Simultaneous determination of serum retinol and alpha- and gamma-tocopherol levels in type II diabetic patients using high-performance liquid chromatography with fluorescence detection

High-dose testosterone supplementation disturbs liver pro-oxidant/antioxidant balance and function in adolescent male Wistar rats undergoing moderate-intensity endurance training

In some countries, anabolic-androgenic steroid abuse is rampant among adolescent boys and young men, including some of those seeking physical fitness and/or pleasing appearance through various exercise types. This tactic carries the risk of severe harmful health effects, including liver injury. Most anabolic-androgenic steroid stacking protocols employed are based on the use of the ‘prototypic’ anabolic-androgenic steroid testosterone and/or its esters. There is a vast body of data on the effects of anabolic-androgenic steroids’ abuse combined with physical exercise training on the liver antioxidant barrier in adult subjects, whereas those concerning adolescents are scant. This study aimed to assess, in adolescent male Wistar rats undergoing a 6-week moderate-intensity endurance training (treadmill running), the influence of concurrent weekly supplementation with intramuscular testosterone enanthate (TE, 8 or 80 mg/kg body weight/week) on selected indices of liver status and oxidative stress. The rats were sacrificed, and their livers and blood samples were harvested two days after the last training session. High-dose TE treatment significantly reduced body and liver weight gains. Neither low-dose nor high-dose TE treatment affected liver α-tocopherol or γ-tocopherol content, whereas low-dose TE treatment significantly lowered hepatic reduced glutathione content. TE treatment significantly elevated liver thiobarbituric acid-reactive substances content and blood activities of alkaline phosphatase and γ-glutamyltransferase, but not of aspartate aminotransferase or alanine aminotransferase. Liver catalase activity was lowered by >50% in both TE-treated groups, while superoxide dismutase activity was significantly but slightly affected (−15%) only by the high-dose TE treatment. Glutathione peroxidase and glutathione reductase activities were not significantly altered. TE treatment significantly increased liver thiobarbituric acid-reactive substances content and lowered blood HDL-cholesterol, but did not significantly affect LDL-cholesterol or triglycerides level. In conclusion, high-dose TE treatment significantly disturbed liver antioxidant barrier and prooxidative-antioxidative balance and hence counteracted favorable effects of concurrent moderate-intensity endurance training in adolescent male rats.

Simultaneous analysis of tert-butylhydroquinone, tert-butylquinone, butylated hydroxytoluene, 2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, α-tocopherol, γ-tocopherol, and δ-tocopherol in edible oils by normal-phase high performance liquid chromatography

A normal-phase high performance liquid chromatography method for the simultaneous determination of tert-butylhydroquinone, tert-butylquinone, butylated hydroxytoluene, 2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, α-tocopherol, γ-tocopherol, and δ-tocopherol in edible oils was investigated. A silica column was used to separate the analytes with the gradient elution. An ultraviolet-visible detector was set at dual wavelengths mode (280 and 310nm). The column temperature was 30°C. The analytes were directly extracted with methanol. Results showed that the normal-phase high performance liquid chromatography method performed well with wide liner ranges (0.10∼500.00μg/mL, R²>0.9998), low limits of detection and quantitation (below 0.40 and 1.21μg/mL, respectively), and good recoveries (81.38∼102.34% in soybean oils and 83.03∼100.79% in lard, respectively). The reduction of tert-butylquinone caused by the reverse-phase high performance liquid chromatography during the injection was avoided with the current normal-phase method. The two isomers of butylated hydroxyanisole can also be separated with good resolution.

Analysis of circulating lipid-phase micronutrients in humans by HPLC: review and overview of new developments

Retinol, tocopherols, coenzyme Q10, carotenoids, and vitamin D are lipophilic compounds shown to function as important health-protective agents by mitigating the damaging effects of oxidative and other injury. Scientific interest in evaluating these compounds has resurfaced in recent years, particularly in the nutritional, clinical and epidemiologic fields, and has precipitated the development of a multitude of new analytical techniques. This review considers recent developments in HPLC-based assays since 2007 for the simultaneous determination of these lipid-phase compounds utilizing exclusively serum or plasma as these matrices are mostly used in clinical and epidemiological investigations. We also provide an overview of blood measurements for selected carotenoids, tocopherols, coenzyme Q10 and retinol from the last 15years of healthy umbilical cord blood, children, and adults.

Effect of occupational lead exposure on α- and γ-tocopherol concentration in plasma

OBJECTIVES

Changes in enzymatic antioxidant activity are frequently observed in workers occupationally exposed to lead. Few studies have investigated the influence of lead on the non-enzymatic antioxidant system. The aim of our study was to assess the influence of occupational exposure to lead on the plasma concentration of two hydrophobic forms of vitamin E: α-tocopherol and γ-tocopherol.

METHODS

A sample of 401 healthy men, aged 19-62, participated in the study. In total, 340 of these subjects were employed at the Mine and Metallurgical Plant in southern Poland. The workers who were occupationally exposed to lead were divided into quartiles (groups of 85 subjects). The lead concentrations in the blood of the subjects in the control group and in the lead exposure quartiles correspond to the following ranges: 10-72 μg/l (control group); 82-206 μg/l (Q1); 209-308 μg/l (Q2); 308-394 μg/l (Q3) and 395-644 μg/l (Q4), respectively.

RESULTS

Significant differences were observed only for the plasma concentration of γ-tocopherol, which differed between the control group and Q1 (by 24.1%, p=0.0368), between Q1 and Q3 (by -18.8%, p=0.0115) and between Q1 and Q4 (by -25.7%, p=0.0002). Multiple linear regression analysis showed that the statistically significant, predictive properties of the γ-tocopherol plasma concentration were as follows: triglycerides (β=0.440)> age (β=0.131)> whole cholesterol (β=0.117)> blood lead concentration (β=-0.108). For α-tocopherol, significant prognostic properties were triglycerides and total cholesterol (β=0.485 and β=0.399, respectively).

CONCLUSIONS

Occupational exposure to lead is strongly correlated with the concentration of γ-tocopherol but not α-tocopherol.

Effects of exposure to 50 Hz, 1 Gauss magnetic field on reproductive traits in male albino rats

The effects of extremely low frequency magnetic field ELF-MF (50 Hz/1 Gauss) on male fertility were studied in rats. Twenty eight adult male Wistar rats were divided into 4 groups, 2 experimental groups exposed to magnetic field for 21 days and 2 control groups (sham exposed). The first exposed group was sacrificed at the end of the exposure period, and the second exposed group was kept for extra 48 days post exposure to assess the delayed effects of exposure. Significant decrease in the testes weights, sperm motility, sperm count, normal sperms and live sperms was detected in the exposed groups compared to control. Serum testosterone concentrations were significantly increased after 21 days of exposure, and then these changes were corrected after 48 days post exposure. Superoxide dismutase, catalase activities and α-tocopherol concentration were significantly decreased after 21 days of exposure, while the later became non-significant after 48 days post exposure. L-ascorbate concentration was significantly increased after 21 days of exposure, and returned to normal 48 days post exposure. Histopathological examination of the testis from the exposed rats showed a disruption in its architecture with an increase in Leydig cell number and activity, whereas 48 days post exposure, the testicular germ cell layers increased with presence of high apoptotic rates. In conclusion, prolonged exposure to 50 Hz, 1 Gauss MF is biologically toxic to the testicular functions with oxidative stress on spermatogenesis that subsequently may affect male fertility and his sexual efficiency.

Combining genomics, metabolome analysis, and biochemical modelling to understand metabolic networks

Now that complete genome sequences are available for a variety of organisms, the elucidation of gene functions involved in metabolism necessarily includes a better understanding of cellular responses upon mutations on all levels of gene products, mRNA, proteins, and metabolites. Such progress is essential since the observable properties of organisms – the phenotypes – are produced by the genotype in juxtaposition with the environment. Whereas much has been done to make mRNA and protein profiling possible, considerably less effort has been put into profiling the end products of gene expression, metabolites. To date, analytical approaches have been aimed primarily at the accurate quantification of a number of pre-defined target metabolites, or at producing fingerprints of metabolic changes without individually determining metabolite identities. Neither of these approaches allows the formation of an in-depth understanding of the biochemical behaviour within metabolic networks. Yet, by carefully choosing protocols for sample preparation and analytical techniques, a number of chemically different classes of compounds can be quantified simultaneously to enable such understanding. In this review, the terms describing various metabolite-oriented approaches are given, and the differences among these approaches are outlined. Metabolite target analysis, metabolite profiling, metabolomics, and metabolic fingerprinting are considered. For each approach, a number of examples are given, and potential applications are discussed.

Simultaneous determination of retinol, retinyl palmitate and β-carotene in rat serum treated with 7,12-dimethylbenz[a]anthracene and Hypericum Perforatum L. by high-performance liquid chromatography with diode-array detection

A new and simple high-performance liquid chromatography method was developed and validated for the simultaneous determination of retinol, retinyl palmitate and β-carotene in rat serum treated with Hypericum Perforatum L. and 7,12-dimethylbenz[a]anthracene. Furthermore, vitamin C was determined spectrophotometrically. High-performance liquid chromatography analysis was performed utilizing an Inertsil ODS3 reversed phase column with methanol-acetonitrile-tetrahydrofuran (65:30:5, v/v/v) as mobile phase, at a flow rate of 1.5 mL min−1 and 40°C. Diode-array detection was conducted at 325 and 450 nm for retinol and retinyl palmitate, and β-carotene, respectively with a running time of 26 min. The high-performance liquid chromatography assay and extraction procedure proposed are simple, rapid, sensitive and accurate. This method was then applied to determine the amounts of retinol, retinyl palmitate and β-carotene in rat serum. Results of this study demonstrated that at 60th day in the 7,12-dimethylbenz[a]anthracene-treated group there was a significant decrease (pa] anthracene + Hypericum Perforatum L. treated group compared to the control group..

Short-term effects of electrically induced tachycardia on antioxidant defenses in the normal and hypertrophied rat left ventricle

Increased oxidative stress resulting from enhanced production of reactive oxygen species and/or inadequate mechanisms of antioxidant defenses has been recognized as an important factor contributing to the initiation and progression of cardiac dysfunction under a wide variety of pathophysiological conditions. The main objective of this study was to examine the effect of electrically induced tachycardia on oxidative stress and the capacity of antioxidant defenses in the normal and hypertrophied left ventricle (LV) in the rat. Left ventricular hypertrophy (LVH) was produced by banding the descending abdominal aorta. The activities of antioxidant enzymes, concentrations of non-enzymatic antioxidants, and biomarkers of oxidative stress were measured in the LV of aortic-banded animals (LVH), untreated or banded rats subjected to short-term (45 min) atrial pacing [(CTR + S) and (LVH + S), respectively], and untreated (CTR) or sham-operated (SHAM) controls. The results indicate that the increase in heart rate in vivo as a result of atrial pacing to a maximum level, independent of sympathetic nerve activity, leads to a substantial increase in oxidative stress and a marked decline in the activities of antioxidant enzymes in both the normal and hypertrophied left ventricle of the rat. The accompanying increase in tissue content of alpha- and gamma-tocopherols seem to contribute to attenuation of the oxidant stress-related loss of thiol stores in the LV. Stable left ventricular hypertrophy induced by aortic banding for six weeks has a minor impact on the capacity of the endogenous antioxidant defense system in the LV, but significantly and negatively affects the ability of the heart LV to tolerate the stress of tachycardia.

Effects of castration and testosterone replacement on the antioxidant defense system in rat left ventricle

There is strong evidence that oxidative stress plays a key role in the pathophysiology of several cardiovascular diseases. On the other hand, the presence of specific receptors for androgens and estrogens in the myocardium implies that sex hormones play a physiological role in cardiac function, myocardial injury, and the regulation of the redox state in the heart. The present study was designed to determine whether castration and androgen replacement result in changes in the capacity of the antioxidant defense system in the left ventricle (LV) of adult male rats. To assess this, the activities of antioxidant enzymes (superoxide dismutase [SOD], glutathione peroxidase [GPX], catalase [CAT], and glutathione reductase [GR]), concentrations of nonenzymatic antioxidants (reduced glutathione [GSH] and alpha- and gamma-tocopherols), and oxidative stress biomarkers (tissue sulfhydryl groups, protein nitrotyrosine levels, and lipid peroxidation) were measured in castrated animals (CAS), castrates replaced with testosterone (CAS+T), and sham-operated controls (Sham). Testosterone was not detectable in serum from gonadectomized rats. The results indicate that castration significantly and negatively affected the antioxidant status of rat LV, as evidenced by a significant decline in activities of all antioxidant enzymes, by a tendency toward lower levels of GSH and protein thiol groups, and by enhanced lipid peroxidation and higher nitrotyrosine concentrations in left ventricular tissue. Increases in LV tissue concentrations of alpha- and gamma-tocopherols seem to be a compensatory response to enhanced oxidative stress induced by gonadectomy. The reestablishment of physiological serum testosterone level by androgen replacement resulted in a tendency toward a further decrease in the antioxidant defense status in the LV tissue.

Comparison of two derivative spectrophotometric methods for the determination of α-tocopherol in pharmaceutical preparations

Simple, sensitive and reliable derivative spectrophotometric methods were developed and validated for determination of alpha-tocopherol in pharmaceutical preparations. The solutions of standard and the sample were prepared in absolute ethanol. The quantitative determination of the drug was carried out using the first derivative values measured at 284, 304 nm and the second derivative values measured at 288, 296 nm. Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of alpha-tocopherol using peak to zero 10-250 microg ml(-1) for first and second derivative spectrophotometric methods. Developed spectrophotometric methods in this study are accurate, sensitive, precise, reproducible, and can be directly and easily applied to Evon dragee form as pharmaceutical preparation. Statistical analysis (Student's t-test) of the obtained results showed no significant difference between the proposed two methods.

The effects of tobacco smoke on plasma alpha- and gamma-tocopherol levels in passive and active cigarette smokers

Tobacco smoke is one of the causes of oxidative stress that is leading to attenuation of the antioxidative body protective barrier by means of decreasing the levels of intra- and extracellular antioxidants. The effect of tobacco smoke on plasma levels of two main forms of Vitamin E, alpha- and gamma-tocopherol, in passive smokers (urinary cotinine concentration 50-500 microg/L) and active smokers (urinary cotinine concentration >500 microg/L) were studied. Slight, but statistically significant decreases in plasma alpha-tocopherol level in passive and active smokers in comparison with non-smokers (by 5.7% and 9.2%, respectively) were found. The plasma gamma-tocopherol levels remained unchanged. The Pearson's correlation coefficient for the plasma alpha-tocopherol level and the urinary cotinine concentration in passive and active smokers was -0.431, P = 0.004 and -0.534, P < 0.001, respectively, and for gamma-tocopherol in similar conditions -0.190, P = 0.217 and 0.346, P = 0.027, respectively. The obtained results indicate the secondary role that alpha- and gamma-tocopherol play in the process of tobacco smoke free radical scavenge, or they may also reflect the body increased anti-oxidative mobilization in response to oxidative stress evoked by tobacco smoke.

Fully automated method for the determination of 24,25(OH)2 and 25(OH) D3 hydroxyvitamins, and Vitamins A and E in human serum by HPLC

A new fully automated method for the determination of metabolites of Vitamin D(3) and Vitamins A and E has been developed. A robotic station for liquid-liquid extraction, connected on line with an automatic system for solid-phase extraction (Prospekt) and a liquid chromatograph were used and the complexity of the overall method was overcome by full automation. The eluate from the chromatograph was monitored by a photodiode-array detector at three wavelengths, namely, 265 nm for Vitamin D(3) metabolites, 291 nm for Vitamin E and 325 nm for Vitamin A-which are the maximum absorption wavelengths for the analytes. The time required per sample analysis was 35 min because of the overlapping development of the steps. The linearity obtained for serum samples (standard addition method) gives correlation coefficients (r(2)) ranging between 0.996 and 0.989, with standard deviation of the slope between 4.0 and 4.9%. The repeatability was between 4.0 and 6.0% and the within-laboratory reproducibility was lower than 10.1% in all cases-both expressed as relative standard deviation-for low concentrations of the analytes, namely, 3 ng/ml for 24,25(OH)(2) dihydroxyvitamin D(3), 10 ng/ml for 25(OH) hydroxyvitamin D(3), 100 ng/ml for Vitamin A and 2 microg/ml for Vitamin E. The method has been validated using a CRM (NIST, SRM968c).

Determination of endogenous levels of retinoic acid isomers in type II diabetes mellitus patients. Possible correlation with HbA1c values

A sensitive HPLC method for simultaneous determination of endogenous levels of all-trans-(ATRA), 13-cis-(13cRA), and 9-cis-retinoic acids (9cRA) was applied to serum samples from healthy volunteers and type II diabetes mellitus patients. Levels of 9cRA (around 0.2 ng/ml in both groups) were below the limit of quantification. The concentrations of ATRA and 13cRA were reliably quantified, and the within-day and between-days variances indicated that they were well maintained with little variation. Concentrations of serum ATRA and 13cRA of diabetic patients (ATRA: 1.76 +/- 0.54 ng/ml; 13cRA: 1.77 +/- 0.39ng/ml, n=13) were rather lower than those of healthy subjects (ATRA: 2.08 +/- 0.53 ng/ml; 13cRA: 2.05 +/- 0.26 ng/ml, n = 18), but the differences were not significant, except for the sum of ATRA and 13cRA (p = 0.033). Interestingly, the serum levels of retinoic acids in diabetic patients correlated positively with the hemoglobin A1c (HbA1c) values (ATRA: r = 0.57, p < 0.05; 13cRA: r = 0.62, p < 0.05). The results warrant further studies on the possible involvement of uncontrolled serum retinoic acids levels in the pathogenesis and/or treatment of diabetes mellitus.

Separation of delta-, gamma- and alpha-tocopherols by CEC

In this study capillary electrochromatography (CEC) was used for the separation of three tocopherols (TOHs), namely delta-, gamma- and alpha-TOH and the antioxidant compound, butylated hydroxytoluene (BHT). The CEC experiments were carried out using an octadecylsilica (ODS) stationary phase packed, in our laboratory, in a fused-silica capillary (100 microm I.D., 365 microm O.D. x 33 cm of total length and 24.6 or 8.4 cm effective length). The mobile phase was composed by a mixture of methanol (MeOH) and acetonitrile (ACN), at different concentrations and 0.01% (w/v) of ammonium acetate. Retention time (t(R)), retention factor (k), resolution (R(s)) of the three TOHs were strongly influenced by the organic solvent composition of the run buffer and by the effective length of the capillary. Optimum experimental conditions were found even employing the short effective length of the capillary achieving the baseline separation of the studied analytes in a relatively short time (less than 5 min). The optimized method was applied to the qualitative analysis of vitamin E (alpha-TOH) present in a human serum extract.

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.

Qualitative and quantitative liquid chromatographic determination of natural retinoids in biological samples

Liquid chromatography continues to be the preferred method for determining retinoids in biological samples. The highly unstable nature of retinoids and the real possibility of artifacts or erroneous results have led to the development of rapid and highly automated protocols for retinoid extraction, separation and detection. Due to strong light absorbance in the ultraviolet region, UV detectors still predominate although mass spectrometric detection is gaining increased popularity. This paper reviews recent advances and provides major guidelines for using liquid chromatography to identify and quantify retinoids in biological samples.

Chromatographic analysis of alpha-tocopherol and related compounds in various matrices

Tocopherols and tocotrienols (Vitamin E) are part of a group of "minor components" of main interest, present in the unsaponifiable fraction of many samples. Their importance in biological, metabolical and nutritional studies makes determination of tocopherols and related compounds of major interest. Present work critically reviews the different ways to perform sample pre-treatment and analysis of these compounds, related to the matrices, other analytes to be measured, sensitivity, and simplicity. The review includes well referenced tables that provide in-depth summaries of methodology for the chromatographic analysis of alpha-tocopherol and related compounds in foods, pharmaceuticals, plants, animal tissues and other matrices.

Rapid and sensitive high-performance liquid chromatographic method for simultaneous determination of retinol, alpha-tocopherol, 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 in human plasma with photodiode-array ultraviolet detection

A new rapid and sensitive high-performance liquid chromatographic method using 0.5 ml of plasma has been developed for the simultaneous determination of retinol (vitamin A), alpha-tocopherol (vitamin E), 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3. The eluate was monitored with a photodiode-array detector with two fixed wavelengths (267 nm for vitamin D, 292 nm for alpha-tocopherol and retinol). For all compounds, including internal standards, the method provides extraction recoveries greater than 81%. Detection limits were equal to or lower than 1.5 microg/l for the 4 vitamins. Linearity of standards was excellent (r>0.999 in all cases). Intra-day and inter-day precision were generally acceptable; the intra-dayassay C.V. was 3/4 7.7 for all compounds and the inter-day-assay C.V. was <9.2% except for the lower concentrations of 25-hydroxyvitamin D3, 25-hydroxyvitamin D2 and alpha-tocopherol (10.8, 11.8 and 11.9, respectively). The important properties of the present method are its ease of use, its rapidity, since sample preparation was achieved in 15 min and all the compounds were eluted in less than 15 min, and its small sample volume required (=0.5 ml), which enables it to be used in pediatric practice.