• Journal of Food Hygiene and Safety
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• v.12 no.3
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• pp.217-227
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• 1997

These experiments were performed to investigate the safety of the three medicinal herbs- Curcuma longa Linne, Paeonia japonica Miyabe, Scutellaria baikalensis George-irradiated with gamma rays in respect of genotoxicity. The methanol-soluble and water-soluble fractions of the methanol-water extracts of the 10 kGy gamma-irradiated herbs were examined in two short-term in vitro tests : (1) Salmonella typhimurium reversion assay (Ames test) in strain TA 98, TA 100 and TA 012 (2) Micronucleus test in cultured Chinese hamster ovary (CHO) cells. No mutagenicity was detected in the assays with or without metabolic activation. From these results, the safety of the herbs irradiated with gamma rays at practical doses could be revealed in further tests of genotoxicity in vivo, chronic and reproductive toxiceity.

• Nuclear Engineering and Technology
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• v.6 no.1
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• pp.23-26
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• 1974

The rates and activation parameters for the halide exchange reactions of methanesulfonyl chloride in dry acetone, acetonitrile, and methanol have been determined. It was found that nucleophilic order is Cl->Br->I-. The rate of chloride exchange with methanesulfonyl chloride decreases in the order of solvent; ($CH_3$)$_2$CO>$CH_3$CN》MeOH. Results are intrpreted in terms of easiness of the initial state desolvation and solvation stabilization of the transition state.

• International Journal of Oral Biology
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• v.36 no.3
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• pp.149-154
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• 2011

In the present study, total methanol extracts prepared from Alpinia katsumadai showed significant protective effects against the oxidative stress induced by hydrogen peroxide, UV-C or ${\gamma}$-ray irradiation. These protective effects were substantially increased by treatment with 20~100 ${\mu}g$/ml of the extract. The A. katsumadai total methanol preparation was further fractionated into n-hexane, dichloromethane, ethylacetate, n-butanol and water fractions. Among these five fractions, the ethylacetate and butanol fractions of A. katsumadai showed the strongest protective effects against oxidative stress induced by UV-C and ${\gamma}$-ray irradiation. These fractions also showed high DPPH radical scavenging and lipid peroxidation inhibitory activities. In addition, both fractions displayed cell proliferation activation effects, as evidenced by significant increases in colony formation. Our current data thus suggest that the mechanisms underlying the protective effects of A. katsumadai against oxidative damage may include radical scavenging, protection against cell membrane damage and stimulation of cell proliferation.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.393-398
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• 1987

Solvolyses of 2-phenylethyl benzenesulfonates have been studied in methanol-water mixtures. Cross interaction constants, $\rho_{YZ}$, between substituents Y in the substrate and Z in the leaving group indicated somewhat closer distance between the two substituents than expected for the reaction system, which supported the involvment of phenyl group assisted pathway in the solvolysis. A smaller magnitude of $\rho_{YZ}$for MeOH was interpreted as the enhencement of solvent assisted pathway since MeOH is more nucleophilic than $H_2O$. Other selectivity parameters, Winstein coefficient m, Hammett's $\rho_Y^{+_Y}$ and $\rho_Z$, as well as activation parameters supported the participation of aryl assisted and aryl unassisted pathways in the $S_{N^2}$ process of the solvolysis reaction.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.413-418
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• 1987

Rates of the reaction for p-nitro benzyl chloride, benzyl chloride and p-methyl benzyl chloride with pyridine in methanol solvent have been measured by an electric conductivity method at 40$^{\circ}$C and 50$^{\circ}$C under various pressures (1∼2000bar). Pseudo first-order rate constants and second-order rate constants were determined. Rates of these reactions were increased in the order p-NO$_2$ < p-H < p-CH$_3$ and increased with temperature, pressure and concentration of pyridine. From those rate constants, the activation parameters were evaluated. The activation volume and the activation compressibility coefficient are both negative values, but the activation enthalpy is positive and the activation entropy is large negative value. From the evaluation of the ground state and transition state which was resulted from substituents and pressure, it was found that this reaction proceeds through S$_N$2 reaction, and S$_N$2 fashion is slightly disappeared as pressure increases.

• Journal of Microbiology and Biotechnology
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• v.18 no.8
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• pp.1423-1426
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• 2008

Nuruk, which is a natural inoculator and source of amylolytic enzymes, is used in Korean traditional rice wine. A methanol extract of nuruk (NE) attenuated lipopolysaccharide (LPS)-induced nitrite and interleukin (IL)-6 in RAW 264.7 cells. Both the n-hexane and water fractions from NE (MEH and MW, respectively) inhibited the production of nitrite and IL-6 in RAW 264.7 cells. MEH and MW also inhibited the LPS-induced inducible nitric oxide synthase expression. Further, and MEH protected against the LPS-induced activation of p38 mitogen-activated protein kinase. Together, these results indicate that nuruk may contribute to the anti-inflammatory and cancer-preventive effects of Korean traditional rice wine.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.416-420
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• 2018

A comprehensive kinetic study has been conducted on dimethyl carbonate synthesis by transesterification reaction of ethylene carbonate with methanol. An alkali base metal (KOH) was used as catalyst in the synthesis of DMC, and its catalytic ability was investigated in terms of kinetics. The experiment was performed in a batch reactor at atmospheric pressure. The reaction orders, the activation energy and the rate constants were determined for both forward and backward reactions. The reaction order for forward and backward reactions was 0.87 and 2.15, and the activation energy was 12.73 and 29.28 kJ/mol, respectively. Using the general factor analysis in the design of experiments, we analyzed the main effects and interactions according to the MeOH/EC, reaction temperature and KOH concentration. DMC yield with various reaction conditions was presented for all ranges using surface and contour plot. Furthermore, the optimal conditions for DMC yield were determined using response surface method.

• Bulletin of the Korean Chemical Society
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• v.16 no.1
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• pp.53-58
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• 1995

Heats of solution of aniline (AN), benzylamine (BA), ethyl-(EBS) and 2-phenylethyl benzenesulfonates (PEB) are calorimetrically measured in acetonitrile-methanol mixtures at 25.0 $^{\circ}C$. The activation parameters, ${\Delta}H^{\neq}$, ${\Delta}S^{\neq}$ and ${\Delta}G^{\neq}$, are determined for the reactions of EBS and PEB with AN and BA using the kinetic data at three temperatures. Calorimetric transfer enthalpies of initial state, ${\delta}H_t^{0{\rightarrow}x})$(IS), and kinetically derived activation enthalpies, ${\delta}\;{\Delta}H^{\neq}$, in the MeCN-MeOH mixtures are combined to determine the transfer enthalpies of transition state, ${\delta}H_t^{0{\rightarrow}x})$(TS); ${\delta}H_t^{0{\rightarrow}x})$(IS) = ${\delta}{\Delta}H^{\neq}\;+\;{\delta}H_t^{0{\rightarrow}x}$(IS) The preferential solvation of anionic charge in the TS predicts a loose TS with a greater degree of bond cleavage for the reactions of PEB than for EBS, and also for the reactions with BA compared to the reactions with AN.

• Journal of the Korean Chemical Society
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• v.63 no.4
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• pp.233-236
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• 2019

In this study, the solvolysis of cyclohexanesulfonyl chloride (1) was studied by kinetics in ethanol-water, methanol-water, acetone-water, and 2,2,2-trifluoroethanol (TFE)-water binary solvent systems. The rate constants were applied to the extended Grunwald-Winstein equation, to obtain the values of m = 0.41 and l = 0.81. These values suggested $S_N2$ mechanism in which bond formation is more important than bond breaking in the transition state (TS). Relatively small activation enthalpy values (11.6 to $14.8kcal{\cdot}mol^{-1}$), the large negative activation entropy values (-29.7 to $-38.7cal{\cdot}mol^{-1}{\cdot}K^{-1}$) and the solvent kinetic isotope effects (SKIE, 2.29, 2.30), the solvolyses of the cyclohexanesulfonyl chloride (1) proceeds via the $S_N2$ mechanism.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.201-202
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• 2001

Mass culture of microalgae as feed for mollusc, crustaceans and fish is an important components of the mariculture industry (Metting Jr., 1996) Growth activator for tetraselmis suecica were screened in methanol and water soluble extracts of several seaweed tissues. Also examined in this study were change in growth rate, biochemical composition, and digestion efficiency, of T.suecica cultured with and without the most effective of these extracts, the water soluble component extracted form M. nitidium. (omitted)