• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3727-3734
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• 2012

An analytical method has been developed for the rapid determination of perfluorinated compounds (PFCs) in human serum samples. The extraction and purification of PFCs from human serum were performed by the modified method of previous report. Ten PFCs were rapidly separated within 3.3 min by C18-monolithic column liquid chromatography (LC) and detected by electrospray ionization (ESI) tandem mass spectrometry (MS/MS) in negative ion mode. The runtime of PFCs on monolithic column LC was up to 4-fold faster than that on conventional column LC. The effect of triethylamine (TEA) to the mobile phase has investigated on the overall MS detection sensitivity of PFCs in ESI ionization. Quantification was performed by LC-MS/MS in multiple-ion reaction monitoring (MRM) mode, using $^{13}C$-labeled internal standards. Method validation was performed to determine recovery, linearity, precision, and limits of quantification, followed by, the analysis of a standard reference material (SRM 1957 from NIST). The overall recoveries ranged between 81.5 and 106.3% with RSDs of 3.4 to 16.2% for the entire procedure. The calibration range extended from 0.33 to 50 $ng\;mL^{-1}$, with a correlation coefficient ($R^2$) greater than 0.995 and the limits of quantification with 0.08 to 0.46 $ng\;mL^{-1}$. This approach can be used for rapid and sensitive quantitative analysis of 10 PFCs in human serum with high performance and accuracy.

• International Journal of Oral Biology
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• 제34권1호
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• pp.29-36
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• 2009

Cyclosporin A (CsA) has been used clinically as an immunosuppressive drug to prevent organ transplant rejection and in basic research as a mitochondrial permeability blocker. It has been reported that CsA has a protective role in severed neurons and a neurotrophic effect in neuronal cells. However, the molecular mechanisms underlying the stimulation of neuronal cell proliferation by CsA have not yet been elucidated. In our current study, we investigated CsA responsive proteins in PC12 cells using a systematic proteomic approach. The viability of these cells following CsA treatment increased in a dose- and time-dependent manner. Proteins in the CsA-treated PC12 cells were profiled by two-dimensional gel electrophoresis (2-DE) and identified by matrix-assisted laser desorption ionization time-of flight (MALDI-TOF) and electrospray ionization quadupole time-of-flight mass spectrometries (EIQ-TOFMS). This differential expression analysis showed significant changes for 10 proteins (6 up-regulated and 4 down-regulated) upon CsA treatment that were related to cell proliferation, metabolism and the stress response. These proteomics data further our understanding of the proliferation mechanisms of PC12 cells exposed to CsA and demonstrate that our methodology has potential to further elucidate the mechanisms and pathways involved.

• Journal of Microbiology
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• 제45권6호
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• pp.499-504
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• 2007

A new antagonistic strain of actinomycete, designated AP19-2, was isolated from the feces of giant pandas inhabiting the Foping National Nature Reserve in China. Cultural characteristic studies strongly suggested that this strain is a member of the genus Streptomyces. The nucleotide sequence of the 16S rRNA gene of strain AP19-2 evidenced profound similarity (97-99 %) with other Streptomyces strains. Two pure active molecules were isolated from a fermentation broth of Streptomyces sp. strain AP19-2 via extraction, concentration, silica gel G column chromatography, and HPLC. The chemical structures of the two related compounds (referred to as chromomycin $A_2$ and chromomycin $A_3$) were established on the basis of their Infrared spectra (IR), High Resolution Electrospray Ionization Mass Spectrometry (HR-ESI-MS), and Nuclear Magnetic Resonance (NMR) data, and by comparison with published data.

• Nutrition Research and Practice
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• 제2권1호
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• pp.46-49
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• 2008

Anthocyanin pigments from varieties of black, red and wild rice were identified and quantified to evaluate their potential as nutritional function, natural colorants or functional food ingredients. Anthocyanin extraction was conducted with acidified methanol with 0.1M HCl (85:15, v/v) and identification of anthocyanin, aglycone and sugar moieties was conducted by comparison with purified standards by HPLC, Ultraviolet-Visible absorption spectrophotometer and paper chromatography. Black and wild rice showed three different types of pigments by HPLC whereas red rice variety did not show any anthocyanins. Out of three pigments detected, one (peak 2) was characterized as cyanidin-3-glucoside (C3G) by comparison of spectroscopic and chromatographic properties with an authentic standard, and another (peak 3) was tentatively identified as cyanidin-fructoside on the basis of spectroscopic properties with ${\lambda}_{max}$ of aglycone in 1% HCl methanol at 537 nm, electrospray ionization mass spectra with major ions at 449 and 287 m/z and chromatographic properties. But another pigment (peak 1) has not been characterized. The most abundant anthocyanin in black and wild rice was C3G.

• 생약학회지
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• 제44권4호
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• pp.350-361
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• 2013

Asarum sieboldii has been used for treatment of fever, pain, common cold, and chronic sinusitis in Korea. In this study, we performed quantification analysis of seven major constituents including aristolochic acid I, aristolochic acid II, ${\alpha}$-asarone, ${\beta}$-asarone, elemicin, methyl eugenol, and safrole in the 70% ethanol extract of Asarum sieboldii and its solvent fractions, n-hexane, ethylacetate, n-butanol, and water ones using a ultra-performance liquid chromatography-electrospray ionization-mass spectrometer(UPLC-ESI-MS) and gas chromatography-mass spectrometer(GC-MS). Regression equations of seven components were acquired with $r^2$ values >0.99. The values of limit of detection(LOD) and quantification(LOQ) were 0.1-3.9 ng/mL and 0.3-11.7 mg/mL, respectively. The amount of the seven compounds in Asarum sieboldii were not detected -143.66 mg/g. The established LC-MS/MS and GC-MS methods will be helpful to improve quality control of Asarum sieboldii.

• Mass Spectrometry Letters
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• 제6권1호
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• pp.7-12
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• 2015

In the present study, we proposed a simple ESI-MS model for determining $Zn^{2+}$ binding (or dissociation) constants for zinc finger peptides (ZFPs) with a unique ${\beta}{\beta}{\alpha}$ fold consensus. The ionization efficiency (response) factors for this model, i.e., ${\alpha}$ and ${\beta}$, could be determined for ZiCo ZFP with a known $Zn^{2+}$ binding constant. We could determine the binding constants for other ZFPs assuming those with a ${\beta}{\beta}{\alpha}$ consensus conformation have the same ${\alpha}/{\beta}$ response ratio. In general, the ZPF dissociation constants exhibited $K_d$ values of $10^{-7}{\sim}10^{-9}M$, while $K_d$ values for a negative control non-specific $Zn^{2+}$ peptides were high, e.g., $5.5{\times}10^{-6}M$ and $4.3{\times}10^{-4}M$ for BBA1 and melittin, respectively.

• Natural Product Sciences
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• 제24권3호
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• pp.206-212
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• 2018

Xanthii Fructus has been traditionally used for the treatment of rhinitis, rheumatoid arthritis, and eczema. In this study, a high-performance liquid chromatography-photodiode array (HPLC-PDA) method was developed and then used for the simultaneous analysis of eight phenylpropanoids in Xanthii Fructus. The analytical column used for this separation was a $SunFire^{TM}$ $C_{18}$ column, maintained at $40^{\circ}C$. The mobile phase used was 1.0% acetic acid in distilled water and 1.0% acetic acid in acetonitrile with gradient elution. For identify of each component, the mass spectrometer (MS) was used a Waters triple quadrupole mass spectrometer requipped with electrospray ionization (ESI) source. The HPLC-PDA method showed good linearity: correlation coefficients were ${\geq}0.9996$. The limits of detection and quantification of the eight compounds were 0.02 - 0.04 and $0.06-0.14{\mu}g/mL$, respectively. The extraction recoveries ranged from 97.51 to 108.67%. The relative standard deviation values of intra- and inter-day precision were 0.06 - 1.55 and 0.09 - 1.68%, respectively. The validated HPLC-PDA method was applied to simultaneously analyse the amounts of eight phenlypropanoids in Xanthii Fructus.

• Mass Spectrometry Letters
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• 제7권1호
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• pp.16-20
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• 2016

Characterization of intact protein structures in the gas phase using electrospray ionization combined with ion mobility mass spectrometry has become an important tool of research. However, the biophysical properties that govern the structures of protein ions in the gas phase remain to be understood. Here, we investigated the impact of host-guest complexation of ubiquitin (Ubq) with macrocyclic host molecules, cucurbit[n]urils (CB[n]s, n = 6, 7), on its structure in the gas phase. We found that CB[n] complexation induces the formation of compact Ubq ions. Both CB[6] and CB[7] exhibited similar effects despite differences in their binding properties in solution. In addition, CB[n] attachment prevented Ubq from unfolding by collisional activation. Based on the experimental results, we suggest that CB[n]s prevent unfolding of Ubq during transfer to the gas phase to promote the formation of compact protein ions. Furthermore, interaction with positively charged residues per se is suggested to be the most important factor for the host-guest complexation effect.

• Mass Spectrometry Letters
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• 제8권4호
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• pp.90-97
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• 2017

Androgenic anabolic steroids (AASs) are synthetic derivatives of testosterone with a common structure containing cyclopentanoperhydrophenanthrene nucleus. Their use enhances the muscle building capacity and is beneficial during performance. The AASs are one of the most abused group of substances in horse doping. Liquid chromatography tandem mass spectrometry ($LC/MS^n$) has been successfully applied to the detection of anabolic steroids in biological samples. However, the saturated hydroxysteroids viz: nandrolone, $5{\alpha}-estrane-3{\beta}$, $17{\alpha}-diol$ exhibit lower detection responses in electrospray ionisation (ESI) because of their poor ionisation efficiency. To overcome this limitation pre-column chemical derivatization has been introduced to enhance their detection responses in $LC-ESI-MS^n$ analysis. The aim of present study was to develop a sensitive method for identification and confirmation of nandrolone and its metabolite in horse urine incorporating pre-column derivatization using picolinic acid. The method consists of extraction of targeted steroid conjugates by solid phase extraction (SPE). The eluted steroid conjugates were hydrolysed by methanolysis and free steroids were recovered with liquid-liquid extraction. The resulting steroids were derivatized to form picolinoyl esters and identification was done using LC-ESI-MS/MS in positive ionization mode. The picolinated steroid adduct enhanced the detection levels in comparison to underivatized steroids.

• Toxicological Research
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• 제29권2호
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• pp.107-114
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• 2013

Mass spectrometry (MS) is a very powerful instrument that can be used to analyze a wide range of materials such as proteins, peptides, DNA, drugs, and polymers. The process typically involves either chemical or electron (impact) ionization of the analyte. The resulting charged species or fragment is subsequently identified by the detector. Usually, single mass uses source-induced dissociation (SID), whereas mass/mass uses collision-induced dissociation (CID) to analyze the chemical fragmentations Each technique has its own advantages and disadvantages. While CID is most effective for the analysis of pure substances, multiple-step MS is a powerful technique to get structural data. Analysis of veterinary drugs ampicillin, chloramphenicol, ciprofloxacin, and oxytetracycline serves to highlight the slight differences between SID and CID. For example, minor differences were observed between ciprofloxacin and oxytetracycline via SID or CID. However, distinct fragmentation patterns were observed for ampicllin depending on the analysis method. Both SID and CID showed similar fragmentation spectra but different signal intensities for chloramphenicol. There are several factors that can influence the fragmentation spectra, such as the collision energy, major precursor ion, electrospray mode (positive or negative), and sample homogeneity. Therefore, one must select a fragmentation method on an empirical and case-by-case basis.