Griseofulvin is a fungicide which works by hindering mitosis, in particular by interfering with the spindle and halting chromosome movement during the anaphase stage of mitosis. The compound is produced by the fungus Penicillium griseofulvum.
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.