• Biomolecules & Therapeutics
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• v.17 no.4
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• pp.412-417
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• 2009

In the course of screening for antioxidant compounds by measuring the radical scavenging effect on DPPH (1,1-diphenyl- 2-picrylhydrazyl), a total extract of the twigs of Vitex rotundifolia (Verbenaceae) was found to show potent antioxidant activity. Subsequent activity-guided fractionation of the methanolic extract led to the isolation of three iridoid compounds, 10-O-vanilloylaucubin (1), 10-O-p-hydroxybenzoylaucubin (2) and aucubin (3), two C-glycoside flavones, vitexin (4) and orientin (5), and a quinic acid derivative, 3,4-di-O-caffeoylquinic acid (6). Their structures were elucidated by spectroscopic studies. Among them, compounds 5 and 6 showed the significant antioxidative effects on DPPH free radical scavenging test. In riboflavin-NBT-light and xanthine-NBT-xanthine oxidase systems, compounds 5 and 6 exhibited the formation of the blue formazan in a dose-dependent manner. Compounds 5 and 6 showed better superoxide quenching activities than vitamin C.

• Speech Sciences
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• v.11 no.3
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• pp.95-109
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• 2004

Metrical Phonology has asserted that stress shift does not occur in English compounds because it violates the Continuous Column Constraint. Noun phrases, on the other hand, freely allow for stress shift, whereby the preceding stress moves forward to the preceding heavy syllable. This paper hypothesizes that stress does not shift in compounds as opposed to noun phrases and compares their pitch accentual patterns in a phonetic experiment. More specifically, we examined two-word combinations, noun phrases and compounds, whose boundaries involve stress clash and assured that the preceding words involve a heavy syllable ahead of the stress to guarantee the place for a shifting stress. Depending on where the preceding pitch accent is aligned, stress shift is determined. Results show that stress shift occurs in approximately 47% of the noun phrases and 59% of the compounds; therefore, the hypothesis is not borne out. This suggests that the surface representations derived by phonological rules may not be implemented in real utterance but that phonetic forms may be determined by the phonetic constraints. directly operating on human speech.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.58-61
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• 2002

An alternative to pump and treat groundwater remediation is the use of reactive barriers. Zero valent iron (ZVI) is particularly useful as a reductant of chlorinated hydrocarbons because of its low cost and lack of toxicity ZVI can drive the dechlorination of chlorinated organic compounds and the reduction of chromium from the Cr(Ⅵ) to the Cr(III) state. The contaminants in subsurface environment usually exist as the mixed compounds. Therefore, the objective of this research is to study the effect of the other compounds on TCE removal by ZVI. The removal mechanism of TCE by ZVI is separated the dechlorination and sorption. TCE removal by ZVI slightly increased in presence of naphthalene as the non-reduced compound. TCE removal by ZVI remarkable decreased in presence of carbon tetrachloride, nitrate, and chromate as the reduced compounds. This research suggests that the effect of the coexisted compounds on the removal chlorinated compounds by reactive barrier technology should be considered for practical application.

• Journal of the Korean Wood Science and Technology
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• v.17 no.3
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• pp.28-44
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• 1989

This experiment was carried out to contribute to the synthetic methods of ligin model compounds. The ligin model compounds of arylglycerol-${\beta}$-arylether structure were synthesized in high yield through three or four reaction steps. The starting compound was commercial 3, 4, 5-trimethoxyace tophenone and the final compounds were 1-(2-methoxyphenoxy)-2 - (3, 4, 5 - trimethoxyphenyl)-ethanol(IV), 1-(3, 4, 5-trimethoxyphenyl)-2-(2-methoxy-phenoxy)-propandiol-1,3 (VI), 1-(2, 6-dimethoxyphenoxy)-2-(3, 4, 5-trimethoxyphenyl)-ethanol (VIII), and 1-(3, 4, 5-trimethoxyphenyl)-2-(2, 6-dimethoxyphenoxy)-propandiol-1, 3 (X). The structures of synthetic compounds were identified by IR, $^1H$-NMR spectroscopy and Mass spectrometry.

• Macromolecular Research
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• v.9 no.1
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• pp.37-44
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• 2001

A premixing effect for the properties of carbon black-filled rubber compounds was investigated using biblends of natural rubber (NR), styrene-butadiene rubber (SBR), and butadiene rubber (BR). Degree of mixing of the biblends was controlled by preblending time of 0.0, 2.5, and 5.0 min. Mooney viscosities of the compounds decreased by increasing the preblending time. Of three carbon black-filled compounds of NR/SBR, NR/BR, and SBR/BR compounds, only the SBR/BR blends showed a specific cure characteristics depending on the preblending time. For the bound rubber composition, the NR content was higher than SBR and BR. The difference in the rubber composition ratio of the bound rubber became smaller with increasing the preblending time. Physical properties of the vulcanizates such as hardness, modulus, tensile property, abrasion loss, and tans were also compared. Differences in properties of the compounds were discussed with miscibility of the dissimilar rubbers and degree of mixing.

• Analytical Science and Technology
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• v.7 no.3
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• pp.403-411
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• 1994

To isolate, purity and identify of bioactive compounds involved in alfalfa allelopathy and/or autotoxicity, experiment was conducted. Isolation and separation procedures used from an 80% methanol extract of fresh alfalfa leaves(1kg), silica gel thin layer chromatography(TLC), followed by Droplet Counter Current Chromatography(DCCC). Preliminary identification was examined by high preformance lipid chromatography(HPLC). Four phenolic compound, salicylic acid, scopoletin, rutin, and quercetin, were identified and identified all compounds were phytotoxic to alfalfa seed germination and seedling growth. Among these compounds, quercetin treatment($10^{-3}M$) was most inhibitory to alfalfa seed germination and seedling growth. These compounds may be, at least in part, involved autotoxicity and allelopathy.

• CELLMED
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• v.6 no.4
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• pp.22.1-22.19
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• 2016

The biologically active compounds derived from different natural organisms such as animals, plants, and microorganisms like algae, fungi, bacteria and merine organisms. These natural compounds possess diverse biological activities like anthelmintic, antibacterial, antifungal, antimalarial, antiprotozoal, antituberculosis, and antiviral activities. These biological active compounds were acted by variety of molecular targets and thus may potentially contribute to several pharmacological classes. The synthesis of natural products and their analogues provides effect of structural modifications on the parent compounds which may be useful in the discovery of potential new drug molecules with different biological activities. Natural organisms have developed complex chemical defense systems by repelling or killing predators, such as insects, microorganisms, animals etc. These defense systems have the ability to produce large numbers of diverse compounds which can be used as new drugs. Thus, research on natural products for novel therapeutic agents with broad spectrum activities and will continue to provide important new drug molecules.

• Journal of Environmental Science International
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• v.11 no.9
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• pp.961-969
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• 2002

This study was performed : 1) to establish the experimental analysis conditions for the sorption and desorption of toxic organic contaminants to/from the activated sludge, sediment, and clay, and 2) to determine the sorption and desorption equilibrium coefficients of some representative halogenated aliphatic compounds. Through the preliminary sorption test using Azo dye, a setting of quantitative experimental conditions to determine the sorption and desorption characteristics was decided as follows; equilibration time of 180 minutes, centrifuge for 15 minutes at 5000$\times$g, and 500mg/$\ell$ of TOC concentration. The sorption and desorption characteristics of halogenated aliphatic compounds onto activated sludge, sediment and clay could be described very well using the Freundlich isotherm. The preference of the average sorption capacity of the overall compounds showed in the sequence sediment 0.26mg/g, clay 0.23mg/g, and activated sludge 0.11 mg/g. The desorption rate of the sorbed compounds onto activated sludge, sediment and clay was approximately 89.8%, 35.3%, and 66.4%, respectively.

• Journal of Environmental Science International
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• v.5 no.6
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• pp.749-755
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• 1996

In order to grasp a characterization of low boiling point chlorinated organic compounds, this study which were carried out at the 8 stations for precipitation samples in the Pusan area during the period from February to September 1995. As a result, low boiling chlorinated organic compounds were estimated that it was dissolved by a portion of precipitation, and it be able to shift at the surface of the each. Concentration of low boiling point chlorinated organic compounds in precipitation are increased with increase of temperature, and estimated that air pollution compounds of as a rule in atmosphere.

• Korean journal of food and cookery science
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• v.12 no.1
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• pp.115-121
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• 1996

Ixeris dentata Nakai (Compositae) is a perennial herb and the young shoots when prepared properly are edible as a bitter appetizing vegetable in the early spring. The whole plant has been used as a folk medicine in treating diabetes in Korea. As a part of our studies on bitter substances, we have investigated the bitterness of the plant through a taste-guided fractionation method. Bitter substances were extracted by the solvent fractionation and the bitterness was evaluated by 10 trained panelists consisted with graduate students of Dept. of Foods and Nutrition. It has been revealed that the bitter compounds were distributed throughout the extracting fractions and the higher intensity of the bitterness was seen in the n-BuOH fractions. The bitter compounds were subfractionated by the silica gel column chromatography and the bitterness was evaluated by the trained panelists. The subfractions which were indicated as the bitter compounds will be further studied to isolate the compounds. The H$_2$O fractions were grouped according to the molecular weight through the ultrafiltration and the group with 1,000 < m.w. < 30,000 was evaluated as the most intense bitter subfraction.