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The study of brain diseases has long been of interest to researchers worldwide, and stroke is the third leading cause of death that threatens human health. At the same time, cerebral ischemia–reperfusion injury is closely associated with high rates of disability and mortality. The conditions of the 6‐aminoquinolyl N‐hydroxysccinimidyl carbamate method for the derivatization of amino acids in the bone marrow fluid and hippocampus of C57BL/6 mice with cerebral ischemia–reperfusion injury were explored and optimized, such as the column temperature, concentration of derivatization reagents and mobile phase concentration. The mobile phase consisted of 20 mm sodium acetate solution (phosphoric acid to adjust pH 5.0) and 60% acetonitrile solution at a flow rate of 1 ml min−1. The 23 analytes were separated and determined in a gradient elution procedure; the correlation coefficient r was >0.9990 in the range 0.1–8.0 μg ml−1. The results showed that the content of relevant analytes was significantly changed in the cerebral ischemia–reperfusion injury model, and the method was suitable for the simultaneous determination of 23 amino acids in the bone marrow fluid and hippocampus of C57BL/6 mice. [ABSTRACT FROM AUTHOR]

Emerging evidence suggests that amino acid (AA) neurotransmitters play important roles in the pathophysiological processes of cerebral ischemia. In this work, an HPLC with fluorescence detection (HPLC‐FLR) method was developed for the simultaneous determination of 18 AAs in the cortex and plasma after cerebral ischemia in mice. The ischemia model was prepared by bilateral common carotid artery occlusion, and then the cortex and plasma of the sham, ischemia, and naringenin groups were collected. Based on the protein precipitation method, a simple and effective sample preparation method was developed. The treated sample contained minimal proteins and lipids. The analysis of the sample was performed by the proposed HPLC‐FLR method in combination with o‐phthalaldehyde. The results showed a statistically significant increase in excitatory AAs (aspartic acid and glutamic acid), inhibitory AAs (glycine and 4‐aminobutyric acid), phenylalanine, citrulline, isoleucine, and leucine levels, and a decrease of glutathione and phenylalanine levels when compared with the sham group in the cortex. Besides, the administration of naringenin had significant effects on excitatory AAs, inhibitory AA (glycine), glutamine, tyrosine, phenylalanine, and leucine levels when compared with the sham group in the cortex. These findings could be utilized in studying and clarifying the mechanisms of ischemia. [ABSTRACT FROM AUTHOR]

Disorders of certain branched‐chain amino acids may be associated with the occurrence and development of non‐alcoholic fatty liver disease. Measurement of related branched‐chain amino acid levels could provide a reference for the clinical and scientific research of the non‐alcoholic fatty liver disease. An established HPLC–FLD method was used to quantify aspartic acid, glutamate, glutamine, glycine, taurine, tyrosine, 4‐amino butanoic acid, tryptophan, methionine, valine, phenylalanine, isoleucine and leucine in mouse brain tissue. Brain tissue samples mixed with internal standard (3‐aminobutyric acid) were processed, then derivatized with 2‐O‐phthaldialdehyde, and finally separated on an ODS2 column through gradient elution at a flow rate of 1.0 ml·min−1. The excitation and emission wavelengths were set at 340 and 455 nm, respectively. The mobile phase A was 100% methanol and the mobile phase B consisted of 30 mmol·L−1 sodium acetate (pH 6.8). The injection volume was 20 μl and the single run time was 45 min. Several parameters, accuracy, precision, and stability, were verified and the results showed the established method had good sensitivity and resolution for all of the 13 compounds and internal standard in mouse brain. [ABSTRACT FROM AUTHOR]

The determination of amino acids with actions like neurotransmitters or modulators has been increasingly important for diagnosis in many neuropsychiatric diseases. A rapid and simple high-performance liquid chromatography with fluorescence detection method was developed for simultaneous determination of seven amino acids: aspartate (Asp), glutamate (Glu), serine (Ser), glutamine (Gln), glycine (Gly), taurine (Tau) and γ-aminobutyric` acid (GABA). Homoserine was used as an internal standard. The analysis was performed on a BDS column with methanol and 50 m m sodium acetate solution (pH 6.5) using a simple gradient elution. Several parameters of the developed method were validated including linearity, accuracy, precision, extraction recovery and stability, which were within the acceptable range. The method was successfully applied to determination of real samples: hippocampus and cortex in depressed rats exposed to chronically unpredictable stress in order to study if there existed differences in the seven amino acids levels between depressed rats and control. The results showed that Asp, Gly, Tau and GABA significantly decreased with increasing Gln in the hippocampus of depressed rats, compared with that of the control group, among which obviously lower level of Asp and higher level of Gln in cortex were observed. The analytical method and the results could be useful for clinical diagnosis and further insight into pathophysiological mechanism of depression. [ABSTRACT FROM AUTHOR]

A high-performance (HPLC) method was established to detect Xeljanz enantiomers in active pharmaceutical ingredients (APIs) and tablets. The separation was achieved on a Chiralpak IC column using a mobile phase of hexane-ethanol-diethylamine (65:35:0.1, v/v). The detection wavelength was 289 nm. The peak areas and the enantiomer concentrations in the range of 0.15-2.25 μg•mL−1 were in high linearity, with correlation coefficients higher than 0.999. The recoveries were 86.44% at the concentrations of 7.5, 18.75, and 37.5 μg•mL−1. The limit of detection (LOD) and limit of quantification (LOQ) were 0.042 and 0.14 μg•mL−1, respectively. This HPLC method is suitable for detecting the enantiomers of Xeljanz in its APIs and tablets. Chirality 27:235-238, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The determination of amino acids and monoamine with actions like neurotransmitters or modulators has become increasingly important for studying the relationship between the dysfunction of neurotransmitters and the pathogenesis of diabetic encephalopathy. Here, a high‐performance liquid chromatography with fluorescence detection method was developed to simultaneously determine nine monoamines and amino acids including three excitatory neurotransmitters (aspartate, glutamate, and serotonin), four inhibitory neurotransmitters (glycine, γ‐aminobutyric acid, taurine, dopamine), a precursor of 5‐HT (tryptophan) and methionine using homoserine as the internal standard. The separation was performed on a BDS column with methanol‐buffer solution of 35 mmol/L sodium acetate and 5 mmol/L citric acid (pH 6.0) using a simple gradient elution. Several parameters including specificity, precision, and recovery were validated after optimization of the analytical conditions. The developed method was successfully applied to determine the cortex and the hippocampus samples from Sprague–Dawley rats. Our results showed that various neurotransmitters involved in diabetes mellitus may tend to be differentially modulated and present a different alteration tendency at different time course, which might be associated with the duration of diabetes mellitus. [ABSTRACT FROM AUTHOR]