• Analytical Science and Technology
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• v.36 no.4
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• pp.143-151
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• 2023

Considering the greater role of α-amino acids in our daily lives, the enantiomer resolution of seven α-amino acids derivatized with fluorogenic reagent (4-fluoro-7-nitro-2,1,3-benzoxadiazole, NBD-F) by chiral HPLC on amylose or cellulose trisphenylcarbamate derived chiral stationary phases (CSPs) under simultaneous ultraviolet (UV) and fluorescence (FL) detection was performed. The degree of enantioseparation and resolution was affected by nature and selector backbones of the CSPs as well as the kind of amino acids. Baseline enantiomer separation and resolutions were observed for the enantiomers of all analytes as NBD derivatives especially on coated type amylose tris(3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak AD-H and Lux Amylose-1). The other CSPs also showed good enantioselectivity except for the CSPs (Chiralpak IB, Chiralcel OD-H and Lux Cellulose-1) having cellulose tris(3,5-dimethylphenylcarbamate) as chiral selectors. The developed analytical chiral method was applied to determine the enantiomeric purity of seven commercially available L-α-amino acids and the impurities as D-forms were found to be in the range 0.08-0.87 %, respectively. The intra- and interday accuracy and precision assays showed high accuracy and precision of the developed analytical method. This chiral HPLC method for the enantiomer resolution of amino acids using fluorescent derivatization could be useful for the determination of enantiomeric purity of pharmaceuticals and biological study for amino acid type compounds among chiral drugs.

• The Korean Journal of Zoology
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• v.4 no.2
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• pp.13-19
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• 1961

Free amino acids at five different developemntal stages (Gastrulation-Hatching -out stage) of Hynobius leechi BOULENGER were analyzed qualitatively by the use of paper paitition chromatography. It was found that the number of free amino acids increased as the development proceeded. The free amino acids identified at each stages are as follows : Gastrulation stage : Alaninie, Aspartic acid, Glutamin acid, Histidine, Methionine. Neural plate formation stage : Alanine , Aspartic acid, Glutamic acid, Glycine, Histidine, MEthionine, Phenylalanine, Proline, Serine, Trypotophan. Middle tail-bud stage : Alanine, Arginine, Asparagine,Aspartic acid, Citrulline, Glutamic acid, Glycine, Histidie,Hydroxyproline, Proline, Leucine, Methionine, Ornithine, Phenylalanine, Serine, Threonine, Tryptophan. Late tail-bud stage : Alanine, Arginine, Asparagine, Aspartic acid, Citrulline, Glutamic acid. Glycine, Histidine, Hydroxyproline, Leucine, Methionine, Ornithine, Phenylalanine, Proline, Serine, Threonine, Tryptophan, Valine. Hatching -out stage : the same with the late tail-bud stage. It seems probable that the metabolic systems of amino acids before and after the middle tail-bud stage are quite different from each other. Before the middle tail=-bud stage, the reaction system of amino acids is thought not to be completed while after that stage the system has been completed , because in the former period of the development , the number of freeamino acids increased rapidly with the development , and after that stage, there is practically no change in the number of free amino acids.

• Bulletin of the Korean Chemical Society
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• v.24 no.4
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• pp.467-472
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• 2003

Optically pure α-mono- and α, α-disubstituted β-amino acids were conveniently prepared in four steps and in 27-40% overall yields from the correspondingly substituted racemic β-hydroxy acids that can be readily obtained from diethyl malonate. In the synthesis, (S)-phenylethylamine has been used as a resolving agent and as a source of the amino group in the β-amino acids.

• Journal of Ginseng Research
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• v.14 no.2
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• pp.117-121
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• 1990

Browning intensity is a major factor to estimate the quality of red ginseng or red ginseng products. The Maillard type of browning reaction proceeds nonenzymatically during extraction and concentration of red ginseng. The present studies were carried out to investigate the effects of amino acids and sugars on the browning reaction during extraction and concentration of red ginseng. Red ginseng was pulverized to 115 mesh and then tenfold (v/w) of water was added to the powder to make the substrate of red ginseng. Solution (0.1 M) of fourteen amino acids and of folly silgars were added to the substrates of red ginseng powder and these were then extracted and concentrated to examine their browning intensities. Amino acids were more effective than sligars in acrelerating the browning reaction. Acceleration of the browning reaction in the concentrate was in the order of arginine> histidine>glycine>alanine>lysine phenyl alanine>aspartic acid>lelicine>threonine>gllitamic acid>tyrosine>valine>istleucine>methionine for amino acids, and was glucose>frlictose >silcrose, maltose for sugars.

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1757-1762
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• 2003

The interrelation between retention factors of several L-amino acids and their physico-chemical and structural properties can be determined in chromatographic research. In this paper we describe a predictor for retention factors with various properties of the L-amino acids. Eighteen L-amino acids are included in this study, and retention factors are measured experimentally by RP-HPLC. Binding energy ($E_b$), hydrophobicity (log P), molecular refractivity (MR), polarizability (${\alpha}$), total energy ($E_t$), water solubility (log S), connectivity index (${\chi}$) of different orders and Wiener index (w) are theoretically calculated. Relationships between these properties and retention factors are established, and their predictive and interpretive ability are evaluated. The equation of the relationship between retention factors and various descriptors of L-amino acids is suggested as linear and multiple linear form, and the correlation coefficients estimated are relatively higher than 0.90.

• Bulletin of the Korean Chemical Society
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• v.10 no.6
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• pp.491-495
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• 1989

Resolution of enantiomers of DNS-amino acids has been achieved by a reversed phase liquid chromatography with an addition of a copper(Ⅱ) complex of N-benzyl-L-hydroxyproline to the mobile phase. N-Benzyl-L-hydroxyproline was prepared and used as a chiral ligand of copper(Ⅱ) chelate for the optical resolution. The pH and the concentration of copper(Ⅱ) chelate, organic solvent, and buffer agent in the mobile phase all affect the optical resolutions of dansyl amino acids. The elution orders between D and L-DNS-amino acids were different depending on the structure of the side chain of the amino acids. The retention mechanism for the chiral separation of the dansyl amino acids can be illustrated by the equilibrium of ligand exchange and by hydrophobic interaction with $C_{18}$ stationary phase. The chiral separation can be illustrated with cis and trans effect of the ligand exchange reaction.

• Bulletin of the Korean Chemical Society
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• v.13 no.3
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• pp.280-285
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• 1992

Enantiomeric separation of free amino acids has been achieved by a reversed phase liquid chromatography with addition of a Cu(Ⅱ) complex of N-alkyl-L-proline (alkyl: propyl, pentyl or octyl) to the mobile phase. The amino acids eluted were detected by a postcolumn OPA system. N-alkyl-L-proline was prepared and used as a chiral ligand of Cu(Ⅱ) chelate for the enantiomeric separation. The concentration of the Cu(Ⅱ) chelate, the organic modifier and pH affect the enantiomeric separation of free amino acids. The retention behaviour, varied with change in pH and the concentration of the Cu(Ⅱ) chelate, was different compared with those of the derivatized amino acids. The elution orders between D- and L-forms were consistent except histidine showing that L-forms elute earlier than D-forms. The retention mechanism for the enantiomeric separation can be illustrated by the stereospecificity of the ligand exchange reaction and the hydrophobic interaction between the substituent of amino acids and reversed phase, $C_18$.

• Journal of Ginseng Research
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• v.44 no.3
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• pp.424-434
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• 2020

Background: Amino acids are one of the major constituents in Panax ginseng, including neutral amino acid, acidic amino acid, and basic amino acid. However, whether these amino acids play a role in ginsenoside conversion during the steaming process has not yet been elucidated. Methods: In the present study, to elucidate the role of amino acids in ginsenoside transformation from fresh ginseng to red ginseng, an amino acids impregnation pretreatment was applied during the steaming process at 120℃. Acidic glutamic acid and basic arginine were used for the acid impregnation treatment during the root steaming. The ginsenosides contents, pH, browning intensity, and free amino acids contents in untreated and amino acid-treated P. ginseng samples were determined. Results: After 2 h of steaming, the concentration of less polar ginsenosides in glutamic acid-treated P. ginseng was significantly higher than that in untreated P. ginseng during the steaming process. However, the less polar ginsenosides in arginine-treated P. ginseng increased slightly. Meanwhile, free amino acids contents in fresh P. ginseng, glutamic acid-treated P. ginseng, and arginine-treated P. ginseng significantly decreased during steaming from 0 to 2h. The pH also decreased in P. ginseng samples at high temperatures. The pH decrease in red ginseng was closely related to the decrease in basic amino acids levels during the steaming process. Conclusion: Amino acids can remarkably affect the acidity of P. ginseng sample by altering the pH value. They were the main influential factors for the ginsenoside transformation. These results are useful in elucidating why and how steaming induces the structural change of ginsenoside inP. ginseng and also provides an effective and green approach to regulate the ginsenoside conversion using amino acids during the steaming process.

• Applied Biological Chemistry
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• v.15 no.2
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• pp.175-180
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• 1972

The chemical composition of amino acids in the rind and fresh of Citrus Junos Sieb was studied and compared with that of Citrus natsudaidai Hayate. The results were summarized as follows. 1. Beth of them contained twenty kinds of amino acids, including three kinds of unknown amino acids. 2. Proline in the rind of Citrus Junos and aspartic acid in the rind of Citrus natsudaidai were the richest of all amino acids but on the contrary. Histidine was the poorest of all amino acids in the rind of them. The content of proline amounted to 16.48 mg/100mg in the rind of Citrus Junos and the content of aspartic acid amounted to 32.18 mg/100mg in the rind of Citrus natsudaidai. 3. Aspartic acid was the richest of all amino acids in the flesh of Citrus Junos and the content of it amounted to 32.68mg/100mg. On the other hand, Proline was the richest of all amino acids in the flesh of Citrus natsudaidai and the content of it amounted to 20.93mg/100mg. But the content of histidine as 1.32 mg/100 mg in the flesh of former and tyrosine as 1.18 mg/100 mg in the flesh of latter were relatively small. 4. In the fruits of Citrus Junos and Citrus natsudaidai, aspartic acid and Proline were rich and histidine was poor in quantity. Generally, Flesh contained more amounts of all kinds of amino acids than those rind and especially glutamic acid was richer, compared with other amino acids in flesh.

• Journal of Mushroom
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• v.10 no.4
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• pp.208-215
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• 2012

Ingredient content for the general composition of essential amino acids and non-essential amino acids were analyzed by the fruiting bodies of Ganoderma sp. The results obtained are as followes. The ASI 7004 showed that high concentrations than other strains in essential amino acids(His, Ile, Leu, Phe, Thr, Val) and the non-essential amino acids(Ala, Ser, Gly). In addition, The ASI 7002 showed that high concentrations than other strains in essential amino acids(Lys) and the non-essential amino acids(Asp, Glu). ASI 7022 showed that high concentrations than other strains in essential amino acids(Met) and the non-essential amino acids(Pro). In General, contents of Amino acid was higher than Phellinus.