• Mass Spectrometry Letters
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• v.9 no.3
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• pp.86-90
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• 2018

Methallylescaline, 2-(3,5-dimethoxy-4-[(2-methylprop-2-en-1-yl)oxy]phenyl)ethanamine, is a new psychoactive substance with potent agonist of 5-HT receptor, but there is little information on its pharmacological effect, metabolism, and toxicity. It is necessary to characterize the metabolic profiling of methallylescaline in human hepatocytes using liquid chromatography-high resolution mass spectrometry. Methallylescaline was metabolized to three hydroxy-methallylescaline (M1-M3) and dihydroxy-methallylescaline (M4) via hydroxylation in human hepatocytes. CYP2D6, CYP2J2, CYP1A2, and CYP3A4 enzymes were responsible for the metabolism of methallylescaline. The metabolites as well as methallylescaline would be used for monitoring the abuse of methallylescaline.

• Mass Spectrometry Letters
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• v.3 no.2
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• pp.50-53
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• 2012

After success of sildenafil for the treatment of erectile dysfunction, a large number of its analogues have been approved from FDA. Recently, the illegal dietary supplements which include sildenafil, vardenafil, tadalafil, or analogues of these drugs as ingredient have been widely distributed. Therefore, the determination of the residue of synthetic phosphodiesterase- 5 (PDE-5) inhibitors in dietary supplements is highly required due to indiscriminate and unintentional overdose caused nausea, chest pains, fainting and irregular heartbeat. In this paper, we report a rapid and sensitive analytical method for the simultaneous determination of nine phosphodiesterase-5 inhibitors by liquid chromatography-high resolution mass spectrometry. The present method was found to be accurate and reproducible with 40 ${\mu}g$/g of the limit of quantification for the nine PDE-5 inhibitors. The developed method can be successfully applied to the analysis of the seven illegal dietary supplements.

• Mass Spectrometry Letters
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• v.2 no.3
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• pp.65-68
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• 2011

The effects of column length and particle size on the efficiency of separation and characterization of phospholipids (PLs) are investigated using nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MS-MS). Since PLs are associated with cell proliferation, apoptosis, and signal transduction, it is of increasing interests in lipidomics to establish reliable analytical methods for the qualitative and quantitative profiling of PLs related to biomarker development in adult diseases. Due to the complexity of PLs, the preliminary separation of PLs is necessary prior to MS analysis. In this study, length of capillary column and the particle size of reversed phase ($C_{18}$) packing materials are varied to find a reliable condition for the high speed and high resolution separation using 8 PL standard mixtures. From experiments, it was found that a capillary column of nLC-ESI-MS-MS analysis for PL mixtures can be minimized to a 5 cm long pulled tip column packed with 3 ${\mu}m$ $C_{18}$ particles without losing resolution.

• Mass Spectrometry Letters
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• v.13 no.1
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• pp.20-25
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• 2022

Fargesin, a tetrahydrofurofuranoid lignan isolated from Flos Magnoliae, shows anti-inflammatory, anti-oxidative, anti-allergic, and anti-hypertensive activities. To evaluate the pharmacokinetics of fargesin in mice, a sensitive, simple, and selective liquid chromatography-high resolution mass spectrometric method using electrospray ionization and parallel reaction monitoring mode was developed and validated for the quantification of fargesin in mouse plasma. Protein precipitation of 6 µL mouse plasma with methanol was used as sample clean-up procedure. The standard curve was linear over the range of 0.2-500 ng/mL in mouse plasma with the lower limit of quantification level at 0.2 ng/mL. The intra- and inter-day coefficient variations and accuracies for fargesin at four quality control concentrations including were 3.6-11.3% and 90.0-106.6%, respectively. Intravenously injected fargesin disappeared rapidly from the plasma with high clearance values (53.2-55.5 mL/min/kg) at 1, 2, and 4 mg/kg doses. Absolute bioavailability of fargesin was 4.1-9.6% after oral administration of fargesin at doses of 1, 2, and 4 mg/kg to mice.

• Analytical Science and Technology
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• v.16 no.1
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• pp.78-81
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• 2003

Peptides separation in high performance liquid chromatography (HPLC) is very important for the analysis of total proteins using mass spectrometry rather than two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). In this study, we investigated the optimal HPLC condition of peptides for the use of mass fingerprinting. As a result of pursuing a combination of solvent additives for HPLC, water and acetonitile containing both 0.1% trifluoroacetic acid and 0.1% acetic acid respectively showed the most efficient resolution and sensitivity.

• Mass Spectrometry Letters
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• v.12 no.3
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• pp.112-117
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• 2021

α-Amanitin and β-amanitin are highly toxic bicyclic octapeptides responsible for the poisoning of poisonous mushrooms such as Amanita, Galerina, and Lepiota by inhibiting RNA polymerase II, DNA transcription, and protein synthesis. A sensitive, simple, and selective liquid chromatography-high resolution mass spectrometric method using parallel reaction monitoring mode was developed and validated for the simultaneous determination of α- and β-amanitin in mouse plasma to evaluate the toxicokinetics of α- and β-amanitin in mice. Protein precipitation of 5 μL mouse plasma sample with methanol as sample clean-up procedure and use of negative electrospray ionization resulted in better sensitivity and less matrix effect. The calibration curves for α- and β-amanitin in mouse plasma were linear over the range of 0.5-500 ng/mL. The intra- and inter-day coefficient of variations and accuracies for α- and β-amanitin at four quality control concentrations were 3.1-14.6% and 92.5-115.0%, respectively. The present method was successfully applied to the toxicokinetic study of α- and β-amanitin after an oral administration of α- and β-amanitin at 1.5 mg/kg dose to male ICR mice.

• Archives of Pharmacal Research
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• v.17 no.6
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• pp.424-427
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• 1994

An acinomycin complex isolated from culture broth of a soil microorganism, SNUS 9305-011 has been examined by High performance liquid chromatography (HPLC). From the analysis of the fractions obtained by column chromatography of the ethyl acetate extract, three actinomycin components are confimed . The HPLC analysis is carried out with a CN-bonded nucleosil column. Comparison of the retention times of the components with those of actinomycin D, C complex, $X_{o{\beta}$, and V and suggests that they are different actinomycins. FBA mass spectra fo the coponents also shows different molecular ions from those of standards and other reported actionbmycins. The present work has demonstrated that actinomycin components can be separated by a CN-bonded HPLC column, and that ocmparison of their HPLC chormatograms with authentic smaples and information on their molecular ions can be successfully employed for indentification of actionmycins.

• Mass Spectrometry Letters
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• v.8 no.2
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• pp.39-43
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• 2017

Meldonium is a drug for treating ischemia by expanding the arteries but it can also enhance the performance of sports players. The World Anti-Doping Agency (WADA) has included it in the list of prohibited substances since 2016. Meldonium is one of the challenging substances for anti-doping testing because it is difficult to recover by general liquid-liquid or solid phase extraction due to its permanent charge and high polarity. Therefore, high-performance liquid chromatography (HPLC) is currently used by injecting a diluted urine sample (known as the "dilute-and-shoot" strategy). There is no loss of target compounds in the extraction/cleanup procedure but its high matrix effect could interfere in their separation or detection from the endogenous urinary compounds. We report a single method using high-resolution mass spectrometry that can be used for both screening and confirmation, which follows the "dilute-and-shoot" strategy. In this method, the endogenous compounds' interfering peaks in the mass spectrum are separated at a high resolution of FWHM 140,000, and the results are suitable for substance detection following the WADA guidelines. The interferences in the obtained mass spectrum of the urine matrix are identified as acetylcholine, lysine, and glutamine by further analysis and database searching. Validation of the method is performed in routine anti-doping testing, and the limit of detection is 50 ng/mL. This method uses simple sample preparation and a general reverse phase HPLC column, and it can be easily applied to other substances.

• Fisheries and Aquatic Sciences
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• v.25 no.3
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• pp.140-150
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• 2022

A method of ultrahigh performance liquid chromatography coupled to high resolution mass spectrometry (UPLC-HRMS) was established for characterization of the lipid profile of Skipjack tuna. Over 300 lipid molecular species were identified through cross-acquisition in both positive and negative ion mode. Phospholipids (PLs) were dominant in Skipjack tuna. Lysophosphatidylethanolamine (LPE), phosphatidylethanolamine (PE), lysophosphatidylcholine (LPC) and phosphatidylcholine (PC) were the main lipid molecular species in PLs, accounting for 89.24% of the total PLs. The ratio of sphingolipids (SLs) and glycerolipids (GLs) were considerable, accounting for 12.30% and 13.60% of the total lipids respectively. Ceramide (Cer) was the main lipid molecular species of SLs, accounting for 64.96% of total SLs, followed by sphingomyelin (SM), accounting for 25.45% of total SLs. Ether diglycerides (ether DG) were the main lipid molecular species of GLs (97.83%). The main fatty acids (FAs) are unsaturated fatty acids (UFAs) in Skipjack tuna. Besides, a new FAs class branched fatty acid esters of hydroxy fatty acids (FAHFA) was detected, together with the FA. The active lipids identified in this study can be used to evaluate the nutritional value of Skipjack tuna.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.617-618
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• 1998

A simple and reproducible pretreatment method was developed for the determination of dioxins in milk sample. Liquid-liquid extraction (LLE) was used for the initial extraction of the analyte from milk. For the elimination of interferences coextracted from milk, acid treatment followed by multilayer silica gel, and then alumina column clean-up were performed. The clean extract could be obtained without carbon column or high performance liquid chromatographic (HPLC) clean-up procedure. Polychlorinated biphenyles (PCBs) and dioxins were separated on neutral alumina activated at 180 ℃ for 12 hours. The final extract was analyzed by HPLC and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The recovery of dioxins spiked in milk at 75-300 ppt level was 83.3-98.9% and their relative standard deviation was 4.1-14%.