Penicillin

Penicillin mostly use as antibiotic agent in a medical cure. A number of penicillin, differing only in the composition of the R-group, have been isolated from natural media, and hundreds have been semisynthesized. Penicillin G USP, with benzyl for R, generally the most clinically desirable, is the type commercially available usually combined in salt from with procaine or potassium.

Not only was penicillin the first antibiotic to be produced for widespread use, but it is important in quantities made and in general usefulness. It is practically nontoxic and is one of the most active antimicrobial agents known. Hypersensitivity reactions occur in about 10% of patients. It is also useful in animal feeds to promote growth. It is a tribute to the pharmaceutical industry that the price of penicillin has been reduced from the initial price of $ 25,000 per gram to $ 35 per kilogram for procaine penicillin, with a production of over 2950 ton in 1981.

It is possible to synthesis of a desired penicillin by supplying the appropriate precursor to the culture, i.e. the acid of the side chain which appears in the amide linkage with 6-aminopenicillanic acid in final product. The mold preferentially incorporates the precursor added into the corresponding penicillin to the relative exclusion of other precursors present in or formed from the nutrient raw materials in the medium. Thus, to produce benzylpenicillin, the precursor phenilacetic acid is used. Several hundred modifications of the penicillin molecule not found in nature have been made by altering the side chain (B) by use of the appropriate precursor in the fermentation. An important modification is penicillin V (V-cillin K, Lilly, potassium phenoxymethyl penicillin), which is produced biosynthetically by using phenoxyacetic acid as a precursor.