CEPHALOSPORINS

The cephalosporins are antibiotics obtained by Brotzu (1945) from species of the fungus Cephalosporium whose culture medium was active against typhoid. Componds having three different chemical structures have been isolated from Cephalosporium. One of these, cephalosporin P, has a steroid structure. It possesses low antibacterial properties and is not used as medicine. Another antibiotic, cephalosporin C, possesses an α-aminoadipoyl side chain and a β-lactam ring, but on hydrolysis it does not yield penicillamine as in case of penicillin.

The removal of the side chain from cephalosporin C gives 7-aminocephalosporanic acid (7-ACA) which provides a means of synthesizinga whole new range of cephalosporins. Treatment with nitrosyl chloride yields an intermediate iminolactone which is then hydrolyzed with water to give α-hydroxyadipic acid and 7-aminocephalosporanic acid.

The antibiotic cephalosporin N, isolated from C. sal nnematum, is an interesting compound. The unusual zwitterionic side chain produces a compound less effective against gram-positive organisms than are other penicillins. However, it is more active than penicillin G against a number of gram-negative organisms and some salmonellae .