• 대한화학회지
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• 제38권5호
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• pp.345-350
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• 1994

클로로포름과 사염화탄소 속에서 티오아세트아미드(TA)와 pyridine(Py), quinoline(Qu), and acridine(Ac)간의 수소 결합에 대한 열역학적 상수들을 조사하기 위해 5$^{\circ}C$ 에서 55$^{\circ}C$까지 TA의 $v_{a^+}$ Amide II조합띠를 사용하였다. 이 조합띠는 두 개의 Lorentzian-Gauss 곱함수의 띠로 분해되며, 각각은 TA단위체 및 수소결합을 이룬 TA의 복합체임이 확인되었다. 온도 및 농도에 따른 이 조합띠의 변화로부터 TA의 수소 결합에 대한 여러가지 열역학적 상수들을 구하였다. 클로로포름에서 TA 와 pyridine, quinoline, acridine의 수소결합 엔탈피는 각각 -7.6 kJ/mol, -6.5 kJ/mol, -5.4 kJ/mol이었고, 사염화탄소에서 TA 와 pyridine, quinoline의 결합 엔탈피는 각각 -13.3kJ/mol, -12.0kJ/mol이었다.

• 한국식품저장유통학회지
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• 제13권2호
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• pp.269-272
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• 2006

황기가 청국장 향기성분에 미치는 영향을 조사하기 위해 청국장과 황기청국장을 제조하여 향기성분을 SDE, headspace, SPME 추출한 후 GC/MS로 정성하였다. 추출방법별 정성된 화합물의 수는 총 30개로 SDE 23개, headspace 6개, SPME 7개로 나타났다. 추출물을 관능기별로 구분하면 ketone류 6개, alcohol류 8개, heterocylic 화합물 3개, aldehyde류 3개, hydrocarbone류 6개, 기타 화합물 5개로 분류할 수 있다. 청국장의 주요향기성분으로 SDE 추출물은 3-hydroxy-2-butane, 2-furanmethanol, 2-methoxy-4-vinylphenol과 4-vinylphenol이었으며 headspace 추출물은 2,3-butanedione, 3-hydroxy-2-butane, ethanol, 2,6-dimethyl pyrazine과 acetic acid, SPME 추출물은 acetone, ethanol, 2,5-dimethyl pazine, tetrameyl pyrazine과 acetic acid이었다. 청국장의 특징적인 향기성분인 2,5-dimethyl pyrazine과 2,6-dimethyl pyrazine, tetramethyl pyrazine 함량은 청국장이 황기청국장에 비해 높게 나타내었다.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.171-176
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• 2003

The sonolytic decomposition of NHCs, such as atrazine［6-chloro-N-ethyl-N＇ -(1-methylethyl)-1,3,5-triazine-2,4-diamine］, simazine( 6-chloro-N,N＇ -diethyl-l ,3,5-triazine-2,4-diamine), trietazine(6-chloro-N,N,N＇-triethyl-l,3,5-triazine-2,4-diamine), in water was investigated at a ultrasound frequency of 200kHz with an acoustic intensity of 200W under argon and air atmospheres. The concentration of NHCs decreased with irradiation, indicating pseudo-first-order kinetics. The rates were in the range 1.06∼2.07 (x10/sup -3/ min/sup -1/) under air and 1.30∼2.59(x10/sup -3/ min/sup -1/)under argon at a concentration of 200μM of NHCs. The rate of hydroxyl radicals(·OH) formation from water is 19.8μM min/sup -1/ under argon and 14.7 μM min/sup -1/ under air in the same sonolysis conditions. The sonolysis of NHCs is effectively inhibited, but not completely, by the addition of t-BuOH(2-methyl-2-propanol), which is known to be an efficient ·OH radical scavenger in aqueous sonolysis. This suggests that the main decomposition of NHCs proceeds via reaction with ·OH radical; a thermal reaction also occurs, although its contribution is small. The addition of appropriate amounts of Fenton's reagent ［Fe/sup 2＋/］ accelerates the decomposition. This is probably due to the regeneration of ·OH radicals from hydrogen peroxide, which would be formed from recombination of ·OH radicals and which may contribute a little to the decomposition.

• Tribology and Lubricants
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• 제32권5호
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• pp.141-146
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• 2016

The diketopyrrolopyrrole (DPP) pigment is a bicyclic 8-π-electron system containing two lactam units. Typical DPP derivative pigments have melting points of over 350°C and very low solubility in most solvents, and show absorption in the visible region with a molar extinction coefficient of 33,000 dm²mol⁻¹ and strong photoluminescence with maxima in the range 500–600 nm. X-ray structure analyses of DPP show that the whole molecule is almost in one plane. The phenyl rings are twisted out of the heterocyclic plane and the intermolecular hydrogen bonding between neighboring lactam NH and carbonyl units influences the structure of the DPP pigment in the solid state. In this study, mono-N-alkylation and mono-N-arylation were undertaken for Pigment Red 264 or Pigment Orange 73 with alkyl halide and aryl halide, respectively, in the presence of sodium tert-butoxide as a base catalyst to improve the solubility of DPP pigments and their application as CO₂ indicators. The synthetic yield was in the range 11–88%. The indicator dyes are highly soluble in organic solvents and shows pH-dependent absorption (λ_max 501 and 572 nm for the protonated and deprotonated forms, respectively) and emission (λ_max 524 and 605 nm for the protonated and deprotonated forms, respectively) spectra. The mono-N-alkylated and mono-N-arylated DPP pigment was identified by ¹H-NMR (¹H-Nuclear Magnetic Resonance Spectrometer), FT-IR (Fourier Transform Infrared Spectroscopy), and MS (Mass Spectrometry). According to the results of color and hue properties obtained by a color matching analyzer, the synthesized DPP pigment material can be used as a CO₂ indicator.

• 한국연초학회지
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• 제23권2호
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• pp.168-178
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• 2001

Essential oil in tobacco leaves influences the taste and aroma of cigarette smoke and is important to tobacco quality. This study was conducted to investigate the change in the level of essential oil components during flue-curing process of two flue-cured tobaccos, NC82 and KEl14. Flue-curing process was divided by six steps; harvest stage, the end of yellowing stage, the middle of color fixing stage, the end of color fixing stage, the middle of midrib drying stage, full-cured stage. NC82 in each stage contained 0.28%, 0.30%, 0.35%, 0.36%, 0.40% and 0.42% essential oil, respectively, and KF114 were 0.29%, 0.31%, 0.34%, 0.36%, 0.39% and 0.41%, respectively. Almost all hydrocarbons on the basis of relative peak area were gradually increased in two varieties with curing, neophytadiene content in them was highest at the full-cured stage. Most of alcohols and esters with curing showed a declining trend, but benzyl alcohol was increased in two tobaccos. Ketones were largely increased at the midrib drying stage during the curing process, especially, the most largely increasing constituent was $\beta$-damascenone among them. The content of 2-butylterahydrofuran, heterocyclic compounds, was largely increased at tile color fixing stage. There was no considerable difference between NC82 and KFl14 at the GC profile of essential oil and the pattern of each components during flue-curing process.

• Toxicological Research
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• 제31권2호
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• pp.97-104
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• 2015

The skin exposure to solar irradiation and photoreactive xenobiotics may produce abnormal skin reaction, phototoxicity. Phototoxicity is an acute light-induced response, which occurs when photoreacive chemicals are activated by solar lights and transformed into products cytotoxic against the skin cells. Multifarious symptoms of phototoxicity are identified, skin irritation, erythema, pruritis, and edema that are similar to those of the exaggerated sunburn. Diverse organic chemicals, especially drugs, are known to induce phototoxicity, which is probably from the common possession of UV-absorbing benzene or heterocyclic rings in their molecular structures. Both UVB (290~320 nm) and UVA (320~400 nm) are responsible for the manifestation of phototoxicity. Absorption of photons and absorbed energy (hv) by photoactive chemicals results in molecular changes or generates reactive oxygen species and depending on the way how endogenous molecules are affected by phototoxicants, mechanisms of phototoxcity is categorized into two modes of action: Direct when unstable species from excited state directly react with the endogenous molecules, and indirect when endogeneous molecules react with secondary photoproducts. In order to identify phototoxic potential of a chemical, various test methods have been introduced. Focus is given to animal alternative test methods, i.e., in vitro, and in chemico assays as well as in vivo. 3T3 neutral red uptake assay, erythrocyte photohemolysis test, and phototoxicity test using human 3-dimensional (3D) epidermis model are examples of in vitro assays. In chemico methods evaluate the generation of reactive oxygen species or DNA strand break activity employing plasmid for chemicals, or drugs with phototoxic potential.

• Toxicological Research
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• 제33권2호
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• pp.79-96
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• 2017

A variety of xenobiotic chemicals, such as polycyclic aromatic hydrocarbons (PAHs), aryl- and heterocyclic amines and tobacco related nitrosamines, are ubiquitous environmental carcinogens and are required to be activated to chemically reactive metabolites by xenobiotic-metabolizing enzymes, including cytochrome P450 (P450 or CYP), in order to initiate cell transformation. Of various human P450 enzymes determined to date, CYP1A1, 1A2, 1B1, 2A13, 2A6, 2E1, and 3A4 are reported to play critical roles in the bioactivation of these carcinogenic chemicals. In vivo studies have shown that disruption of Cyp1b1 and Cyp2a5 genes in mice resulted in suppression of tumor formation caused by 7,12-dimethylbenz[a]anthracene and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, respectively. In addition, specific inhibitors for CYP1 and 2A enzymes are able to suppress tumor formation caused by several carcinogens in experimental animals in vivo, when these inhibitors are applied before or just after the administration of carcinogens. In this review, we describe recent progress, including our own studies done during past decade, on the nature of inhibitors of human CYP1 and CYP2A enzymes that have been shown to activate carcinogenic PAHs and tobacco-related nitrosamines, respectively, in humans. The inhibitors considered here include a variety of carcinogenic and/or non-carcinogenic PAHs and acethylenic PAHs, many flavonoid derivatives, derivatives of naphthalene, phenanthrene, biphenyl, and pyrene and chemopreventive organoselenium compounds, such as benzyl selenocyanate and benzyl selenocyanate; o-XSC, 1,2-, 1,3-, and 1,4-phenylenebis(methylene)selenocyanate.

• 한국식품과학회지
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• 제27권6호
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• pp.964-971
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• 1995

키조개 부산물로 부터 향미제로 응용하기 위하여 제조한 가수분해물의 유리아미노산 및 휘발성 향기성분을 분석한 결과, 유리아미노산의 경우 가수분해물이 생시료에 비해 3배 이상 증가하였으며 taurine의 함량이 가장 많았다. 그리고 생시료와 가수분해물의 휘발성 향기성분을 분석한 결과 총 109종의 화합물이 동정되었는데 이중에서 생시료는 88종, 가수분해물은 65종이 검출되었다. 그리고 이들은 주로 알데히드류(16종), 케톤류(17종), 알콜류(31종), 함질소화합물류(16종), 방향족화합물류(8종), 에스테르류(3종) 및 기타 화합물류(17종)으로 구성되어 있었다. 특히 생시료에서의 산화취 성분인 알데히드류 및 방향족화합물은 가수분해물에서 상당량 감소되었으며 반면에 고소한 향기성분인 heterocyclic 화합물이 상당량 검출되었다.

• Archives of Pharmacal Research
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• 제28권10호
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• pp.1114-1121
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• 2005

Flavonoids are polyphenols composed of two aromatic rings (A, B) and a heterocyclic ring (C). In order to determine the effects of the number of hydroxyl groups in the B-ring of the flavonoids on human cytochrome P450 (CYP) 1 family enzymes, we evaluated the inhibition of CYP1A-dependent 7-ethoxyresorufin O-deethylation activity by chrysin, apigenin and luteolin, using bacterial membranes that co-express human CYP1A1, CYP1A2, or CYP1B1 with human NADPH-cytochrome P450 reductase. Chrysin, which possesses no hydroxyl groups in its B-ring, exhibited the most pronounced inhibitory effects on CYP1A2-dependent EROD activity, followed by apigenin and luteolin. On the contrary, CYP1A1-mediated EROD activity was most potently inhibited by luteolin, which is characterized by two hydroxyl groups in its B-ring, followed by apigenin and chrysin. However, all of the 5,7-dihydroxyflavones were determined to similarly inhibit CYP1B1 activity. Chrysin, apigenin, and luteolin exhibited a mixed-type mode of inhibition with regard to CYP1A2, CYP1B1, and CYP1A1, with apparent Ki values of 2.4, 0.5, and 2.0 ${\mu}M$, respectively. These findings suggested that the number of hydroxyl groups in the B-ring of 5,7-dihydroxyflavone might have some influence on the degree to which CYP1A enzymes were inhibited, but not on the degree to which CYP1B1 enzymes were inhibited.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3304-3308
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• 2010

Condensation of 4-amino-5-mercapto-3-($\alpha$-naphthyl)-s-triazole (1) with cyanogen bromide gives 6-amino-3-($\alpha$-naphthyl)-s-triazolo[3,4-b]-1,3,4-thiadiazole (2) which on condensation with chloranil yields 3,9-di-($\alpha$-naphthyl)-6,14-dioxo-bis-(s-triazolo[3,4-b]-1,3,4-thiadiazolo[3,2-b]imidazo[4,5-b]cyclohexane]-5a,6a-diene) (3). 3-($\alpha$-naphthyl)-s-triazolo[3,4-b]-1,3,4-thiadiazolo[3,2-b]imidazo[4,5-b]quinoxaline (4) is obtained by a similar condensation of (2) with 2,3-dichloroquinoxaline. The reaction of (2) with $\alpha$-haloketones followed by bromination affords 7-aryl-3-($\alpha$-naphthyl)-imidazo[2,1-b]-1,3,4-thiadiazolo[2,3-c]-s-triazoles (5) and their 6-bromo analogues 6 respectively. The structures of all newly synthesized compounds were established on the basis of elemental analyses, IR, $^1H$-NMR. The antibacterial and antifungal activities of all newly synthesized compounds have also been evaluated.