• Journal of the Korean Chemical Society
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• v.51 no.6
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• pp.506-512
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• 2007

Various long chain aliphatic acid hydrazides react with aromatic and heterocyclic aldehydes in alcoholic medium in refluxing conditions to give corresponding 2-hydroxy benzylidene and 1H-indol-3-ylmethylene hydrazides, a newer class of mosquito para-pheromones. We describe here synthesis of various novel long chain aliphatic acid (2- hydroxy benzylidene and 1H-indol-3-ylmethylene) hydrazides by conventional as well as microwave irradiation techniques. The structures of these compounds have been confirmed by spectroscopic techniques (FTIR, NMR & MS). Some of the interesting features of the electron impact mass spectral fragmentation pattern of these compounds have also been discussed.

• Journal of the Korean Applied Science and Technology
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• v.18 no.4
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• pp.306-315
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• 2001

Our study is aimed at proposal of systematic verification method of molecular structure using measuring method of selective ionic determination and spectrometry on 34 kinds of surfactants such as sodium dodecyl sulfate(SDS) which are most widely used today. In the IR spectrum, unsaturated fatty acids reveal themselves by HC= at $3000{\sim}3020cm^{-1}$, and intensity of $720cm^{-1}$ depends on carbon length of alkyl group. Also ethylene oxide(EO) adducts exhibit weak characteristic bands by $-CH_{2}-CH_{2}-O$ at 1350, 1100 and $950cm^{-1}$. Isethionate can be distinguished from diester succinate by intensity ratio of 1740 and $1200cm^{-1}$ spectrums, the ratio of latter is close to 1 due to 2 carboxylate radical in diester succinate. Quaternary ammonium salts exhibit characteristic band of $C_{4}N^{+}$ at $1000-900㎝^{-1}$. In the case of dialkyl dimethyl ammonium salts in quaternary ammonium surfactants, the spectrum of $3000cm^{-1}$ by $N-CH_{3}$ collapses to a very weak band at $3020cm^{-1}$. In ammonium heterocyclic derivatives, pyridinium salts show characteristic bands at 1640 and $1460cm^{-1}$, while imidazolinium salts exhibit characteristic band at $1620-1610cm^{-1}$. In the characteristic spectrum at $1080-1050cm^{-1}$ on OH radicals of the alkyl esters, primary alcohol appears as weak band and the 2 bands show in almost same intensity when primary and secondary alcohols exist together in one molecule. Also, alkyl ester of polyhydric alcohols appears as various broad band.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.1
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• pp.117-126
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• 1984

Aflatoxins are toxic and carcinogenic secondary metabolites which are produced by trains of A. flavus and A. parasiticus during their growth on foods and feedstuffs. Aflatoxins are a group of closely related heterocyclic compounds of which $B_1$, $B_2$, and $G_2$ are the major members. Aflatoxins are synthesized via a polyketide pathway in which the general steps are acetate, an-thraquinones, xanthone and aflatoxins. Aflatoxin formation is favored by high moisture or high $a_w$(0.95${\sim}$0.99). The limiting $a_w$ for aflatoxin production on agricultural commodities is 0.83. Optimum temperature for aflatoxin production by the molds is $25{\sim}30^{\circ}C$ and the incubation time for the maximum production of the toxin is 7${\sim}$15 days. The limiting temperatures for aflatoxin production are ${\leq}7.5^{\circ}C\;and\;\geq40^{\circ}C$. Cycling temperatures may or may not stimulate aflatoxin production depending on the amplitude of cycling, substrate and strains of molds. Aflatoxin pro-ducing molds are aerobic organisms and thus have a requirement for oxygen. A decreasing $O_2$ concentration and/or increasing concentrations of $CO_2$ or $N_2$ depress the mold growth and aflatoxin formation. A. flavus grows competitively or associatively in the presence of other microorganisms and occasionally loses the competition with other microorganisms. Some lactic acid bacteria have been shown to reduce growth and aflatoxin production by A. parasiticus. Carbon source is the most important nutritional factors affecting aflatoxin formation by the molds. Sucrose, fructose and glucose are the most favorable carbon sources. Food substrates of plant derived products which have high carbohydrate content such as agricultural commodities and their products are most vulnerable to contamination by aflatoxins.

• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.62-67
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• 1993

The microscopic origin of nonlinear optical properties of quinoline derivatives have been investigated theoretically using MOPAC-AM1 method. In order to prepare promising nonlinear optical active polymers of polyquinoline derivatives, the optimized positions of strong electron donor and electron acceptor are determined in the heterocyclic ring for the energetically favorable structures. For each compound, the effect of the substituted positions on the microscopic nonlinear coefficients were investigated. Polyquinoline was already evaluated to have outstanding physical and mechanical properties so that its monomeric analogues were designed and synthesized for developing new second and third order nonlinear optical main chain polymers. Using the MOPAC-AM1 method, properties calculated include the intrinsic ground-state dipole moments, the polarizabilities, first and second hyperpolarizabilities under the condition of finite-field $(\omega$ = 0).

• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.947-952
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• 2007

Mycobacterium tuberculosis is a pathogen responsible for 2-3 million deaths every year worldwide. The emergence of drug-resistant and multidrug-resistant tuberculosis has increased the need to identify new antituberculosis targets. Acetohydroxy acid synthase, (AHAS, EC 2.2.1.6), an enzyme involved in branched-chain amino acid synthesis, has recently been identified as a potential anti-tuberculosis target. To assist in the search for new inhibitors and “receptor-based” design of effective inhibitors of tubercular AHAS (TbAHAS), we constructed four different structural models of TbAHAS and used one of the models as a target for virtual screening of potential inhibitors. The quality of each model was assessed stereochemically by PROCHECK and found to be reliable. Up to 89% of the amino acid residues in the structural models were located in the most favored regions of the Ramachandran plot, which indicates that the conformation of each residue in the models is good. In the models, residues at the herbicide-binding site were highly conserved across 39 AHAS sequences. The binding mode of TbAHAS with a sulfonylurea herbicide was characterized by 32 hydrophobic interactions, the majority of which were contributed by residue Trp516. The model based on the highest resolution X-ray structure of yeast AHAS was used as the target for virtual screening of a chemical database containing 8300 molecules with a heterocyclic ring. We developed a short list of molecules that were predicted to bind with high scores to TbAHAS in a conformation similar to that of sulfonylurea derivatives. Five sulfonylurea herbicides that were calculated to efficiently bind TbAHAS were experimentally verified and found to inhibit enzyme activity at micromolar concentrations. The data suggest that this time-saving and costeffective computational approach can be used to discover new TbAHAS inhibitors. The list of chemicals studied in this work is supplied to facilitate independent experimental verification of the computational approach.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.167-173
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• 2013

A series of highly efficient red phosphorescent heteroleptic iridium(III) complexes 1-6 containing two cyclometalating 2-(2,4-substitued phenyl)quinoxaline ligands and one chromophoric ancillary ligand were synthesized: (pqx)$_2Ir$(mprz) (1), (dmpqx)$_2Ir$(mprz) (2), (dfpqx)$_2Ir$(mprz) (3), (pqx)$_2Ir$(prz) (4), (dmpqx)$_2Ir$(prz) (5), (dfpqx)$_2Ir$(prz) (6), where pqx = 2-phenylquinoxaline, dfpqx = 2-(2,4-diflourophenyl)quinoxaline, dmpqx = 2-(2,4-dimethoxyphenyl)quinoxaline, prz = 2-pyrazinecarboxylate and mprz = 5-methyl-2-pyrazinecarboxylate. The absorption, emission, electrochemical and thermal properties of the complexes were evaluated for potential applications to organic light-emitting diodes (OLEDs). The structure of complex 2 was also determined by single-crystal X-ray diffraction analysis. Complex 2 exhibited distorted octahedral geometry around the iridium metal ion, for which 2-(2,4-dimethoxyphenyl)quinoxaline N atoms and C atoms of orthometalated phenyl groups are located at the mutual trans and cis-positions, respectively. The emission spectra of the complexes are governed largely by the nature of the cyclometalating ligand, and the phosphorescent peak wavelengths can be tuned from 588 to 630 nm with high quantum efficiencies of 0.64 to 0.86. Cyclic voltammetry revealed irreversible metal-centered oxidation with potentials in the range of 1.16 to 1.89 V as well as two quasi-reversible reduction waves with potentials ranging from -0.94 to -1.54 V due to the sequential addition of two electrons to the more electron-accepting heterocyclic portion of two distinctive cyclometalated C^N ligands.

• Journal of People, Plants, and Environment
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• v.23 no.4
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• pp.399-410
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• 2020

The United Nations project the world population to reach 10 billion by the year 2057. To increase the food of the ever-increasing world population, agrochemicals are indispensable tools to the boon in agriculture production. These agrochemicals are a serious threat to the health of humans, plants, and animals. Agrochemicals are ultimately reached to the main reservoir/sink such as soil and contaminating the groundwater, disturb the soil health and in turn a serious threat to biogeochemical cycling and the entire biosphere. Among agrochemicals, quinalphosis one of the most repeatedly and widely used insecticides in the control of a wide range of pests that attack various crops. Quinalphos is shown to be primarily toxic in organisms by acetylcholinesterase enzyme action. Hydrolysis of quinalphos produces amajor metabolite 2-hydroxyquinoxaline (2-HQ), which has shown secondary toxicity in organisms. 2-HQ is reported to be mutagenic, carcinogenic, growth inhibition and induce oxidative stress in organisms. Quinoline is a heterocyclic compound and structural resemblance of 2-HQ with minor changes, but its degradation studies are enormous compared to the 2-HQ compound. Biotic factors in fate and behavior of 2-HQ in the environment are least studied. 2-HQ interactions with soil enzymes are vary from soil to soil. Based on the toxicity of 2-HQ in our stockpile we need to isolate a handful of microorganisms to treat this persistent metabolite and also other metabolites/compounds.This brief review will be significant from the point of biological and environmental safety.

• The Korean Journal of Pain
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• v.35 no.4
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• pp.440-446
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• 2022

Background: The authors showed in a previous study that some novel triazine derivatives had an anti-inflammatory effect. The present study was designed to evaluate the antinociceptive effect of five out of nine compounds including two vanillintriazine (5c and 5d) and three phenylpyrazole-triazine (10a, 10b, 10e) derivatives which showed the best anti-inflammatory effect. Methods: Male Swiss mice (25-30 g) were used. To assess the antinociceptive effect, acetic acid-writhing, formalin, and hot plate tests were used after intraperitoneal injection of each compound. Results: All compounds significantly (P < 0.001) reduced acetic acid-induced writhing at tested doses (50, 100, and 200 mg/kg). Also, the percent inhibition of writhing in the acetic acid test showed that at the maximum tested dose of these compounds (200 mg/kg), the order of potencies is as follows: 10b > 10a > 10e > 5d > 5c. In the formalin test, compounds 5d, 10a, and 10e showed an antinociceptive effect in the acute phase and all compounds were effective in the chronic phase. In the hot plate test, compounds 5c, 5d, and 10a demonstrated an antinociceptive effect. Conclusions: The results clearly showed that both vanillin-triazine and phenylpyrazole-triazine derivatives had an antinociceptive effect. Also, some compounds which showed activity in the early phase of formalin test as well as in the hot plate test could control acute pain in addition to chronic or inflammatory pain.

• Journal of Microbiology and Biotechnology
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• v.33 no.6
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• pp.707-714
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• 2023

Plant-derived insecticide-neonicotinoid insecticides (NIs) played a crucial role in the development of agriculture and food industry in recent years. Nevertheless, synthesis of these nitrogen-containing heterocyclic compounds with an effective and greener routing remains challenging especially to the notion raise of "green chemistry" and "atom economy". While bio-catalyzed methods mediated by nicotinate dehydrogenase (NDHase) then provide an alternative. The current review mainly focuses on the introduction of sources, components, structure, catalytic mechanism and applications of NDHase. Specifically, NDHase is known as nicotinic acid hydroxylase and the sources principally derived from phylum Proteobacteria. In addition, NDHase requires the participation of the electron respiratory chain system on the cell membrane. And the most important components of the electron respiratory chain are hydrogen carrier, which is mainly composed of iron-sulfur proteins (Fe-S), flavin dehydrogenase (FAD), molybdenum binding protein and cytochromes. Heterologous expression studies were hampered by the plasmid and host with high efficiency and currently only Pseudomonas entomophila L48 as well as Comamonas testosterone was successfully utilized for the expression of NDHase. Furthermore, it is speculated that the conjugate and inductive effects of the substituent group at position 3 of the substrate pyridine ring exerts a critical role in the hydroxylation reactions at position 6 concerning about the substrate molecular recognition mechanism. Finally, applications of NDHase are addressed in terms of pesticide industry and wastewater treatment. On conclusion, this critical review would not only deepen our understanding of the theory about NDHase, but also provides the guideline for future investigation of NDHase.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.503-508
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• 2023

Tryptane derivatives are substances that treat acute migraines, and many studies have been conducted on analysis methods such as chromatography, electrochemistry, spectroscopy, and capillary electrophysiology. Recently, analytical chemists have become more interested in drug analysis and solving fundamental problems of biological importance. Therefore, in this study, the chemical properties of each derivative were investigated by calculating the total energy, band gap, electrostatic potential, and charge of Sumatriptan, Lizatriptan, Naratriptan, and Eletriptan using HyperChem8.0's semi-empirical PM3 method. As a result of this study, in the case of Sumatriptan, Naratriptan, and Eletriptan, chemical reactions are expected to proceed centering on oxygen and nitrogen atoms bonded to sulfur atoms. In addition, in the case of Rizatriptan without a sulfur atom, it was shown that the chemical reaction proceeds at the 17th and 19th nitrogens of the 5-membered heterocyclic compound.