• Proceedings of the Korean Society of Toxicology Conference
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• 2001.10a
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• pp.41-42
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• 2001

The chemopreventive effect of tea against 2-amino-l-methyl-6-phenylimidazo［4, 5-b ］pyridine (PhIP)-DNA adduct formation and its mechanism were studied. Rats were exposed to freshly prepared aqueous extracts of green tea (3% w/v) as the sole source of drinking water for 10 days prior to administration with a single dose of PhIP (10 mg/kg body wt) by oral gavage. PhIP-DNA adducts in the liver, colon, heart, and lung were measured using the $^{32}$ P-postlabelling technique.(omitted)

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1245-1250
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• 2003

Pseudo-first-order rate constants ($k_{obs}$) have been measured spectrophotometrically for the reactions of 4-nitrophenyl benzoate with a series of pyridines in $H_2O$ containing 20 mol % DMSO. The plots of kobs vs pyridine concentration are linear up to ca. 0.1 M pyridines, indicating that the effect of self-association of pyridines with their conjugate acids are insignificant in this concentration range. The Bronsted-type plot has been obtained to be linear with a ${\beta}_{nuc}$ value 1.11, suggesting that the pyridinolyses proceed through a rate-determining breakdown of the zwiterionic addition intermediate. The pyridines studied have shown higher reactivity than isobasic primary and secondary amines toward the substrate. 1-Benzoyl-4-dimethylaminopyridinium ion, a possible intermediate, has not been detected since the rate of its hydrolysis in the reaction condition is comparable with or even faster than its formation.

• Journal of the Korean Electrochemical Society
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• v.13 no.1
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• pp.50-56
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• 2010

The multi-wall carbon nano-tube composite mixed with carbon paste electrode presented more sensitive and selective amperometric signals in the oxidation of glucose than general screen-printed carbon electrodes(SPCEs). Redox mediators to transport electrodes from enzyme to electrodes are very important part in the biosensor. A novel osmium redox complex was synthesized by the coordinating pyridine group containing primary amines which were electrochemically immobilized onto the MWCNT-SPCEs surface. Electrochemical studies of osmium complexes were investigated by cyclic voltammetry, chronoamperometry. The surface coverage of osmium complexes on the modified carbon nano-tube electrodes were significantly increased at 100 time (${\tau}_0=2.0\;{\times}\;10^{-9}\;mole/cm^2$) compared to that of the unmodified carbon electrodes. It's practical application of the glucose biosensor demonstrated that it shows good linear response to the glucose concentration in the range of 0-10 mM.

• Food Science of Animal Resources
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• v.29 no.6
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• pp.719-725
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• 2009

Heterocyclic aromatic amines (HCAs) are potent mutagens and possible human carcinogens that are formed during the heating of protein-rich foods. The effects of preheating treatment of beef patties using a microwave prior to frying at $220^{\circ}C$ for 10 min on each side on the reduction of HCAs (amino-carbolines and amino-imidazo-azaarenes) were evaluated. The amount of HCAs was then evaluated by solid-phase extraction and high pressure liquid chromatography (HPLC) analysis. The beef patties were treated by microwaving for various times (0, 1, 1.5, 2, or 3 min) before pan-frying. The results revealed the presence of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), 3-amino-1,4-dimethyl-5H-pyrido-[4,3-b] indole (Trp-P-1), 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1), 2-aminodipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2), 9H-pyrido[3,4-b]indole (Norharman), 1-methyl-9H-pyrido[3,4-b]indole (Harman), 2-amino-9H-pyrido[2,3-b] indole ($A{\alpha}C$), 2-amino-3,8 dimethylimidazo[4,5-f]-quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine (PhIP) in all samples. However, microwave pretreatment for 1 min inhibited the formation of these HCAs by up to 90% when compared to the control.

• Polymer(Korea)
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• v.31 no.3
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• pp.255-262
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• 2007

In this work, two types of copolymers are manufactured by a radical polymerization to develop a material for humid membrane. Each copolymer contains three monomers that have functions to improve humid-resistance, membrane stability, flexibility, impedance, and adhesion to the electrode. MDBAB (N,N'-dimethyl-2-methacryloxyethyl-3-bromopropyl ammonium bromide) having a salt form decreases the impedance of the humid membrane and reacts with amines to produce a cross-linking structure. HEMA (2-hydroxyethyl methacrylate) has an important role which reduces the impedance and increases the adhesion strength to the electrode. The other monomers are DAEMA (N,N'-dimethylamino ethyl methacrylate), 4-VP(4-vinyl pyridine), and 2-EHA(2-ethylhexyl acrylate) and all the monomers are formulated with several compositions to make a humid membrane. At specific composition, we could attain a satisfactory results having good performance and long term durability.

• Bulletin of the Korean Chemical Society
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• v.10 no.4
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• pp.382-388
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• 1989

The approximate rates and stoichiometry of the reaction of excess potassium tri-sec-butylborohydride ($K_s-Bu_3BH$) with selected organic compounds containing representative functional groups were determined under the standard conditions (0$^{\circ}C$, THF) in order to define the characteristics of the reagent for selective reductions. Primary alcohols evolve hydrogen in 1 h, but secondary and tertiary alcohols and amines are inert to this reagent. On the other hand, phenols and thiols evolve hydrogen rapidly. Aldehydes and ketones are reduced rapidly and quantitatively to the corresponding alcohols. Reduction of norcamphor gives 99.3% endo- and 0.7% exo-isomer of norboneols. The reagent rapidly reduces cinnamaldehyde to the cinamyl alcohol stage and shows no further uptake of hydride. p-Benzoquinone takes up one hydride rapidly with 0.32 equiv hydrogen evolution and anthraquinone is cleanly reduced to the 9,10-dihydoxyanthracene stage. Carboxylic acids liberate hydrogen rapidly and quantitatively, however further reduction does not occur. Anhydrides utilize 2 equiv of hydride and acyl chlorides are reduced to the corresponding alcohols rapidly. Lactones are reduced to the diol stage rapidly, whereas esters are reduced moderately (3-6 h). Terminal epoxides are rapidly reduced to the more substituted alcohols, but internal epoxides are reduced slowly. Primary and tertiary amides are inert to this reagent and nitriles are reduced very slowly. 1-Nitropropane evolves hydrogen rapidly without reduction and nitrobenzene is reduced to the azoxybenzene stage, whereas azobenzene and azoxybenzene are inert. Cyclohexanone oxime evolves hydrogen without reduction. Phenyl isocyanate utilizes 1 equiv of hydride to proceed to formanilide stage. Pyridine and quinoline are reduced slowly, however pyridine N-oxide takes up 1.5 equiv of hydride in 1 hr. Disulfides are rapidly reduced to the thiol stage, whereas sulfide, sulfoxide, sulfonic acid and sulfone are practically inert to this reagent. Primary alkyl bromide and iodide are reduced rapidly, but primary alkyl chloride, cyclohexyl bromide and cyclohexyl tosylate are reduced slowly.

• Archives of Pharmacal Research
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• v.25 no.3
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• pp.258-269
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• 2002

2-Thiouracil-5-sulfonylchloride 1 reacted with a series of aromatic and heterocyclic amines to give 2a-j. The same compound 1 was reacted with a series of sulphonamides giving different sulphonamides of type 3a-e. On the other hand compound 1 was allowed to react with p-aminoacetophenone givining compound 4 which in turn was allowed to react with derivatives of alkyl thiosemicarbazides to give thiosemicarbazones of type 5a-e, also compound 4 was monobrominated to give compound 6 which in turn was reacted thiosemicarbazones of some aldehydes to give the corresponding thiazole derivatives 7a-f. In the same time compound 4 was reacted with a series of aromatic and heterocyclic aldehydes givining chalcones 8a-g (Claisen-Schemidt reaction). Also compound 4 was allowed to react with a series of aromatic and heterocyclic aldehydes, ethyl cyano acetate and/or malononitrile, and ammonium acetate giving pyridine derivatives 9a-d and 10a-e respectively. The biological effects of some of the new synthesized compounds was also investigated.

• Bulletin of the Korean Chemical Society
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• v.16 no.5
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• pp.416-421
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• 1995

The approximate rates and stoichiometry of the reaction of excess lithium gallium hydride with selected organic compounds containing representative functional groups were examined under the standard conditions (diethyl ether, 0 $^{\circ}C)$ in order to compare its reducing characteristics with lithium aluminum hydride and lithium borohydride previously reported, and enlarge the scope of its applicability as a reducing agent. Alcohols, phenol, and amines evolve hydrogen rapidly and quantitatively. However lithium gallium hydride reacts with only one active hydrogen of primary amine. Aldehydes and ketones of diverse structure are rapidly reduced to the corresponding alcohols. Conjugated aldehyde and ketone such as cinnamaldehyde and methyl vinyl ketone are rapidly reduced to the corresponding saturated alcohols. p-Benzoquinone is mainly reduces to hydroquinone. Caproic acid and benzoic acid liberate hydrogen rapidly and quantitatively, but reduction proceeds slowly. The acid chlorides and esters tested are all rapidly reduced to the corresponding alcohols. Alkyl halides and epoxides are reduced rapidly with an uptake of 1 equiv of hydride. Styrene oxide is reduced to give 1-phenylethanol quantitatively. Primary amides are reduced slowly. Benzonitrile consumes 2.0 equiv of hydride rapidly, whereas capronitrile is reduced slowly. Nitro compounds consumed 2.9 equiv of hydride, of which 1.9 equiv is for reduction, whereas azobenzene, and azoxybenzene are inert toward this reagent. Cyclohexanone oxime is reduced consuming 2.0 equiv of hydride for reduction at a moderate rate. Pyridine is inert toward this reagent. Disulfides and sulfoxides are reduced slowly, whereas sulfide, sulfone, and sulfonate are inert under these reaction conditions. Sulfonic acid evolves 1 equiv of hydrogen instantly, but reduction is not proceeded.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.3
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• pp.537-542
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• 1998

The present study was performed to elucidate desmutagenic principles from Ecklonia stolonifera extracts against 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine(PhIP) and 2-amino-3,8-dime-thylimidazo[4,5-f]duinoxaline(MeIQx) with Salmonella/mammalian-microsome mutagenicity test. Alginate, phenols, chlorophyll and carotenoids from Ecklonia stolonifera were extracted and their desmutagenicities were assayed. Alginate hydroysates showed desmutagenic activities against PhIP and MeIQx at high level dose. Phenol fractions and bromophenol showed desmutagenic activity of about MeIQx at high level dose. Phenol fractions and bromophenol showed desmutagenic activity of about 90% per 0.5mg against PhIP and MeIQx. Chlorophyllin among chlorophyll derivatives exhibited remarkable desmutagenic activities of 92.9% and 82.7% at 20uM against PhIP and MeIQx, respectively. Carotenoids, such as lutein and $\alpha$-cryptoxanthin isolated from Ecklonia stolonifera exerted also high desmutagenic activity. Major desmutagenic substances from Ecklonia stolonifera are considered to be chlorophyllin, phenols, lutein, $\alpha$-cryptoxanthin and low molecular alginates.

• Journal of the Korean Chemical Society
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• v.23 no.4
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• pp.243-247
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• 1979

Kinetics of the reaction of phenethyltosylate with substituted pyridines at 50, 60 and 70$^{\circ}C$ in acetonitrile were investigated by an electric conductivity method. The effects of substituents on the reaction of phenethyltosylate with pyridines were discussed. The rates of reaction were increased with electron donating power of substituents of pyridines. The isokinetic relationship was shown $E_{\alpha}$ and ${\Delta}S^{\neq}$, it's temperature was 240$^{\circ}$K. Bronsted plots were excellent linear except for 4-amino pyridine given by the following equation, logk=O. 22pKa-3.71 (r=O. 986). According to a plot of log k against Hammett substituent constants, the Iinearity was good except for bamino pyridine too, log k= -1.330${\sigma}$+0.08 (r= -0.987). In both cases, deviation of 4-amino pyridine from linearity was considered to solvent effect, resonance effect and ${\sigma}$ value itself. From all the above results, this reaction was found typical $S_N2$ reaction which the rates of reaction was determined by C…N bond formation at transition state.