• Biomolecules & Therapeutics
• /
• v.23 no.3
• /
• pp.283-289
• /
• 2015

The half-dried leaves of Stewartia. pseudocamellia were extracted with hot water (SPE) and partitioned with n-hexane (SPEH), dichloromethane (SPED), and ethyl acetate (SPEE) successively. SPE and SPEE showed significant inhibitory effects against melanogenesis and tyrosinase activities. By bioassay-guided isolation, ten phenolic compounds were isolated by column chromatography from SPEE. The whitening effect of the isolated compounds from SPEE were tested for the inhibitory activities against melanogenesis using B16 melanoma cells, in vitro inhibition of tyrosinase, and L-3,4-dihydorxy-indole-2-carboxylic acid (L-DOPA) auto-oxidation assay. A cytotoxic activity assay was done to examine the cellular toxicity in Raw 264.7 macrophage cells. Of the compounds isolated, gallic acid and quercetin revealed significant inhibitory activities against melanogenesis compared to arbutin. In particular, quercetin exhibited similar inhibitory activities against tyrosinase and L-DOPA oxidation without cytotoxicity. These results suggested that SPE could be used as a potential source of natural skin-whitening material in cosmetics as well as in food products.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.64 no.4
• /
• pp.236-240
• /
• 2015

Natural ester has a higher biodegradability, flash and fire points, and a greater permittivity compared to conventional mineral oils. However, natural ester also has a higher pour point, viscosity, and water content. These characteristics hamper circulation and the electrical properties of oil-filled transformer. Thus, this paper applied electromagnetic-thermal-flow coupled analysis method to predict temperature distribution inside 154kV single phase power transformer using natural ester. It modeled in the actual appearance for the tank and winding of the power transformer to improve the accuracy of analysis and applied heat flow analysis that considered hydromechanics and heat transfer at the same time. It calculated the power loss, the main cause of temperature rise, from winding and core with electromagnetic analysis then used for the heat source for the heat flow analysis. It then compared the reasonability of result of measurement analysis based on the result acquired from temperature rise test using FBG sensor on the power transformer.

• Natural Product Sciences
• /
• v.15 no.4
• /
• pp.234-240
• /
• 2009

Phytochemical investigation of the MeOH extract of the aerial parts of Bistorta manshuriensis resulted in the isolation of two cerebrosides, two lactams, six phenolic compounds and seven flavonoids. Their chemical structures were characterized by spectroscopic methods to be pinelloside (1), soyacerebroside I (2), pterolactam (3), 5-hydroxypyrrolidine-2-one (4), vanillic acid (5), caffeic acid methyl ester (6), protocatechuic acid (7), caffeic acid (8), 3,5-di-O-caffeoyl quinic acid methyl ester (9), chlorogenic acid methyl ester (10), avicularin (11), afzelin (12), quercetin (13), isoorientin (14), quercetin 3-O-${\beta}$-D-glucoside (15), quercitrin (16), and luteolin (17). The isolated compounds (1 - 4, 7, 12, 14) were isolated for the first time from this plant source and the compounds 1 - 4, 9 and 10 were first reported from the genus Bistorta. Compound 17 exhibited moderate cytotoxicity and compound 6 exhibited weak cytotoxicity against four human cancer cell lines in vitro using an SRB bioassay.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.6
• /
• pp.802-810
• /
• 2013

This work aims at investigating the production of yellow, orange, and red natural colorants in a submerged culture of Penicillium purpurogenum DPUA 1275. For this purpose, different experimental conditions evaluating the effect of incubation time, type and size of inoculum, and different carbon and nitrogen sources were performed. Furthermore, the growth kinetics were obtained in the conditions of $10^8$ spores/ml and 5 mycelia agar discs during 360 h. These experiments showed that 5 mycelia agar discs and 336 h promoted the highest yellow (3.08 $UA_{400nm}$), orange (1.44 $UA_{470nm}$), and red (2.27 $UA_{490nm}$) colorants production. Moreover, sucrose and yeast extract were the most suitable carbon and nitrogen sources for natural colorants production. Thus, the present study shows a new source of natural colorants, which can be used as an alternative to others available in the market after toxicological studies.

• Natural Product Sciences
• /
• v.15 no.1
• /
• pp.44-49
• /
• 2009

Seven monoterpenes, three sesquiterpenes, three phenolics and one flavonoid were isolated from the MeOH extract of Amomum xanthioides. Their structures were determined by spectroscopic methods to be caryophyllene oxide (1), bornyl acetate (2), nerolidol (3), spathulenol (4), (-)-borneol (5), (+)-5-endohydroxycamphor (6), vanillic acid (7), protocatechuic acid methyl ester (8), betulabuside A (9), (1R,4S,6R)-6-hydroxyfenchan-2-one-6-O-$\beta$-D-glucopyranoside (10), (1S,4R,6S)-6-hydroxybornan-2-one-6-O-$\beta$-D-glucopyranoside (11), (1R,2S,4S,5R)-angelicoidenol 2-O-$\beta$-D-glucopyranoside (12), 1-O-vanilloyl-$\beta$-D-glucopyranoside (13), and quercetin-3-rhamnopyranoside (14). Compounds 6-14 were isolated for the first time from this plant source. Compounds 3 and 4 exhibited moderate cytotoxicity against four human cancer cell lines in vitro using a SRB bioassay.

• Journal of Life Science
• /
• v.11 no.2
• /
• pp.63-69
• /
• 2001

bacterium having high abilities to solubilize in-organic phosphate was isolated from cultivated soils. The strain was identified as Aeromonas hydrophila DA33, based on the physiological and biochemical properties. The optimum temperature and initial pH to solubilize insoluble phosphate in sucrose minimal medium were 3$0^{\circ}C$ and pH 5.0, respectively. In these conditions, phosphate-solubilizing activities of the strain against two types of insoluble phosphate were quantitatively determined. When glucose was used for carborn source, the strain had a marked mineral phospahte solubilizing activity. Inorganic phospahte solubilization was directly related to the pH drop by the strain. Analysis of the culture medium confirmed the production of gluconic acid as the main organic acid released by Aeromonas hydrophila DA33.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.6 no.2
• /
• pp.107-111
• /
• 2001

The addition of a limited concentration of yeast extract to a minimal salt medium (MSM) enhanced cell growth and increased the production of curdlan whereas nitrogen-limitation was found to be essential for the higher production of curdlan by Agrobacterium sp. ATCC 31749. As the amount of the inoculum increased, the cell growth as well as the production of curdlan also increased in the MSM without a nitrogen source. The cell growth and production of curdlan increased as the initial pH of the medium decreased as low as 5.0. The conversion rate and concentration of curdlan from 2% (w/v) glucose in the MSM with concentrated cells under nitrogen deletion was 67% and 13.4 g/L, respectively. The highest conversion rate of curdlan under the conditions optimized in this study was 71% when the glucose concentrations was 1% (w/v).

• Advances in Energy Research
• /
• v.5 no.3
• /
• pp.255-275
• /
• 2017

The advantages of using natural circulation (NC) as a cooling system, has prompted the worldwide development to investigate this phenomenon more than before. The interesting application of the NC in low power experimental facilities and research reactors, highlights the obligation of study in these laminar flows. The inherent oscillations of NC between hot source and cold sink in low Grashof numbers necessitates stability analysis of cooling flow with experimental or numerical schemes. For this type of analysis, numerical methods could be implemented to desired mass, momentum and energy equations as an efficient instrument for predicting the behavior of the flow field. In this work, using the explicit, implicit and Crank-Nicolson methods, the fluid flow parameters in a natural circulation experimental test loop are obtained and the sensitivity of solving approaches are discussed. In this way, at first, the steady state and transient results from explicit are obtained and compared with experimental data. The implicit and crank-Nicolson scheme is investigated in next steps and in subsequent this research is focused on the numerical aspects of instability prediction for these schemes. In the following, the assessment of the flow behavior with coarse and fine mesh sizes and time-steps has been reported and the numerical schemes convergence are compared. For more detail research, the natural circulation of fluid was modeled by ANSYS-CFX software and results for the experimental loop are shown. Finally, the stability map for rectangular closed loop was obtained with employing the Nyquist criterion.

• Journal of the Korean Dietetic Association
• /
• v.19 no.4
• /
• pp.389-399
• /
• 2013

This study compared the nutritional composition and antioxidative activity of different parts of Taraxacum coreanum (aerial parts and roots) according to different drying methods (natural drying and freeze-drying). There were no significant differences in vitamin C content in roots depending on the drying methods. However, vitamin A (P<0.01), E (P<0.001) and C (P<0.001) content of aerial parts, and vitamin A (P<0.001) and E (P<0.05) content of roots were significantly higher after freeze-drying compared to natural drying. For organic acids, the oxalic acid content of the aerial parts and roots were the highest. The total polyphenol and total flavonoid content in extracts from the aerial parts (P<0.01) and roots (P<0.05) were significantly higher after freeze-drying compared to natural drying. In addition, the total polyphenol and flavonoid content, DPPH radical scavenging activity, and antioxidative index from the natural drying and freeze-drying of Taraxacum coreanum extracts were significantly higher in the aerial parts compared to the roots (P<0.05). These results suggest that the nutritional composition and antioxidative activity of Taraxacum coreanum are higher in the aerial parts compared to the roots, and higher after freeze-drying compared to natural drying. Therefore, the aerial parts of Taraxacum coreanum could be suggested as an antioxidative functional food source.

• Journal of Environmental Health Sciences
• /
• v.27 no.2
• /
• pp.60-66
• /
• 2001

Natural organic matters(NOMs) are found everywhere such as soil, surface and ground waters and consist of both humic and nonhumic components, and their heterogeneith makes each source unique. This study was carried to evaluate the removal characteristics of NOMs by mixing coagulants and the variation of apparent molecular weight distribution(AMWD) in coagulation process. Ratio of optimum coagulants dosage for removal of DOC and turbidity by mixing coagulants was 1.83 mM F $e^{3+}$/mM $Al^{3+}$. DOC removal increased at lower pH. The pH6 control focused on the removal of organic matters could reduce the amount of coagulant consumption by 2 to 3 times based on the pH8.5 of natural water. The dissolved organic matters in the natural water from the mid-stream of Han River were composed of the low molecular weight(LMW,<1 K) of 59.7%, and the medium and high molecular weight(M.HMW, 1~30 K) of 40.3%, respectively. At pH6, the DOC removal efficiencies of LMW(<1 K) and M.HMW(1~30 K) in coagulation process were 27~35%, 62~72%, respectively. The fraction smaller than 1 K was not eliminated to a noticeable degree, while the fraction of 1~30 K was relatively well removed. In conclustion, mixing coagulants were fairly effective in the removal of natural organic matter.r.