4- Erythromycin

Erythromycins. A shunt metabolite of erythromycin biosynthesis has been isolated from the ferQientation broth of a block mutant of Streptomyces erythraeus, and structure (107) was determined for the compound 

Maridomycins. The maridomycins are a new group of macrolide antibiotics from Streptomyces hygroscopicus and are designated maridomycins I— VI. The aglycones of the antibiotics have the general structure (108).  

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Erythromycin is active against gram-positive and certain gram-negative bacteria, also against Rickettsia and spirochaetes. It is used for patients who are allergic to or do not respond to treatment with penicillins or tetracyclines. 

Erythromycins from Streptomyces erytkreua strains are probably the structurally most complex of the best selling drugs. Erythromycin A costs only about 5 DM per gram. The two principal erythromycins A and B differ only with respect to hydroxylation at C-12. 

Many natural products are lactones and it is not unusual to find examples m which the ring size is rather large A few naturally occurring lactones are shown m Figure 19 8 The macrohde antibiotics of which erythromycin is one example are macrocychc (large ring) lactones The lactone ring of erythromycin is 14 membered... 

A new countercurrent continuous centrifugal extractor developed in the former USSR (214) has the feature that mechanical seals are replaced by Hquid seals with the result that operation and maintenance are simplified the mechanical seals are an operating weak point in most centrifugal extractors. The operating units range between 400 and 1200 mm in diameter, and a capacity of 70 m /h has been reported in service. The extractors have been appHed in coke-oven refining (see Coal conversion processes), erythromycin production, lube oil refining, etc. 

Antibiotics. Solvent extraction is an important step in the recovery of many antibiotics (qv) such as penicillin [1406-05-9] streptomycin [57-92-17, novobiocin [303-81-1J, bacitracin [1405-87-4] erythromycin, and the cephalosporins. A good example is in the manufacture of penicillin (242) by a batchwise fermentation. Amyl acetate [628-63-7] or -butyl acetate [123-86-4] is used as the extraction solvent for the filtered fermentation broth. The penicillin is first extracted into the solvent from the broth at pH 2.0 to 2.5 and the extract treated with a buffet solution (pH 6) to obtain a penicillin-rich solution. Then the pH is again lowered and the penicillin is re-extracted into the solvent to yield a pure concentrated solution. Because penicillin degrades rapidly at low pH, it is necessary to perform the initial extraction as rapidly as possible for this reason centrifugal extractors are generally used. 

Antibiotics. The genes involved in the synthesis of a variety of antibiotics have been isolated (34,35). These include antibiotics such as erythromycin, streptomycin, and also peptide antibiotics such as gramicidin and tyrocidin. Characterization of these gene products facUitates the design of novel antibiotics. In addition, overexpression of some of these gene products is also expected to improve the yield of the antibiotic (34,35). 

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