• 한국응용과학기술학회지
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• 제28권4호
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• pp.438-448
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• 2011

Chitosan is widely used in cosmetics and medical fields. Special emphasis has been put on the chemical modification of chitosan to explore its full potential. We have described the synthesis and biological activity of novel peptide amino acid derivatives. The polyamino acid derivatives were synthesized by introducing alkylamine functional group on chitosan at C-6. The poor aqueous solubility of chitosan derivatives hinder both pharmacological studies and pharmaceutical development. To make amino acid coupled chitosan derivatives with improved biological effect and solubility, some attempts have been taken to consist of amino peptide group like aspartic acid and phenylalanine-aspartic acid derivatives onto chitosan C-6. The resultingly substituted chitosan was characterized by solubility in various solvents. We measured chitosan derivatives with $^1H$-NMR and $^{13}C$-NMR. Also, We were investigated on the physical properties and biological activities of these products.

• Biomolecules & Therapeutics
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• 제4권2호
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• pp.162-166
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• 1996

This study was done to investigate whether cholic acid derivatives have anti-stress activity and what is a cause of this anti-stress effect. Seven cholic acid derivatives (cholic acid, taurocholic acid, ursodeoxycholic acid, tauroursodeoxychoic acid, chenodeoxy cholic acid, dehydrocholic acid, hyodeoxycholic acid) were used, silymarin and valproic acid were used as positive controls. Stress was induced by restraint immobilization technique plus water immersion (24hrs) and adrenal weight, spleen weight, adrenal ascorbic acid, serum cholesterol, lactate dehydrogenase (LDH), alkaline phosphatase (ALP), adrenal cholesterol, glucose and corticosterone levels were measured as stress indicators. Most cholic acid derivatives markedly decreased the adrenal weight, and TUDCA and DHCA increased the spleen weight. The restraint stress induced increments in serum LDH, ALP and cholesterol were attenuated by most cholic acid derivatives. Cholic acid, taurocholic acid and tauroursodeoxycholic acid only increased the content of adrenal ascorbate. While valproic acid showed an inhibitory effect against stress, silymarin did not. Our findings suggest that most cholic acid derivatives have anti-stress effect and that their anti-stress effect is, in part, related to choleretic activity.

• 통합자연과학논문집
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• 제8권2호
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• pp.111-116
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• 2015

Liquid chromatographic enantiomer separation of ${\alpha}$-amino acid esters as nitrobenzoxadiazole (NBD) derivatives was performed using several chiral stationary phases (CSPs) based on polysaccharide derivatives under fluorescence detection. For enantiomer separation by normal HPLC, the non-aqueous derivatization method of ${\alpha}$-amino acid esters for NBD analytes was introduced. Among the six CSPs used in this study, the performance of Chiralpak IA was superior for enantiomer resolution of NBD derivatives of several ${\alpha}$-amino acid methyl esters. Also the convenient analytical method using polysaccharide-derived CSPs developed in this study was applied to determine the optical purity of ${\alpha}$-amino acids esters. It was investigated that the enantiomeric impurity levels of 0.02-1.73% were found after determination of enantiomeric purities of several commercially available L-amino acid methyl esters. It is expected to be quite useful for enantiomer separation of other ${\alpha}$-amino acid esters as NBD derivatives by normal HPLC.

• Archives of Pharmacal Research
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• 제16권4호
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• pp.322-326
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• 1993

For the development of new antinflammatory and analgesic drugs, new 5-alkylthio (or sulfonyl) methyl-5-m-methoxyphenylhydantoin-3-acetic acid derivatives(alkyl; ethyl, propyl, butyl) were prepared. The 5,5 -disubstituted hydantoins which were used as starting materials, were prepared acording to Bucherer-Berg method. The reaction of ethyl chloroacelate with these compounds gave 3-acetate and the subsequent hydrolysis with dilute sodium hydroxide resulted in hydantoin 3-acetate and the subsequent hydrolysis with dilute sodium hydroxide resulted in hydantoin 3-acetic acid derivatives. Through the same procedure of equivalent hydroxide resulted in hydantoin 3-acetic acid derivatives. Through the same procedure of equivelent hydantions or the oxidation of 5-alkylthiohydantoin ocmpounds described above, 5-alkylsulfonylme-thyl-5-m-methoxyphenylhydantoin-30acetic acid derivatives were also synthesized.

• 약학회지
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• 제43권1호
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• pp.28-32
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• 1999

Four derivatives of kojic acid were synthesized and their inhibitory activities against tyrosinase were evaluated. The C-2 hydroxymethyl and C-7 hydroxyl of kojic acid were replaced by carboxylate and amine, respectively. These derivatives were coupled to L-phenylalanine, producing two amide compounds. The carboxylate derivative (3), its amide compound (5), and the amine derivative (7) were weak inhibitors. The amide compound (9) where amine derivative (7) coupled to L-phenylalanine showed strong inhibitory activity ($IC_{50}=24.6{\;}{\mu}M$) comparable to kojic acid.

• KSBB Journal
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• 제28권6호
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• pp.423-427
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• 2013

A new convenient derivatization method of ${\alpha}$-amino acid esters as nitrobenzoxadiazole (NBD) derivatives for chiral resolution was introduced and the enantiomer separation of ${\alpha}$-amino acid esters as NBD derivatives was performed by normal HPLC using chiral columns based on polysaccharide derivatives. The NBD derivatives were readily prepared by stirring NBD-Cl and ${\alpha}$-amino acid methyl ester HCl with $NaHCO_3$ in ethanol. The performance of Chiralpak IA was superior to the other chiral stationary phases for enantiomer resolution of NBD derivatives of several ${\alpha}$-amino acid methyl esters. Owing to fluorescence detection as well as strong UV absorption, it is expected that the convenient analytical method developed in this study will be very useful for enantiomer separation of ${\alpha}$-amino acid esters as NBD derivatives on polysaccharide-derived chiral columns.

• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.1006-1009
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• 2002

The biological activities of farnesoic acid derivatives against pathogenic fungi and bacteria were investigated. Farnesoic acid and its derivatives showed growth inhibitory activities against various bacteria. Among the compounds tested, geranylgeranoic acid (3) had potent antibacterial activity against Salmonella typhimurium, Proteus vulgaris, and Bacillus subtilis with minimum inhibitory concentration (MIC) in the range of $6.25-12.5{\mu}g/ml$. On the other hand, amide derivatives of farnesoic acid showed some antifungal activities. In particular, 3,7,11-trimethyl-dodeca-2,6,10-trienoic acid amide (5a) had a potent antifungal activity against Aspergillus niger, Candida albicans, and Trichophyton sp. with MIC in the range of $6.25-12.5{\mu}g/ml$.

• Biomolecules & Therapeutics
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• 제6권3호
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• pp.232-241
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• 1998

This study was done to investigate whether cholic acid derivatives have anti-stress activity in various stress models. Two cholic acid derivatives, ursodeoxycholic acid (UDCA) and tauroursodeoxycholic acid (WDCA), were used. physical, psychological, chemical and environmental stress models were performed. Adrenal weight, serum glucose levels and ALP activity were elevated in restraint stress model, but this elevation was prevented by UDCA treatment. Moreover, UDCA and TUDCA inhibited exploratory and spontaneous movements in oscillation stress model. In alcohol-induced stress model, TUDCA improved rotarod performance. UDCA and TUDCA significantly reduced the involution of lymphoid organs and the increment of WBC counts in cold stress model. These findings suggest that choric acid derivatives have antistress effects in various stress models.

• Biomolecules & Therapeutics
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• 제3권1호
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• pp.72-79
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• 1995

The antiulcer effects of newly synthesized prostaglandin derivatives were investigated in various experimental ulcer models and on gastric secretion in rats. HK-3 and HK-4, PG $E_2$derivatives, prevented the formation of acute gastric ulcer induced by ethanol or aspirin in pylorus-ligated rats. The ulcer formation was moderately inhibited by HK-1 and HK-2, PG $F_{2{\alpha}}$ derivatives, and aggravated by SK-1, SK-2 and SK-3, PG $F_{2{\alpha}}$ derivatives. HK-3 and HK-4 reduced the volume, acid output and pepsin output of gastric juice in pylorus-ligated rats. The gastric perfusion with physiologic saline(pH 6.0) showed relatively constant acid secretion and indomethacin increased the acid secretion. The acid secretion was markedly decreased by PG $E_2$but PG $F_{2{\alpha}}$ caused little change. Prostaglandin derivatives, especially HK-3 arid HK-4, significantly inhibited the acid secretion induced by indomethacin. The results show that, PG $E_2$ derivatives, HK-3 and HK-4, inhibit acid secretion and also have protective effects on gastric ulceration induced by ethanol or aspirin.

• KSBB Journal
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• 제27권3호
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• pp.167-171
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• 2012

A convenient liquid chromatographic enantiomer separation of several ${\alpha}$-amino acid esters as benzophenone Schiff base derivatives on covalently immobilized chiral stationary phases (CSPs) derived from polysaccharide derivatives was developed. The benzophenone imine derivatives of ${\alpha}$-amino acid esters were readily prepared by stirring benzophenone imine and the ${\alpha}$-amino acid ester hydrochloride salts in 2-propanol. The chromatographic conditions used on all CSPs were 0.5% or 5% 2-propanol/hexane (V/V) as the mobile phases at 1 mL/min of flow rate and UV 254 nm detection. The performance of Chiralpak IC among all CSPs was superior to that of the other CSPs for resolution of benzophenone imine derivatives of ${\alpha}$-amino acid esters. It is expected that the developed analytical method will be useful for enantiomer resolution of other ${\alpha}$-amino acid esters as benzophenone Schiff base derivatives.