1.2 Synthetic and semi-synthetic antibiotics

The very first antibiotics were discovered by screening large numbers of existing compounds from collections of chemical compounds known as chemical libraries . These were arsenic derivatives in the case of Salvarsan in 1909, and azo-dyes for sulfonamides in the 1930s.

More targeted screening of chemical libraries later became the norm, such as looking for inhibitors of bacteria-specific metabolic pathways. This is how synthetic carbapenems were discovered (Silver, 2011).

Semi-synthetic antibiotics are derivatives of natural antibiotics with slightly different but advantageous characteristics. For example, they can act against bacteria which are resistant to the original compound, have a greater spectrum of activity or cause fewer side effects.

Semi-synthetic derivatives of penicillins and cephalosporins are known as generations . You will find out more about cephalosporin generations in this week’s case study.

In the next section, you will find out how antibiotics are produced on an industrial scale.