Question

new generation of semi-synthetic penicillin are made by altering groups around what ?

Answer 1

Penicillins are antibiotics from the group of beta-lactams. Most penicillins are 6-aminopenicillanic acid derivatives, differing from each other according to the substitution in the side chain of their amino group. Its analogy to the terminal D-alanyl-D-alanine, located in the peptide side chain of the peptidoglycan subunit, suggests that its bactericidal character derives from its intervention as an inhibitor of the transpeptidation process during the synthesis thereof. In this way, penicillin acts by weakening the bacterial wall and favoring the osmotic lysis of the bacteria during the multiplication process.

There is a great diversity of penicillins. Some species of fungi of the genus Penicillium naturally synthesize penicillins, as the first isolated type, penicillin G. However, due to the emergence of resistance, other families have been developed following basically two strategies: the addition of precursors to the chain lateral in the culture medium of the producer fungus, which translates into the production of biosynthetic penicillins; and the chemical modification of penicillin obtained by biotechnological fermentation, which gives rise to semi-synthetic penicillins. Typically, the industrial design of the process is initiated by fermentation production of penicillin G or, in some cases, penicillin V; after its purification, the side chain is eliminated by the enzyme penicillin acylase, which gives rise to the nucleus 6-aminopenicillanic acid; finally, this compound is chemically modified to give rise to an antibiotic with improved characteristics. Semi-synthetic penicillins, widely used, have some element of advantage over natural penicillins: stability at acidic pH, resistance to beta-lactamases encoded by plasmids or chromosomes, extended spectrum of action, etc.

Semisynthetic penicillins are generated by the isolation of a stable intermediate during an industrial microbiological production (fermentation in bioreactors) continued by the chemical or enzymatic modification of the isolated compound. They are divided according to their antibacterial action into five groups: resistant to ?-lactamases, aminopenicillins, antipseudomonas, amidinopenicillins and resistant to ?-lactamases (Gram-negative). That is, they are antibiotics from the group of beta-lactams, which are obtained through the chemical modification of derivatives of penicillin G.