• Journal of Microbiology and Biotechnology
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• v.26 no.10
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• pp.1790-1799
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• 2016

Matrix assisted laser desorption ionization (MALDI)-time of flight/mass spectrometry (TOF/MS) was applied to investigate alterations in phospholipids in mitophagic cancer cells. Several phospholipids, including phosphatidylcholines (PCs), sphingomyelins (SMs), and phosphatidylinositols (PIs), were successfully analyzed in control and mitophagy-induced H460 cells in the positive and negative ion modes. Principal component analysis was applied to differentiate the two groups. The upregulated and downregulated phospholipid species in the mitophagic cells were also represented in a heatmap. In the volcano plot (fold change > 1.3 and p value < 0.01), individual species of seven PCs, two SMs, and three PIs were selected as differentially regulated phospholipids. In particular, almost all the molecular species of PC, SM, and PI were downregulated in the mitophagic cells. Quantification of these lipids indicated that mitophagy induces altered metabolism of phospholipids. Therefore, phospholipid alterations during the mitophagic process of lung cancer cells were well characterized by MALDI-TOF/MS.

• Journal of Pharmaceutical Investigation
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• v.37 no.3
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• pp.179-186
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• 2007

A simple, sensitive and selective liquid chromatographic/tandem mass spectrometric method (LC-MS/MS) was developed and validated for doxifluridine and 5-fluorouracil (5-FU) quantification in dog heparinized plasma. Sample preparation was based on liquid-liquid extraction using a mixture of isopropanol/ethyl acetate (1/9 v/v) to extract doxifluridine, 5-FU and 5-chlorouracil (5-CU, an internal standard) from plasma. Chromatography was performed on a C-18 analytical column and the retention times were 2.7, 1.5 and 1.7 min for doxifluridine, 5-FU and 5-CU, respectively with shorter analysis time within 5 min than previously reported methods. The ionization was optimized using ESI negative mode and selectivity was achieved by tandem mass spectrometric analysis by multiple reaction monitoring (MRM) using the transformations of m/z 244.8>107.6, 129.0>42.0 and 144.9>42.1 for doxifluridine, 5-FU and 5-CU, respectively. The achieved low limit of quantification was 20.0 ng/mL and the assay exhibited linear range of 20-2000 ng/mL ($R^2>0.99957$ for doxifluridine and $R^2>0.99857$ for 5-FU), using $100{\mu}L$ of plasma. Accuracy and precision of quality control samples for both doxifluridine and 5-FU met KFDA and FDA Guidance criteria of 15% for accuracy with coefficients of variation less than 15%. This method demonstrated adequate sensitivity, specificity, accuracy, precision and stability to support the simultaneous analysis of doxifluridine and 5-FU in dog plasma samples in pharmacokinetic and bioequivalence studies.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1446-1449
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• 1996

Thin films of diamond-like carbon(DLC) have been deposited using a magnetron plasma-enhanced chemical vapor deposition(PECVD) method with an rf(13.56 MHz) plasma of $C_{3}H_{8}$. From the Langmuir probe I-V characteristics, it can be observed that increasing the magnetic field yields an increase of the temperature($T_e$) and density($N_e$) of electron. At a magnetic field of 82 Gauss, the estimated values of $T_e$ and $N_e$ are approximately $1.5\;{\times}\;10^5$ K(13.5 eV) and $1.3\;{\times}\;10^{11}\;cm^{-3}$, respectively. Such a highly dense plasma can be attributed to the enhanced ionization caused by the cyclotron motion of electrons in the presence of a magnetic field. On the other hand, the negative dc self-bias voltage($-V_{sb}$) decreases with an increasing magnetic field, which is irrespective of gas pressure in the range of $1{\sim}7$ mTorr. This result is well explained by a theoretical model considering the variation of $T_e$. Deposition rates of DLC films increases with a magnetic field. This may be due to the increased mean free path of electrons in the magnetron plasma. Structures of DLC films are examined by using various techniques such as FTIR and Raman spectroscopy. Most of hydrocarbon bonds in DLC films prepared consist of $sp^3$ tetrahedral bonds. Increasing the rf power leads to an enhancement of cross-linking of carbon atoms in DLC films. At approximately 140 W, the maximum film density obtained is about 2.4 $g/cm^3$.

• Korean Journal of Pharmacognosy
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• v.49 no.1
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• pp.76-83
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• 2018

A traditional herbal formula, Gyeji-tang has been used to treat the early colds, headache, chills, and fever in Asian countries. In this study, we were performed simultaneous determination of the 14 bioactive marker compounds, gallic acid, spinosin, paeoniflorin, albiflorin, liquiritin apioside, liquiritin, 6'''-feruloylspinosin, liquilitigenin, coumarin, cinnmamic acid, benzoylpaeoniflorin, cinnamaldehyde, glycyrrhizin, and 6-gingerol in Gyeji-tang using an ultra-performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS/MS). Analytical column was used a Waters Acquity UPLC BEH $C_{18}$ analytical column ($2.1{\times}100mm$, $1.7{\mu}m$) and maintained at $45^{\circ}C$ with a flow rate of 0.3 mL/min. The mobile phase consists of 0.1% (v/v) formic acid in water and acetonitrile with gradient elution. The MS analysis was conducted using multiple reaction monitoring in the positive and negative modes by a Waters ACQUITY TQD LC-MS/MS system. The calibration curves of 14 bioactive marker compounds showed linearity with correlation coefficients ${\geq}0.9798$. The limits of detection and quantification values were in the range of 0.11-6.66 ng/mL and 0.34-19.99 ng/mL, respectively. As a result of the analysis using the established LC-MS/MS method, the amounts of tested 14 compounds in the lyophilized Gyeji-tang sample were detected up to $85.7{\mu}g/g$. These results may be useful for quality assessment of a traditional herbal formulas.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.3
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• pp.244-249
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• 2011

A sensitive and rapid high-performance liquid chromatographic-tandem mass spectrometric (HPLC/MS/MS) assay was developed for the determination of soyasaponins in soybean. Among soyasaponins, soyasaponin I was isolated and characterized from methanol extracts of soybean as analytical standards and the development of a new analytical procedure for quantification of its content in various cultivars. The structures of these compound was elucidated by $^1H$, $^{13}C$ NMR experiments and by mass spectrometric analysis. Aqueous ethanol extracts of soybean samples were injected on an Agilent XDB-C18 column ($4.6mm{\times}50mm$, $1.8{\mu}m$) with a mobile phase consisting of 10 mM ammonium acetate-acetonitrile, a flow rate of 0.3 mL/min and a total run time of 8 min. Detection was performed by mass spectrometer bin the multiple reaction monitoring (MRM) mode with negative electrospray ionization (ESI) m/z at 941 ${\rightarrow}$ 615 for soyasaponin I. In the 9 soybean samples, contents of soyasaponin I ranged from 205 to 726 mg/kg, and correlated negatively with seed size.

• Journal of the Korean Chemical Society
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• v.35 no.3
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• pp.196-203
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• 1991

The $pK_a$ values of benzoic acid and meta, para-halogen substituted benzoic acids in MeOH-$H_2O$ mixtures (0∼80% of MeOH) have been determined at 25$^{\circ}$C using a conductometric method on the basis of the Fuoss-Kraus equation, and further verified using modified conductometric method of Gelb. The dependence of $pK_a$ on halogen substituents has been discussed in terms of substituent-constant (${\sigma}$), which is devided into electron-withdrawing inductive contribution (${\sigma}_1$) and electron-donating ${\pi}$-resonance one (${\sigma}_R$). The linear-dependence of ${\sigma}_1$'s on $D^{-1}$ with positive slope and that of ${\sigma}_R$'s on $D^{-1}$ with negative slope have been interpreted on the basis of field effect and through-space interaction of ${\pi}$-lone pair of halogen substituent and ionization center via ${\pi}$-system of benzene ring.

• Journal of Pharmaceutical Investigation
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• v.25 no.4
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• pp.353-363
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• 1995

The purpose of this study was to investigate the intestinal and nasal absorption enhancement of cefotaxime (CTX) by ion-pairing with counterions and to design an effective oral and intranasal drug delivery system for antibiotics. Counterions for absorption promotion were cationic surfactants [cetylpyridinium chloride (CP), cetrimide (CT) and benzalkonium chloride (BA)]. In the presence of counterions, the apparent partition coefficient of cefotaxime was increased depending on the molar concentration of the counterions. Anion interference was observed for ion-pairing of cefotaxime with counterions because of the counterbalance between an anion and counterions. The present study employed the in situ simultaneous nasal and intestinal perfusion technique in rats. The apparent permeabilities $(P_{app})$ of cefotaxime were $1.43{\pm}0.04{\times}10^{-5}\;cm/sec(mean{\pm}S.E)$ in the nasal cavity and 0 in the jejunum, respectively, which indicated that the intrinsic absorptivity of cefotaxime was greater in the nasal cavity than in the jejunum. When ionupairing formers were used, the decreasing order of apparent cefotaxime permeability $(P_{app},\;10^{-5}\;cm/sec)$, corrected for surface area of absorption, was as followings: $BA\;(7.50{\pm}0.36)\;>\;CT\;(4.92{\pm}0.24)\;>\;CP\;(3.01{\pm}0.17)$ in the jejunum and $BA\;(22.31{\pm}1.36)\;>\;CP\;(18.24{\pm}0.81)\;>\;CT \;(16.22{\pm}1.87)$ in the nasal cavity. The increase in permeability of cefotaxime was about 13-fold in the rat nasal cavity and was marked in the rat jejunum for ion-pairing with counterions as compared to those without ion-pairing. The damages of jejunal and nasal mucosal membrane by counterions were observed within approximately 2hrs after removal of ion-pair of cefotaxime with counterions from the nasal cavity and jejunum. These results suggest that CP can be used as an ion-pairing former in the jejunum and CP and CT can be used as ion-pairing formers in the nasal cavity for cefotaxime, as well as for poorly absorbed drugs with a negative charge due to ionization.

• Analytical Science and Technology
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• v.29 no.4
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• pp.155-161
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• 2016

Distribution of various illegal or counterfeit drugs of seven approved erectile dysfunction drugs and their analogues has been increased, causing health problems such as cardiovascular disorder, tachycardia, headache, or vision disturbance. We used liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) to determine the erectile dysfunction drugs and their analogues in various counterfeit drugs. Eleven erectile dysfunction drugs and their analogues were detected, with sildenafil and its analogues being the most counterfeited compounds (73.8 %), followed by tadalafil and its analogues (25.4 %). The limits of detection (LOD) and the limits of quantitation (LOQ) of liquid-type and solid-type negative samples ranged from 0.1 to 3.3 ng/mL or ng/g and from 0.3 to 10.0 ng/mL or ng/g, respectively. The recoveries ranged from 84.3 to 112.3 % and 83.2 to 110.2 %, respectively. The contents of sildenafil and tadalafil in the various counterfeit drugs ranged from 21.0 to 947.5 mg/g and from 0.2 to 170.2 mg/g, respectively.

• Bulletin of the Korean Chemical Society
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• v.2 no.2
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• pp.71-75
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• 1981

Vacuum ultraviolet photolysis of ethyl bromide was studied at 104.8-106.7 nm (11.4-11.6 eV) in the pressure range of 0.2-18.6 torr at $25^{\circ}$ using an argon resonance lamp with and without additives, i.e., NO and He. Since the ionization potential of $CH_3CH_2Br$ is lower than the photon energy, the competitive processes between the photoionization and the photodecomposition were also investigated. The observations indicated that 50% of absorbed light leads to the former process and the rest to the latter one. In the absence of NO the principal reaction products for the latter process were found to be $CH_4, C_2H_2, C_2H_4, C_2H_6, and C_3H_8$. The product quantum yields of these reaction products showed two strikingly different phenomena with an increase in reactant pressure. The major products, $C_2H_4$ and $C_2H_6$, showed positive effects with pressure whereas the effects on minor products were negative in both cases, i.e., He and reactant pressures. Addition of NO completely suppresses the formation of all products except $C_2H_4$ and reduces the $C_2H_4$ quantum yield. These observations are interpreted in view of existence of two different electronically excited states. The initial formation of short-lived Rydberg transition state undergoes HBr molecular elimination and this state can across over by collisional induction to a second excited state which decomposes exclusively by carbon-bromine bond fission. The estimated lifetime of the initial excited state was ${\sim}4{\times}10^{-10}$ sec. The extinction coefficient for $CH_3CH_2Br$ at 104.8-106.7 nm and $25{\circ}$ was determined to be ${varepsilon} = (1/PL)ln(I_0/I_t) = 2061{\pm}160atm^{-1}cm6{-1}$ with 95% confidence level.

• Korean Journal of Pharmacognosy
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• v.50 no.1
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• pp.65-71
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• 2019

One of the oriental medicine prescriptions, Sagunja-tang consists of four herbal medicines (Ginseng Radix, Poria Sclerotium, Atractylodis Rhizoma Alba, and Glycyrrhiziae Radix et Rhizoma) and has been used as a medicine to enhance tonify the function of spleen and stomach in Korea. In this study, we conducted simultaneous analysis of the 9 marker components, liquiritin apioside, liquiritin, ginsenoside Rg1, liquiritigenin, ginsenoside Rb1, glycyrrhizin, atractylenolide III, atractylenolide II, and atractylenolide I in Sagunja-tang using a liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS). Marker compounds were separated on a Waters Acquity UPLC BEH $C_{18}$ analytical column ($2.1{\times}100mm$, 1.7 mm) and the column was maintained at $45^{\circ}C$. The mobile phase consists of 0.1% (v/v) aqueous formic acid and acetonitrile with gradient condition. The LC-MS analysis was performed using a Waters ACQUITY TQD LC-MS/MS system with multiple reaction monitoring (MRM) method in the positive and negative modes. The calibration curves of the nine marker components showed good linearity with coefficient of determination ${\geq}0.9984$ within tested range. The limits of detection and limits of quantification values were 0.27-2.42 ng/mL and 0.81-7.27 ng/mL, respectively. The concentrations of tested 9 analytes in the lyophilized Sagunja-tang sample using the established LC-ESI-MS/MS MRM method were detected up to 16.593 mg/g. These results can be useful as a basic data for the quality control of an oriental medicine prescriptions.