• 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.

• Journal of Microbiology and Biotechnology
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• v.33 no.6
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• pp.831-839
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• 2023

Tylosin is a potent veterinary macrolide antibiotic produced by the fermentation of Streptomyces fradiae; however, it is necessary to modify S. fradiae strains to improve tylosin production. In this study, we established a high-throughput, 24-well plate screening method for identifying S. fradiae strains that produce increased yields of tylosin. Additionally, we constructed mutant libraries of S. fradiae via ultraviolet (UV) irradiation and/or sodium nitrite mutagenesis. A primary screening of the libraries in 24-well plates and UV spectrophotometry identified S. fradiae mutants producing increased yields of tylosin. Mutants with tylosin yield 10% higher than the wild-type strain were inoculated into shake flasks, and the tylosin concentrations produced were determined by high-performance liquid chromatography (HPLC). Joint (UV irradiation and sodium nitrite) mutagenesis resulted in higher yields of mutants with enhanced tylosin production. Finally, 10 mutants showing higher tylosin yield were re-screened in shake flasks. The yield of tylosin A by strains UN-C183 (6767.64 ± 82.43 ㎍/ml) and UN-C137 (6889.72 ± 70.25 ㎍/ml) was significantly higher than that of the wild-type strain (6617.99 ± 22.67 ㎍/ml). These mutant strains will form the basis for further strain breeding in tylosin production.

• Journal of Life Science
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• v.16 no.5
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• pp.859-865
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• 2006

When thin slits (e.g., $1mm{\times}10mm$) of maize (Zea mays) coleoptiles were floated on a buffer, they spontaneously curved outward because of unbalanced tissue tension between inner and outer faces. Exogenously applied auxin induced inward curvature of the thin strip of the maize coleoptile in a dose-dependent manner. This bioassay system was used to screen endogenous substances that work together with auxin. In methanol extract of maize coleoptiles including the leaves inside, Active fractions that promote the auxin-induced inward curvature of maize coleoptile slices were found. The curvature-enhancing activity of the extract was not related to energy supply. The active substances were adsorbed to $C_{18}$ cartridges even at pH 10 and eluted in two fractions by 50% and 80% methanol. These substances were named as Curvature-Enhancing Factor-1 (CEF-1) and Curvature-Enhancing Factor-2 (CEF-2), respectively. The CEF-2 was resolved on a reversed phase $C_{18}$ column by HPLC.

• Applied Biological Chemistry
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• v.39 no.2
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• pp.153-158
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• 1996

During the screening of herbicidal substances from microbial secondary metabolites using photoautotrophic cells, a strain of ME-13 with strong herbicidal activity was isolated from soil. Based on the taxonomic studies, the strain was identified as Streptomyces. Two active compounds were purified from the culture broth through the column chromatographies using active charcoal, silica gel, MCI gel, and ODS HPLC. The compounds were identified as AB3217-A and B, respectively, related to anisomycin by spectroscopic methods. AB3217-A and B completely suppressed the germination of radish and barnyard grass at 25 ppm. In comparison to anisomycin, they showed the 6 times higher inhibitory activities against the growth of shoot and root of radish and barnyard grass with EC5O of around 6 ppm.

• Microbiology and Biotechnology Letters
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• v.39 no.3
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• pp.218-223
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• 2011

To obtain eicosapentaenoic acid (EPA)-producing bacteria, some 600 strains of bacteria were isolated from Antarctic sediment and marine organisms during the summer expedition of 1999-2000 and 7 EPA-producing bacteria were obtained through screening with TLC and GC. A strain designated as L93 showed the highest EPA production, which was gram-negative, rod-shaped bacterium. L93 strain was identified as Shewanella sp., from the sequence analysis of 16S rDNA. Optimal conditions temperature and pH for the growth and EPA production were about $4^{\circ}C$ and pH 7. In addition, its production was optimized by 50%(w/v) sea salt. We establish the optimal production system to produce about 320 mg per liter by using this optimal EPA production conditions. EPA-methyl ester was purified from cultured L93 strain to a purity of higher than 97% and typical purification yield is greater than 72% of the input amount via urea complexation and HPLC.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1253-1258
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• 2012

Two phenolic allopyranosides and two phenolic amide allopyranosides, along with eight known phenolic compounds, including cimicifugic acids, shomaside B, fukiic acid, isoferulic acid, and piscidic acid, were isolated from the n-butanolic extract of rhizomes of Cimicifuga heracleifolia. On-line spectroscopic data for UV, NMR, and MS from a combination of LC-NMR and LC-MS techniques directly and rapidly provided sufficient structural information to identify and confirm all the structures of major phenolic compounds in the extract, in addition to their HPLC profiles. This combined analytic information was then used as a dereplication tool for structure-guided screening in order to isolate unknown phenolic compounds in the extract. Successive fractionation and purification using semi-preparative HPLC acquired four unknown allopyranosides, and their structures were identified as cis-ferulic acid 4-O-${\beta}$-D-allopyranoside, trans-ferulic acid 4-O-${\beta}$-D-allopyranoside, trans-feruloyltyramine 4-O-${\beta}$-D-allopyranoside, and trans-feruloyl-(3-O-methyl)dopamine 4-O-${\beta}$-D-allopyranoside, based on a subsequent spectroscopic interpretation.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.680-683
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• 2003

Through the screening of caspase-3 inducing inhibitors in U937 human monocytic leukemia cell from natural sources, Caesalpiniae sappan, which showed a high level of inhibition, was selected. The inhibition compound was purified from methanol extract by silica gel column chromatography and HPLC. The inhibitor was identified as brazilin by spectroscopic methods of ESI-MS, $^1H-NMR$, and $^{13}C-NMR$. Brazilin showed inhibitory activity of caspase-3 induction, a major protease of apoptosis cascade, with $IC_{50}$ value of $4.5\;{\mu}g/mL$ after 7 hr of treatment in U937 cells.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.448-453
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• 2000

During the screening of inhibitors of caspase-3 induction in U937 human monocytic leukemia cells from natural sources, Petasites japonicum, which showed a high level of inhibition was selected. The inhibiting compound was purified from the methanol extract by Sephadex LH-20 column chromatography and HPLC. The inhibitor was identified as [3-(3,4-dihydroxyphenyl)-2-oxopropyl]ester, petasiphenol, by spectroscopic methods of UV, EIMS, $^1H-NMR$, $^{13}C-NMR$ and HMBC. It showed a caspase-3 inducing inhibitory activity at $8\;{\mu}g/ml$ of $IC_{50}$ value with DNA fragmentation inhibition in U937 human leukemia cells. It also showed a free radical scavenging ability of 1,1-diphenyl-2-picrylhydrazyl.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.49-55
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• 2011

Thirty Streptomyces sp. and 200 Bacillus sp. isolated from Korean soils and traditional foods were screened for their abilities to inhibit ${\alpha}$-glucosidase and produce 1-deoxynojirimycin (DNJ). This screening identified a Bacillus sp. bacterium that strongly inhibited ${\alpha}$-glucosidase and produced high levels of DNJ from Chungkookjang, a Korean traditional food. The bacterium was characterized in terms of its biochemical and molecular biological properties such as sugar utilization, cellular quinone composition, cell wall fatty acid composition, and 16S rDNA sequence. In addition, scanning electron microscopy was used to visualize the morphology of the bacterium. These analyses identified the bacterium as B. subtilis, a bacterium with Generally Recognized as Safe (GRAS) status. The selected strain was named B. subtilis MORI.

• Korean Journal of Clinical Pharmacy
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• v.26 no.1
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• pp.70-76
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• 2016

Background: The use of the extracts from evening primrose seeds as a health functional food has been gradually increased. Therefore, the monitoring and screening process has been considerably required for its quality control. Objective: This study aimed to estimate the measurement uncertainty associated with determination of penta-o-galloyl ${\beta}$-D-glucose (PGG) in extracts from evening primrose seeds by high-performance liquid chromatography. Methods: The sources of measurement uncertainty was expressed in accordance with mathematical/statistical theories of GUM & EURACHEM Guide. The expanded uncertainty was calculated by using the relative standard uncertainty between analytical result and sources of uncertainty in measurement (sample weight, final volume, extraction volume, standard solution, matrix and instrument etc). Results: In the results of 95% confidence interval, the uncertainty in measurement was $10,253.34{\pm}1,844.50{\mu}g/kg$ (k = 2.0). Conclusion: In this study, it showed that the value of uncertainty in measurement for determination of PGG in extracts from evening primrose seeds by HPLC has about 18.0% influence on PGG contents of the analytical results. The results would be very useful for the monitoring and screening of evening primrose seeds marketed in Korea for its quality control as dietary supplement.