Aphidicolin is a tetracyclic diterpene antibiotic isolated from the fungus Cephalosporum aphidicola with antiviral and antimitotic properties.

Aphidicolin is a reversible inhibitor of eukaryotic nuclear DNA replication.

It blocks the cell cycle at early S phase.

It is a specific inhibitor of DNA polymerase Alpha and Delta in eukaryotic cells and in some viruses (vaccinia[1][2] and herpesviruses) and an apoptosis inducer in HeLa cells.

Natural aphidicolin is a secondary metabolite of the fungus Nigrospora oryzae.