• Journal of Food Hygiene and Safety
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• v.36 no.3
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• pp.228-238
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• 2021

The aim of this research was to develop a rapid and easy multi-residue method for determining dimethipin, omethoate, dimethipin, chlorfenvinphos and azinphos-methyl in agricultural products (hulled rice, potato, soybean, mandarin and green pepper). Samples were prepared using QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) and analyzed using gas chromatography-tandem mass spectrometry (GC-MS/MS). Residual pesticides were extracted with 1% acetic acid in acetonitrile followed by addition of anhydrous magnesium sulfate (MgSO₄) and anhydrous sodium acetate. The extracts were cleaned up using MgSO₄, primary secondary amine (PSA) and octadecyl (C₁₈). The linearity of the calibration curves, which waas excellent by matrix-matched standards, ranged from 0.005 mg/kg to 0.3 mg/kg and yielded the coefficients of determination (R²) ≥ 0.9934 for all analytes. Average recoveries spiked at three levels (0.01, 0.1, 0.5 mg/kg) and were in the range of 74.2-119.3%, while standard deviation values were less than 14.6%, which is below the Codex guideline (CODEX CAC/GL 40).

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2309-2317
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• 2009

Depurination, the release of purine bases from nucleic acids by hydrolysis of the N-glycosidic bond, gives rise to alterations of the cell genome. Though cells have evolved mechanisms to repair these lesions, unrepaired apurinic sites have been shown to have two biological consequences: lethality and base substitution errors. 2-Bromopropane (2-BP) is used as an intermediate in the synthesis of pharmaceuticals, dyes, and other organics. In addition, 2-BP has been used as a replacement for chloroflurocarbons and 1,1,1-trichloroethane as a cleaning solvent in electronics industry. However, 2-BP was found to cause reproductive and hematopoietic disorders in local workers exposed to it. Owing to the toxicity of 2-BP, there has been a tendency to use 1-BP as an alternative cleaning solvent to 2-BP. However, 1-BP has also been reported to be neurotoxic in rats. Though $N^7$-guanine adduct of 2-BP has been reported previously, massive depurination of the nucleosides and calf thymus DNA was observed in this study. We incubated the nucleosides (ddG, dG, guanosine, ddA, dA and adenosine) with excess amount 2-BP at the physiological condition (pH 7.4, $37\;{^{\circ}C}$), which were analyzed by HPLC and LC-MS/MS. In addition, the time and dose response relationship of depurination in nucleosides induced by 2-bromopropane at the physiological condition was investigated. Similarly, incubation of calf-thymus DNA with the excess amount 2-BP at the physiological condition was also performed. In addition, the time and dose response relationship of depurination in calf-thymus DNA induced by 2-BP at the physiological condition was investigated. Those results suggest that the toxic effect of 2-BP could be both from the depurination of nucleosides and DNA adduct formation.

• Journal of Microbiology and Biotechnology
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• v.19 no.12
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• pp.1569-1572
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• 2009

The pharmacokinetics of decursin and decursinol angelate (D/DA) were investigated in male SD rats following oral and intravenous administration. D/DA and metabolites obtained from in vitro samples were evaluated by LC/MS. The levels of D/DA and metabolized decursinol in the blood following oral and intravenous administrations declined according to first-order kinetics, with $T_{1/2}$ values of 56.67, 58.01, and 57.22 h, respectively, being observed after administration of a dose of 2 mg/kg body weight. The large intestine was the major site of disposition following oral administration. These data indicate that D/DA is rapidly absorbed from the gastrointestinal tract. In in vitro experiment utilizing liver microsomal protein, the major metabolic reaction of D/DA occurred to change decursinol. The cumulative biliary, urinary, and fecal excretions of D/DA in bile duct-cannulated rats was $36.10{\pm}2.9%$, $25.35{\pm}3.8%$, and $34.20{\pm}3.2%$, respectively, at 72 h after administration. These results indicate that the absorption of D/DA is almost complete, and that its metabolites are primarily excreted into feces through the bile. These results indicate that D/DA is subject to enterohepatic circulation.

• Korean Journal of Pharmacognosy
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• v.52 no.4
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• pp.203-207
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• 2021

LC/MS approach targeting secondary metabolites of bacterial strain resulted in the discovery of boholamide A (1), from the culture of marine actinomycete strain which was isolated from a tidal mudflat in Muan, Republic of Korea. Boholamide A (1), a cyclodepsipeptide with HDMN, APD, glycine, and valine was structurally determined by using 1D/2D NMR spectroscopy, mass spectrometry and UV spectroscopy. Boholamide A (1) showed the inhibitory activity against Bacillus subtilis, with IC₅₀ value of 0.08 mM.

• Proceedings of the Ginseng society Conference
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• 1980.09a
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• pp.59-69
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• 1980

A new HPLC-method for separation and quantitative determination of ginsenosides in Panax ginseng, Panax quinquefolium and in pharmaceutical drug preparations is elaborated. A reversed-phase-system with ${\mu}Bondapak\;C_{18}$ column (3.9 mm $I.D.{\times}30\;cm$) using acetonitrile-water (30:70) 2 ml/min and acetonitrile-water (18:82) 4 ml/min is suitable for the base-line separation of $Rb_1,\;Rb_2,\;Rc,\;Rd,\;Rf,\;Rg_2,\;respectively\;Re,\;Rg_1$ in 30 minutes. The ginsenosides are directly detected at 203 nm (without derivatization) with the LC-55 or LC-75 spectrophotometer (Perkin-Elmer) at $100\%$ transmission. Detection limit is 300 ng at a signal-to-noise ratio of 10:1. The ginsenosides-peak identification is carried out with HPTLC (high performance thin layer chromatography), with MIR-IR (multiple internal reflection-IR-spectros-copy) and with FD-MS (field desorption mass spectrometry). The calibration curve of each ginsenoside has a correlation coefficient very near to 1. Relative standard deviation for quantitative determinations depends upon the amount of ginsenosides and is approximately 1\%$ for ginsenoside contents of 1\%$. This method is adaptable for routine analysis in quality control laboratories.

• Biomolecules & Therapeutics
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• v.17 no.4
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• pp.430-437
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• 2009

Metabolites of Soyasaponin I, a major constituent of soybean, by human intestinal microflora were investigated by LC-MS/MS analysis. We found four peaks, one parental constituent and three metabolites: m/z 941 [M-H]$^-$, m/z 795 [M-rha-H]$^-$, m/z 441 [aglycone-$H_2O$+H]$^+$, and m/z 633 [M-rha-gal-H]$^-$, which was an unknown metabolite, soyasapogenol B 3-$\beta$-D-glucuronide. When soyasaponin I was incubated with the human fecal microbial fraction from ten individuals for 48 h, soyasaponin I was metabolized to soyasapogenol B via soyasaponin III and soyasapogenol B 3-$\beta$-D-glucuronide or via soyasaponin III alone. Both soyasaponin I and its metabolite soyasapgenol B exhibited estrogenic activity. Soyasaponin I increased the proliferation, mRNA expression of c-fos and pS2, in MCF7 cells more potently than soyasapogenol B. However, soyasapogenol B showed potent cytotoxicity against A549, MCF7, HeLa and HepG2 cells, while soyasaponin I did not. The cytotoxicity of soyasapogenol B may prevent its estrogenic effect from increasing dose-dependently. These findings suggest that orally administered soyasaponin I may be metabolized to soyasapogenol B by intestinal microflora and that soyasapogenol B may express a cytotoxic effect rather than an estrogenic effect.

• Journal of Microbiology
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• v.44 no.4
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• pp.375-382
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• 2006

From its initial colonization to causation of disease, Streptococcus pneumoniae has evolved strategies to cope with a number of stressful in vivo environmental conditions. In order to analyze a global view of this organism's response to heat shock, we established a 2-D electrophoresis proteome map of the S. pneumoniae D39 soluble proteins under in vitro culture conditions and performed the comparative proteome analysis to a 37 to $42^{\circ}C$ temperature up-shift in S. pneumoniae. When the temperature of an exponentially growing S. pneumoniae D39 culture was raised to $42^{\circ}C$, the expression level of 25 proteins showed changes when compared to the control. Among these 25 proteins, 12 were identified by MALDI-TOF and LC-coupled ESI MS/MS. The identified proteins were shown to be involved in the general stress response, energy metabolism, nucleotide biosynthesis pathways, and purine metabolism. These results provide clues for understanding the mechanism of adaptation to heat shock by S. pneumoniae and may facilitate the assessment of a possible role for these proteins in the physiology and pathogenesis of this pathogen.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.696-704
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• 2017

In this study, we investigated antioxidative and matrix metalloproteinases (MMPs) inhibitory effects of Sorbus commixta twig extracts and fermented extracts with Lactobacillus pentosus and analyzed active ingredients. The free radical scavenging activity ($FSC_{50}$) of non-fermented and fermented extracts of S. commixta twig' were 41.04 and $58.2{\mu}g/mL$, respectively. In the $Fe^{3+}-EDTA/H_2O_2$ system, the active oxygen scavenging activity ($OSC_{50}$) was 2.6 and $3.0{\mu}g/mL$, respectively. In the dermal fibroblasts, the intracellular reactive oxygen species (ROS) scavenging activity was 35.3% for non-fermented extract and 40.2% for fermented extracts at the concentration of $10{\mu}g/mL$. Also at the same concentration, the expression of MMPs (MMP-1, -2, -3) by western blot was 68.3, 35.0 and 24.2%, respectively for non-fermented extracts and 84.3, 70.5 and 69.2% for fermented extracts. TLC, HPLC, and LC/ESI-MS/MS were used for measuring the changes in the components of the extract before and after fermentation. As a result, caffeic acid, (-)-epicatechin, isoquercitrin, and quercetin were identified. From the results, S. commixta twig fermented extracts by L. pentosus showed greater ROS scavenging activity and inhibitory effects on MMPs expression than those of using non-fermented extracts. Therefore, it is suggested that S. commixta twig fermented extracts can be used as an anti-aging cosmetic material.

• Journal of Food Hygiene and Safety
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• v.30 no.1
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• pp.81-86
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• 2015

The purpose of our paper was to investigate the migration level of 4,4'-MDA(4,4'-methylenedianiline), 2,4-TDA(2,4-toluenediamine), aniline, acrylonitrile and methylmeth acrylate from plastic cookwares into food simulants and to evaluate the safety of each monomers. The test articles for monomers were PA (polyamide) items for 4,4'-MDA, 2,4-TDA and aniline, PU (polyurethane) items for 4,4'-MDA, ABS (acrylonitrile-butadiene- styrene) items for acrylonitrile, and acrylic resin items for methylmethacrylate. All the article samples of 321 intended for contact with foods were purchased in domestic market. 4,4'-MDA, 2,4-TDA and aniline were analyzed by LC-MS/MS (liquid chromatography -tandem mass spectrometer), acrylonitrile by GC-NPD (gas chromatography-nitrogen phos phorus detector) and methyl methacrylate by GC-FID (gas chromatography-flame ionization detector). The migration level of monomers were within the migration limits of Ministry of Food and Drug Safety (MFDS). As a result of safety evaluation, our results showed that the estimated daily intake (EDI, mg/kg bw/day)s were $2.39{\times}10^{-9}$ and $1.20{\times}10^{-9}$ for 4,4'-MDA and 2,4-TDA of PA, $4.32{\times}10^{-9}$ for acrylonitrile of ABS and $2.27{\times}10^{-7}$ for methylmethacrylate of acrylic resin. Reference Dose (RfD, mg/kg bw/day) of acrylonitrile and tolerable daily intake (TDI, mg/kg bw/day) of methacrylate were established respectively as 0.001 by EPA (US Environmental Protection Agency) and as 1.2 by WHO (World Health Organization). When comparing with RfD and TDI, the EDIs of acrylonitrile and methylmethacrylate accounted for $4.32{\times}10^{-4}%$ and $1.89{\times}10^{-5}%$ respectively.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.3
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• pp.213-217
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• 2006

We evaluated the potential of major components of Phellodendri cortex to inhibit the activities of CYP2D6 and p-glycoprotein. The abilities of berberine, palmatine, limonin, and rutaecarpine to inhibit CYP2D6-mediated dextromethorphan O-demethylation and calcein AM accumulation were tested using human liver microsomes and L-MDR1 cell, respectively. Berberine strongly inhibited CYP2D6 isoform activity, whereas limonin and reuaecarpine did not. The $IC_{50}$ value of berberine was reduced after preincubation with microsomes in the presence of NADPH generating system, suggesting that berberine is a mechanism based inhibitor. In addition, all chemicals tested, didn't show inhibitory effect on p-glycoprotein activity. These results suggest that berberine has potential to inhibit CYP2D6 activity in vitro. Therefore, in vivo studies investigating the interactions between berberine and CYP2D6 substrates are necessary to determine whether inhibition of CYP2D6 activity by berberine is clinically relevant.