• Proceedings of the PSK Conference
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• 2003.04a
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• pp.290.1-290.1
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• 2003

Oxidative DNA damage has been associated with many disease. Quantation of DNA adducts is considered to be a useful biomarker of oxidative DNA damage because its formation can also be induced by oxidative stress. Extensive efforts have been taken to identify the analytical methods for minimizing the artifactual formation of oxidative DNA damage. We have done direct analysis of DNA adducts using LC/ESI-MS without urine sample extraction. (omitted)

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1094-1104
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• 2018

The peel of astringent persimmon (Diospyros kaki Thunb. cv. Cheongdo-Bansi) is a by-product of dried persimmon (gotgam). We investigated if deastringent peel extracts of persimmon cv. Cheongdo-Bansi had antioxidative and neuroprotective properties. Two different extracts were prepared: thermally and nonthermally treated persimmon peel extracts (TPE and NTPE, respectively). Both TPE and NTPE were fractionated sequentially in n-hexane, chloroform, ethyl acetate, n-butanol, and water. The TPE and NTPE ethyl acetate fractions had the highest total phenolic and flavonoid contents as well as antioxidant capacities among all the fractions. Pretreatment of neuronal PC-12 and SH-SY5Y cells with the TPE and NTPE ethyl acetate fractions increased cell viability after exposure to oxidative stress. The ethyl acetate fraction of TPE attenuated oxidative stress inside both PC-12 and SH-SY5Y cells more effectively than that of NTPE. Furthermore, the TPE and NTPE ethyl acetate fractions inhibited acetylcholinesterase and butyrylcholinesterase. Analysis of ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry results revealed gallic acid, kaempferol, kaempferol-3-O-galactoside, kaempferol-3-O-glucoside, quercetin, quercetin3-O-galactoside, quercetin-3-O-galactoside-2'-O-gallate, and quercetin-3-O-glucoside as the major phenolics of the TPE and NTPE ethyl acetate fractions. Taken together, these results suggest that the ethyl acetate fraction of deastringent persimmon peel is rich in antioxidants and has potential as a functional food to reduce oxidative stress.

• Food Engineering Progress
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• v.22 no.4
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• pp.295-303
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• 2018

Polyphenol profiles, physicochemical properties, antioxidant activities, and inhibitory effect of adipocyte differentiation of Houttuynia cordata fermented with Lactobacillus brevis B84 were evaluated. Six polyphenols were characterized for this plant by using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), and the results were compared with total phenolic content by a spectrophotometric method. The total amount of the identified polyphenols was lower than that determined by the spectrophotometric method. However, the fermentation process influenced polyphenol composition such as content of vanillic acid and caffeic acid. The phytochemical profiles were evaluated by high-performance liquid chromatography with UV and electrospray ionization mass spectrometry detection ($HPLC-DAD-ESI-MS^n$). Total sugar and reducing sugar contents decreased after fermentation. Antioxidant activities such as DPPH, ABTS, and superoxide anion radical scavenging and reducing power were evaluated to compare the beneficial effect after fermentation. Fermented H. cordata increased the lipolytic effect in 3T3-L1 adipocytes. Overall, the results indicate that the fermentation of H. cordata with L. brevis B84 produces changes of phenolic compounds, antioxidant activity, and lipolytic effect.

• Archives of Pharmacal Research
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• v.22 no.2
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• pp.189-193
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• 1999

Reversed-phase high-performance liquid chromatography/mass spectrometry (HPLC/MS) with an eletcrospray ionization (ESI) interface was applied to the identification of metabolites of IY81149 in the rat plasma. Fragments obtained using collision-induced dissociation (CID) in both positive and negative modes were utilized to elucidate the structure of metabolites. The eluent from the conventional HPLC column was split and directly introduced into an ESI-mass spectrometer for the identification of the structures. the CID technique allowed the sensitive identification of sulfonyl-IY81149 and hydroxy-IY81149 from the rat plasma.

• Analytical Science and Technology
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• v.17 no.3
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• pp.263-270
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• 2004

A method is described for the analysis of short-chain alkylphenol ethoxylates (APEOs), 4-octylphenol-di-ethoxylate (OP2EO) and 4-nonylphenol-di-ethoxylate (NP2EO), in drinking water or wastewater using reversed phase high-performance liquid chromatography with electrospray ionization mass spectrometry. The solvent system was water and methanol containing $10{\mu}M$ trifluoroacetic acid as an ionization solvent. We acidified 1 L of water samples to less than pH 2 with concentrated $H_2SO_4$ and loaded onto Sep-Pak $C_{18}$, and eluted with acetone. The calibration of OP2EO and NP2EO was performed for the concentration range from 20 to 500 ng/L and the correlation coefficients were 0.999 and 0.990, respectively. The limits of detection were 20 ng/L (OP2EO) and 50 ng/L (NP2EO) at a signal-to-noise ratio of 3. Accuracy and precision of this analytical method were 85.8 ~ 122.1% and 8.2 ~ 18.8%, respectively. The proposed method allowed a sensitive and rapid detection of OP2EO and NP2EO and it could be applied for monitoring of APEOs from environmental samples.

• ALGAE
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• v.18 no.3
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• pp.233-238
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• 2003

Cyanobacteria were dominant from June to September in the Nakdong River and the Hoedong Reservoir. Microcystis aeruginosa was dominant from June to September; Anabaena flos-aquae from June to August and Aphanizomenon flos-aquae from July to August. Cyanobacterial neurotoxins, Anatoxin-a and saxitoxin were analyzed by electrospray ionization-mass spectrometry with strains of Aphanizomenon flos-aquae NIES-81 and Anabaena flosaquae NIER-10002. Anatoxin-a was not detected from the cultured Anabaena flos-aquae nor from the wild samples. Low levels of saxitoxin were detected in the cultured Aphanizomenon flos-aquae however, those of field samples were below the detection limit.

• Archives of Pharmacal Research
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• v.25 no.5
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• pp.647-651
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• 2002

An LC/MS/MS method for the simultaneous determination of a neuroprotective agent for ischemia-reperfusion damage, KR-31378 and its N-acetyl metabolite KR-31612 in human plasma was developed. KR-31378, KR-31612 and the internal standard. KR-31543 were extracted from human plasma by liquid-liquid extraction. A reverse-phase HPLC separation was performed on Luna phenylhexyl column with the mixture of acetonitrile-5 mM ammonium formate (55:45, v/v) as mobile phase. The detection of analytes was performed using an electrospray ionization tandem mass spectrometry in the multiple reaction monitoring mode. The lower limits of quantification for KR-31378 and KR-31612 were 2.0 ng/ml. The method showed a satisfactory sensitivity, precision, accuracy, recovery and selectivity.

• Mass Spectrometry Letters
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• v.5 no.2
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• pp.42-48
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• 2014

A specific and sensitive liquid chromatography-electrospray ionization tandem mass spectrometry method (LC-ESI-MS/MS) was developed and validated for the simultaneous quantification of porphyrins (coproporphyrin, pentacarboxylporphyrin, hexacarboxylporphyrin, heptacarboxylporphyrin, and uroporphyrin) in human plasma and urine. Acidified plasma samples and urine samples were prepared by using liquid-liquid extraction using ethyl acetate and protein precipitation with acetonitrile, respectively. The separation was achieved onto a Synergi Fusion RP column ($150mm{\times}2.0mm$, $4{\mu}m$) with a gradient elution of mobile phase A (0.1% formic acid in 2 mmol/L ammonium acetate, v/v) and mobile phase B (20% methanol in acetonitrile, v/v) at a flow rate of $450{\mu}L$/min. Porphyrins and the internal standard (IS), coproporphyrin I-$^{15}N_4$, were detected by a tandem mass spectrometer equipped with an electrospray ion source operating in positive ion mode. Multiple reaction monitoring (MRM) transitions of the protonated precursor ions and the related product ions were optimized to increase selectivity and sensitivity. The proposed method was validated by assessing selectivity, linearity, limit of quantification (LOQ), precision, accuracy, recovery, and stability. The calibration curves were obtained in the range of 0.1-100 nmol/L and the LOQs were estimated as 0.1 nmol/L for all porphyrins. Results obtained from the validation study of porphyrins showed good accuracy, precision, recovery, and stability. Finally, the proposed method was successfully applied to clinical studies on the autism spectrum disorder (ASD) diagnosis of 203 Korean children.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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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.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3629-3634
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• 2013

In this study, an improved method for the quantitative analysis of ginkgolic acids (GAs) in Ginkgo biloba leaf extract was developed. The samples were extracted with a mixture of chloroform and 50 % ethanol, after which the chloroform extract was dried and reconstituted in methanol. GAs with 13:0, 15:1, and 17:1 in the extract were successfully separated within 40 min and determined with high throughput performance using an online column-switching HPLC method using an SP column C8 SG80 ($4.6{\times}150mm$, $5{\mu}m$) and a Cadenza 5CD C18 column ($4.6{\times}150mm$, $3{\mu}m$). The developed HPLC method was validated for Ginkgo biloba leaf extract. The validation parameters were specificity, linearity, precision, accuracy, and limits of detection and quantitation (LODs and LOQs, respectively). It was found that all of the calibration curves showed good linearity ($r^2$ > 0.9993) within the tested ranges. The LODs and LOQs were all lower than $0.04{\mu}g/mL$. The established method was found to be simple, rapid, and high throughput for the quantitative analysis of GAs in ten commercial Ginkgo biloba leaf extract and dietary supplements. The samples were also analyzed in LC-electrospray ionization (ESI) tandem mass spectrometry (MS/MS) - multiple-ion reaction monitoring (MRM) mode to confirm the identification results that were obtained by the column switching HPLC-DAD method. The developed method is considered to be suitable for the routine quality control and safety assurance of Ginkgo biloba leaf extract.