• Journal of the Korean Society of Food Science and Nutrition
• /
• v.41 no.10
• /
• pp.1363-1370
• /
• 2012

In this study, methanol extract and its organic solvent fractions were prepared from Prunus davidiana (Carriere) Franch. fruit. Antioxidative activities, polyphenolic and flavonoid contents, and tyrosinase inhibitory activities were evaluated. Among the fractions, ethyl acetate fraction showed the highest antioxidative activity with $IC_{50}$ values of 5.8 ${\mu}g/mL$ and 88.1 ${\mu}g/mL$ for DPPH radical and nitrite scavenging, respectively, which were comparable to those of ascorbic acid. Further, total flavonoid and polyphenolic contents were highest in the ethyl acetate fraction with $IC_{50}$ values of 244.5 mg/g and 210.2 mg/g, respectively. $IC_{50}$ values for tyrosinase inhibitory activity were 0.310 mg/mL and 0.329 mg/mL for the ethyl acetate and n-butanol fractions, respectively. Based on these results, it is suggested that the ethyl acetate fraction of Prunus davidiana (Carriere) Franch. fruit could be used as a functional material in the food and pharmaceutical industries.

• Applied Chemistry for Engineering
• /
• v.31 no.6
• /
• pp.612-623
• /
• 2020

This study was initiated to quantitatively evaluate the inhibitory effects of five heavy metals (Cd, Cu, Zn, Pb, Ni) on bacterial growth and phosphorus removal in the binary culture of Alcaligenes sp. plus Pseudomonas sp. IC50 values of Alcaligenes sp. plus Pseudomonas sp. for Cd, Cu, Zn, Pb, and Ni were 0.75, 10.93, 7.08, 13.30, and 15.78 mg/L, respectively. For the binary treatments of heavy metals, IC50 was the lowest in the treatment of Cd + Cu, whereas, it was the highest in the Ni + Pb treatment. The EC50 values for Cd, Cu, Zn, Pb, and Ni were 0.54, 11.08, 6.14, 9.33, and 13.81 mg/L, respectively. For the binary treatments of heavy metals, EC50 was the lowest in the Cd + Zn, whereas, the highest in the Zn + Ni. Based on both IC50 and EC50 values for the binary culture of bacteria with the binary mixtures of heavy metals, the most interactive effect was found to be antagonistic, though the only synergistic effect was found in Cu + Ni treatment. Therefore, our results can provide basic data on the toxic effects of heavy metals on the bacterial growth and phosphorus removal in the wastewater treatment process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.9
• /
• pp.535-540
• /
• 2017

The changes in the electrical characteristics of CMOS ICs due to coupling with a narrow-band electromagnetic wave were analyzed in this study. A magnetron (3 kW, 2.45 GHz) was used as the narrow-band electromagnetic source. The DUT was a CMOS logic IC and the gate output was in the ON state. The malfunction of the ICs was confirmed by monitoring the variation of the gate output voltage. It was observed that malfunction (self-reset) and destruction of the ICs occurred as the electric field increased. To confirm the variation of electrical characteristics of the ICs due to the narrow-band electromagnetic wave, the pin-to-pin resistances (Vcc-GND, Vcc-Input1, Input1-GND) and input capacitance of the ICs were measured. The pin-to-pin resistances and input capacitance of the ICs before exposure to the narrow-band electromagnetic waves were $8.57M{\Omega}$ (Vcc-GND), $14.14M{\Omega}$ (Vcc-Input1), $18.24M{\Omega}$ (Input1-GND), and 5 pF (input capacitance). The ICs exposed to narrow-band electromagnetic waves showed mostly similar values, but some error values were observed, such as $2.5{\Omega}$, $50M{\Omega}$, or 71 pF. This is attributed to the breakdown of the pn junction when latch-up in CMOS occurred. In order to confirm surface damage of the ICs, the epoxy molding compound was removed and then studied with an optical microscope. In general, there was severe deterioration in the PCB trace. It is considered that the current density of the trace increased due to the electromagnetic wave, resulting in the deterioration of the trace. The results of this study can be applied as basic data for the analysis of the effect of narrow-band high-power electromagnetic waves on ICs.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.6
• /
• pp.239-245
• /
• 2016

In this study, a 12 V PWM boost converter was designed with the optimal values of the external components of the power stage was well as the compensation stage for smart electronic applications powered by a battery device. The 12 V boost PWM converter consisted of several passive elements, such as a resistor, inductor and capacitor with a diode, power MOS switch and control IC chip for the control PWM signal. The devices of the power stage and compensation stage were designed to maintain stable operation under a range of load conditions as well as achieving the highest power efficiency. The results of this study were first verified by a simulation in SPICE from calculations of the values of major external elements comprising the converter. The design was also implemented on the prototype PCBboard using commercial IC LM3481 from Texas Instruments, which has a nominal output voltage of 12 V. The output voltage, ripple voltage, and load regulation with the line regulation were measured using a digital oscilloscope, DMM tester, and DC power supply. By configuring the converter under the same conditions as in the circuit simulation, the experimental results matched the simulation results.

• Journal of Applied Biological Chemistry
• /
• v.60 no.1
• /
• pp.49-54
• /
• 2017

In the course of screening tyrosinase inhibitory activity, EtOAc-soluble fraction of Coix lachryma-jobi var. mayuen Stapf. (Gramineae) roots showed significant inhibition. Further fractionation of the EtOAc-soluble fraction resulted in six compounds, which were identified as (+)-icariol $A_2$ (1), zhepiresionol (2), 4-hydroxybenzaldehyde (3), trans-${\rho}$-coumaric acid (4), N-(2-hydroxy-4-methoxyphenyl)-2-hydroxyacetamide (5), and coixol (6). The chemical structures of these compounds were identified on the basis of spectroscopic methods (MS, 1D and 2D NMR) and comparison with literature values. Compound 1 was first reported from this plant. Also, this is the first time that the isolation of compound 5 has been reported from nature source. Among the isolated compounds, compounds 4 and 6 showed enzyme inhibitory activity, with $IC_{50}$ values of 6.5 and $62.4{\mu}M$, respectively, in comparison with these of positive control, arbutin.

• Journal of Applied Biological Chemistry
• /
• v.54 no.1
• /
• pp.47-50
• /
• 2011

To develop a new natural whitening agent, we investigated the tyrosinase inhibitory effects of Persicaria tinctoria Flower extracts (PTFE). PTFE showed inhibitory activity on mushroom tyrosinase with the $IC_{50}$ values of $70.8{\pm}2.2{\mu}g/mL$. We purified two active compounds from PTFE by LH-20 column chromatography and prep-high performance liquid chromatography (HPLC) and identified as quercetin-3-O-rhamnoside (Q3R) and myricetin-3-O-rhamnoside (M3R) by $^1H$nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS) analysis. Q3R and M3R showed tyrosinase inhibitory activities with the $IC_{50}$ values of $47.0{\pm}0.1{\mu}g/mL$ and $150.5{\pm}1.6{\mu}g/mL$, respectively. These results suggest that PTFE and its active compounds reduced melanin formation by the inhibition of tyrosinase activity. Thus, P. tinctoria flower extracts may be a candidate for cosmetic use.

• Korean Journal of Food Science and Technology
• /
• v.32 no.3
• /
• pp.699-705
• /
• 2000

The superoxide scavenging activities of thirteen kinds of herbal extracts were examined together with their cytotoxic and immunomodulating effects. The extracts of 6 kinds of herbs such as eucalyptus, mate, peppermint, sage, thyme and yarrow, so called medicinal herbs, showed above 70% of the superoxide scavenging activities. They also showed cytotoxicities against the cancer cell lines of Hepa-1c1c7 and KB-3-1 as well as the normal fibroblast cell line of mouse. The $IC_{50}$ values of above 6 herb extracts on the cancer cell lines were above or similar to the $IC_{50}$ values on the normal cell line, so it was unable to observe the herb extract which showed cytotoxicity only to the cancer cell lines. Considering the results of nitric oxide test that the sage extract was the only one having the immunomodulating effect(37% of positive control), there was no significant relationship between the superoxide scavenging activities of herbs and their immunomodulating effects.

• Geotechnical Engineering
• /
• v.11 no.4
• /
• pp.63-74
• /
• 1995

Much of Taegu and Kyungpook areas are composed of sedimentary rocks. This paper is concerned with the engineering characteristi os of weathered shale soils and mudstone soils. In this study, the engineering characteristics of weathered shale soils and mudstone soils are investigated by performing tests such as compaction, gradation, CBR permeability and crushability according to compaction energy and water content. The experiments were carried out to obtain the relationships of the ratio of surface area(Sw'/Sw) and the indez of crushing(IC) The results are found as follows : (1) Weathered shale soils are larger than weathered mudstone soils in maximun dry den sixty, but weathered shale soils are smaller than weathered mudstone soils in OMC. (2) Minimum permeability is found in OMC's 1~2% wet side, and the more compaction energy is high, the more the change's range of permeability becomes narrow. (3) There is linear correlation between the ratio of surface area and the indez of crushing. IC : 14.286sw'/Sw -8.429(r=0.9937) (4) Soaked CBR value becomes maximum in OMC's dry side, and it decreases as the water content increases. Whereas the more compaction energy is high the more unsoaked and soaked CBR values are high in OMC's dry side, unsoaked and soaked CBR values are opposed to that in OMC's wet side.

• Journal of Nutrition and Health
• /
• v.30 no.1
• /
• pp.19-24
• /
• 1997

This study was carried out to investigate the effects of enzyme activities on male Sprague-Dawley rats intoxicated by CCI4 on IS(Godulbaegi) diets for 4 weeks. We divides into 5 diet groups which were normal diet(N), normal diet intoxicated by CCI4(NC) and 3 IS diets ; leaves diet(ILC), roots diet(IRC) and mixed diet of leaves and roots which were also injected by CCI4 3 times for 4 weeks. The activity of glutamic pyruvic transaminase(GPT) in serum in NC was higher than in N as we expected. The GPT activites and the values of malondial-dehyde(MDA) of IS groups were all lower than in NC, IC as lowest. The activity of superoxide dismutase(SOD) in NC was higher than in N and IS groups had values less than the values of N. Catalase showed similarity in results as above. The values of glutathione S-transferase(GST) and cytochrome P-450 in NC were lower than in N. IS groups had higher values than in NC. Godulbaegi might be important not only as one of the traditional Korean foods but also as therapeutic agent for hepatotoxicity and for shortening the recovery time in liver disease.

• Biomolecules & Therapeutics
• /
• v.18 no.2
• /
• pp.205-210
• /
• 2010

Several studies have shown that plant-derived polyphenols reduce cardiovascular accidents in high-risk patients and the inhibition of platelet function may be responsible for part of this benefit. Lindera obtusiloba is widely used in traditional herbal medicine for the treatment of cardiovascular and inflammatory diseases. Therefore, the antiplatelet and antithrombotic activities of Lindera obtusiloba Extracts (LOE) on in vitro platelet aggregation, radical scavenging activity and in vivo murine pulmonary thrombosis were examined. LOE was able to directly scavenge the stable DPPH radical in a concentration-dependent manner and its $IC_{50}$ value was 3.9 ${\pm}$ 0.1 ${\mu}g$/ml. LOE significantly inhibited collagen- and ADP-induced platelet aggregation in a concentration-dependent manner and its $IC_{50}$ value is 0.9 ${\pm}$ 0.1 mg/ml and 0.4 ${\pm}$ 0.1 mg/ml respectively. The inhibitory effect of LOE was comparable to aspirin ($IC_{50}$ values were 1.0 ${\pm}$ 0.5 and 1.0 ${\pm}$ 0.7 mg/ml, respectively). Furthermore, oral administration of LOE suppressed the death of mice with pulmonary thrombosis induced by intravenous injection of collagen plus epinephrine. Taken together, our results suggest LOE may be a promising candidate for antithrombotic agent, and the antithrombotic effect of LOE may be due to, at least in part, antiplatelet activity.