Development and validation of a fast and sensitive chromatographic assay for all-trans-retinol and tocopherols in human serum and plasma using liquid-liquid extraction

Biological autoluminescence as a perturbance-free method for monitoring oxidation in biosystems

Biological oxidation processes are in the core of life energetics, play an important role in cellular biophysics, physiological cell signaling or cellular pathophysiology. Understanding of biooxidation processes is also crucial for biotechnological applications. Therefore, a plethora of methods has been developed for monitoring oxidation so far, each with distinct advantages and disadvantages. We review here the available methods for monitoring oxidation and their basic characteristics and capabilities. Then we focus on a unique method - the only one that does not require input of additional external energy or chemicals - which employs detection of biological autoluminescence (BAL). We highlight the pros and cons of this method and provide an overview of how BAL can be used to report on various aspects of cellular oxidation processes starting from oxygen consumption to the generation of oxidation products such as carbonyls. This review highlights the application potential of this completely non-invasive and label-free biophotonic diagnostic method.

A Rapid and Sensitive HPLC-FLD Method for the Determination of Retinol and Vitamin E Isomers in Human Serum

Background:

Retinol and vitamin E are fat-soluble vitamins crucial for human health, yet their isomers’ distributions in the human body are still known roughly. In order to figure out the physical condition and evaluate the nutritional status of an individual, it is imperative to analyze retinol and VE isomers in human serum.

Objective:

This work aims to establish a rapid and simple high-performance liquid chromatography with fluorescence detection for simultaneous determination of retinol and vitamin E isomers in human serum.

Methods:

Separation was accomplished on a common C18 column thermostated at 25 oC, using a simple isocratic elution program of methanol/acetonitrile (85:15, v/v) at a flow rate of 1.0 mL/min. Fluorescence detection was operated using excitation/emission wavelengths of 329 nm/472 nm for retinol and 294 nm/338 nm for VE isomers, respectively.

Results:

Rapid separation was achieved within 13 min. Linear ranges of the method were 0.020-50.0 µg/mL, with correlation coefficients greater than 0.999. Detection limits and the quantification limits were 0.001-0.004 µg/mL and 0.003- 0.013 µg/mL, respectively. Mean recoveries were 84.1%- 98.2%, with intra-day and inter-day relative standard deviations less than 12.3% and 13.6%, respectively. This method has been applied to the simultaneous determination of retinol and 8 VE isomers in human serum samples with satisfactory results.

Conclusion:

A rapid, simple and robust method was developed for routine analysis of retinol and eight vitamin E isomers in human serum, providing a useful tool for clinical diagnosis and nutritional evaluation.

Levels and effectiveness of oral retinol supplementation in VLBW preterm infants

Retinol palmitate oral administration is convenient, but it is difficult to assess/monitor its nutritional status in preterm infants and literature is controversial about the administration route and the effectiveness of vitamin A supplementation. We primarily evaluated retinol plasma levels to assess the vitamin A nutritional status in preterm infants (<1500 g; 32 weeks) after 28 days of oral supplementation (3000 IU/kg/day, retinol palmitate drops), in addition to vitamin A standard amount as suggested by European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) guidelines. We then observed the rate of typical preterm pathologies in the supplemented group (31 newborns) and in 10 matching preterm infants, hospitalized in neonatal intensive care unit (NICU) in the same period, who received neither vitamin A supplementation nor parents allowed plasma sampling. Oral integration resulted in constant retinol plasma concentration around the desired level of 200 ng/mL, but without statistical increase during the study period. Due to the complexity of vitamin A metabolism and the immaturity of preterm infant’s organs, retinol supplementation may had first saturated other needy tissues; therefore, plasmatic measures may not be consistent with improved global vitamin A body distribution. Therefore, achieving a constant retinol concentration is a valuable result and supportive for oral administration: decreasing levels, even after parenteral/enteral supplementation, were reported in the literature. In spite of favourable trend and no adverse events, we did not report statistical difference in co-morbidities. This investigation confirms the necessity to perform further trials in preterm newborns, to find an index reflecting the complex nutritional retinol status after oral administration of vitamin A, highlighting its effectiveness/tolerability in correlated preterm infant’s pathologies.

Approaches and Methods to Measure Oxidative Stress in Clinical Samples: Research Applications in the Cancer Field

Reactive oxygen species (ROS) are common by-products of normal aerobic cellular metabolism and play important physiological roles in intracellular cell signaling and homeostasis. The human body is equipped with antioxidant systems to regulate the levels of these free radicals and maintain proper physiological function. However, a condition known as oxidative stress (OS) occurs, when ROS overwhelm the body's ability to readily detoxify them. Excessive amounts of free radicals generated under OS conditions cause oxidative damage to proteins, lipids, and nucleic acids, severely compromising cell health and contributing to disease development, including cancer. Biomarkers of OS can therefore be exploited as important tools in the assessment of disease status in humans. In the present review, we discuss different approaches used for the evaluation of OS in clinical samples. The described methods are limited in their ability to reflect on OS only partially, revealing the need of more integrative approaches examining both pro- and antioxidant reactions with higher sensitivity to physiological/pathological alternations. We also provide an overview of recent findings of OS in patients with different types of cancer. Identification of OS biomarkers in clinical samples of cancer patients and defining their roles in carcinogenesis hold great promise in promoting the development of targeted therapeutic approaches and diagnostic strategies assessing disease status. However, considerable data variability across laboratories makes it difficult to draw general conclusions on the significance of these OS biomarkers. To our knowledge, no adequate comparison has yet been performed between different biomarkers and the methodologies used to measure them, making it difficult to conduct a meta-analysis of findings from different groups. A critical evaluation and adaptation of proposed methodologies available in the literature should therefore be undertaken, to enable the investigators to choose the most suitable procedure for each chosen biomarker.

Vitamin E and a-Lipoic Acid Supplementation Increase Bleeding Tendency via an Intrinsic Coagulation Pathway

Vitamin E and a-lipoic acid are potent nutritional antioxidants, and when used together, their antioxidant capabilities are improved as a-lipoic acid recycles vitamin E. Supplementation of vitamin E has been shown to prolong platelet aggregation but the effects of vitamin E and a-lipoic acid supplementation on bleeding tendency have yet to be reported. Young, male rats consumed either control diet (n=5) or vitamin E and a-lipoic acid-supplemented diet (n=5) for 14 weeks. Activated partial thromboplastin time (APTT) and prothrombin time (PT) were measured as markers of intrinsic and extrinsic coagulation pathways respectively in addition to lipid peroxidation (malondialdehyde). Supplementation significantly prolonged APTT (23.8±1.5 vs 31.4±1.2s, p<0.05) compared to the control diet; however, there was no significant difference in PT (27.8±1.5 vs 26.6±0.9s, p>0.05). While vitamin E was increased (p<0.05), there was no significant difference in plasma levels of malondialdehyde (p>0.05). Dietary supplementation of vitamin E and a-lipoic acid increases bleeding tendency via inhibition of the intrinsic coagulation pathway with no change in markers of lipid peroxidation. Such supplementation could benefit patients with cardiovascular disease who exhibit elevated levels of coagulation and oxidative stress.

Ultra-performance liquid chromatographic determination of tocopherols and retinol in human plasma

A rapid, selective and sensitive ultra-performance liquid chromatography method has been developed for the detection and quantification of tocopherols and retinol in human plasma. Alpha-tocopherol, gamma-tocopherol and retinol are assayed using fluorescence detection. Excitation/emission wavelengths are 295/330 nm and 325/470 nm for the analysis of both tocopherols and retinol, respectively. Retinol acetate is employed as the internal standard. The reversed-phase method incorporates gradient elution with a mobile phase consisting of methanol and acetonitrile. Separation of vitamin compounds is achieved using a bridged ethyl hybrid C18 column. The retention times for retinol, retinol acetate, gamma-tocopherol and alpha-tocopherol are 1.6, 1.8, 3.9 and 4.3 min, respectively. The limits of quantification for retinol, gamma-tocopherol and alpha-tocopherol were 0.02, 0.02 and 0.1 µg/mL, respectively. The assay method is suitable for the analysis of tocopherols and retinol in human plasma. The method may be applied following the ingestion of foods fortified with these fat-soluble vitamins.

Serum factors and clinical characteristics associated with serum E-screen activity

BACKGROUND

The E-Screen bioassay can measure the mitogenicity of human serum and thus may be useful as a biomarker in epidemiologic studies of breast cancer. While the assay's MCF-7 cells are known to proliferate in response to estrogen, the specific determinants of variation in E-Screen activity in human serum samples are poorly understood. We sought to identify serum molecules and patient characteristics associated with serum E-Screen activity among postmenopausal women.

METHODS

Postmenopausal women (N = 219) aged 55 to 70 years with no history of postmenopausal hormone use or breast cancer completed a questionnaire and provided a blood sample. Serum was analyzed for E-Screen activity and a variety of molecules including sex hormones, growth factors, and environmental chemicals. Stepwise selection procedures were used to identify correlates of E-Screen activity.

RESULTS

Serum samples from all women had detectable E-Screen activity, with a median estradiol equivalents value of 0.027 ng/mL and interquartile range of 0.018-0.036 ng/mL. In the final multivariable-adjusted model, serum E-Screen activity was positively associated with serum estradiol, estrone, insulin-like growth factor-binding protein (IGFBP)-3, and testosterone levels (all P < 0.05), as well as body mass index (P = 0.03). Serum E-Screen activity was lower among women with higher SHBG (P < 0.0001) and progesterone levels (P = 0.03).

CONCLUSION

Serum E-Screen activity varies according to levels of endogenous estrogens and other serum molecules. Obesity appears to confer additional serum mitogenicity beyond its impact on the measured hormones and growth factors.

IMPACT

By capturing mitogenicity due to a variety of patient and serum factors, the E-Screen may provide advantages for use as a biomarker in breast cancer studies.

The vitamin D pathway and mammographic breast density among postmenopausal women

Laboratory studies have demonstrated that vitamin D has a number of chemopreventive properties, and that these properties may be mediated or modified by other molecules in the vitamin D pathway, such as parathyroid hormone (PTH) or calcium. However, there is little epidemiologic data exploring the effects of vitamin D on breast cancer risk in the context of these other molecules. We examined a panel of molecules in the vitamin D pathway in relation to mammographic breast density, a marker of breast cancer risk, in the Wisconsin Breast Density Study. A total of 238 postmenopausal women (ages 55-70, with no history of postmenopausal hormone use) were enrolled from mammography clinics in Madison, Wisconsin. Subjects provided blood samples that were analyzed for levels of 25-hydroxy vitamin D [25(OH)D], PTH, insulin-like growth factor-1 (IGF-1), IGF-binding protein 3 (IGFBP-3), retinol, and calcium. Percent breast density was measured using Cumulus software. In age-adjusted analyses there was a positive association between 25(OH)D and percent breast density (P = 0.05; mean percent density = 11.3% vs. 15.6% for 1st vs. 4th quartile of 25(OH)D). Breast density was inversely associated with PTH (P = 0.05; 16.0% vs. 11.4% for Q1 vs. Q4) and positively associated with the IGF-1:IGFBP-3 molar ratio (P = 0.02; 11.9% vs. 15.6% for Q1 vs. Q4). However, these associations were all null after further adjustment for body mass index (BMI; P > 0.25). The independent relation between 25(OH)D and breast density remained null among subgroups defined by BMI and serum levels of retinol, calcium, and estradiol. These results suggest no strong independent associations between the circulating molecules of the vitamin D pathway and mammographic breast density in postmenopausal women. While it remains possible that vitamin D could influence breast cancer risk, our results suggest that such an effect would be mediated through pathways other than breast density.

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..

HPLC method for simultaneous determination of retinoids and tocopherols in human serum for monitoring of anticancer therapy

A simple and rapid HPLC method requiring small volumes (250 microL) of human serum after C18 SPE sample preparation was developed using monolithic technology for simultaneous determination of all-trans-retinoic acid, 13-cis-retinoic acid, retinol, gamma- and alpha-tocopherol. The monolithic column, Chromolith Performance RP-18e (100x4.6 mm), was operated at ambient temperature. The mobile phase consisted of a mixture of acetonitrile (ACN) and 1% ammonium acetate in water (AMC) at pH 7.0. The mobile phase started at 98:2 (v/v) ACN/AMC (column pre-treatment) at a flow rate of 2 mL/min, then changed to 95:5 (v/v) ACN/AMC for 4 min at a flow rate of 1.5 mL/min and a further 3 min at a flow rate of 3.2 mL/min. Detection and identification were performed using a photodiode array detector. Retinol, 13-cis- and all-trans-retinoic acid were monitored at 325 nm. Both alpha- and gamma-tocopherol were detected at 295 nm. The total analysis time was 7.2 min. Tocol (synthesized tocopherol, not occurring in humans) was used as internal standard. The method was linear in the range of 0.125-10.00 micromol/L for all-trans-retinoic acid, 0.125-5.00 micromol/L for 13-cis-retinoic acid, 0.25-10.00 micromol/L for retinol, 0.5-50.00 micromol/L for gamma-tocopherol, and 0.5-50.00 micromol/L for alpha-tocopherol. The present method may be useful for monitoring of retinoids and tocopherols in clinical studies.

A validated liquid chromatography method for the simultaneous determination of vitamins A and E in human plasma

A fast (15 min) and simple HPLC method for determination of all-trans-retinol and alpha-, gamma- and delta-tocopherols in human plasma has been developed. The assay utilized 200 microl of plasma to which 20 microl of internal standard solution (retinol acetate) was added followed by 200 microl of water, 400 microl of ethanol and 800 microl of hexane. The hexane layer was collected, evaporated, the residue dissolved in 200 microl of methanol and analyzed on a Zorbax Eclipse XDB-C18 column using a step gradient with a polar organic mobile phase composed of acetonitrile and methanol and variable wavelength fluorescence detection. The quantification limits for all-trans-retinol and gamma-tocopherol were 20 ng/ml and for alpha- and delta-tocopherols 500 ng/ml and 10 ng/ml, respectively. The procedure was validated and applied to the analysis of plasma samples from the Baltimore Longitudinal Study of Aging.

The effect of consecutive days of exercise on markers of oxidative stress

We examined the influence of 3 consecutive days of high-intensity cycling on blood and urinary markers of oxidative stress. Eight highly-trained male cyclists (VO2 max76 ± 4 mL·kg–1·min–1; mean ± SD) completed an interval session (9 exercise bouts lasting 30 s each, at 150% peak power output) on day 1, followed by 2 laboratory-simulated 30 km time trials on days 2 and 3. The cyclists also completed a submaximal exercise trial matched to the interval session for oxygen consumption. Blood was collected pre- and post-exercise for the determination of malondialdehyde (MDA), total antioxidant status (TAS), vitamin E, and the antioxidant enzyme activity of superoxide dismutase and glutathione peroxidase, while urine was collected for the determination of allantoin. There were significant increases in plasma MDA concentrations (p < 0.01), plasma TAS (p < 0.01), and urinary allantoin excretion (p < 0.01) following the high-intensity interval session on day 1, whereas plasma vitamin E concentration significantly decreased (p = 0.028). Post-exercise changes in plasma MDA (p = 0.036), TAS concentrations (p = 0.039), and urinary allantoin excretion (p = 0.031) were all significantly attenuated over the 3 consecutive days of exercise, whereas resting plasma TAS concentration was elevated. There were no significant changes in plasma MDA, TAS, or allantoin excretion following submaximal exercise and there were no significant changes in antioxidant enzyme activity over consecutive days of exercise or following submaximal exercise. Consecutive days of high-intensity exercise enhanced resting plasma TAS concentration and reduced the post-exercise increase in plasma MDA concentrations.

Comparison of the absorption efficiency of alpha- and beta-cryptoxanthin in female Wistar rats

Xanthophylls, such as lutein and zeaxanthin, have received increasing interest in recent years because of positive correlations between their consumption and the prevention of eye diseases. Numerous human intervention studies have been conducted with lutein to estimate the bioavailability from different formulations. The present study was designed to obtain basic data on the absorbance efficiency of the monohydroxylated counterparts of lutein and zeaxanthin: alpha- and beta-cryptoxanthin. A corn-oil-based diet comprising beta-cryptoxanthin from papaya purée and alpha-cryptoxanthin from green carrot leaves was fed to five female Wistar rats for 8 consecutive days at a rate of 17.3 nmol/d and 9.2 nmol/d, respectively. The identity of the xanthophylls in the supplement was ascertained by LC-(APCI)MS analyses, and xanthophylls present in liver and plasma samples were determined by HPLC/diode array detector (DAD). The beta-cryptoxanthin concentrations of rat livers in the treatment group were statistically distinguishable (P < 0.01) from those present in the livers of the control group that were fed a basic diet. Alpha-cryptoxanthin, the second xanthophyll present in the supplement, was not found in rat livers in the treatment group. Plasma samples were free of xanthophylls. This is the first report proving that beta-cryptoxanthin has a higher absorption efficiency than alpha-cryptoxanthin in rats, at least from a minimally processed oil-based xanthophyll supplement.

Comparison of a novel ultra-performance liquid chromatographic method for determination of retinol and α-tocopherol in human serum with conventional HPLC using monolithic and particulate columns

Retinol and alpha-tocopherol are biologically active compounds often monitored in blood samples because of their evident importance in human metabolism. In this study a novel ultra-performance liquid chromatographic (UPLC) method used for determination of both vitamins in human serum has been compared with conventional HPLC with particulate and monolithic C(18) columns. In UPLC a sub-two-micron particle-hybrid C(18) stationary phase was used for separation, in contrast with a five-micron-particle packed column and a monolithic column with a highly porous structure. Methanol, at flow rates of 0.48, 1.5, and 2.5 mL min(-1), respectively, was used as mobile phase for isocratic elution of the compounds in the three methods. Detection was performed at 325 nm and 290 nm, the absorption maxima of retinol and alpha-tocopherol, respectively. Analysis time, sensitivity, mobile-phase consumption, validation data, and cost were critically compared for these different chromatographic systems. Although cost and mobile-phase consumption seem to make UPLC the method of choice, use of the monolithic column resulted in almost the same separation and performance with a slightly shorter analysis time. These methods are alternatives and, in routine laboratory practice, more economical means of analysis of large numbers of biological samples than use of a traditional particulate column.

Identification and determination of fat-soluble vitamins and metabolites in human serum by liquid chromatography/triple quadrupole mass spectrometry with multiple reaction monitoring

A method for determination of fat-soluble vitamins K(1), K(3), A, D(2), D(3) and E (as alpha- and delta-tocopherol) and metabolites 25-hydroxyvitamin D(2) and D(3) and 1,25-dihydroxyvitamin D(3) in human serum by liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) in positive mode is proposed. Highly selective identification of the target compounds in serum was confirmed by the most representative transitions from precursor ion to product ion. Quantitative MS/MS analysis was carried out by multiple reaction monitoring optimizing the most sensitive transition for each analyte in order to achieve low detection limits (from 0.012 to 0.3 ng/mL estimated with serum). The analysis was performed with 1 mL of serum, which was subjected to protein precipitation, liquid-liquid extraction to an organic phase, evaporation to dryness and reconstitution with methanol. The precision of the overall method ranged from 3.17-6.76% as intra-day variability and from 5.07-11.53% as inter-day variability. The method, validated by the standard addition method, provides complete information on the fat-soluble vitamins profile, which is of interest in clinical and metabolomics studies.

Optimization and validation of a high performance liquid chromatography method for the simultaneous determination of vitamins A and E in human serum using monolithic column and diode-array detection

In this study a novel, simple and rapid reversed-phase high performance liquid chromatography (HPLC) procedure for simultaneous determination of vitamins A and E (retinol and alpha-tocopherol) in blood serum has been developed and validated using monolithic column and diode-array detection (DAD). The monolithic column Chromolith Performance RP-18e (100 mm x 4.6 mm) was operated at ambient temperature. One hundred percent methanol at flow rate 2.5 ml min(-1) was used as a mobile phase. Detection of both compounds was performed with diode-array detector, retinol was monitored at 325 nm and alpha-tocopherol at 295 nm. The linear dependence between peak area and concentration ranged from 0.25 to 10.00 micromol l(-1) for retinol and 0.5-50.0 micromol l(-1) for alpha-tocopherol. The limit of detection (LOD) for retinol was 0.02 micromol l(-1) and limit of quantification (LOQ) was 0.07 micromol l(-1). The limit of detection (LOD) for alpha-tocopherol was 0.1 micromol l(-1) and limit of quantification (LOQ) was 0.3 micromol l(-1). Retinol was eluted in 0.8 min and alpha-tocopherol in 1.4 min. The simultaneous analysis of vitamin A and E can be achieved in less than 2 min. The implementation of monolithic column Chromolith Performance shortens the time of analysis of both vitamins four times in comparison with using traditional particulate column Pecosphere C18 (150 mm x 4.6 mm), 5 microm. This fact may play an important role for routine clinical analysis of biological samples.

Cyclosporine A induced changes to plasma and erythrocyte antioxidant defences

Organ transplant recipients develop pronounced cardiovascular disease, and decreased antioxidant capacity in plasma and erythrocytes is associated with the pathogenesis of this disease. These experiments tested the hypothesis that the immunosuppressant cyclosporine A (CsA) alters erythrocyte redox balance and reduces plasma antioxidant capacity. Female Sprague-Dawley rats were randomly assigned to a control or CsA treated group. Treatment animals received 25 mg/kg/day of CsA via intraperitoneal injection for 18 days. Control rats were injected with the same volume of the vehicle. Three hours after the final CsA injection, rats were exsanguinated and plasma analysed for total antioxidant status (TAS), alpha-tocopherol, malondialdehyde (MDA), and creatinine. Erythrocytes were analysed for superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glucose-6-phosphate dehydrogenase (G6PD) activities, alpha-tocopherol, and MDA. CsA administration resulted in a significant (P < 0.05) decrease in plasma TAS and significant increases (P < 0.05) in plasma creatinine and MDA. Erythrocyte CAT was significantly (P < 0.05) increased in CsA treated rats compared to controls. There were no significant differences (P > 0.05) in erythrocyte SOD, GPX, G6PD, alpha-tocopherol or MDA between groups. In summary, CsA alters erythrocyte antioxidant defence and decreases plasma total antioxidant capacity.

Simple and rapid high-performance liquid chromatographic method for endogenousα-tocopherol determination in human plasma

A simple and rapid reversed-phase high-performance liquid chromatographic method was developed and validated for the determination of endogenous alpha-tocopherol in human plasma. Following addition of alpha-tocopheryl acetate as the internal standard, the plasma was deproteinized using acetonitrile and isopropanol mixture prior to HPLC analysis. Methanol was used as the mobile phase and the effluent was quantitated at 292 nm. By this developed method, the concentrations of alpha-tocopherol were linearly related to their responses in the range of 0.8-30 microg/mL. The relative standard deviations intra-day and inter-day for alpha-tocopherol in plasma were less than 10%. The percentage of bias was within +/-4%, which confirmed the accuracy of the method. The method has been successfully applied for determining endogenous alpha-tocopherol in healthy Thai male volunteers.

Antioxidant supplementation enhances erythrocyte antioxidant status and attenuates cyclosporine-induced vascular dysfunction

The aim of this study was to determine the effects of dietary antioxidant supplementation with alpha-tocopherol and alpha-lipoic acid on cyclosporine-induced alterations to erythrocyte and plasma redox balance, and cyclosporine-induced endothelial and smooth muscle dysfunction. Rats were randomly assigned to either control, antioxidant, cyclosporine or cyclosporine + antioxidant treatments. Cyclosporine A was administered for 10 days after an 8-week feeding period. Plasma was analyzed for alpha-tocopherol, total antioxidant capacity, malondialdehyde and creatinine. Erythrocytes were analyzed for glutathione, methemoglobin, superoxide dismutase, catalase, glutathione peroxidase, glucose-6-phosphate dehydrogenase, alpha-tocopherol and malondialdehye. Vascular endothelial and smooth muscle function was determined in vitro. Antioxidant supplementation resulted in significant increases in erythrocyte alpha-tocopherol concentration and glutathione peroxidase activity in both of the antioxidant-supplemented groups. Cyclosporine administration caused significant decreases in glutathione concentration, methemoglobin concentration and superoxide dismutase activity. Antioxidant supplementation attenuated the cyclosporine-induced decrease in superoxide dismutase activity. Cyclosporine therapy impaired both endothelium-independent and -dependent relaxation of the thoracic aorta, and this was attenuated by antioxidant supplementation. In summary, dietary supplementation with alpha-tocopherol and alpha-lipoic acid attenuated the cyclosporine-induced decrease in erythrocyte superoxide dismutase activity and attenuated cyclosporine-induced vascular dysfunction.

alpha-Tocopherol and alpha-Lipoic Acid Enhance the Erythrocyte Antioxidant Defence in Cyclosporine A-Treated Rats

The aim of this study was to determine the effects of dietary antioxidant supplementation with alpha-tocopherol and alpha-lipoic acid on cyclosporine A (cyclosporine)-induced alterations to erythrocyte and plasma redox balance. Rats were randomly assigned to either control, antioxidant (alpha-tocopherol 1000 IU/kg diet and alpha-lipoic acid 1.6 g/kg diet), cyclosporine (25 mg/kg/day), or cyclosporine + antioxidant treatments. Cyclosporine was administered for 7 days after an 8 week feeding period. Plasma was analysed for alpha-tocopherol, total antioxidant capacity, malondialdehyde, and creatinine. Erythrocytes were analysed for glutathione, methaemoglobin, superoxide dismutase, catalase, glutathione peroxidase, glucose-6-phosphate dehydrogenase, alpha-tocopherol and malondialdehye. Cyclosporine administration caused a significant decrease in superoxide dismutase activity (P<0.05 control versus cyclosporine) and this was improved by antioxidant supplementation (P<0.05 cyclosporine versus cyclosporine + antioxidant; P<0.05 control versus cyclosporine + antioxidant). Animals receiving cyclosporine and antioxidants showed significantly increased (P<0.05) catalase activity compared to both groups not receiving cyclosporine. Cyclosporine administration induced significant increases in plasma malondialdehyde and creatinine concentration (P<0.05 control versus cyclosporine). Antioxidant supplementation prevented the cyclosporine induced increase in plasma creatinine (P<0.05 cyclosporine versus cyclosporine + antioxidant; P>0.05 control versus cyclosporine + antioxidant), however, supplementation did not alter the cyclosporine induced increase in plasma malondialdehyde concentration (P>0.05 cyclosporine versus cyclosporine + antioxidant). Antioxidant supplementation resulted in significant increases (P<0.05) in plasma and erythrocyte alpha-tocopherol in both of the supplemented groups compared to non-supplemented groups. In conclusion, dietary supplementation with alpha-tocopherol and alpha-lipoic acid enhanced the erythrocyte antioxidant defence and reduced nephrotoxicity in cyclosporine treated animals.

Cyclosporine A-Induced Changes to Erythrocyte Redox Balance is Time Course-Dependent

Cyclosporine A-treated transplant recipients develop pronounced cardiovascular disease and have increased oxidative stress and altered antioxidant capacity in erythrocytes and plasma. These experiments investigated the time-course of cyclosporine A-induced changes to redox balance in plasma and erythrocytes. Rats were randomly assigned to either a control or cyclosporine A-treated group. Treatment animals received 25 mg/kg of cyclosporine A via intraperitoneal injection for either 7 days or a single dose. Control rats were injected with the same volume of the vehicle. Three hours after the final injections, plasma was analysed for total antioxidant status, alpha-tocopherol, malondialdehyde, and creatinine. Erythrocytes were analysed for reduced glutathione (GSH), alpha-tocopherol, methaemoglobin, malondialdehyde, and the activities of superoxide dismutase, catalase, GSH peroxidase, and glucose-6-phosphate dehydrogenase (G6PD). Cyclosporine A administration for 7 days resulted in a significant increase (P<0.05) in plasma malondialdehyde, methaemoglobin, and superoxide dismutase and catalase activities. There was a significant decrease (P<0.05) in erythrocyte GSH concentration and G6PD activity in cyclosporine A animals. There were no significant differences (P>0.05) between groups following a single dose of cyclosporine A in any of the measures. In summary, cyclosporine A alters erythrocyte redox balance after 7 days administration, but not after a single dose.

Simultaneous Determination of Tocopherols and Tocotrienols in Hazelnuts by a Normal Phase Liquid Chromatographic Method

A normal-phase high-performance liquid chromatography (NP-HPLC) method for the determination of tocopherols and tocotrienols in hazelnuts is reported. Three extraction procedures (with and without saponification) were assayed; the best results were obtained with a simple solid-liquid extraction procedure. Chromatographic separation was achieved using an Inertsil 5 SI column using isocratic elution with hexane/1,4-dioxane (95.5:4.5, v/v) at a flow rate of 0.7 mL/min. The effluent was monitored by a series arrangement of a diode-array followed by a fluorescence detector. All compounds were separated in a short period of time (17 min). The method proved to be rapid, sensitive, reproducible and accurate, allowing the simultaneous determination of all vitamin E homologues.

Automated method for the determination of fat-soluble vitamins in serum

A new fully automated high-performance liquid chromatography (HPLC) method using 1 ml of serum has been developed for the determination of retinol (Vitamin A), alpha-tocopherol (Vitamin E), 25-hydroxyvitamin D(3) and 24 R,25-hydroxyvitamin D(3). The eluate was monitored with a photodiode-array detector at three wavelengths-namely: 265 nm for Vitamin D(3), 291 nm for Vitamin E and 325 nm for Vitamin A. The detection limits were equal to or lower than 1 ng ml(-1) for all vitamins. The linearity obtained with serum samples (standard addition method) gives correlation coefficients (r(2)) ranging between 0.999 and 0.996 in all cases, with standard deviation of the slope between 3.2 and 1.6%. The repeatability was between 4.0 and 6.0% and the within-laboratory reproducibility was lower than 10% in all cases. The most outstanding features of the present method are its ease of use, its rapidity and fully automation, which enables its use for routine analysis. The time required per sample was 30 min, because the overlapped development of the steps. This method was used for the determination of normality range of these vitamins in healthy people in the 18-80-year-old interval.