• Bulletin of the Korean Chemical Society
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• v.25 no.3
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• pp.357-360
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• 2004

We developed in the present study molecular imprinted polymers (MIPs), using single templates (pentoxifylline, caffeine and theophylline) and mixed-templates (pentoxifylline-caffeine, pentoxifylline-theophylline and caffeine-theophylline). The MIPs were prepared with methacrylic acid (MAA) as the monomer, ethylene glycol dimetharylate (EGDMA) as the crosslinker and 2,2'-azobis(isobutyronitrile) (AIBN) as the initiator. The obtained polymer particles (particle size after grinding was about 25-35 ${\mu}$m) were packed into a HPLC column (3.9 mm i.d. ${\times}$ 150 mm). The selectivity and chromatographic characteristics of the MIPs were studied using acetonitrile as the mobile phase at a flow rate of 0.8 mL/min. UV detector wavelength was set at 270 nm. Different single template MIPs showed different molecular recognitions to the templates and the structurally analogues, according to the rigidity and steric hindrance of the compounds. Recognition was improved on the mixed-template MIPs as a result of the cooperation or sum effect of the templates, whereas on the pentoxifylline-theophylline imprinted polymer, the highest selectivity and affinity were obtained. Separations of the test compounds on different polymers were also investigated.

• YAKHAK HOEJI
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• v.43 no.6
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• pp.756-761
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• 1999

Lipid peroxidation mediated by hydroxyl radicals which are generated during myocardial ischermia has suggested as a possible mechanism of ischemic myocardial damage. Recently, it has been reported that anti-arrhythmic action of lidocaine, a local anesthetic, is attributed to its "membrane-stabilizing" properties through scavenging free radicals, thus, inhibiting lipid peroxidation. Aldehyde oxidase and xanthine oxidase which catalyze the oxidation of many purine, pyrimidine and pteridine derivatives are known as free radical generating systems. In this experiment, we studied the effect of lidocaine and procainamide on the hepatic aldehyde and xanthine oxidase activity and antioxidative activities. It was found that lidocaine and procainamide inhibited both NADPH-dependent and independent lipid peroxidation. Both of tested compounds were found to be ineffective in inhibiting xanthine oxidase. Lidocaine and procainamide, however, inhibited aldehyde oxidase activity in vitro as well as in vivo. Based on the above results, lidocaine and procainamide could be employed as a therapeutic agent for aldehyde oxidaserelated disease.d disease.

• Journal of Life Science
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• v.34 no.9
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• pp.656-665
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• 2024

Enzymes, as proteins that regulate various metabolic processes within the human body, play a crucial role in maintaining health. However, the overexpression of certain enzymes can disrupt metabolic balance, leading to various diseases. Enzyme inhibitors are vital in treating these diseases or conditions by inhibiting the action of these enzymes, making them indispensable in the development of effective therapies for a wide array of diseases. Quercetin, a natural product derived from plants, is a type of flavonoid that belongs to the polyphenol family. Quercetin, a natural flavonoid from the polyphenol family, has emerged as a potent enzyme inhibitor. This low-molecular-weight secondary metabolite is known for its inhibitory effects on enzymes such as α-glucosidase, acetylcholinesterase, bacterial neuraminidase, and xanthine oxidase due to its structural advantages. Quercetin is isolated from biomaterials and can be classified into glycosylated, methoxylated, and alkylated derivatives based on its structural variations. These natural quercetin derivatives possess unique substituents that enable specific binding patterns with catalytic residues in enzyme active sites. Therefore, quercetin derivatives can be expected to have better enzyme inhibitory activity than basic quercetin. Due to their specificity and enhanced activity, quercetin and its derivatives hold promise as candidates for developing potent enzyme inhibitors to treat diseases resulting from enzyme imbalances.

• Journal of Yeungnam Medical Science
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• v.9 no.1
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• pp.90-101
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• 1992

In rat kidney, the changes in concentrations of nucleotides and their derivatives during ischemia induced by renal artery ligation was measured quantitatively with high performance liquid chromatography(HPLC). After the ligation of renal artery for 60minutes, the concentrations of the nucleotides and derivatives were measured. In ischemic tissue, IDP was significantly decreased from $217.4{\pm}12.68{\mu}g$ in control to $80.7{\pm}18.39{\mu}g$ (p<0.01) ; ATP, $307.2{\pm}56.63{\mu}g$ to $47.6{\pm}5.95{\mu}g$ (p<0.01) ; ADP+AMP, $227.1{\pm}7.98{\mu}g$ to $61.4{\pm}3.92{\mu}g$(P<0.01); $NAD^+$, $217.9{\pm}4.49{\mu}g$ to $126.6{\pm}10.44{\mu}g$(P<0.01) ; GTP, $202.5{\pm}23.76{\mu}g$ to $117.7{\pm}14.24{\mu}g$ (P<0.05) ; GMP, $54.5{\pm}9.03{\mu}g$ to $23.7{\pm}0.46{\mu}g$(p<0.05), and inosine, $16.6{\pm}3.45{\mu}g$ to $7.8{\pm}0.87{\mu}g$ (P<0.05). But hypoxanthine and xanthine were significantly increased from $113.0{\pm}15.58{\mu}g$ to $159.7{\pm}12.07{\mu}g$ (P<0.05) and from $87.7{\pm}6.77{\mu}g$ to $173.1{\pm}12.52{\mu}g$ (P<0.01). In ischemic kidney, concentration of ATP was decreased to 39.9% of control at 10 minutes, 19.8% at 30 minutes, and 15.5% at 60 minutes, and ADP+AMP were decreased to 70.3% of control at 10 minutes, 67.3% at 30 minutes, and to 27.0% at 60 minutes, but hypoxanthine and xanthine were increased to 121.5% and 127.1% at 10 minutes, 126.0% and 174.4% at 30 minutes, and 141.4% and 197.3% at 60 minutes Total adenosine nucleotides were decreased to 20.3% of control during 60 minutes of ischemia, but hypoxanthine and xathine were increased to 157.5 % of control. These results suggest that the changes in the concentration of nucleotides and their metabolic derivatives are useful indices of the extents of tissue ischemia in rat kidney.

• Natural Product Sciences
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• v.4 no.3
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• pp.161-169
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• 1998

The analogues of lichen components showing anti-tyrosinase activities were synthesized. 4-Alkylresorcinol derivatives showed both the inhibitory activity and cytotoxicity in B-16 melanoma cells at the doses of 10 mM to 1.2 mM. Resorcinol and 4-methylresorcinol showed the inhibitory effect with a low cytotoxicity at the doses of 2.5 mM and $600\;{\mu}M$ among 4-alkylresorcinols, respectively. Some diphenylmethane derivatives (Type A, B, and C) had strong activities with a low cytotoxicity. While xanthine derivatives had no effect. Glucosides of 4,5-alkylresorcinol and the diphenylmethane derivative (Type B) were prepared to decrease the cytotoxicity. As a result, no effect were observed. Liposome of the diphenylmethane derivative (Type B) was prepared for the same purpose, and the latter showed a remarkable effect at the dose of $15\;{\mu}M$ with a low cytotoxicity.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.212-213
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• 2002

Using the isolated perfused rat heart this study investigated 1) the cardiac uptake of idarubicin (IDA), 2) the role of P-glycoprotein (P-gp) in the uptake process, 3) the formation of IDOL from IDA in the heart, and 4) the effect of P-gp inhibitors (verapamil, amiodarone, PSC 833), doxorubicin, hypothermia, xanthine derivatives (caffeine, theophylline) and metabolism inhibitors (rutin, phenobarbital) on the pharmacokinetics and pharmacodynamics of IDA using a mathematical modeling approach. A minimal model was constructed; the differential equations were numerically solved and fitted to the data using the ADAPT II-software package using maximum likelihood estimation assuming that the measurement error has a standard deviation which is a linear function of the measured quantity［1］. (omitted)

• Bulletin of the Korean Chemical Society
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• v.27 no.1
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• pp.71-76
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• 2006

Porous polymer monolithic columns were prepared by the direct free radical copolymerization of methacrylic acid and ethylene glycol dimethacrylate within the confines of a chromatographic column in the presence of toluene-dodecanol as a porogenic solvent. The separation characteristics of the monolithic columns were tested by a homologous series of xanthine derivatives, theophylline and caffeine. The effects of the polymerization mixture composition and polymerization condition, mobile phase composition, flow rate and temperature on the retention times and separation efficiencies were investigated. The results showed that the selection of correct porogenic solvents and appropriate polymerization conditions are crucial for the preparation of the monolithic stationary phases. The separation efficiency was only extremely weakly dependent on flow rate and temperatures. Hydrogen-bonding interaction played an important role in the retention and separation. Compared with conventional particle columns, the monolithic column exhibited good stability, ease of regeneration, high separation efficiency and fast analysis.