• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.59-64
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• 2010

The synthesis of a series of fluorinated thiadiazoles 3, triazoles 4 and oxadiazoles 5 are synthesized from thiosemicarbazides 2 containing (2-(6-methyl-2-p-tolyl-lH-imidazo[1,2-a]pyridin-3-yl nucleus. These reactions were carried out by conventional method as well as ultra sound irradiation method. All products have been characterized by IR, 1H NMR, MS study and screened for their antimicrobial activity.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1236-1242
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• 2011

Xanthomonas oryzae pv. oryzae (Xoo) is the most devastating pathogen to Oryza sativa and has been shown to cause bacterial blight. Two bioactive compounds showing antimicrobial activities against Xoo strain KACC 10331 were isolated from a Streptomyces bottropensis strain. The ethyl acetate extract was fractionated on a Sephadex LH-20 column, and then purified by preparative HPLC. The purified compounds were identified as bottromycin A2 and dunaimycin D3S by HR/MS and $^1H$ NMR analyses. The MIC value against Xoo and the lowest concentration still capable of suppressing rice bacterial blight were 2 ${\mu}g$/ml and 16 ${\mu}g$/ml for bottromycin A2, and 64 ${\mu}g$/ml and 0.06 ${\mu}g$/ml for dunaimycin D3S, respectively. These two compounds were shown to exert different bioactivities in vitro and in rice leaf explants.

• Natural Product Sciences
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• v.20 no.3
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• pp.152-159
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• 2014

A phytochemical investigation of Spergularia marina (L.) Griseb. growing in Egypt, has been carried out, which resulted in the isolation of seven compounds from the different extracts of the plant namely; ${\beta}$-sitosterol glucoside, tricin (1) dihydroferulic acid (2), vanillic acid (3), 4-hydroxybenzoic acid (4), uracil (5) and 8-hydroxy cuminoic acid (6) Structure elucidation of the isolated compounds was carried out using different spectroscopic techniques. This is the first report for the isolation of these compounds from genus Spergularia. Furthermore, 8-Hydroxy cuminoic acid and uracil were isolated for the first time from family Caryophyllaceae. The chemical composition of the volatile components present in the petroleum ether extract of Spergularia marina (L.) Griseb. using combined gas chromatography-mass spectrometry (GC-MS) is reported here for the first time. Of the 97 components present, 59 were identified including three sulfur containing compounds which represented about 1.8% of the volatiles of the total petroleum ether extract. This prompted us to study and report its possible antimicrobial activity. In addition, the antibacterial and antifungal screening of different extracts of Spergularia marina (L.) Griseb. as well as some isolates have been performed using agar diffusion method.

• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.623-632
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• 2006

To find potential targets of novel antimicrobial agents, we identified essential genes of Staphylococcus aureus N315 by using comparative genomics and allele replacement mutagenesis. By comparing the genome of S. aureus N315 with those of Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Streptococcus pneumoniae, a total of 481 candidate target genes with similar amino acid sequences with at least three other species by >40% sequence identity were selected. of 481 disrupted candidate genes, 122 genes were identified as essential genes for growth of S. aureus N315. Of these, 51 essential genes were those not identified in any bacterial species, and 24 genes encode proteins of unknown function. Seventeen genes were determined as non-essential although they were identified as essential genes in other strain of S. aureus and other species. We found no significant difference among essential genes between Streptococcus pneumoniae and S. aureus with regard to cellular function.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1669-1678
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• 2011

Six new binuclear copper(II) complexes have been prepared by template condensation of the dialdehydes 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-a) and 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-b) with appropriate aliphatic diamines, and copper(II) perchlorate. The structural features of the complexes have been confirmed by elemental analysis, IR, UV-vis and mass spectra etc. The electrochemical behavior of all the copper(II) complexes show two irreversible one electron reduction process. The room temperature magnetic moment studies depict the presence of an antiferromagnetic interaction in the binuclear complexes. The catechol oxidation and hydrolysis of 4-nitrophenylphosphate were carried out by using the complexes as catalyst. The antimicrobial screening data show good results. The binding of the complexes to calf thymus DNA (CT DNA) has been investigated with absorption and emission spectroscopy. The complex [$Cu_2L^{1a}$] displays significant cleavage property of circular plasmid pBR322 DNA in to linear form. Spectral, electrochemical, magnetic and catalytic studies support the distortion of the copper ion geometry that arises as the macrocyclic ring size increases.

• Applied Biological Chemistry
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• v.46 no.3
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• pp.257-261
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• 2003

Chemical components relevant to the characteristic antimicrobial activities of the Korean chestnut (Castanea crenata S. et Z.) leaves and flowers were analyzed. The composition of free sugar were sucrose, maltose in the chestnut flowers and sucrose, glucose, fructose in the chestnut leaves. The contains of tannin were 0.16% in the chestnut flower and 1.98% in the chestnut leaves. In fatty acids case, the linoleic contents were significantly high in the chestnut leaves and flowers. The organic acids showed high composition to succnic and citric acid in the chestnut leaves. The ammo acid compositions showed high contents to aspatic acid, proline, glutamic acid, glycine and methionine in the chestnut leaves and flowers. The total amino acid showed significantly higher in the chestnut leaves than flowers. The major minerals contained in the chestnut leaves and flowers were K, Ca, Ng, Fe, Mn and Al. Ascorbic acids were detected highly in the chestnut leaves and flowers.

• Korean Journal of Plant Resources
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• v.24 no.2
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• pp.200-207
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• 2011

This study was designed to investigate the possible utilization of Castanopsis cuspidata as a source of antiseptic agents. The leaves of C. cuspidata, extracted by 80% ethanol, were sequentially fractionated with n-hexane, dichloromethane, ethylacetate, and n-butanol. In order to effectively screen for a natural preservative agent, we first investigated the antioxidant activities such as DPPH radical scavenging capacity, superoxide radical scavenging capacity, and xanthine oxidase inhibitory activity of the C. cuspidata ethanol extracts and fraction. Using a screening system, we found that the ethylacetate fraction had the strongest antioxidant activity, which followed a dose-dependent manner. The antimicrobial activities were shown in the ethylacetate fraction of C. cuspidata. Among the five fractions, the ethylacetate fraction showed the highest antimicrobial activities against microorganisms tested, which were Bacillus sublitis, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Salmonella enteritidis and Salmonella typhimurium. In addition, leaf extracts of C. cuspidata could be suitable for the development of food preservatives.

• Journal of Microbiology and Biotechnology
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• v.20 no.10
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• pp.1386-1392
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• 2010

A bacterial strain designated GR5$^T$, previously isolated from a freshwater culture pond in Taiwan while screening for bacteria for antimicrobial compounds, was characterized using a polyphasic taxonomic approach. Strain GR5$^T$ was found to be Gram-negative, aerobic, greenish-yellow colored, rod-shaped, and motile by means of a single polar flagellum. Growth occurred at $10-40^{\circ}C$ (optimum, $35^{\circ}C$), pH 7.0-8.0 (optimum pH 8.0), and with 0-2.0% NaCl (optimum, 0.5-1.0%). The major fatty acids were $C_{16:1}{\omega}7c$(36.3%), $C_{16:0}$(16.6%), $C_{12:0}$ 3-OH (12.5%), and $C_{18:1}{\omega}7c$(9.1%). The major respiratory quinone was Q-8, and the DNA G+C content of the genomic DNA was 51.9 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain GR5$^T$ belongs to the genus Rheinheimera, where its most closely related neighbors are Rheinheimera texasensis A62-14B$^T$ and Rheinheimera tangshanensis JA3-B52$^T$ with sequence similarities of 98.1% and 97.5%, respectively, and the sequence similarities to any other recognized species within Gammaproteobacteria are less than 96.5%. The mean level of DNA-DNA relatedness between strain GR5$^T$ and R. texasensis A62-14B$^T$, the strain most closely related to the isolate, was $26.5{\pm}7.6%$. Therefore, based on the phylogenetic and phenotypic data, strain GR5$^T$ should be classified as a novel species, for which the name Rheinheimera aquatica sp. nov. is proposed. The type strain is GR5$^T$ (=BCRC 80081$^T$=LMG 25379$^T$).

• Korean Journal of Medicinal Crop Science
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• v.8 no.4
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• pp.342-350
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• 2000

This study was carried out to screen antioxidative by in vitro bioassay method from 89 Korean natural sources extracted by 100% MeOH. Antioxidant activity test was used the DPPH method. MeOH extracts from Castanea crenata and Ulmus davidiana var. japonica showed high antioxidant activity by $5.8{\mu}g\;(RC_{50})$ and $12.2{\mu}g\;(RC_{50})$, respectively, among 13 plants exhibiting the activity. The extracts from Platycarya strobilacea, Lindera erythrocarpa, Chrysanthemum boreale, Rumex crispus and Viburnum awabuki also showed over 90% antimicrobial activity, according to in vivo bioassay method.

• Journal of Microbiology and Biotechnology
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• v.26 no.6
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• pp.1026-1034
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• 2016

In the current study, a total of 135 enterococci strains from different sources were screened for the presence of the enterocin-encoding genes entA, entP, entB, entL50A, and entL50B. The enterocin genes were present at different frequencies, with entA occurring the most frequently, followed by entP and entB; entL50A and L50B were not detected. The occurrence of single enterocin genes was higher than the occurrence of multiple enterocin gene combinations. The 80 isolates that harbor at least one enterocin-encoding gene (denoted "Gene⁺ strains") were screened for antimicrobial activity. A total of 82.5% of the Gene⁺ strains inhibited at least one of the indicator strains, and the isolates harboring multiple enterocin-encoding genes inhibited a larger number of indicator strains than isolates harboring a single gene. The indicator strains that exhibited growth inhibition included Listeria innocua strain CLIP 12612 (ATCC BAA-680), Listeria monocytogenes strain CDC 4555, Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, S. aureus ATCC 29213, S. aureus ATCC 6538, Salmonella enteritidis ATCC 13076, Salmonella typhimurium strain UK-1 (ATCC 68169), and Escherichia coli BAC 49LT ETEC. Inhibition due to either bacteriophage lysis or cytolysin activity was excluded. The growth inhibition of antilisterial Gene⁺ strains was further tested under different culture conditions. Among the culture media formulations, the MRS agar medium supplemented with 2% (w/v) yeast extract was the best solidified medium for enterocin production. Our findings extend the current knowledge of enterocin-producing enterococci, which may have potential applications as biopreservatives in the food industry due to their capability of controlling food spoilage pathogens.