Cephalosporanic adds

Lactams, i.e., penicillins and cephalosporins, represent the most important class of antibiotics. Penicillins consist of a common core, 6-aminopenicillanic acid (6-APA) and different side chains. Penicillin G (pen G), with a phenyl acetate side chain, and penicillin V (pen V), with a phenoxyacetate side chain, are fermented from the fungus Penicillium chrysogenum all the others are produced from 6-APA, which nowadays is produced mostly from pen G via penicillin G amidase (pen G amidase, pen G acylase, PGA, E.C. 3.5.1.11 Figure 7.33). Cephalosporins feature 7-aminocephalosporanic acid (7-ACA) or its deacetyl-form, 7-aminodesacetyl-cephalosporanic add (7-ADCA) as their common core cephalosporin C (Ceph C) is obtained through fermentation, and all the others are derived from 7-A(D)CA. 

U,7i )-7-[(i )-2-amino-2-phenylacetamido]-3-chloro-8-oxo-5-thia-l-azabi[Pg.1502]

Amino Acids acides amin6s 7-Amino-cephalosporanic Add adde 7-amino-c6phalosporanique 6-Amino-penicillanic Add adde 6-amino-pdnicillanique... 

Cephalosporines are derived from natural cephalosporin C produced by Cephalosporinum acre-monium. They possess a cephem nucleus (7-amino-cephalosporanic acid) substituted with two side chains. They are commonly divided into three classes differing in their spectra and toxicity. Cephalosporines can be analyzed both by normal and reversed-phase TLC or HPTLC hence, more efficient separation is obtained on sUanized gel than on bare, untreated silica gel. Mobile phases are polar and similar to those used for penicillins. Acetic add or acetates are very often components of solvents for normal phase (NP) TLC, the ammonium acetate-acetic acid buffer for RP TLC. All cephalosporines can be detected at 254 nm. The detection limit can be diminished by applying reagents such as ninhydrin, iodoplatinate, chloroplatinic acid, or iodine vapor. Alternative to UV detection is bioautography with, for instance. Neisseria catarrhalis. 

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