Chapter 2 : Antibiotics and Antibacterial Agents: Classifications and Structure-Activity Relationship

Abstract:

This chapter focuses on the classification and structural-activity relationship of antibiotics and antibacterial agents. The β-lactam family comprises four groups of molecules: penams, penems, cephems, and monocyclic β-lactams. To these should be added the β-lactamase inhibitors, some of the structures of which are featured in the four main groups. The azetidinone nucleus alone can be replaced, and monobactams, monocarbams, monophosphatams, and other heterocycles can be distinguished according to the substituents of the nitrogen atom. Based on studies by researchers, who demonstrated the transferability of resistance to certain antibiotics between Escherichia coli and Shigella spp., other researchers were able to demonstrate that shigellae inactivated chloramphenicol. The majority of aminoglycosides have similar basic structures and are divided into four groups: streptomycin derivatives, 2-deoxystreptamine derivatives, spectinomycin derivatives, and fortimicin derivatives. The macrolides are macrocyclic antibiotics characterized by a central lactone ring containing 12 to 16 members, few double bonds, and no nitrogen atom; one or two amino sugars and/or neutral sugars are attached to the lactone or aglycone ring. More than 400 compounds constitute the family of peptide antibiotics. Dihydrofolate reductase (DHFR) inhibitors used therapeutically are the result of studies relating to the specificity of this enzyme for bacterial, parasitic, or epithelial cells. The antibacterial compounds display good antibacterial activity and a lack of inhibitory activity against epithelial cell DHFR.