Of antibiotics

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 ... 

CONTROLLED RELEASE TECHNOLOGY - PHARMACEUTICAL] (Vol 7) -bacitracin treatment of [ANTIBIOTICS - PEPTIDES] (Vol 3)... 

Fractional extraction has been used in many processes for the purification and isolation of antibiotics from antibiotic complexes or isomers. A 2-propanol—chloroform mixture and an aqueous disodium phosphate buffet solution are the solvents (243). A reciprocating-plate column is employed for the extraction process (154). 

When a mminant is bom, it consumes colostmm within a few hours. Colostmm contains antibodies from the mother s milk that serve to immunize the neonate against disease (37). These antibodies can be absorbed by the neonate only within the first few days of its life there is no placental transfer of antibiotics in mminants (37). 

The modem fermentation industries developed from the early era of antibiotics. Over 4000 antibiotics have been discovered since the 1950s. However, only about 100 are produced on a commercial scale and over 40 of these are prepared by a combination of microbial synthesis and chemical modifications. Antibiotics produced by fermentation and used as starting materials in chemical syntheses are given in Table 2. 

China, the world s largest producer of antibiotics, had a volume that ex-ceeded 10,000 Values are estimates. tin 1991 (25). ... 

Lactic Acid B cteri. The lactic acid bacteria are ubiquitous in nature from plant surfaces to gastrointestinal tracts of many animals. These gram-positive facultative anaerobes convert carbohydrates (qv) to lactic acid and are used extensively in the food industry, for example, for the production of yogurt, cheese, sour dough bread, etc. The sour aromatic flavor imparted upon fermentation appears to be a desirable food trait. In addition, certain species produce a variety of antibiotics. 

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). 

Table 1. Benefits of Subtherapeutic Level of Antibiotic in Food-Producing Animals, % Improvement...

Mechanism of Action. The mechanisms by which antibiotic adrninistration at subtherapeutic levels enhance growth rate and efficiency of gain in growing animals have not been clarified. Possible modes of action include disease control, nutrient sparing, and metaboHc effects. There is extensive evidence that the principal benefit from subtherapeutic use of antibiotics results from the control of harmfiil microorganisms. 

The nutrient sparing effect of antibiotics may result from reduction or elimination of bacteria competing for consumed and available nutrients. It is also recognized that certain bacteria synthesize vitamins (qv), amino acids (qv), or proteins that may be utilized by the host animal. Support of this mode of action is found in the observed nutritional interactions with subtherapeutic use of antibiotics in animal feeds. Protein concentration and digestibiHty, and amino acid composition of consumed proteins may all influence the magnitude of response to feeding antibiotics. Positive effects appear to be largest... 

Chapman and Hall Chemical Database Chapman and Hall, Ltd. Dialog Dictiona of Organic Compounds (5th ed.), Dictiona of Organometallic Compounds, Carbohydrates, Mmino Mcids, Peptides, Dictionay of Antibiotics and Eelated Compounds, and Dictionay of Organophosphorus Compounds... 

Methyl acetoacetate (MAA) and ethyl acetoacetate (EAA) are the most widely used esters they are found ia the pharmaceutical, agricultural, and allied industries. Both esters are used extensively as amine protecting agents ia the manufacture of antibiotics and synthetic sweeteners (Dane Salts) (147). Principal outiets for MAA are the manufacture of the organophosphoms insecticide dia2inon [33341-5] (148,149) and the uracil herbicides bromacil [31440-9] and terbacil [5902-51-2] (150,151) (see Insect conztiol technology Herbicides). 

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