Semisynthesis or partial chemical synthesis is a type of chemical synthesis that uses compounds isolated from natural sources (e.g. plant material or bacterial or cell cultures) as starting materials. These natural biomolecules are often large and complex molecules. This is opposed to a total synthesis where large molecules are synthesized through a stepwise combination of small and inexpensive (usually petrochemical) building blocks.

Semisynthesis or partial chemical synthesis is a type of chemical synthesis that uses compounds isolated from natural sources (e.g. plant material or bacterial or cell cultures) as starting materials. These natural biomolecules are often large and complex molecules. This is opposed to a total synthesis where large molecules are synthesized through a stepwise combination of small and inexpensive (usually petrochemical) building blocks.