2.2 Producing synthetic and semi-synthetic antibiotics

Antibiotics are very complex molecules. Synthetic compounds that resemble or mimic a natural antibiotic are rarely made for this reason. An exception is chloramphenicol (Figure 3). Novel synthetic antibiotics can be made in laboratories from scratch using a multi-step process that starts with the requisite chemical building blocks and ends with the pure compound. However, this process involves considerable development time and production costs.

Figure 3 First synthesis of chloramphenicol in 1949. Originally isolated from Streptomyces venezuelae in 1947, it is cheaper to synthesise this relatively simple antibiotic than to produce the natural compound. You do not need to study this figure in detail.

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This figure is a series of chemical reactions showing the synthesis of chloramphenicol from chemical precursors. It is cheaper to synthesise this relatively simple antibiotic than to produce the natural compound.

Figure 3 First synthesis of chloramphenicol in 1949. Originally isolated from Streptomyces venezuelae in 1947, it is cheaper to ...

Semi-synthetic antibiotics represent a half-way house. They are made by chemically modifying the active part of a natural antibiotic to create a single new molecule. A large amount of natural antibiotic is produced by batch fermentation. Then it is purified and chemically modified to create new antibiotics with enhanced therapeutic activity. Promising compounds identified by screening chemical libraries can similarly be modified to enhance activity and safety.

Next, you will find out how many existing antibiotics are still effective against bacterial infection.