serum (22.39 +/- 0.11 mmol/mL) compared to CG (0.56 +/- 0.056 mmol/mL). We conclude that the acute inflammatory process causes important alterations in the metabolism of vitamin E and lipid peroxidation leading to a significantly increased excretion of this vitamin in the urine.

New synthesis of (+/-)-alpha-CMBHC and its confirmation as a metabolite of alpha-tocopherol (vitamin E).

There is currently interest in the metabolism of the various compounds which make up the vitamin E family, especially with regards to the possible use of vitamin E metabolites as markers of oxidative stress and adequate vitamin E supply. A number of vitamin E metabolites have been described to date and we have recently developed a method to extract and quantitate a range of vitamin E metabolites in human urine. During the development of this method a new metabolite of alpha-tocopherol was identified, which we tentatively characterised as 5-(6-hydroxy-2,5,7,8-tetramethyl-chroman-2-yl)-2-methyl-pentanoic acid (alpha-CMBHC).(1) Here we describe the synthesis of alpha-CMBHC as a standard and confirm that it is a metabolite of alpha-tocopherol.

Chromatographic techniques for the determination of putative dietary anticancer compounds in biological fluids.

Although a great number of papers demonstrate an association between high intake of fruits and vegetables and reduced risk of certain types of cancer, the epidemiological evidence is not conclusive. The identification and quantification of specific dietary anticancer compounds in plasma, urine and tissues is an important aspect of this research. We surveyed the recent literature for original papers which involved the use of separation techniques for the detection and quantification in biological fluids and tissues of putative anticancer compounds which are present in the diet. The compounds included in this review are flavonoids, phytoestrogens, carotenoids, retinoids, vitamin E and ascorbic acid. The review covers papers published in the last 3 years. For each class of compounds we discuss the sample preparation, chromatographic conditions, and validation of the methods used, in order to identify current trends in the bioanalysis of each class of these substances.

A new method for the analysis of urinary vitamin E metabolites and the tentative identification of a novel group of compounds.

There is currently interest in measuring urinary metabolites of vitamin E. It has been suggested that alpha-to-copheronolactone (alphaTL), with an oxidized chroman ring, may be an indicator of in vivo oxidative stress and 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman (alpha-CEHC), with a shortened side chain but intact hydroxychroman ring, may provide a measure of adequate or excess vitamin E status. To date, methods in the literature have tended to concentrate on the estimation of single metabolites. We describe the establishment and validation of a relatively simple and reproducible method to extract and quantitate a range of vitamin E metabolites using 0.5 ml of human urine. The vitamin E metabolites were extracted from urine using solid phase extraction cartridges, deconjugated enzymatically, and analyzed using gas chromatography-mass spectrometry. Using this method we have identified alphaTL and the CEHC metabolites derived from alpha-, delta-, and gamma-tocopherol. In addition we have tentatively identified a novel group of vitamin E metabolites, which are related to the CEHCs but have three extra carbons in the side chain. The possibility of the artifactual oxidation of alpha-CEHC to alphaTL during the assay procedure is also discussed.

Nutritional assessment of vitamin E in malnourished patients with AIDS.

Malnourished patients with acquired immunodeficiency syndrome (AIDS) may have low serum levels and reduced intake of alpha-tocopherol, mainly in the presence of acute-phase response. The aims of this study were to compare intake and serum levels of alpha-tocopherol between malnourished (MN) and non-malnourished (NMN) AIDS patients and to correlate alpha-tocopherol intake and serum levels. Undernutrition was defined as having a body mass index lower than 18. 5 kg/m(2) or a height-creatinine index lower than 70%. A semiquantitative food frequency questionnaire assessed alpha-tocopherol intake. High-performance liquid chromatography determined vitamin serum levels. The patients were divided into MN (n = 14) and NMN (n = 15) groups. There were no statistical differences in relation to clinical findings between MN and NMN, respectively, including moniliasis (7/14 versus 4/15), neurocryptoccocosis and neurotoxoplasmosis (6/14 versus 6/15), pulmonary tuberculosis (4/14 versus 2/15), and fever (1/14 versus 3/15). MN and NMN groups had similar peripheral blood CD(4) levels (111.4+/-87.1 versus 124.4+/-90.9 cells/mm(3)), and both groups had similar and adequate alpha-tocopherol intake (MN = 50.0+/-11.0 versus NMN = 47.2+/-16.5 mg) and serum levels (MN = 17.8+/-7.2 versus NMN = 19.8+/-6.3 micromol/L). Vitamin E intake and serum levels did not show a significant correlation (r = -0.22, P 0.05). Protein-energy nutrition status and acute-phase response were not factors determining vitamin status among AIDS patients.

Studies of the metabolism of alpha-tocopherol stereoisomers in rats using [5-methyl-(14)C]SRR- and RRR-alpha-tocopherol.

We investigated the distribution and metabolism of SRR-alpha-tocopherol (SRR-alpha-Toc), synthetic alpha-Toc compared with RRR-alpha-Toc, in rats after a single oral administration of 2 mg (20 microCi) SRR- and RRR-alpha-[5-methyl-(14)C]Toc. In the liver, there was no difference in the recovery of radioactivity until 12 h after administration, and it reached a maximum of 4.4% of the dose after 12 h, but in other tissues, radioactivity derived from RRR-alpha-Toc was clearly higher than that derived from SRR-alpha-Toc after 12 h. For 96 h after administration, urinary excretions of SRR-alpha-Toc were 7.8% of the dose and significantly greater than that of RRR-alpha-Toc, which was 1.3% of the dose. On the other hand, total fecal excretions of SRR- and RRR-alpha-Toc were 87.6% and 83.0%, respectively. Therefore, radioactivity in the urine was assumed to have transferred out of the liver. Furthermore, the urine samples were hydrolyzed with 3 N methanolic HCl and analyzed by high performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry. The results showed that about 73% of the total radioactivity injected into HPLC was found to be 2,5,7, 8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxy chroman (alpha-CEHC), as well as RRR-alpha-Toc. Thus, there is no difference between SRR-alpha-Toc and RRR-alpha-Toc in metabolic pathways, and it is suggested that SRR-alpha-Toc discriminated in the liver is rapidly metabolized by the liver and excreted as the conjugate of alpha-CEHC in the urine.

A novel 5'-carboxychroman metabolite of gamma-tocopherol secreted by HepG2 cells and excreted in human urine.

HepG2 cells were incubated with a medium containing fetal bovine serum enriched with RRR-gamma-tocopherol (gamma-TOH). After 48 h the medium was extracted and analyzed for gamma-TOH metabolites by gas chromatography-mass spectrometry. In addition to gamma-CEHC, the 3'-carboxychroman metabolite of gamma-TOH previously reported in human urine, these cells secreted a second substance whose extraction and mass spectral characteristics were consistent with those of the 5'-carboxychroman analog of gamma-CEHC, 2,7, 8-trimethyl-2-(delta-carboxymethylbutyl)-6-hydroxychroman. This is the first report of metabolism of gamma-TOH to carboxychroman metabolites in cell culture. Analysis of human urine samples revealed the consistent presence of the novel 5'-carboxychroman metabolite, along with that of gamma-CEHC. Oral supplementation with purified RRR-gamma-TOH resulted in elevated urinary concentrations of both metabolites, although the concentration of the 5'-gamma-carboxychroman metabolite was consistently and substantially less than that of gamma-CEHC. The presence of both metabolites is consistent with the involvement of an omega-oxidation-like process in the phytyl tail shortening of gamma-TOH to water soluble metabolites excreted in urine.

A rapid method for the extraction and determination of vitamin E metabolites in human urine.

A method for the direct extraction and routine analysis of the vitamin E metabolites gamma- and alpha-carboxyethyl hydroxychroman (gamma- and alpha-CEHC) from human urine has been developed. A relatively small sample volume (5 ml) can be used and, after enzymatic hydrolysis of the conjugated forms and acidification, the metabolites are extracted with diethyl ether. Recovery of alpha- and gamma-CEHC was compared to that of trolox, used as an internal standard, added to 24-h urine collections from vitamin E-unsupplemented volunteers. Various solvent conditions were initially tested; acidification and ether extraction gave the highest recovery. It was found that after addition and extraction from urine, trolox, alpha- and gamma-CEHC are recovered to a similar extent, hence trolox is viable as an internal standard. The samples were analyzed by both GC and HPLC with electrochemical detection (ECD). HPLC-ECD was found to give higher selectivity and higher sensitivity compared to GC or HPLC with UV detection at 290 nm. The HPLC-ECD detection limit was 10 fmol, linearity (r(2) > 0.98) was achieved in the range of 40 to 200 fmol, which was found to be optimal for 24-h urines from unsupplemented subjects. Inter-sample variability was typically 2-5%. This greater sensitivity and selectivity means that vitamin E metabolites can be analyzed even in unsupplemented subjects. It is also possible to measure unconjugated forms of the metabolites. Typically these were found to represent approximately 10% of the total alpha- and gamma-CEHC. This method can be used routinely for the determination of vitamin E metabolites in urine. The new extraction and detection methods described are relatively quick, less laborious, and more cost-effective than previously available methods.

Urinary excretion of 2,7, 8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman is a major route of elimination of gamma-tocopherol in humans.

Little is known of the post-absorptive, metabolic fate of gamma-tocopherol, the major form of vitamin E in North American diets. The objective of this study was to determine the extent of urinary excretion of 2,7, 8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman (gamma-CEHC), a recently identified metabolite of gamma-tocopherol. A method for measurement of urinary gamma-CEHC was developed, using gas chromatography-mass spectrometry (GC-MS) with a deuterated internal standard, 2,7,8-trimethyl-2-(beta-carboxyethyl)-(3, 4-2H2)-6-hydroxychroman (d2-gamma-CEHC). This standard was synthesized by dehydrogenation of 6-acetyl-gamma-CEHC followed by deuteration of the resulting 3,4-double bond. The use of d2-gamma-CEHC resulted in accurate determinations of the concentration of d0-gamma-CEHC in human urine. Urine samples containing added d2-gamma-CEHC were treated with beta-glucuronidase, extracted with an organic solvent, and analyzed by GC-MS. Analysis of 24-h urine pools from healthy subjects revealed gamma-CEHC concentrations, normalized against creatinine, ranging from 2.5 to 31.5 micromol/g creatinine, or a total of 4.6 to 29.8 micromol per day. These results correspond to 2-12 mg gamma-tocopherol excreted daily as gamma-CEHC in the urine. Given an estimated mean intake of gamma-tocopherol of 20 mg/day, catabolism of gamma-tocopherol to gamma-CEHC, followed by glucuronide conjugation and urinary excretion, is a major pathway for elimination of gamma-tocopherol in humans.

Urinary excretion and plasma vitamin E levels in patients with AIDS.

Individuals with acquired immunodeficiency virus (HIV) and patients with acquired immunodeficiency syndrome (AIDS) present a variety of pathologic alterations that influence their nutritional status during various stages of the disease. Previous studies have reported a reduction in plasma vitamin E levels in these patients associated with a higher production of free radicals. Individuals with infection, fever, or acute diarrhea excrete considerable amounts of vitamin A in urine. This observation raised the hypothesis that this may also be the case for vitamin E and that its urinary excretion may play a significant role in the reduction of plasma vitamin E levels. In the present investigation, 28 serologically positive HIV-1 (HIV group) divided into a group of 16 patients with AIDS (< 200/mm3 CD4+ T lymphocytes) were studied. The control group consisted of 11 healthy individuals. Urinary and plasma vitamin E levels were determined by high-performance liquid chromatography. Patients with AIDS presented reduced plasma vitamin E levels (15.25 +/- 12.19 mumol/L) compared with the HIV (26.40 +/- 17.01 mumol/L) and control (40.03 +/- 31.80 mumol/L) groups. On the other hand, urinary excretion was higher in the AIDS group (0.86 +/- 0.99 mumol/24 h) than in the HIV group (0.62 +/- 0.46 mumol/24 h) and considerably higher than in the control group (0.05 +/- 0.13 mumol/24 h). These results indicate elevated vitamin E excretion in the urine of both patients with AIDS and patients with HIV-1, levels is recommended for patients with HIV and patients with AIDS and, if necessary, the combination of existing medical therapy with vitamin supplementation to maintain the nutritional status related to vitamin E.

Effect of repeated exercise on urinary 8-hydroxy-deoxyguanosine excretion in humans.

The purpose of this study was to investigate the effect of repeated exercise on oxidative damage to DNA in 10 well trained long distance runners who participated in an 8-day training camp. The average running distance during the camp was 30 +/- 3 km/day. The amount of urinary 8-hydroxy-deoxyguanosine (8-OHdG) excretion was used to estimate the oxidative DNA damage. Urine samples were collected for both a 3-day control period as well as throughout the camp. Blood samples were drawn after overnight fasting both before and after the camp. Urinary 8-OHdG excretion was significantly increased during the camp compared to the control period (265.7 +/- 75.5 vs. 335.6 +/- 107.4 pmol/kg/day, P < 0.05). The content of 8-OHdG in the lymphocyte DNA on the day after finishing the camp did not differ from that before the camp. Plasma TBARS, LDH, CK, CK-MB, and myoglobin significantly rose after the camp (P < 0.05). The plasma beta-carotene levels tended to rise after the camp, while the plasma alpha-tocopherol levels increased significantly after the camp (P < 0.05). These results indicate that repeated exercise augments oxidative stress and the DNA is also injured by exercise-induced reactive oxygen species. However, the oxidative damage to DNA is not accumulated by consecutive exercise, although it is sustained as long as the exercise is repeated.