Monensin analysis

Marecek and colleagues developed a new electrochemical method for the rapid quantitative analysis of the antibiotic monensin in the fermentation vats used during its production. The standard method for the analysis, which is based on a test for microbiological activity, is both difficult and time-consuming. As part of the study, samples taken at different times from a fermentation production vat were analyzed for the concentration of monensin using both the electrochemical and microbiological procedures. The results, in parts per thousand (ppt), are reported in the following table. 

Crooks et al. developed a monensin immunoassay for the detection of residues in broiler livers. Livers were homogenized in aqueous acetonitrile, subsequently extracted with sodium hydroxide followed with hexane-diethyl ether, and the remaining solvent was evaporated before reconstitution in buffer for analysis. The LOD (mean-I-3 SD) was 2.9qgkg and the LOQ (mean- -6SD) was 4.6p.gkg . Incurred samples showed considerable animal-to-animal variation, but all samples were below the detection limit after 3 days. 

Chromatographic analysis of the incurred livers showed how many metabolites were present in the analyzed extracts. It was found that only 7% of tire radioactivity detected in liver and 70% of that in fat were due to the presence of the parent monensin. The rapid metabolism and depletion of the unchanged monensin were attributed to (9-demetlrylation and oxidation at various positions along the carbon backbone of its molecule. 

The most widely used and researched growth promotant of this type is the polyether antibiotic monensin (63). Monensin, at levels of 33 p.p.m. in feed, has been shown to increase efficiency of feed utilization in both sheep and cattle fed a variety of rations by up to 12%. Slaughter and carcass analysis data indicate that the main effect of the compound is to increase the efficiency of dietary energy retention in the carcass. Its mode of action is thought to be related to its ability to increase the molar proportion of propionate, at the expense of acetate and butyrate, produced in rumen fermentation probably by an effect on the relative microfloral populations. Theoretically this should make more energy available to the animal. 

Quantification of five different drugs in pigs kidney Separation of carboxylic polyether antibiotics (monensin, salinomycin, and narasin) with an amino bonded phase and 15% methanol in carbon dioxide using light-scattering detector Analysis of hydroxylated metabolites of dialkyldithio-carbamates... 

Selected examples of other biocatalytic asymmetric oxidations are shown in Figure 20.10. In the area of the polyether ionophore monensin a recently proposed mechanism of oxidative cycUzation of a linear polyketide intermediate by four enzymes, the products of monBI, monBll, monCI, and monCII, has been supported experimentally by analysis of a biosynthetic gene cluster [110] and the accumulation of an B,F,F-triene, when oxidative cydization was blocked [111]. 

Y., Staunton, J. and Leadlay, P.F. (2003) Analysis of the biosynthetic gene cluster for the polyether antibiotic monensin in Streptomyces cinnamonensis and evidence for the role of monB and monC genes in oxidative cyclization. Molecular Microbiology. 49,1179-1190. 

A conformational analysis of naproxen anion and monensin sodium has been performed by the use of the /hc couplings. Especially extensive use of these couplings has been made by the authors in the case of the latter compound. They concluded that the conformation of monoensin in solution is very close to that in crystals. Further examples of the application of vicinal proton-carbon couplings in the conformational analysis of compounds include the NMR and quantum-chemical study of the stereochemistry of spiroepoxides obtained by oxidation of (Z)-3-arylidene-l-thioflavan-4-ones performed by Toth et and the elucidation of the structure of isomalyngamides A and B isolated from a collection of the cyanobacterium Lyngbya majuscula from Hawaiian waters by Kan et... 

Wallace KK, Zhao B, McArthur HAI, Reynolds KA. In vivo analysis of straight-chain and branched-chain fatty acid biosynthesis in streptomycetes. FEMS Lett 1995 131 227-234-Omura S, Tsuiuki K, Tanaka Y, Sakakibara H, Aiiawa M, Lukacs G. Valine as a precursor of n-butyrate unit in the biosynthesis of macroUde aglycone. J Antibiot 1983 36 614-616. Pospisil S, Sedmera P, Havtanek M. Kmmphanil V, Vanek Z. Biosynthesis of monensins A and B. J Antibiot 1983 36 617-619. 

Antibiotics form a large proportion of the remaining natural products which have been examined by X-t y analysis. The crystallographic interest in antibiotics centres both on the ability to form a variety of complexes with different metal ions, and also on the polarization of hydrophobic and hydrophilic properties within the moiecuies, since it has been suggested that both these features may be implicated in the biological functions of such molecules. One antibiotic, monensin (158), has been studied both as the free acid, and also as the silver(i) salt. In the metal complex, the... 

The Kishi synthesis ot monensin teatures allylic conformational analysis to predict stereochemistry of hydroboratlon-oxidations in acyclic systems. The Still synthesis features acyclic diastereoselection in carbonyl addition reactions (chelation control and Felkin-Ahn control). 

Monensin, a compound produced by Streptomyces cinnamonensis. is an inhibitor of alkali metal cation transport into rat liver mlto ondria and is claimed to have broad spectrum anticoccidial activity. The complete structure was determined by x-ray analysis of the silver salt. 

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