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Modification of side-chains in position 7 of the lactam ring seems to affect the antibacterial activity while position 3 of the dihydrothiazine ring alters pharmacokinetic properties and receptor binding affinity. Modification of side chains on the relevant positions has been used to create a whole new class of cephalosporin antibiotics. Cephalosporin C contains a side-chain which is derived from D-aminoadipic acid. Chemical compounds containing this core are relatively stable to acid hydrolysis and tolerance to β-lactamases. The core itself can also be referred to as 7-aminocephalosporanic acid which can be derived by hydrolysis from the natural compound cephalosporin C. The core of the basic cephalosporin molecule consists of a two ring system which includes a β-lactam ring condensed with dihydrothiazine ring.
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