• Journal of the Korean Chemical Society
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• v.35 no.1
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• pp.70-77
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• 1991

1-Benzyl-4-iodomethyl-2-azetidinone(BIMA) was synthesized and its electrochemical reduction was investigated by direct current, differential pulse polarography, cyclic voltammetry and controlled potential coulometry. The irreversible two electron transfer on reductive dehalogenation of iodo group proceeded to form 1-benzyl-4-methyl-2-azetidinone by EEC electrode reaction mechanism at the first reduction step(-1.35 volts vs. Ag-AgCl). The polarographic reduction waves separated into two reduction steps due to anionic surfactant (sodium lauryl sulfate) effects, while the waves were shifted to the positive potential as the concentration of cationic surfactant (cetyltrimethylammonium bromide) increased. Upon the basis of results on the product analysis and interpretation of polarogram with pH variable, EEC electrochemical reaction mechanism was suggested.

• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.160-168
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• 1994

Pentadentate Schiff base molybdenum(Ⅴ) complexes such as [Mo(Ⅴ)O(Sal-DET)(NCS)] and [Mo(Ⅴ)O(Sal-DPT)(NCS)] were synthesized by Sabat method. The structure of these complexes were identified by elemental analysis, spectroscopy, and thermogravimetric analysis(T.G.A.). It was found that the mole ratio of Schiff base ligand to the complexes was found to be 1 : 1. The redox processes of the complexes were investigated by cyclic voltammetric and differential pulse polarographic technique in nonaqueous solvent containing 0. 1 M tetraethyl ammonium perchlorate(TEAP) as supporting electrolyte at glassy carbon electrode. It was found that diffusion controlled reduction processes of four steps with one electron were 2Mo(Ⅴ)$\rightleftarrow^{e-}$ Mo(Ⅴ)Mo(Ⅳ) $\longrightarrow^{e-}$ 2Mo(Ⅳ), Mo(Ⅳ) $\longrightarrow^{e-}$ Mo(Ⅲ) $\longrightarrow^{e-}$ Mo(Ⅱ)

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.6
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• pp.959-963
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• 1994

To detect bioactive compounds present in unused marine resources, the screening for the 5-lipoxygenase inhitors in Asterina pectinifera, Halocynthia roretzi skin, Nototodarus sloani ink, Anthocidaris crassispina skin, SArgassum horneri, Agarum cribrosum, Odonthalia corymbifera and Desmarestia ligulata was carried out. THe ether and acetone extracts of Sargassum horneri had the strongest antioxygnic activityon lipid oxidation by potato lipoxygenase-1 (one of 5-lipoygenase) among the tested marine samples and their $IC_{50}$ were 0.3 and 1.1g/ml, respectively. The ether and acetone extracts of Asterina pectinifera, the acetone extracts of Halocynthia roretizi, and the acetone extracts of Nototodarus sloani ink had strong inhibitory activity and their $IC_{50}$ were 72.5, 65, 13.3 and $13.3\mu\textrm{g}/ml$, respectively. In addition, the $IC_{50}$ of the acetone extracts of Agarum cribrosum and Desmarestia ligulata, and the ether extracts of Desmarestia ligulata were 15.5, 35 and $30.5\mu\textrm{g}/ml$, respectively. The nonpolar solvent (ether, acetone) extracts of tested marine organism had more antioxigenic effect against 5-lipoxygenase than the polar solvent(water) extracts.

• Applied Biological Chemistry
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• v.37 no.6
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• pp.451-455
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• 1994

To detect naturally occurring bioactive compounds from unused marine resources, the screening for the 5-lipoxygenase(potato lipoxygenase-II) inhibitors in Asterina pectinifera, Halocynthia roretzi skin, Nototodarus sloani ink, Anthocidaris crassispina skin, Sargassum horneri, Agarum cribrosum, Odonthalia corymbifera and Desmarestia ligulata was carried out. Water, ether, acetone and methanol fractions extracted from Sargassum horneri had strong inhibitory effect on enzymatic lipid oxidation by potato lipoxygenase-II, and their $IC_{50}$ were 320, 18, 9.5 and $100\;{\mu}g/mL$, respectively. The $IC_{50}$ of ether fraction extracted from Asterina pectinifera and acetone fraction extracted from Nototodarus sloani ink were 29.5 and $34.3\;{\mu}g/mL$, and these extracts showed relatively excellent inhibitory activity. Nonpolar solvent (ether, acetone) extracts of tested marine organisms had more inhibitory effect against 5-lipoxygenase than the polar solvent(water) extracts.

• Analytical Science and Technology
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• v.11 no.5
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• pp.366-373
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• 1998

Polydentate Schiff base ligands, BSDT(1,9-bis(2-hydroxyphenyl)-2,5,8-triaza-1,8-nonadiene) having $N_3O_2$ atoms, BSTT(1,12-bis(2-hydroxyphenyl)-2,5,8,11-tetraaza-1,11-dodecadiene) having $N_4O_2$ atoms, BSTP(1,15-bis(2-hydroxyphenyl)-2,5,8,11,14-pentaaza-1,14-pentadodecadiene) having $N_5O_2$ atoms were synthesized. Protonation constants of these polydentate ligands were measured by potentiometry. Stability constants of the complexes between these ligands and the metal ions such as Cu(II), Ni(II) and Zn(II) were measured in DMSO by a polarographic method. It was observed that all metal(II) ions employed in this study formed 1:1 complexes with Schiff base ligands. Stability constants for the complex formation were in the order of Cu(II)>Ni(II)>Zn(II), and for the ligands were in the order of BSTP>BSTT>BSDT. There are due to the increase in the number of donor atoms. Both enthalpy and entropy changes were obtained in negative values. Exothermicity for the complex formation indicated tight binding between the ligands and metal ions. The negative entropy change would be related to the fact that solvent molecules are strongly interacting with the metal complexes.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.233-242
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• 1988

The uranium(VI) complexes with new unsaturated macrocyclic ligands of cryptand types and the neodymium(III) complexes with cryptand 222 and DBC ligands have been investigated polarographically in dimethylsulfoxide solvent. The reduction states, electron numbers involved in the reduction process, effects of the added acid on the polarograms of complexes, and the mechanisms of the reduction electrode reactions have been examined. The stability constants and mole-ratio of new complexes were also obtained by polarographic method. The reaction of ligands was controlled by the diffusion in the reduction with four electrons at a step, whereas the redox reaction with six electrons at three steps in $UO_2\;^{2+}$ complexes with macrocyclic ligands and the redox reaction with one electron at a step in $Nd^{3+}$ complexes with cryptand 222 and DBC have been observed. The imine ligands formed stable complexes with uranium(VI) above pH 7.0, and the neodymium(III) complexes with cryptand 222 and DBC ligands were stable above pH 4.0.