• Natural Product Sciences
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• v.8 no.4
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• pp.133-136
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• 2002

GC-MS data on the volatile oil (CS-oil) of Chrysanthemum sibiricum herbs led to the identification of 2-methoxythioanisol, (+)-camphor, geraniol, citral, thymol, eugenol, ${\beta}-caryophyllene$ oxide, ${\beta}-caryophyllene$, ${\beta}-eudesmol$, juniper camphor together with an unknown substance using the mass spectral library and literature data. CS-oil exhibited significant cytotoxicities on HL-60 $(IC_{50}\;12.5\;{\mu}g/ml)$ cell and mild on HepG-2 cell $(IC_{50}\;102.4\;{\mu}g/ml)$, though the antioxidant ability was found not to be potent $(IC_{50}\;97.2\;{\mu}g/ml)$. However, the component eugenol showed potent antioxidant ability but mild cytotoxicity. Methyleugenol with no phenolic OH showed less potent cytotoxic and antioxidative properties than eugenol suggesting that phenolic OH plays an important role for the cytotoxic and antioxidant abilities. The oil-pretreatment prevented lipid peroxidation induced by bromobenzene in the rat. Therefore, it was demonstrated that CS-oil could be a cytotoxic agent with antioxidant properties.

• Journal of Applied Biological Chemistry
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• v.60 no.1
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• pp.49-54
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• 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
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• v.54 no.1
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• pp.47-50
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• 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
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• v.33 no.3
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• pp.345-352
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• 2001

The volatile compounds of traditional Kyungsando squid sikhe were identified by GC-MS. The amount of ${\alpha}-zingibirene$ among identified volatile compounds was 19.73 mg/kg. The major volatile compounds of sikhe were (Z)-Di-2-propenyl disulfide, ${\alpha}-curcumene$, methyl allyl disulfide, (E, E)-a-farnesene, pentanol, z-citral, 3-ethyl-1,2-dithi-5-ene-${\beta}-elemene$, ${\beta}-elemene$, acetic acid, and ${\beta}-phellandrene$. The volatile compounds of sikhe were compose of 49 including hydrocarbone groups, 15 aldehydes groups, 33 alcohol groups kinds, 11 ketone and ester groups. The fraction obtained from sikhe were tested for electron donating ability, angiotensin converting enzyme inhibitory activity and xanthine oxidase inhibitory activity. There were no electron donating abilities$(SC_{50})$ in hexane and water soluble fractions. On the other hand, the angiotensin converting enzyme abilities of ethylacetate and butanol soluble fractions were $310.64\;{\mu}g/mL$ and $1096.49\;{\mu}g/mL$, respectively. Angiotensin converting enzyme inhibitory activities$(IC_{50})$ of ethylacetate butanol soluble fractions were 1.623 mg/mL and 1.303 mg/mL, respectively. Xanthine oxidase inhibitory activities$(IC_{50})$ of ethylacetate fraction and butanol soluble fractions were 3.591 mg/mL and 2.083 mg/mL, respectively.

• The Journal of the Petrological Society of Korea
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• v.21 no.4
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• pp.415-429
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• 2012

The monitoring methods for volcanic gases are divided into remote sensing and direct gas sampling approaches. In the remote sensing approach, COSPEC and Li-COR are used to measure $SO_2$ and $CO_2$, respectively, with FT-IR for detection of a range of volcanic gases. However, the remote sensing approach is not applicable to Mt. Baegdu, where the atmospheric contents of volcanic gases are very low as a result of the strong interaction of volcanic gases with the nearby surface water and groundwater. On the other hand, the direct gas sampling approach involves the collection of volcanic gases from volcanic vents or fumaroles and the subsequent laboratory analysis, thus making it possible to measure even very low levels of volcanic gases. The direct sampling approach can be subdivided into the evacuated bottle method and the flow-through bottle method. In applying both methods, sampling bottles typically contain reaction media to trap specific volcanic gases. For example, NaOH solution(Giggenbach bottle), $NH_4OH$ solution, and acid condensates have been experimented for volcanic gas sampling. Once taken from vents and fumaroles, the samples of volcanic gases are pretreated and subsequently analyzed for volcanic gases using GC, IC, HPLC, titrimetry, TOC-IC, or ICP-MS. Recently, there has been the increasing number of evidences on the potential volcanic activity of Mt. Baegdu. However, little technical development has been made for the sampling and analysis of volcanic gases in Korea. In the present work, we reviewed various volcanic gas monitoring methods, and provided the detailed information on the monitoring methods applied to Mt. Baegdu.

• Korean Journal of Plant Resources
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• v.37 no.2
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• pp.110-119
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• 2024

This study was conducted to provide information on the possibility of using Rhododendron micranthum as resource plant. Through polyphenol profiling of R. micranthum shoot extract, useful components were selected and the content of useful components and antioxidant activity by extraction solvent were compared. As a result, 37 polyphenol compounds were identified in R. micranthum shoot extract through LC-ESI-MS analysis. Contents by extraction solvent were compared of chlorogenic acid, astragalin, myricetin, and afzelin. Chlorogenic acid was highest at 6.57±0.12 mg/g in the ethanol extract, astragalin was 2.29±0.02 mg/g in the ethanol extract, myricetin was 4.77±0.06 and 4.52±0.27 mg/g in the methanol, ethanol extracts, and afzelin was highest at 0.10±0.01 mg/g in the methanol extract. Total polyphenol content of the R. micranthum shoot extract according to the extraction solvent was highest in the ethanol extract at 80.01±2.36 mg/g, and total flavonoid content was also highest in the ethanol extract at 78.08±3.44 mg/g. The IC₅₀ value of DPPH radical scavenging activity according to the extraction solvent of R. micranthum shoot was lowest in methanol extract at 943.57±10.68 mg/L, and the IC₅₀ value of ABTS radical scavenging activity was also lowest in methanol extract at 641.60±7.58 mg/L.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.12
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• pp.53-60
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• 2005

This work proposes a 10b 100 MS/s $1.4\;mm^2$ CMOS ADC for low-power multimedia applications. The proposed two-step pipeline ADC minimizes chip area and power dissipation at the target resolution and sampling rate. The wide-band SHA employs a gate-bootstrapping circuit to handle both single-ended and differential inputs with 1.2 Vp-p at 10b accuracy while the second-stage flash ADC employs open-loop offset sampling techniques to achieve 6b resolution. A 3-D fully symmetrical layout reduces the capacitor and device mismatch of the first-stage MDAC. The low-noise references are integrated on chip with optional off-chip voltage references. The prototype 10b ADC implemented in a 0.18 um CMOS shows the maximum measured DNL and INL of 0.59 LSB and 0.77 LSB, respectively. The ADC demonstrates the SNDR of 54 dB, the SFDR of 62 dB, and the power dissipation of 56 mW at 100 MS/s.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.10
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• pp.1310-1316
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• 2009

In this study, we investigated the change of antioxidant activity and flavonoid contents by fermentation of Citrus grandis Osbeck peel (CGP) using the Saccharomyces cerevisiae (KCCM35053), comparing to unfermented CGP. Total flavonoid content in the fermented Citrus grandis Osbeck peel (FCGP) was 3,768 g/100 g sample and higher than that of CGP. The antioxidant activities of FCGP was determined by DPPH, hydroxyl, alkyl radicals, and hydrogen peroxide scavenging assays. FCGP showed higher activities than CGP in all scavenging assays. The $IC_{50}$ values of FCGP were 261.3 ${\mu}g$/mL for DPPH; 1,474 ${\mu}g$/mL for hydroxyl; 90.9 ${\mu}g$/mL for alkyl and 1,195 ${\mu}g$/mL for $H_2O_2$ in respective scavenging assays. Flavonoid compositions of both samples were determined by liquid chromatography/mass spectrometry (LC/MS). In the spectrum FCGP was similar to CGP in the contents of neohesperidin, naringin and an unknown No. 7 compound, but some unknown compounds (No. 1, 2, 4, 5, 6) were higher than CGP in each flavonoid contents. Therefore, the fermentation of CGP could increase the contents of unknown compound and improved antioxidant activities.

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.470-476
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• 2015

In this study, three dicaffeoylquinic acids (DCQAs) isolated from Gnaphalium affine D. DON. extracts were structurally identified and evaluated for their antioxidant activities, cellular protective effects, and tyrosinase inhibitory activities. The ethyl acetate fraction of G. affine was chromatographed, which yielded 3 DCQA derivatives of 1-3 : 3,5-dicaffoylquinic acid (3,5-DCQA, 1), 4,5-dicaffeoylquinic acid (4,5-DCQA, 2), 1,5-dicaffoylquinic acid (1,5-DCQA, 3). The structure of each compounds was determined using $^1H$ NMR and MS analyses. Compounds of 1-3 showed strong free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activities ($FSC_{50}=3.70$, 5.80, and $5.50{\mu}M$, respectively) compared to those of a commonly used lipophilic antioxidant, (+)-${\alpha}$-tocopherol ($21.90{\mu}M$). Cellular protective effects of 1-3 compounds on the $^1O_2$ sensitized photohemolysis of human erythrocytes were similar to (+)-${\alpha}$-tocopherol. 1-3 compounds also exhibited higher tyrosinase inhibitory effects ($IC_{50}=0.15$, 0.16, and 0.13 mM) compared to arbutin (0.33 mM), known as a skin-whitening agent. These results indicate that three DCQA derivatives may be applied as an antioxidant and a skin whitening agent in food or cosmetic industries.

• The Korean Journal of Physiology
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• v.28 no.2
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• pp.215-224
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• 1994

The presence of a calcium current $(i_{Ca^{2+}})$ passed via a specific channel was examined in the unfertilized hamster egg using the whole-cell voltage clamp technique. Pure inward current was isolated using a $Ca^{2+}-rich$ pipette solution containing 10 mM TEA. This current was independent of external $Na^+$ and was highly sensitive to the $Ca^{2+}$ concentration in the bathing solution, indicating that the inward current is carried by $Ca^{2+}$. The maximal amplitude was $-4.12{\pm}0.58nA\;(n=12)$ with 10mM $Ca^{2+}$ at -3OmV from a holding potential of -8OmV. This current reached its maximum within 20ms beyond -3OmV and decayed rapidly with an inactivation time constant $({\tau})$ of 15ms. Activation and inactivation of this $i_{Ca^{2+}}$ was steeply dependent on the membrane potential. The $i_{Ca^{2+}}$ began to activate at the lower voltage of -55 mV and reached its peak at -35 mV, being completely inactivated at potentials more positive than -40 mV. These result suggest that $i_{Ca^{2+}}$ in hamster eggs passes through channels with electrical properties similar to low voltage-activated T-type channels. Other results from the present study support this suggestion; First, the inhibitory effect of $Ni^{2+}\;(IC_{50}=13.7\;{\mu}M)$ was more potent than $Cd^{2+}\;(IC_{50}=123\;{\mu}M)$. Second, $Ba^{2+}$ conductance was equal to or below that of $Ca^{2+}$. Third, $i_{Ca^{2+}}$ in hamster eggs was relatively insensitive to nifedipine $(IC_{50}=96.6\;{\mu}M)$, known to be a specific t-type blocker. The physiological role of $i_{Ca^{2+}}$ in the unfertilized hamster eggs remains unclear. Analysis from steady-state inactivation activation curves reveals that only a small amount of this current will pass in the voltage range $(-70{\sim}-30\;mV)$ which partially overlaps with the resting membrane potential. This current has the property that it can be easily activated by a weak depolarization, thus it may trigger a certain kind of a intracellular event following fertilization which may cause oscillations in the membrane potential.