• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.440-445
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• 1996

An attempt was made to study the relative composition of Monohydroperoxide isomers of methyl linoleate oxidized to different peroxide values at 60, 90, 120 and $150^{\circ}C$, respectively. HPLC was used to analyze and isolate the monohydroperoxide isomers fractionated by silica gel column after reduction with NaBH.. GC-MS was used to identify four monnhydroperoxide isomers as trimethylsilyl (TMS) in mixtures of oxidized methyl linoleate In the geometrical isomers, the proportions of 9/13-OOH-trans, trant-diene were higher than those of 9/13-OOH-cis, trans-diene at $60^{\circ}C$ and $90^{\circ}C$. However in the initial stage at $150^{\circ}C$, the proportions of 9/13-OOH-cis, trans-diene were slightly higher than those of 9/13-OOH-trans, trans-diene. In case of positional isomers, equal proportions of 9-OOH-10, 12-diene and 13-OOH-9, 11-diene were found in all samples of methyl linoleate oxidized at different temperatures and peroxide levels.

• Archives of Pharmacal Research
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• v.23 no.2
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• pp.151-154
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• 2000

Two sesquiterpene endoperoxides, 1S, 4R, 6R-1, 4-endoperoxy-bisabola-2, 10-diene (1), 1R, 4S, 6R-1, 4-endoperoxy-bisabola-2, 10-diene (II), and a sesquiterpene hydroperoxide, 1$\beta$-hydroperoxygermacra-4 (15), 5, 10 (14)-triene (III) were isolated from the aerial parts of Artemisia stolonifera (Compositae). Their chemical structures were assigned by spectral evidences. Compounds I and II exhibited cytotoxicity against five human tumor cell lines with their $\ED_50 values ranging from 0.20 to 5.43 ${\mu}g/m\ell$ and from <0.1 to 0.87 ${\mu}g/m\ell$, respectively.

• Korean Journal of Pharmacognosy
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• v.19 no.4
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• pp.228-232
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• 1988

From the rhizome of Atractylodes japonica Koidzumi (Compositae) which is the original plant of oriental medicine 'Cang-Zhu', four essential oil compounds were isolated. Three of them were identified as atractylon, hydroxyatractylon and $5{\alpha}H,\;10{\beta}-selina-4(14),\;7(11)-diene-8-one$, which were already known as the constitutents of Atractylodes Rhizoma. The fourth is a novel polyacetylene type compound, and the structure is postulated as 1, 4-diacetoxytetradeca-6, 12-diene-8, 10-diyne by the spectral data.

• Journal of Pharmaceutical Investigation
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• v.40 no.3
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• pp.155-160
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• 2010

A gas chromatographic-mass spectrometric (GC-MS) method was developed for the simultaneous determination of valproic acid (VPA) and its toxic metabolites, 4-ene-VPA and 2,4-diene-VPA in rat plasma. Extraction was performed in weak acidic condition (pH 5.2) to avoid degradation of 4-ene-VPA and 2,4-diene-VPA. The recoveries for 4-ene-VPA and 2,4-diene-VPA were more than 70% and that for VPA was 33-42%. R value for each compounds exceeded 0.998 in calibration curve during all the analysis. Accuracy and precision ranged from 88.3 to 113.2% and from 2.16 to 14.2%, respectively The method was successfully applied to monitor plasma concentrations of VPA, 4-ene-VPA and 2,4-diene-VPA after intravenous administration of VPA at the dose of 100 mg/kg, suggesting that these toxic metabolites may involved in the hepatotoxicity induced by VPA.

• Bulletin of the Korean Chemical Society
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• v.17 no.9
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• pp.849-853
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• 1996

Hetero Dieis-Alder reactions containing phosphorus atom at various positions of diene and dienophile as well as standard Dieis-Alder reaction between ethylene and cis-l,3-butadiene have been studied using ab initio method. Activation energy showed a good linear relationship with the FMO energy gap between diene and dienophile, which can be normally used to explain Dieis-Alder reactivity. Since π-bond cleavage and σ-bonds formation occur concertedly at the TS, geometrical distortion of diene and dienophile from the reactant to the transition state is the source of barrier. Based on the linear correlations between activation barrier and deformation energy, and between deformation energy and π-bond order change, it was concluded that the activation barrier arises mainly from the breakage of π-bonds in diene and dienophile. Stabilization due to favorable orbital interaction is relatively small. The geometrical distortions raise MO levels of the TS, which is the origin of the activation energy. The lower barrier for the reactions of phosphorus containing dienophile (reactions C, D, and E) can be explained by the electronegativity effect of the phosphorus atom.

• Bulletin of the Korean Chemical Society
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• v.8 no.4
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• pp.270-272
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• 1987

1,1-Dichloro-2,3,4,5-tetraphenyl-1-silacyclopenta- 2,4-diene was synthesized through the reaction of $SiCl_4$ with 1,4-dilithiotetraphenylbutadiene in 50% yield. From the reaction of this silole with metal, an air sensitive red-brownish solid was obtained. Treatment of this reaction product with $CH_3I\; and\; Me_3SiCl$ gave 1,1-dimethyl-2,3,4,5-tetraphenyl-1-silacyclopenta- 2,4-diene and 1,1-bis(trimethylsilyl)-2,3,4,5-tetraphenyl-1-silacyclopenta-2,4-diene, respectively. From these results, the formation of reactive 2,3,4,5-tetraphenyl-1-silacyclopenta-2,4-dienyl dianion was confirmed.

• The Korean Journal of Food And Nutrition
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• v.28 no.1
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• pp.40-46
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• 2015

Hamcho (Salicornia herbacea) extracts were evaluated for total polyphenol content, antioxidant and pro-oxidant activities. The total polyphenol content was 1.81 g and 0.72 g per 100 g of dried sample in water and ethanol extracts respectively. Both water and ethanol extracts of Hamcho significantly exhibited antioxidant activity. The scavenging activity of hydroxyl radical was 13.8~26.2% and 14.2~16.0% in water and ethanol extracts respectively. The inhibitory effect of conjugated diene formation was 24.6~39.1% and 28.4~39.6% in water and ethanol extracts respectively. However, pro-oxidative effect was also observed in the Hamcho extracts. The Hamcho water extract showed the pro-oxidant effect by enhancing the formation of hydroxyl radical and conjugated diene. The ethanol extract of Hamcho induced conjugated diene formation at 0.5 mg/mL but not at 1 mg/mL. The hydroxyl radical formation was not induced by the Hamcho ethanol extract. Taken together, these results show that Hamcho extracts can act as pro-oxidants by generating hydroxyl radical or conjugated diene in addition to their antioxidant properties. Therefore, this study suggests that the physiological properties of Hamcho and its use as food materials should be considered with caution because antioxidant dietary plants such as Hamcho possess possible adverse effects induced by pro-oxidant activity.

• Bulletin of the Korean Chemical Society
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• v.23 no.6
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• pp.829-837
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• 2002

Recently it was reported that cycloaddition of 6,6-disubstituted cyclohexa-2,4-dienone, 1 with cyclopentadiene gave solely the adduct of type 1.while its reaction with 1,3-cyclohexadiene gave both Ⅱ and Ⅲ. Semiempirical MO calculations were done to elucidate the origin of the selectivity difference between the two dienes. Cycloaddition of 1 with cyclopentadiene is controlled thermodynamically to give only 1-diene adduct by ΔGvalues of 10.6-20.3 kcal/mol, while its reaction with 1,3-cyclohexadiene does not show 1-diene/1-dienophile selectivity due to similar stabilities of the two adducts. Thermodynamic parameters also show that 두애 adducts are more fabourably fromed in the cycloadditions of 1 with both cyclopentadiene and 1,3-cyclohexadiene, which coincides with experimental observations. Cope rearrangements of endo adducts are another avenue to convert between 1-diene and 1-dienophile.

• School Mathematics
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• v.10 no.3
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• pp.339-355
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• 2008

This article tried to review the meaning and implication of six stages theory of learning mathematics suggested by Zoltan Dienes in "Building up Mathematics" in 1971. It was not much concretely known to Korean mathematics education society. In particular, there is no mathematical example which could cover all the stages to know what the theory tells. So this article focused on the example which Dienes developed for learning integers in 2000 to dig the theory. As a result, some critical aspects and problems of six stages theory were found. And finally educational implication was described.

• YAKHAK HOEJI
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• v.48 no.1
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• pp.65-69
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• 2004

The chromatographic separation of MeOH extract of the aerial parts of Aster glehni (Compositae) led to the isolation of three sesquiterpenes, two sterols and four terpenes. Their structures were determined to be $\beta$-amyrin acetate (1), phytol (2), alismol (3), $\alpha$-tocopheryl quinone (4), $\alpha$-spinasterol (5), 10-O-methyl alismoxide (6), alismoxide (7), and 3-O-(6'-O-palmitoyl-$\beta$-D-glucosyl)-spinasta 7,22-diene (8) by physicochemical and spectroscopic methods . These compounds (1-8) were first isolated from the Aster glehni.