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Antibiotic Activity (antibiotic + activity)
Selected AbstractsChemInform Abstract: Novel Microwave-Assisted One-Pot Synthesis of Heterocycle Phosphor Esters and Cyclic Oxophospholes with Antibiotic Activity.CHEMINFORM, Issue 6 2009Wafaa M. Abdou Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Convergent Ring-Closing Metathesis Approach to Carbohydrate-Based Macrolides with Potential Antibiotic Activity.CHEMINFORM, Issue 15 2006Petra Blom Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Antibiotic activity of pentadecapeptides modelled from amino acid descriptorsJOURNAL OF PEPTIDE SCIENCE, Issue 2 2001Tore Lejon Abstract Pentadecapeptides based on modified murine lactoferricin (LFM) sequences show varying degrees of antibacterial activity against Escherichia coli and Staphylococcus aureus. By means of projections to latent structures (PLS), a good correlation is obtained if the biological activity is modelled as a function of variables describing peptide properties, e.g. ,-helicity, hydrophobicity/hydrophilicity and charge. Using variables derived from a principal component analysis (PCA) of all naturally occurring amino acids, it is possible to describe the amino acid content of the peptides using three variables per amino acid position. The resulting descriptor matrix is then used to develop quantitative structure,activity relationships (QSAR). It is shown that the theoretically derived descriptors model the activity of the peptides better than the earlier model, and that properties of the peptides other than antibacterial activity can be predicted. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd. [source] Synthesis and Evaluation of S - and C(1) -Substituted Analogues of LincomycinHELVETICA CHIMICA ACTA, Issue 2 2009Marie-Pierre Collin Abstract New thioglycosides and C(1) -alkylated thioglycosides (S -ulosides) of lincomycin were synthesized, and their antibiotic activities were determined. The S -aryl and S -arylalkyl analogues 11a,11i were obtained by S -glycosylation of the sulfoxides 7 with arenethiols, or by S -alkylation of the thiol 14 with alkyl bromides. Lincomycin derivatives 27, 32a, 32b, 38a, 38b, 44, and 47 were prepared via Henry reaction or Michael addition of the lincosamine-derived 1-deoxy-1-nitropyranoses 22. The S -alkyl derivatives showed a similar activity and specificity as lincomycin. Lipophilic S -uloside analogues were two- to fourfold less active than the parent antibiotic, whilst the hydrophilic analogues were inactive. [source] Carolacton , A Macrolide Ketocarbonic Acid that Reduces Biofilm Formation by the Caries- and Endocarditis-Associated Bacterium Streptococcus mutans,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2010Rolf Jansen Abstract The macrolide ketocarbonic acid carolacton (1) was isolated from the myxobacterium Sorangium cellulosum, strainSo ce960, because of its antibiotic activity. Subsequently, carolacton (1) was discovered to be a highly potent agent against biofilms containing the caries- and endocarditis-associated bacterium Streptococcus mutans. The 2D structure of 1 was elucidated by HRMS, IR and 2D NMR spectroscopy. Initially, the stereogenic centres were determined by chemical derivatization in combination with computional methods and finally verified by X-ray analysis. [source] Permeation of tetracyclines through membranes of liposomes and Escherichia coliFEBS JOURNAL, Issue 2 2000Albrecht Sigler Uptake of tetracycline (tc), 2-tetracyclinonitrile (CN-tc), and 9-(N,N -dimethylglycylamido)-6-demethyl-6-deoxytetracycline (DMG-DMDOT) by liposomes containing Tet repressor (TetR) and by Escherichia coli cells overexpressing TetR was examined. TetR specifically binds to tetracyclines, enhances their fluorescence and thereby allows selective detection of tetracyclines that have crossed the membranes. Analysis of the diffusion of tc and DMG-DMDOT into liposomes yielded permeation coefficients of (2.4 ± 0.6) × 10,9 cm·s,1 and (3.3 ± 0.8) × 10,9 cm·s,1, respectively. Similar coefficients were obtained for uptake of these tetracyclines by E. coli, indicating that diffusion through the cytoplasmic membrane is the rate-limiting step. The permeation coefficients translate into half-equilibration times of approximately 35 ± 15 min and explain how efflux pumps can mediate resistance against tetracyclines. Furthermore, diffusion of CN-tc into liposomes was at least 400-fold slower than that of tc, indicating that the carboxamide group at position C2 is required for efficient permeation of tc through lipid membranes and thereby explaining the lack of antibiotic activity of CN-tc. [source] Bacillus cereus is common in the environment but emetic toxin producing isolates are rareJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2006M. Altayar Abstract Aims:, To determine the incidence of emetic toxin producing Bacillus cereus in soil, animal faeces and selected vegetable produce to compare the results with the previously reported high incidence in rice paddy fields. To examine whether the emetic toxin has antibiotic activity. Methods and Results:, The incidence of emetic toxin producing B. cereus was evaluated by plating on selective agar 271 samples of soils, animal faeces, raw and processed vegetables. Overall, 45·8% of samples were positive for B. cereus. One hundred and seventy-seven B. cereus isolates were recovered at 30°C with the grand mean spore count being 2·6 ± 1·7 log10 CFU g,1 and 148 B. cereus isolates were recovered at 7°C with the grand mean spore count being 2·2 ± 1·2 log10 CFU g,1 of the177 B. cereus isolated at 30°C, only 3 were positive for emetic toxin production at a titre of 1/64, 1/32, 1/16, respectively. Also, 1 of 148 B. cereus isolated at 7°C was positive for emetic toxin production to a titre of 1/128. All positive isolates came from washed or unwashed potato skins, one was psychrotrophic as determined by PCR and growth at 7°C on subculture. The emetic toxin was not shown to have any antibiotic effects in growth inhibition studies. Conclusions:, While B. cereus was a common isolate, the incidence of the emetic strain was rare. This is in contrast to previous findings of the high incidence in rice paddy fields and the processing environment, which may suggest rice is a selective area for growth of the emetic strain of B. cereus. Significance and Impact of Study:, The finding that a psychrotrophic isolate of B. cereus can produce emetic toxin is the first ever such observation and suggests the possibility that psychrotrophic isolates could grow in refrigerated fresh foods and cause emesis. The incidence of emetic B. cereus strains in rice paddy fields now requires further study for comparison with the low incidence found in other soils. The emetic toxin failed to inhibit the growth of other bacterial, fungal and yeast species. Whether the toxin (which is similar in structure to the antibiotic valinomycin) plays a competitive role in the environment therefore remains unclear. [source] HP(2,9)-magainin 2(1,12), a synthetic hybrid peptide, exerts its antifungal effect on Candida albicans by damaging the plasma membraneJOURNAL OF PEPTIDE SCIENCE, Issue 4 2004Yoonkyung Park Abstract In our previous study, HP(2,9)-MA(1,12), HP-MA for short, a hybrid peptide incorporating residues 2,9 of Helicobacter pylori ribosomal protein L1 (HP) and residues 1,12 of magainin 2 (MA) was shown to have strong antibacterial activity. In this study the antifungal activity of HP-MA was evaluated using various fungi, and it was shown that the activity was increased when compared with the parent peptides. In order to investigate the fungicidal mechanism(s) of HP-MA its action against fungal cell membranes was examined by the potassium-release test, which showed that HP-MA caused an increase in the amount of K+ released from the cells. Furthermore, HP-MA induced significant morphological changes. These facts suggested that the fungicidal effect of HP-MA involves damaging the fungal cell membranes. CD investigators suggested that the ,-helical structure of these peptides plays an important role in their antibiotic effect, but that ,-helicity is less directly correlated with the enhanced antibiotic activity of the hybrid. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source] Synthesis and study of a gramicidin B mutant possessing a ditryptophan crosslinkJOURNAL OF PEPTIDE SCIENCE, Issue 9 2002Alice L. Presley Bodnar Abstract Recent studies of peptide dimers linked by Trp-Trp (ditryptophan) crosslinks suggest that the crosslinks can reinforce antiparallel ,-structure. Depending on environment, gramicidins A, B and C form either helical ion channels with parallel ,-structure or non-functional pores with antiparallel ,-structure. In the channel conformation of the gramicidins Trp9 and Trp15 are close in space, but in the pore conformation Trp9 and Trp15 are far apart. We hypothesized that a ditryptophan crosslink between Trp9 and Trp15 could pre-organize gramicidin in an active conformation. To test the potential for pre-organization, an intramolecular ditryptophan crosslink was formed between Trp9 and Trp15 in a W13F mutant of gramicidin B. Photooxidative conditions were shown to generate ditryptophan crosslinks in low yields. While not preparatively useful, photooxidative tryptophan crosslinking may have implications for protein aging processes like cataract formation. The ditryptophan crosslink in the gramicidin B mutant substantially lowered the antibiotic activity of the gramicidin B mutant, unlike the ditryptophan crosslink in the antibiotic X-indolicidin. The biaryl chromophore generated diagnostic Cotton effects in the CD spectrum that revealed the absolute stereochemistry of the biaryl chromophore, but the biaryl chromophore obscured diagnostic features below 220 nm. However, changes in peptide conformation were reflected in changes in the biaryl region of the CD spectrum above 240 nm. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd. [source] Activity of Zanthoxylum clava-herculis extracts against multi-drug resistant methicillin-resistant Staphylococcus aureus (mdr-MRSA)PHYTOTHERAPY RESEARCH, Issue 3 2003Simon Gibbons Abstract In a continuing search for compounds with antibiotic activity against methicillin-resistant Staphylococcus aureus (MRSA) possessing multidrug ef,ux systems, we have demonstrated activity associated with extracts from Southern prickly ash bark, Zanthoxylum clava-herculis. Bioassay-guided isolation of an alkaloid extract led to the characterization of the benzo[c]phenanthridine alkaloid chelerythrine as the major active principle. This compound exhibited potent activity against strains of MRSA, which were highly resistant to clinically useful antibiotics via multidrug ef,ux mechanisms. Copyright © 2003 John Wiley & Sons, Ltd. [source] Recurrent selection for maysin, a compound in maize silks, antibiotic to earwormPLANT BREEDING, Issue 4 2001N. W. Widstrom Abstract A thorough knowledge of the inheritance of maysin, a flavone glycoside with antibiosis to corn earworm, Helicoverpa zea Boddie, in the silks of maize will assist breeders in choosing the most efficient method of incorporating this trait into elite inbreds. Two breeding populations, one having exotic origin (EPM), the other from southern inbred lines (SIM) were subjected to six cycles of recurrent selection for increased silk maysin. Ten per cent of the individuals evaluated in populations were selected for recombination as S1 progenies in each cycle. Progress was evaluated as C0 to C6 population cycles in a randomized complete-block experiment with five replications in 1997 and 1998. Maysin fresh weights in silks of the C0 populations were 0.54% for EPM and 0.36% for SIM. Responses of 0.19% per cycle in EPM and 0.22% per cycle in SIM resulted in an EPM (C6) population with 1.76% maysin and an SIM (C6) population with 1.69% maysin. Silk maysin concentrations above 0.2% begin to substantially reduce larval growth and prevent completion of the life cycle when husk coverage is sufficient to force the insect to feed on silks while entering the ear. Chlorogenic acid and two analogues of maysin, apimaysin and 3,-methoxymaysin, were found in such minor quantities in silks that they could not be credited with any impact on antibiotic activity against the insect. Selection has effectively increased silk maysin concentration in both EPM and SIM. Trait responses for maysin are highly heritable and will allow the plant breeder to introgress resistance to the corn earworm into elite material easily. [source] Mixed aryl,alkyl organotin compounds, ArnMeSnCl3,n (Ar = RC6H4, R = H, ethyl, i-propyl, t-butyl; n -hexyl, n -octyl) and the effect of R upon antibiotic activity,APPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2005Ramesh N. Kapoor Abstract The synthesis of a new series of arylmethyltin chlorides is reported, ArnMeSnCl3,n (Ar = RC6H4, R = H, ethyl, i-propyl, t-butyl; hexyl, octyl). The synthesis involves initial formation of triarylmethyltin compounds, Ar3MeSn, via Grignard techniques followed by HCl,Et2O aryl group cleavage, preferably in a stepwise manner. Preliminary biological activity against Staphylococcus aureus illustrates the importance of the para-alkyl substituents and reinforces that an optimal hydrophobic character is needed for maximum efficacy. Copyright © 2005 John Wiley & Sons, Ltd. [source] Oxytetracycline inactivation by putative reactive oxygen species released to nutrient medium of Helianthus annuus hairy root cultures,BIOTECHNOLOGY & BIOENGINEERING, Issue 4 2005Ninad P. Gujarathi Abstract When subjected to stress, plants produce reactive oxygen species (ROS) as a part of the defense response. The oxidative response is also used to degrade organic pollutants. Hairy roots of Helianthus annuus (sunflower) are shown to oxidize oxytetracycline (OTC) through the action of the ROS released to the nutrient medium by the hairy root cultures. Methyl jasmonate (MeJA) elicits ROS formation in the hairy root cultures. The activities of the antioxidant enzymes, ascorbate peroxidase (APX), catalase (CAT), and guaiacol peroxidase (GPX), are reported for hairy root cultures treated with increasing concentrations of MeJA. A bioassay using Enterococcus hirae as the test microorganism demonstrates the root-catalyzed oxidation process results in conversion of OTC into product(s) devoid of antibiotic activity. Direct evidence for putative ROS oxidation of OTC is obtained by mass spectrometry (MS) and HPLC/MS showing first quinone formation followed possibly by ring cleavage, which disrupts UV absorption and destroys antibiotic activity. © 2005 Wiley Periodicals, Inc. [source] Organisation of the Biosynthetic Gene Cluster and Tailoring Enzymes in the Biosynthesis of the Tetracyclic Quinone Glycoside Antibiotic PolyketomycinCHEMBIOCHEM, Issue 6 2009Martina Daum Abstract Surprising results regarding the function of methyltransferases and oxygenases: Investigations on oxygenase and methyltransferase genes that are located in the polyketomycin biosynthetic gene cluster of Streptomyces diastatochromogenes Tü6028 shed light into polyketide-modifying reactions. Polyketomycin is a tetracyclic quinone glycoside produced by Streptomyces diastatochromogenes Tü6028. It shows cytotoxic and antibiotic activity, in particular against Gram-positive multi-drug-resistant strains (for example, MRSA). The polyketomycin biosynthetic gene cluster has been sequenced and characterised. Its identity was proven by inactivation of a ,-ketoacyl synthase gene (pokP1) of the "minimal polyketide synthase II" system. In order to obtain valuable information about tailoring steps, we performed further gene-inactivation experiments. The generation of mutants with deletions in oxygenase genes (pokO1, pokO2, both in parallel and pokO4) and methyltransferase genes (pokMT1, pokMT2 and pokMT3) resulted in new polyketomycin derivatives, and provided information about the organisation of the biosynthetic pathway. [source] Medicinal Chemistry Optimization of Acyldepsipeptides of the Enopeptin Class AntibioticsCHEMMEDCHEM, Issue 7 2006Berthold Hinzen The therapy of life-threatening infections is significantly weakened by the global spread of antibiotic resistance. Synthetic exploration of enopeptin type acyldepsipeptide antibiotics revealed a remarkable structure,activity relationship. New compounds with improved in,vitro antibiotic activity against Gram-positive pathogens (including multiresistant strains) and in,vivo activity in mouse models of lethal infection are described. [source] | |||||||||||||