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At least 19 recordsLinked to original sources
PubMed1975

The mode of action of pleuromutilin derivatives. Location and properties of the pleuromutilin binding site on Escherichia coli ribosomes.

Using equilibrium dialysis techniques it could be demonstrated that (a) the pleuromutilin derivative 14-deoxy-14[(2-diethylaminoethyl)-mercaptoacetoxy] dihydromutilin HCl binds to one site per ribosome specifically, (b) the binding constant is 1.3 times 10(7) M(-1) and (c) chloramphenicol and puromycin compete with binding of the pleuromutilin derivative. Similarly the nucleotides CpA and CpCpA also displace the unsaturated derivative of the above-mentioned pleuromutilin compound. These findings suggest that the ribosomal binding site for pleuromutilin overlaps with that for chloramphenicol and analogs of the 3'-terminus of a tRNA, like puromycin or the nucleotides CpA and CpCpA.

Anti-Bacterial Agents↗
PubMed2006

Interaction of pleuromutilin derivatives with the ribosomal peptidyl transferase center.

Tiamulin is a pleuromutilin antibiotic that is used in veterinary medicine. The recently published crystal structure of a tiamulin-50S ribosomal subunit complex provides detailed information about how this drug targets the peptidyl transferase center of the ribosome. To promote rational design of pleuromutilin-based drugs, the binding of the antibiotic pleuromutilin and three semisynthetic derivatives with different side chain extensions has been investigated using chemical footprinting. The nucleotides A2058, A2059, G2505, and U2506 are affected in all of the footprints, suggesting that the drugs are similarly anchored in the binding pocket by the common tricyclic mutilin core. However, varying effects are observed at U2584 and U2585, indicating that the side chain extensions adopt distinct conformations within the cavity and thereby affect the rRNA conformation differently. An Escherichia coli L3 mutant strain is resistant to tiamulin and pleuromutilin, but not valnemulin, implying that valnemulin is better able to withstand an altered rRNA binding surface around the mutilin core. This is likely due to additional interactions made between the valnemulin side chain extension and the rRNA binding site. The data suggest that pleuromutilin drugs with enhanced antimicrobial activity may be obtained by maximizing the number of interactions between the side chain moiety and the peptidyl transferase cavity.

Anti-Bacterial Agents↗
PubMed1976

Studies on pleuromutilin and some of its derivatives.

A number of derivatives of pleuromutilin (I) and of its degradation product, mutilin (II1, was prepared. The new monotosylation product of pleuromutilin (IIIc) served as the key substance for modification of the glycolic acid side chain. From the pleuromutilin monosuccinate (IIIk) water-soluble salts were obtained, among them the crystallized diethylaminoethanol salt that was investigated more closely. Some of the pleuromutilin derivatives showed antimicrobial activity.

Anti-Bacterial Agents↗
PubMed2004

Inhibition of peptide bond formation by pleuromutilins: the structure of the 50S ribosomal subunit from Deinococcus radiodurans in complex with tiamulin.

Tiamulin, a prominent member of the pleuromutilin class of antibiotics, is a potent inhibitor of protein synthesis in bacteria. Up to now the effect of pleuromutilins on the ribosome has not been determined on a molecular level. The 3.5 A structure of the 50S ribosomal subunit from Deinococcus radiodurans in complex with tiamulin provides for the first time a detailed picture of its interactions with the 23S rRNA, thus explaining the molecular mechanism of the antimicrobial activity of the pleuromutilin class of antibiotics. Our results show that tiamulin is located within the peptidyl transferase center (PTC) of the 50S ribosomal subunit with its tricyclic mutilin core positioned in a tight pocket at the A-tRNA binding site. Also, the extension, which protrudes from its mutilin core, partially overlaps with the P-tRNA binding site. Thereby, tiamulin directly inhibits peptide bond formation. Comparison of the tiamulin binding site with other PTC targeting drugs, like chloramphenicol, clindamycin and streptogramins, may facilitate the design of modified or hybridized drugs that extend the applicability of this class of antibiotics.

Crystallography, X-Ray↗
PubMed1976

Pleuromutilins. Fermentation, structure and biosynthesis.

Derivatives of pleuromutilin, formed during the fermentation of pleuromutilin, were isolated and their structure determined. 14-Acetyl-mutilin and mutilin as well as different unsaturated fatty acid esters of pleuromutilin were identified. The proportion of each derivative formed depends to a considerable degree on the conditions of the fermentation process. The possible biosynthetic pathways are shown.

Agaricales↗
PubMed1976

New pleuromutilin derivatives with enhanced antimicrobial activity. I. Synthesis.

A series of new derivatives of the antibiotic pleuromutilin, produced by some Basidiomycetes, was synthesized by chemical modification of natural pleuromutilin. Most of them contain basic functional groups in the side chain at C14 of the mutilin skeleton. The monotosylate of pleuromutilin was used as a versatile intermediate for displacement by N-, O- and S-nucleophiles.

Anti-Bacterial Agents↗
PubMed2001

Susceptibility to pleuromutilins in Brachyspira (Serpulina) hyodysenteriae.

The pleuromutilins are the only antimicrobial agents with sufficient minimum inhibitory concentration (MIC) values left to treat swine dysentery in Sweden. Other antimicrobials are either not approved for use against swine dysentery or only partly active against Brachyspira hyodysenteriae. To date, in Sweden two pleuromutilins, tiamulin and valnemulin, are authorized for use in pigs. This study includes a comparison between MICs of tiamulin and valnemulin for Swedish field isolates of B. hyodysenteriae, as determined by broth dilution. For different isolates the MIC of tiamulin was between 0 and 8 times higher than that of valnemulin. No resistance to pleuromutilins was recorded (tiamulin MIC range 0.031-2 microg/ml, valnemulin MIC range < or =0.016-1 microg/ml). In vitro development of tiamulin resistance was also studied. Two B. hyodysenteriae and two B. pilosicoli strains became resistant to tiamulin following reiterated passages on agar containing tiamulin in increasing concentrations. The resistance emerged slowly and three of the strains that went through more than 60 passages increased their tiamulin MICs from 0.031-0.25 to more than 128 microg/ml. The tiamulin MIC for one B. hyodysenteriae strain that went through 29 passages increased from 0.0125 to 4 microg/ml. One B. pilosicoli strain developed cross-resistance to valnemulin; the MIC increased from 0.25 to more than 64 microg/ml. The valnemulin MIC for one B. hyodysenteriae strain increased from 0.031 microg/ml to 32 microg/ml. Valnemulin MIC was not determined for the B. hyodysenteriae strain that only went through 29 passages. The valnemulin MIC of the other B. pilosicoli strain increased from 0.031 to 4 microg/ml.

Animals↗
PubMed2003

Synthesis and activity of a C-8 keto pleuromutilin derivative.

A C-8 keto pleuromutilin derivative has been synthesized from the biotransformation product 8-hydroxy mutilin. A key step in the process was the selective oxidation at C-8 of 8-hydroxy mutilin using tetrapropylammonium perruthenate. The presence of the C-8 keto group precipitated interesting intramolecular chemistry to afford a compound (10) with a novel pleuromutilin-derived ring system.

Biotransformation↗
PubMed2001

Pleuromutilins. Part 1. The identification of novel mutilin 14-carbamates.

A novel series of mutilin 14-carbamates has been discovered as a result of structure-activity studies on the naturally occurring antibiotic pleuromutilin (1). In particular, the 4-methoxybenzoylcarbamate, SB-222734 (15o) displays potent antibacterial activity against a number of bacterial pathogens which are resistant to currently used agents and shows enhanced metabolic stability when compared to earlier pleuromutilin derivatives. Such derivatives therefore have the potential to provide a new class of antibacterial agents for human therapy which address the threat of bacterial resistance.

Anti-Bacterial Agents↗
PubMed2001

Treatment of resistant mycoplasma infection in immunocompromised patients with a new pleuromutilin antibiotic.

Patients with primary antibody deficiency (PAD) are prone to mycoplasma infection with unusual strains which may be resistant to conventional antibiotics. Mycoplasmas were isolated from the joint fluid (Ureaplasma urealyticum) of two PAD patients with arthritis and from the cerebral spinal fluid (Mycoplasma maculosum) in one with meningitis, the latter probably originating from the patient's dog. Combinations of doxycycline and quinolones or macrolides failed to clear the infections, but after demonstrating in-vitro sensitivity to the pleuromutilin, Econor, for two of the isolates, all three patients responded to oral treatment with Econor. The infection was completely eradicated in two patients, with the emergence of a resistant strain in the third. Mycoplasma infection should be considered in PAD patients with unexplained sepsis. Pleuromutilins such as Econor are powerful new anti-mycoplasmal agents which provide an additional therapeutic option when patients fail to respond to conventional antibiotics.

Adolescent↗
PubMed2006

The Cfr rRNA methyltransferase confers resistance to Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A antibiotics.

A novel multidrug resistance phenotype mediated by the Cfr rRNA methyltransferase is observed in Staphylococcus aureus and Escherichia coli. The cfr gene has previously been identified as a phenicol and lincosamide resistance gene on plasmids isolated from Staphylococcus spp. of animal origin and recently shown to encode a methyltransferase that modifies 23S rRNA at A2503. Antimicrobial susceptibility testing shows that S. aureus and E. coli strains expressing the cfr gene exhibit elevated MICs to a number of chemically unrelated drugs. The phenotype is named PhLOPSA for resistance to the following drug classes: Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A antibiotics. Each of these five drug classes contains important antimicrobial agents that are currently used in human and/or veterinary medicine. We find that binding of the PhLOPSA drugs, which bind to overlapping sites at the peptidyl transferase center that abut nucleotide A2503, is perturbed upon Cfr-mediated methylation. Decreased drug binding to Cfr-methylated ribosomes has been confirmed by footprinting analysis. No other rRNA methyltransferase is known to confer resistance to five chemically distinct classes of antimicrobials. In addition, the findings described in this study represent the first report of a gene conferring transferable resistance to pleuromutilins and oxazolidinones.

Anti-Bacterial Agents↗
PubMed1975

Antimicrobial activities of 81.723 hfu, a new pleuromutilin derivative.

The new pleuromutilin derivative 81.723 hfu is extremely active against gram-positive organisms such as streptococci, staphylococci, and against mycoplasmas. A number of Shigella, Klebsiella, and Escherichia coli strains were also found to be quite susceptible to this new agent, whereas other gram-negative organisms like Pseudomonas aeruginosa, Proteus species, and Alcaligenes faecalis proved to be naturally resistant to 81.723 hfu. The new compound acts bacteriostatically. Bactericidal effects have been observed only at concentrations which are 100-fold higher than the minimal inhibitory concentrations. The new antibiotic is well tolerated in all animal species tested so far and has been successfully used in the treatment of experimental infections with gram-positive organisms and with mycoplasmas in mice and rats. Resistance against this new compound arose gradually in all microorganisms investigated. It is noteworthy that the rate at which resistance against 81.723 hfu emerged in mycoplasmas (Mycoplasma gallisepticum and Mycoplasma hyorhinis) was significantly slower than the corresponding rate at which resistance against tylosin tartrate appeared. Mycoplasma strains which became insensitive to 81.723 hfu were also resistant to tylosin tartrate, whereas mycoplasmas which developed resistance against tylosin tartrate, although less sensitive to 81.723 hfu than wild-type strains, were still eliminated by this drug. In a strain of Klebsiella pneumoniae, complete cross-resistance was observed between the pleuromutilin derivative on one hand and lincomycin and erythromycin on the other. Modest degrees of cross-resistance were also observed with chloramphenicol. However, it appears unlikely that the latter phenomenon is sufficiently pronounced to affect treatment with either antibiotic.

Agaricales↗
PubMed1975

In vivo efficacy of 81.723 hfu, a new pleuromutilin derivative against experimentally induced airsacculitis in chicks and turkey poults.

The efficacy of the pleuromutilin derivative 81.723 hfu was tested in chicks and turkey poults by experimentally infecting them with Mycoplasma gallisepticum. The data were treated to obtain the mean effective doses, and these were compared to those obtained with tylosin tartrate. The compounds were administered either by ingluvial catheter or via the drinking water. Therapy was started on the day of inoculation or 7 days thereafter, respectively. The experiments showed that the compound 81.723 hfu was significantly more active in chickens than tylosin tartrate by both methods of administration of drinking water. In turkey poults the pleuromutilin derivative and tylosin tartrate had comparable activity.

Air Sacs↗
PubMed1981

Affinity labeling of Escherichia coli ribosomes with a covalently binding derivative of the antibiotic pleuromutilin.

Reaction of an alkylating pleuromutilin derivative with E. coli ribosomes led to the binding of the compound to both proteins and RNA. If ribosomes of the E. coli strain MRE600 were used, mainly S18 and L2 became labeled. Ribosomes from E. coli D10 bound the reagent to S18 and frequently to L27 instead of L2. Possibly at slight difference in the structure of these ribosomes exposes different, although closely neighboring, L proteins to the reagent. The simultaneous labeling of L and S proteins seems to reflect the presence of two binding sites for the antibiotic and indicates that the binding sites are located at the interphase region between large and small ribosomal subunits. Analysis of the RNA showed that the affinity label is mainly attached to the 23S species. These data are in good agreement with the known effects of pleuromutilin derivatives on ribosomal functions.

Affinity Labels↗
PubMed1976

New pleuromutilin derivatives with enhanced antimicrobial activity.II.Structure-activity correlations.

Structural modification of the antibiotic pleuromutilin has afforded several derivatives with considerably enhanced activity against bacteria and mycoplasmas, and has permitted conclusions to be reached about structure-activity relationships. The carbonyl group in the five-membered ring and the hydroxyl group at C11 seem to be essential for activity. The vinyl group can be hydrogenated without loss of activity. Chemical modification at C14 offers the most possibilities for achieving the best activity and solubility properties. Mutilin, and other compounds with a free OH at C14, are inactive. It was shown that mutilin esters of substituted thioglycolic acids had distinctly superior MIC values, especially in combination with a tertiary amino group in the side chain, the latter group of derivatives having MIC values better than pleuromutilin by a factor of more than 10. Further variation within this group led to the development of 14-deoxy-14-[(2-diethylaminoethyl) thioacetoxy]-mutilin hydrogen fumarate (81.723 hfu, tiamulin) for extensive investigation of its chemotherapeutic potential.

Anti-Bacterial Agents↗
PubMed2006

Cyclopentanone ring-cleaved pleuromutilin derivatives.

Ring-cleaved pleuromutilin derivatives comprised of a [5.3.1] bicyclic core structure have been synthesized and evaluated in vitro as antibacterial agents. Four of the compounds described were found to have MICs<or=4 microg/mL against marker strains of Streptococcus pneumoniae and Staphylococcus aureus.

Anti-Bacterial Agents↗