General structure of penicillin

                   Structure of Penicillin

                Penicillin consists of a Thiazolidine ring (α) attached to a β – lactam ring . 

The rings constitute the fundamental nucleus of all the penicillin called 6-amino-penicillanic acid (6-APA).  β- lactam ring carries a free amino group to which acid radical can be attached to synthesis a newer penicillin.

structure of penicillin

·         β-lactam ring is responsible for the antibiotic action of the penicillin.

·         Thiazolidine ring  is responsible for absorption, distribution and hypersensitivity reaction of the penicillin.

·         Different radicals attached to free amino group determine the pharmacological properties of the new drug.