نتایج جستجو برای: monobactams
تعداد نتایج: 1571 فیلتر نتایج به سال:
Jadomycins are anticancer antibiotics isolated from Streptomyces venezuelae. The core of these natural products consists of a dihydro-phenanthridine ring-system. Another unique feature built to the core is a fused 1,3-oxazolidine-5-one ring. Recent synthetic reports suggest a structural revision of the fused oxazolidinone ring in jadomycin S and jadomycin T. This review will focus on the synthe...
In searching for macromolecular antitumor antibiotics, a new screening method was developed that consisted of 1) a macromolecular antibiotic detecting system employing macro-molecule permeable mutants of Escherichia coli, 2) a system to detect DNA-affecting antibiotics using DNA repair mutants, and 3) a mutagenicity detecting system, employing a valine resistance test. This new test system was ...
The synthesis and uses of different kinds of carbohydrate-based lactones are described. This group of compounds includes aldonolactones, other related monocyclic lactones and bicyclic systems. The latter can arise from uronic acids, carboxymethyl ethers or glycosides, or from C-branched sugars.
Macrolide antibiotics are widely used for a range of indications, including pneumonia. Both high-level and low-level resistance to macrolides is increasing in pneumococci globally. Macrolide resistance in pneumococci is of limited clinical relevance where ß-lactams remain the mainstay of treatment, such as for moderate/severe pneumonia; however, data suggest that macrolides may not be able to b...
Bleomycins, a group of glycopeptide antibiotics differ from one another in their terminal amine moieties. 14C-Methyl-labeled 3-aminopropyl-dimethylsulfonium was confirmed to be incorporated into the amine moiety of bleomycin A2. Addition of amines of bleomycin A2, A2'-a, A2'-b, A2'-c, A5, B2 and B4 to fermentation media increased the rate of production of the bleomycin which contained the added...
A concise synthesis of the marine alkaloids (-)-lepadins A-C from a phenylglycinol-derived tricyclic lactam is reported. Key steps from the stereochemical standpoint involve stereoselective cyclocondensation, double bond hydrogenation, oxazolidine opening, hydroboration-oxidation, and Horner-Wadsworth-Emmons reactions.
We report methods to generate protoplasts, to regenerate mycelia, and to transform Micromonospora echinospora. This actinomycete produces the unusual antitumor antibiotics, the calicheamicins. These protocols may be applied to other actinomycetes that have been difficult to transform. These methods also may facilitate the cloning of calicheamicin biosynthetic genes by genetic complementation.
A nonmucoid colonial variant of a mucoid Bacillus subtilis strain produced less amylase activity and a transparent colonial variant of a B. licheniformis strain produced less protease activity compared with their parents. Antibiotic susceptibility patterns of the colonial variants differed, and increased resistance to beta-lactam antibiotics was correlated with increased production of extracell...
R-factor strains which are streptomycin-resistant and spectinomycin-sensitive have been found to inactivate streptomycin by a new mechanism. The 3'-OH group of the 2-deoxy-2-methylamino-l-glucopyranosyl moiety is phosphorylated.
The in vitro antimicrobial susceptibility of Yersinia enterocolitica and newly related species isolated from foods was examined. Only 4 of 375 isolates displayed resistance to non-ss-lactam antibiotics. MICs of ampicillin and carbenicillin determined by agar dilution with respect to 125 isolates showed the high susceptibility of Y. kristensenii and biovar 3 of Y. enterocolitica to carbenicillin...
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