High-performance liquid chromatographic determination of taurine in human plasma using pre-column extraction and derivatization

In Vitro Permeability Study of Homotaurine Using a High-Performance Liquid Chromatography with Fluorescence Detection Pre-Column Derivatization Method

Homotaurine (HOM) is considered a promising drug for the treatment of Alzheimer's and other neurodegenerative diseases. In the present work, a new high-performance liquid chromatography with fluorescence detection (HPLC-FLD) (λex. = 340 nm and λem. = 455 nm) method was developed and validated for the study of substance permeability in the central nervous system (CNS). Analysis was performed on a RP-C18 column with a binary gradient elution system consisting of methanol-potassium phosphate buffer solution (pH = 7.0, 0.02 M) as mobile phase. Samples of homotaurine and histidine (internal standard) were initially derivatized with ortho-phthalaldehyde (OPA) (0.01 M), N-acetylcysteine (0.01 M) and borate buffer (pH = 10.5; 0.05 M). To ensure the stability and efficiency of the reaction, the presence of different nucleophilic reagents, namely (a) 2-mercaptoethanol (2-ME), (b) N-acetylcysteine (NAC), (c) tiopronin (Thiola), (d) 3-mercaptopropionic acid (3-MPA) and (e) captopril, was investigated. The method was validated (R2 = 0.9999, intra-day repeatability %RSD < 3.22%, inter-day precision %RSD = 1.83%, limits of detection 5.75 ng/mL and limits of quantification 17.43 ng/mL, recovery of five different concentrations 99.75-101.58%) and successfully applied to investigate the in vitro permeability of homotaurine using Franz diffusion cells. The apparent permeability (Papp) of HOM was compared with that of memantine, which is considered a potential therapeutic drug for various CNSs. Our study demonstrates that homotaurine exhibits superior permeability through the simulated blood-brain barrier compared to memantine, offering promising insights for enhanced drug delivery strategies targeting neurological conditions.

Clinical Findings in Healthy Dogs Fed With Diets Characterized by Different Carbohydrates Sources

In recent years, pet owners have become more interested in the ingredients, and quality of pet-food, and several studies have demonstrated that feed management could affect healthy status. Recently, some authors indicated that commercial diets formulated without cereals, or using unconventional protein, and starch sources, can cause a reduction in taurine levels in both whole blood, and plasma. Nevertheless, the specific mechanism by means of which nutritional factors determine this reduction is not completely clear. Thirty neutered half-breed dogs were recruited at a kennel in the province of Naples (Italy) to investigate the influence of carbohydrates sources, and dietary density of nutrients on healthy status of dogs in terms of blood count, and biochemical parameters. The dogs were housed in the kennel and divided into three distinct groups. Three iso-energy, and iso-nitrogen commercial kibble diets (named GF1, GF2, and CB) with different protein, and carbohydrates contents, and carbohydrates sources were chosen for the trial. The chemical composition and amino acid profile of each of the three tested diets were analyzed. Moreover, blood samples of each dog were collected to evaluate the hematological and biochemical profiles. The taurine level was determined both on plasma and whole blood. The effect of the diets was analyzed statistically, and all tested diets were compared to the control one. There were significant differences between the three tested diets as regards their chemical composition. The concentrations of all amino acids seem to reflect protein content diets. The hematological profile resulted within the ranges considered physiological for the canine species for all subjects. Compared to the control diet, the three tested diets showed significant differences in blood count for MCHC and platelets. The biochemical profile showed significant differences between the diets, particularly their AST, fructosamine, lipase, and triglycerides values. The diets did not affect the blood and plasma taurine levels. They resulted in higher than optimal reserve levels. Preliminary results showed that the sources of carbohydrates and use of balanced diets affected only some biochemical parameters and did not alter the levels of taurine in healthy adult dogs.

Effects of Dietary Taurine Supplementation on Blood and Urine Taurine Concentrations in the Elderly Women with Dementia

The purpose of this research is to investigate the effects of dietary taurine supplementation on blood and urine taurine concentrations of the elderly women with dementia. Subjects were 31 female elderly with dementia hospitalized in a geriatric hospital. They were divided randomly into control group and dietary taurine supplemented group. Basically, same meals were served to both groups. Scorched rice water without taurine were served to control group. Scorched rice water containing 3 g of taurine were reserved to taurine group with lunch similarly. Food ingredients containing high concentration of taurine were eliminated from the meal menu. Blood and urine samples were obtained from each subject at the beginning of study, after 2 week and 4 weeks in the morning fasting state. Taurine concentrations in serum and urine were measured as taurine-fluorescamine derivatives using high performance liquid chromatography (HPLC). Data were analyzed using SPSS 20.0. The average taurine concentrations in serum and urine of subjects were 89.2 ± 9.5 μM and 876.7 ± 97.1 μM at the beginning. After 4 weeks, the taurine concentrations in serum and urine of dietary taurine supplemented group were 218.0 ± 15.6 μM and 6502.6 ± 380.6 μM, which were significantly higher compared to control group. Dietary taurine supplemented group showed positive changes in the score on language and execute performance. So taurine supplementation can provide beneficial effects to the elderly and the elderly with dementia.

Comparison of Urinary Excretion of Taurine Between Elderly with Dementia and Normal Elderly

The purpose of this study was to investigate the differences in dietary intake, serum level and urinary excretion of taurine between the elderly with dementia and the normal elderly. Subjects with dementia were 22 (8 men, 14 women) and normal were 26 (2 men, 24 women). The general characteristics, anthropometric data were considered together. The blood and urine samples were obtained from the elderly in the morning fasting state. Taurine concentrations in serum and urinary excretion were determined using high performance liquid chromatography (HPLC). Dietary intake data were collected using questionnaires, and analyzed by Computer Aided Nutritional analysis program (CAN-pro 4.0). Statistical analyses were carried out using SPSS 20.0. There were no significant differences in age and BMI (body mass index) between the elderly with dementia and the normal elderly, however, blood total cholesterol, LDL cholesterol and HDL cholesterol levels of the elderly with dementia were relatively higher than the normal elderly. The elderly men with dementia took more lipid, riboflavin higher than the normal elderly men (P < 0.05). The elderly women with dementia took more nutrients except vitamin D, vitamin B12 and taurine than the normal elderly (P < 0.001). There were slight differences in serum taurine level between the two groups. However, urinary excretion of taurine in the elderly with dementia was significantly higher than the normal elderly (41.2%, P < 0.05).

Relationship among serum taurine, serum adipokines, and body composition during 8-week human body weight control program

Human adipose tissue is not only a storage organ but also an active endocrine organ to release adipokines. This study was conducted to investigate the relationship among serum taurine and adipokine levels, and body composition during 8-week human body weight control program in obese female college students. The program consisted of diet therapy, exercise, and behavior modification. After the program, body weight, body fat mass, percent body fat, and body mass index (BMI) were significantly decreased. Serum triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels were significantly decreased. Also serum adiponectin level was significantly increased and serum leptin level was significantly decreased. There were no differences in serum taurine and homocysteine levels. The change of serum adiponectin level was positively correlated with change of body fat mass and percent body fat. These results may suggest that body fat loss by human body weight control program is associated with an increase in serum adiponectin in obese female college students. Therefore, further study such as taurine intervention study is needed to know more exact correlation between dietary taurine intake and serum adipokines or body composition.

Evaluation of Taurine by HPTLC Reveals the Mask of Adulterated Edible Bird’s Nest

Detection of amino acid is an effective and common method to determine adulteration in edible bird’s nest. Therefore, a simple and sensitive method was developed to detect taurine for determining adulteration in edible bird’s nest in the future. Sample was separated on precoated silica gel GF254 high-performance thin layer chromatographic plates. Separation of taurine was performed by n-propyl alcohol : ethanol : water : glacial acetic acid (5.2 : 0.8 : 2 : 2, v : v : v : v). Densitometric analysis of taurine was carried out in the absorbance mode at 485 nm. The method was validated for precision, intra- and interday variation, and recovery. This study proved that high-performance thin layer chromatography is a simple, rapid, precise, and selective method for qualitative and quantitative analysis of taurine in edible bird’s nest.

Effects of taurine on nitric oxide and 3-nitrotyrosine levels in spleen during endotoxemia

Taurine (2-aminoethanesulfonic acid) is a free sulfur-containing β-amino acid which has antioxidant, antiinflammatory and detoxificant properties. In the present study, the role of endotoxemia on peroxynitrite formation via 3-nitrotyrosine (3-NT) detection, and the possible antioxidant effect of taurine in lipopolysaccharide (LPS)-treated guinea pigs were aimed. 40 adult male guinea pigs were divided into four groups; control, endotoxemia, taurine and taurine+endotoxemia. Animals were administered taurine (300 mg/kg), LPS (4 mg/kg) or taurine plus LPS intraperitoneally. After 6 h of incubation, when highest blood levels of taurine and endotoxin were attained, the animals were sacrificed and spleen samples were collected. The amounts of 3-nitrotyrosine and taurine were measured by HPLC, and reactive nitrogen oxide species (NOx) which are stable end products of nitric oxide was measured spectrophotometrically in spleen tissues. LPS administration significantly decreased the concentration of taurine whilst increased levels of 3-NT and NOx compared with control group. It was determined that taurine treatment decreased the levels of 3-nitrotyrosine and NOx in taurine+endotoxemia group. The group in which taurine was administered alone, contradiction to well-known antioxidant effect, taurine caused elevated concentration of 3-NT and NOx. This data suggest that taurine protects spleen against oxidative damage in endotoxemic conditions. However, the effect of taurine is different when it is administered alone. In conclusion, taurine may act as an antioxidant during endotoxemia, and as a prooxidant in healthy subjects at this dose.

Taurine: a novel tumor marker for enhanced detection of breast cancer among female patients

INTRODUCTION

The antioxidant Taurine found to display antineoplastic effect through down regulation of angiogenesis and enhancement of tumor cell apoptosis. It has been found that progressive inhibition of apoptosis and induction of angiogenesis may contribute to tumor initiation, growth and metastasis in the pathogenesis of breast cancer.

AIM OF THE STUDY

To correlate taurine level with the levels of some bioomolecules operating in both angiogenesis (VEGF, CD31) and apoptosis (TNF-α and Caspas-3) which could help for breast cancer pronostication and to evaluate a possible role of serum taurine level as an early marker for breast cancer in Egyptian patients.

PATIENTS AND METHODS

Four groups of a total 85 female candidates were studied in this work. The first group consists of 50 female patients at National Cancer Institute (NCI), Cairo University were diagnosed and undergoing surgery for breast carcinoma. In the second group 10 having benign breast lesions, were included. The third group consists of five cases, with positive family history. Twenty healthy females were also recruited as control. A preoperative blood sample were taken from each patient to measure serum level of VEGF; Taurine; CA15.3 and TNF- α. Sample of fresh tumor and their corresponding safety margins were obtained from the first and second groups, for determination of caspase-3; histopathological examination and immunohistochemical assay of VEGF and CD31.

RESULT

No significant differences in the serum level of CA15.3 between the breast cancer patients, the high risk and the control group. TNF-α (apoptotic biomolecule) level showed a significant difference only between breast cancer group and control group. The VEGF (angiogenic biomarker) showed a highly significant difference between breast cancer patients, the high risk and the control group. Regarding the antioxidant taurine (antiangiogenic biomolecule) serum level in breast cancer group exhibited a value strongly lower than the high risk and control group. Also the correlative ratio between the angiogenic/apoptotic biomarker (VEGF/TNF-α) showed a highly significant difference between the main previous three groups. Same observation were also noticed in the correlation between angiogenic/antiangiogenic (VEGF/taurine) ratio in the same groups. Moreover the enzymatic activities of Casp-3 in the tissue homogenate were statistically higher in adjacent normal tissues than in malignant tissues. The result of immunohistochemical investigation showed a significant increase in the density of intracellular VEGF and microvessel density expressed as CD31 in cancer cases compared to normal adjacent tissue.

CONCLUSION

It is suggested that assessment of taurine level in sera of patients with high risk for breast cancer are of great value in the early diagnosis of malignant changes in the breast.

The relationship between taurine and 3-nitrotyrosine level of hepatocytes in experimental endotoxemia

It has been proposed that taurine may function as an oxidant in a dose-dependent manner in vivo and in vitro. The present study was carried out to investigate the relationship between taurine concentration and 3-nitrotyrosine level, a stable marker of peroxynitrite action, in hepatocytes of guinea pig in endotoxemia before and after taurine administration. The levels of taurine and 3-nitrotyrosine were measured by HPLC method. In the present study, taurine was low concentration in hepatocytes exposed to endotoxemia. In taurine plus endotoxin treated animals, HPLC analysis showed higher taurine level compared with animals only supplemented with taurine. But 3-nitrotyrosine levels were same in both taurine alone and taurine plus endotoxin groups. In conclusion, taurine is able to prevent the damaging effect of peroxynitrite, at concentration measured in hepatocytes, in our experimental conditions.

The effect of taurine on polymorphonuclear leukocyte functions in endotoxemia

The aim of the present study was to measure MPO activity in PMN leukocytes after endotoxin administration, and to compare the levels of NO2- competing with taurine for reaction with HOCl. Furthermore we aimed to determine TauCl levels, a product of MPO-H2O2-Halide system, and to evaluate anti-inflammatory properties of PMN in endotoxemia. In addition, our second objective was to investigate the effect of taurine, an antioxidant amino acid, on anti-bactericidal and anti-inflammatory functions of PMN after administration of endotoxin together with taurine. All experiments were performed with four groups (control, taurine, endotoxemia, and taurine plus endotoxin) of ten guinea pigs. After endotoxin administration (4 mg/kg), MPO activities increased and taurine levels decreased. Therefore levels of TauCl, NO2*- increased. We observed the effects of taurine as conflicting. When taurine was administrated alone (300 mg/kg), all of these parameters decreased.Consequently, we suggested that taurine is influential in infected subjects but not on healthy ones as an antioxidative amino acid. In addition, we believe that in vivo effects of taurine may differ from those in vitro depending on its dosage.

Quantitative on-chip determination of taurine in energy and sports drinks

A new method for the quantitative determination of taurine in beverages by microchip electrophoresis was developed. A rapid and simple sample preparation procedure, only including two dilution steps and the addition of the fluorogenic labeling reagent NBD-Cl (4-chloro-7-nitrobenzofurazan), is applied. Using a home-built wavelength-resolved fluorescence detector, the separation and determination of the taurine derivative could be achieved in only 12 s, while the additional spectral information was utilized to ensure peak purity. Spanning from 0.1 to 50 mmol L(-1), the linear dynamic range of the applied method was adapted to the apparent contents in common taurine containing beverages. The smallest detectable amount of the taurine derivative actually injected into the separation channel was as low as 60 amol. The method was successfully validated by an independent liquid chromatographic method.

Development of capillary electrophoresis methods for quantitative determination of taurine in vehicle system and biological media

CE methods have been developed for the determination of taurine in pharmaceutical formulation (microemulsion) and in biological media such as sweat. The CE system with end-column pulsed amperometric detection has been found to be an interesting method in comparison with UV and fluorescence detection for its simplicity and rapidity. A gold-disk electrode of 100 mm diameter was used as the working electrode. The effects of a field decoupler at the end of the capillary, separation voltage, injection and pressure times were investigated. A detection limit of 4 x 10(-5) mol/L was reached using integrated pulsed amperometric detection, a method successfully applied to taurine analysis of the biological samples such as sweat. For taurine analysis of oil-in-water microemulsion, fluorescence detector was the favored method, the detection limit of which was 4 x 10(-11) mol/L.

Development of capillary electrophoresis methods for quantitative determination of taurine in vehicle system and biological media

In the present study, we demonstrate the benefits of a shear-driven rotating microchamber system for the enhancement of microarray hybridizations, by comparing the system with two commonly used hybridization techniques: purely diffusion-driven hybridization under coverslip and hybridization using a fully automated hybridization station, in which the sample is pumped in an oscillating manner. Starting from the same amount of DNA for the three different methods, a series of hybridization experiments using mouse lung and testis DNA is presented to demonstrate these benefits. The gain observed using the rotating microchamber is large: both in terms of analysis speed (up to tenfold increase) and in final spot intensity (up to sixfold increase). The gain is due to the combined effect of the hybridization chamber miniaturization (leading to a sample concentration increase if comparing iso-mass conditions) and the transport enhancement originating from the rotational shear-driven flow induced by the rotation of the chamber bottom wall.

Determination of taurine in plasma by high-performance liquid chromatography using 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride as a fluorescent labeling reagent

A sensitive high-performance liquid chromatography method for the determination of taurine in human plasma was developed. Taurine and N-methyltaurine (internal standard) were derivatized with 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride to produce fluorescent sulfonamides. The labeling reaction was carried out at 70 degrees C for 20 min at pH 7.5. The fluorescent derivatives were separated on a reversed-phase column by a stepwise elution using (A) acidic phosphate buffer/acetonitrile (83/17) and (B) acetonitrile and detected by fluorescence measurement at excitation and emission wavelengths of 318 and 392 nm, respectively. The detection limit (signal-to-noise ratio=3) of taurine was 3 fmol per injection. The within-day and day-to-day relative standard deviations were 3.0-4.8 and 2.5-4.7%, respectively. The concentration (means) of taurine in normal human plasma was 48.9+/-7.5 microM.

Separation methods for taurine analysis in biological samples

Taurine plays an important role in a variety of physiological functions, pharmacological actions and pathological conditions. Many methods for taurine analysis, therefore, have been reported to monitor its levels in biological samples. This review discusses the following techniques: sample preparation; separation and determination methods including high-performance liquid chromatography, gas chromatography, ion chromatography, capillary electrophoresis and hyphenation procedures. It covers articles published between 1990 and 2001.

Possible ameliorative effect of taurine in the treatment of iron-deficiency anaemia in female university students of Gaza, Palestine

The aim of the study was to evaluate the haematological effects of adding the antioxidant taurine to iron sulfate in the treatment of iron-deficiency anaemia (IDA). A sample of 730 students from Al-Azhar University, Gaza, in Palestine underwent screening with complete blood counts and serum samples. In subjects with microcytosis/hypochromasia, Alpha2 delta2 (HbA2) and serum concentrations of iron, total iron binding capacity (TIBC), ferritin and taurine were determined. Samples from 17 normocytic, normochromic, and non-anaemic subjects were used as baseline controls. At base-line, 81 of the 730 subjects (11.1%) had microcytosis/hypochromasia, 26 (3.6%) were diagnosed as beta-thalassemia carriers, none of which was iron deficient. Four subjects had microcytosis of unknown cause. Fifty-one subjects (all females) had iron-deficiency anaemia and were included in the therapeutic study, which lasted for 20 wk. They were matched for Hb into pairs and were treated with oral iron (325 mg of slow-release iron sulfate). In addition, they were, in a double-blind procedure, randomised to additional oral taurine (1000 mg d(-1) at a cost comparable to that of adding ascorbic acid) or placebo. Mean S-taurine was significantly lower in the IDA subjects than in the controls. After 20 wk of iron supplementation, both the taurine and placebo group significantly improved their Hb concentrations and normalised the markers of iron deficiency. Apart from the expected, albeit in this study mild side-effects of oral iron, no significant side-effects were noted. In the taurine group, there was a statistically significant additive positive change from the baseline values on Hb (2.67 +/- 1.24 g dL(-1)), red blood cell (RBC) count [(0.57 +/- 0.25) x 1012 L(-1)] and serum ferritin (30.33 +/- 17.99 microg L(-1)) as compared to placebo group values, which were 1.80 +/- 1.10 g dL-1, (0.39 +/- 0.36) x 1012 L(-1), and 20.11 +/- 7.34 microg L(-1), respectively. Oral taurine appears to increase the effectiveness of oral iron in the treatment of IDA, and has no significant side-effects. This merits further cost-benefit and clinical analyses.

Determination of taurine in plasma by capillary zone electrophoresis following derivatisation with fluorescamine

A novel capillary zone electrophoresis method is described for the determination of taurine in plasma. The method is rapidly executed and is highly selective for taurine as separation is based on the difference in ionisation of this amino acid from that of other amino acids. Following addition of homotaurine as internal standard, plasma proteins were precipitated with acetonitrile and the supernatant was derivatised with fluorescamine in the presence of a borate buffer. Capillary electrophoresis (CE) separations were carried out in reverse polarity mode at 27.5 kV on a Beckman P/ACE MDQ CE instrument, equipped with a diode array detector (DAD) set at 266 nm. The sample tray was cooled to 5 degrees C and separations were carried out at 20 degrees C. The fused-silica capillary was 50.2 cm in length (40.2 cm to detector) with an internal diameter of 75 microm. A capillary conditioning solution was applied daily in order to suppress the residual electroosmotic flow (EOF). The method, which was validated using feline plasma as the blank matrix, was shown to be linear and reproducible over the concentration range 2.5-100 microg/mL. The coefficients of variation (CVs) of replicate analyses were less than 4.5% at 1 microg/mL taurine in feline plasma and less than 3% for 2.5 microg/mL in human plasma. Recovery was estimated at 99.2% with a CV of 4.85%. It has been demonstrated that quantitation in aqueous solution yields similar results to those obtained by interpolation on a plasma calibration curve provided that subtraction for the taurine peak in unspiked plasma is carried out and that a suitable internal standard is employed.