7-Aminocephalosporanic Acid

The enzymatic conversion of cephalosporin C gives 7-aminocephalosporanic acid (7-ACA) [A1266], which is used as a starting compound for semisynthetic cephalosporin antibiotics. Modification of 7-ACA at the 3- and 7-positions gives rise to a number of third and fourth semisynthetic cephalosporin antibiotics that are significantly generally more active against Gram-negative bacteria than first and second generation ones. Differences in side chain structure at the 7-position directly affect their antibiotic activity, whereas modifications made at the 3-position influence their metabolism and pharmacokinetic properties of the drugs.