• Food Science and Biotechnology
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• v.18 no.1
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• pp.66-72
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• 2009

An aqueous ribose-cysteine model system (initial pH 5.6) was conventionally heated to the same browning at varying temperatures ($120-180^{\circ}C$), supercritical carbon dioxide (SC-$CO_2$, 20 MPa) was also applied on the same matrices for same periods at each temperature and about 20% reduction of the absorbance at 420 nm was observed as compared with sole thermal treatment. The headspace volatiles from Maillard reaction mixtures were analyzed by solid-phase microextraction (SPME) in combination with gas chromatography and mass spectrometry (GC-MS), and predominated with sulfur containing compounds, such as thienothiophenes, polysulfur alicyclics, thiols, and disulfides. Reaction temperature exhibited complex effects on volatiles formation and those effects became further complicated by the SC-$CO_2$ treatment. The formation of noncarbonyl polysulfur heterocyclic compounds and thienothiophenes was generally favored at high temperatures. Most volatiles were inhibited in SC-$CO_2$ as compared with thermal treatment alone, however, the well-known meaty aromatic compounds, such as thiols and disulfides, were obviously enhanced.

• Journal of Environmental Science International
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• v.30 no.8
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• pp.673-684
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• 2021

Raw leachates from three landfills and treated leachates from two landfills on Jeju Isalnd were analyzed for ten perfluorinated compounds (PFCs) detected in aquaruc environments. The leachates were collected six times in 2014 and 2015. Among the ten PFCs, three were not detected, namely perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), and perfluorodecane sulfonate (PFDS). The total concentrations of PFCs ranged as 724-3313 ng/L (mean 1999 ng/L) in raw leachates and from less than the limit of quantification (LOQ) to 394 ng/L (mean 133.2 ng/L) in treated leachates. The domonant compounds measured were perfluorooctanoic acid (PFOA) (mean contribution 37.7%) and perfluorobutane sulfonate (PFBS) (mean contribution 38.2%) in raw leachates, and PFOA (mean contribution 40.7%), perfluorohexanoic acid (PFHxA) (mean contribution 27.3%) and PFBS (mean contribution 26.5%) in treated leachates. No significant correlations were observed between total/several individual PFCs and leachate pH and COD_Cr, which may be due to complex chemical nature of landfill leachates and characteristics of waste and landfills.

• Journal of Integrative Natural Science
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• v.15 no.4
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• pp.137-144
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• 2022

This paper presents the effect of the supramolecular complex of GA (Glycyrrhizic acid) and Mt(menthol) and GA: Mt (4: 1) obtained on their basis can restore functional dysfunction of the liver mitochondria in alloxan diabetes, ie, inhibit lipid peroxidation. The hypoglycemic activity and mitochondrial membrane stabilizing properties of the supramolecular compound GA: Mt (4: 1) in alloxan diabetes were more pronounced than those of menthol, GA and its GK: Mt (2: 1) and GA: Mt (9: 1) compounds. According to the results obtained, the concentration of GA did not affect the peroxidation of lipid membranes of the liver mitochondria. However, a concentration of 15 μM of GA was found to reduce LPO (lipid peroxidation) formed by the effect of Fe²+ / ascorbate on the mitochondrial membrane by 58.0 ± 5.0% relative to control. The inhibitory effect of GA and its supramolecular compounds in different proportions with menthol on the peroxidation of lipids in rat heart and brain tissue has been studied

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.4
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• pp.371-380
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• 2022

Objectives: To ensure that employers handling petroleum compounds understand whether petroleum-based UVCB (unknown or variable composition, complex reaction products, or biological materials) substances contain hazardous substances and comply with the Occupational Safety and Health Act, petroleum-based UVCB substances were analyzed and the results from samples were compared with MSDS (Material Safety Data Sheet) contents. Methods: Twenty-one petroleum samples were analyzed using GC-MS (Gas Chromatography-Mass Spectrometry), targeting ten volatile organic compounds regulated by the Occupational Safety and Health Act. Results: The target chemicals were detected in 13 out of 21 samples. All 13 samples were in the naphtha (low boiling point naphthas (gasolines)) group. There were also naphtha group samples containing 2% benzene. Some naphtha samples used as solvents contained about 1% benzene. Conclusions: This study shows that naphtha group petroleum substances contain hazardous chemicals in many cases. In particular, if benzene, n-hexane, and toluene with low occupational exposure limits are contained above the limit concentration. Such information should be delivered in the article on MSDS legal regulations.

• Journal of the Korean Chemical Society
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• v.7 no.3
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• pp.216-224
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• 1963

Reaction of organic chlorine containing ester, alcohol, and acids with metallic tin and zinc in dimethyl formamide solvent gave a good yield of organo metallic complex. The same reaction under a mixed U.V. irradiation could not give an appreciable yield of the complex except in the case of an elevated reaction temperature. The solvation effect of dimethyl formamide of the metallic complex formation was markedetly increased as compared to the reaction in toluene and cyclohexane. In case of chlorine containing carboxylic acid, the formation of organo chloro zinc complex of the salt was observed. The reaction of organo zinc complex with a carbonyl precursor gave the addition product together with a dimerized product. Especially the aldehyde species enhanced the formation of zinc complex. The addition reaction was simple and convenient, but the yield was not high.(30-40% for the acid, 73% for the ester, 14.6% for alcohol). The result was discussed on basis of solvent effect and the procedures were described.

• Applied Chemistry for Engineering
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• v.17 no.2
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• pp.119-124
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• 2006

Natural organic matter (NOM) should be carefully considered in terms of its constituent and effect because NOM is complex substances that occur in spatially and seasonally varying concentrations in natural water. This review presents characteristics of natural organic matter present in water. These compounds mainly include humic substances, carbohydrates, proteins (amino acids), hexosamines, fats, oils, greases, and trace organic compounds (endocrine disrupting chemicals and pharmaceuticals and personal care products).

• Natural Product Sciences
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• v.24 no.3
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• pp.139-147
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• 2018

The essential oils are fragrant products whose complex compositions are obtained from various parts of plants by dry or steam distillation. Plants with variable biological activities have been explored worldwide. The presence of a large number of phenols, terpenes and other aromatic compounds make essential oils more precise in their mode of action. Because of this, they are known to possess many biological activities like antimicrobial, antioxidant and anti-inflammatory etc. In this article, we will review the published literature summarizing the chemistry of essential oils and their important biological activities.

• Journal of Environmental Science International
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• v.3 no.4
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• pp.373-380
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• 1994

Volatile organic compounds in the ambient air were gathered irregularly by normal temperature concentrating method at Odea-ri and Oceon-ri Ulsan-gun in the neighbourhood of Ulsan Petrochemical Industrial Complex and analyzed with gas chromatograph. Several hydrocarbons in common aklospheric air or emitted fugitively from the chemical plants were identified and quantified by comparison with the retention times of standard compounds. The results from several field surveys in 1992 show that the concentrations of styrene at residential area of Odea-ri and Ocheon-ri were less than 0.4 ppm, but once a while greater within the chemical plants area. When it smelled unpleasantly in these area, the concentration of hydrocarbons were also high. It was concluded that the close and long-term investigation about other odorous components but hydrocarbons will be necessary to ascertain the cause of unpleasant odor of these area.

• Preventive Nutrition and Food Science
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• v.2 no.4
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• pp.360-367
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• 1997

The chemistry background of the Maillard reaction focused on pyrazines and factors affecting the reaction products were reviewed. The Maillard reaction, also called a non-enzymatic browning reaction, is quite complex and generates numerous reaction products. In processed foods, it is generally accepted as a key reaction to produce flavor components. Specially, pyrazines possess an important impact character on the roasted foods with other heterocyclic compounds. The Maillard reaction is initiated by condensation between reducing sugar and amino group, and N-glycosylamines are produced via Schiff base with dehydration of water. After the rearrangement of the N-glycosylamines, they follow transformation into deoxyhexosones which are reactive intermediates. Degradation and fragmentation are facilitated by rearranged compounds. By condensation, pyrazine, one of the final Maillard products, is generated as a relatively stable form to provide specific aromas. During the processes of the reaction, chemical or physical environmental parameters affect the formation of the products.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.41-49
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• 1994

The most common conventional method of discovering a drug involves a massive screening of a large number of compounds in chemical libraries or in the extracts from natural sources such as plants or microbial broths followed by chemical modification of one or more active compounds to improve their properties as a drug. When the three-dimensional structure of the target molecule for which the drug is searched is known the drug discovery process can be significantly simplified, This is especially true when the three-dimensional structure of a complex between the target and a lead compound is known. In this lecture our experience on the structure-based drug design for human CDK2(cyclin-dependent protein kinase 2) will be discussed with special emphasis on the strength and weakness of this approach of drug discovery. The regulation of the activity of CDK2 plays an important role in the cell proliferation of normal and cancer cells.