Tetracycline skeleton

The tetracyclines (Table 3.3) are a group of broad spectrum, orally active antibiotics produced by species of Streptomyces, and several natural and semi-synthetic members are used clinically. They contain a linear tetracyclic skeleton of polyketide origin in which the starter group is malonamyl-CoA (Figure 3.54), i.e. the coenzyme A ester of malonate semi-amide. Thus, in contrast to most acetate-derived compounds, malonate supplies all carbon atoms of the tetracycline skeleton, the starter group as well as the chain extenders. The main features of the pathway (Figure 3.54) were deduced from extensive studies of mutant strains of Streptomyces aureofaciens with genetic blocks... 

Scheme 6.29 Woodward s construction of the tetracycline skeleton by sequential anel-lation reactions...

M.p. 296 C. Accepts an electron from suitable donors forming a radical anion. Used for colorimetric determination of free radical precursors, replacement of Mn02 in aluminium solid electrolytic capacitors, construction of heat-sensitive resistors and ion-specific electrodes and for inducing radical polymerizations. The charge transfer complexes it forms with certain donors behave electrically like metals with anisotropic conductivity. Like tetracyanoethylene it belongs to a class of compounds called rr-acids. tetracyclines An important group of antibiotics isolated from Streptomyces spp., having structures based on a naphthacene skeleton. Tetracycline, the parent compound, has the structure ... 

The tetracyclines are a group of antibiotics having an identical 4-ring carbocycHc structure as a basic skeleton and differing from each other chemically only by substituent variation. Figure 1 shows the principal tetracycline derivatives now used commercially. 

The overall biosynthetic pathway to the tetracychnes has been reviewed (74). Studies (75—78) utilising labeled acetate and malonate and nmr analysis of the isolated oxytetracycline (2), have demonstrated the exclusive malonate origin of the tetracycline carbon skeleton, the carboxamide substituent, and the folding mode of the polyketide chain. Feeding experiments using [1- 02] acetate and analysis of the nmr isotope shift effects, led to the location of... 

DeMoss, D.L. and Wright, G.L. 1997 Analysis of whole skeleton 3H-tetracycline loss as a measure ofbone resorption in maturing rats. Calcified Tissue International 61 412 17. 

In the area of antibacterials, there are three important classes not yet mentioned. First, there are tetracyclines, the name reflecting their structural skeleton. Tetracycline itself... 

Tetracycline one of a class of antibacterials based on a tetracyclic skeleton and that act as a bacterial protein synthesis inhibitors. 

Tetracyclines (TCs) are chemically characterized by a partially conjugated octahydronaphtacene four-ring skeleton with a carboxyamide functional group. They are amphoteric compounds soluble in polar and moderately polar solvents, and they show the ability to form strong complexes... 

A number of anthracycline antibiotics, e.g. doxorubicin (Figure 3.56) from Streptomyces peuceticus and daunorubicin from S. coeruleoru-bicus, have structurally similar tetracyclic skeletons and would appear to be related to the tetracyclines. There are similarities in that the molecules are essentially acetate derived, but for... 

Correct answer = A. Most urinary tract infections are due to E. coii and can usually be treated with cotrimoxazole. However, this patient is near term and the sulfa in the cotrimoxazole might put the infant at risk due to kernicterus. Thus, the first generation cephalosporin, cefadroxil, is appropriate since it would be effective orally against penicillinase producing E. coii. Ceftriaxone, while it would be effective, would have to be administered parenterally. Penicillin V is not effective against E. coii. Tetracycline deposits in teeth and skeleton of the fetus and is contraindicated. 

Tetracyclines, consisting of a octahydronaphthacene skeleton, are broad-spectrum antibiotics produced by Streptomyces or obtained semisyntheticaUy. They can be separated both by RP and NP TLC. Cellulose,... 

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