Novel meroterpenoids from Cystoseira mediterranea: use of the crown-gall bioassay as a primary screen for lipophilic antineoplastic agents.

Using a slight modification of the crown-gall potato disc bioassay, we were able to apply this test for two previously described antineoplastic lipophilic metabolites, didemnin B and mediterraneol A [1], and to use it as a guide for chromatographic separations of meroterpenoids from Cystoseira mediterranea. An active compound, mediterraneone [3], was isolated, and its structure was found to be a novel norsesquiterpenoid by chemical and spectral methods.