Cephalosporins

Cephalosporins

The cephalosporins were isolated from the fungus Cephalosporium acremonium in 1948 by Pro Tzu, Newton, and Abraham (1953). The main product being cephalosporin-C, the molecular modification of cephalosporin-C gave origin to semisynthetic substances. They are β-lactam antibiotics with same fundamental structural requirements as penicillins, the main difference between the two is that cephalosporins contain dihydrometathiazine ring, while penicillin contains a tetrahydrothiazole (thiazolidine) ring. The cephalosporins are much more acid stable than the corresponding penicillins and also have a mechanism of action similar to that of penicillins; they mainly inhibit the cross-linking of the peptidoglycan units in bacterial cell walls by inhibiting transpeptidase enzyme. However, they bind in the target proteins other than penicillins binding proteins.

Cephalosporins can be divided into three classes:

1.           Cephalosporin N: It has a penicillin-like structure being a derivative of 6-aminopenicillanic acid.

2.           Cephalosporin P: An acidic antibiotic, which is steroidal in nature.

3.           Cephalosporin-C: It is a true cephalosporin and it is a derivative of 7 amino-cephalosporanic acid.