Why have the chemical structure of some antimicrobial drugs been modified into semisynthetics?

Many antibiotics or antimicrobial drugs halt bacterial infection by interfering with the microorganism’s ability to produce a protective cell wall. Some antibiotics combat bacterial ribosomes, arresting protein synthesis in bacteria without affecting vital functions in human cells.

However, random mutations in bacterial DNA sometimes encode new versions of these targeted proteins in bacterial cells. Such a mutation may give a bacterium antibiotic resistance trait that the cell can pass on to its descendants whenever antibiotics are present.

Therefore, medicinal chemists replenished the natural antibiotics by semisynthetic and to fully synthetic routes. Semisynthetic antibacterials are novel compounds that are produced by chemical synthesis using as starting material a natural product. These semisynthetic drugs have distinct chemical and medicinal properties.