Cephalosporins are ┚lactam antibiotics. In cephalosporin C, four membered ┚lactam ring (which is mainly responsible for the activity) is fused with six membered dihydrothiazine ring to form the basic nucleus, 7-aminocephalosporanic acid (7-ACA) and to which ┙aminoadipic acid side chain is attached through an amide bond (Fig 1). (Mandell and Sande,1991)Although cephalosporin was found to be acti...