Magnolol is an organic compound that is classified as lignan. It is a bioactive compound found in the bark of the Houpu magnolia (Magnolia officinalis) or in M. grandiflora. The compound exists at the level of a few percent in the bark of species of magnolia, the extracts of which have been used in traditional Chinese and Japanese medicine. In addition to magnolol, related lignans occur in the extracts including honokiol, which is an isomer of magnolol.