Postinfectional inhibitors from plants. XXIII. Sesquiterpenoid phytoalexins from fruit capsules of Datura stramonium

Datura stramonium fruit capsules inoculated with Monilinia fructicola or several other non-pathogenic fungi produced diffusates inhibitory to M. fructicola in spore germination assays. Detailed analysis of diffusates that are induced by M. fructicola indicated that they were complex and that antifungal activity was widely distributed through a number of column chromatographic fractions. Four compounds were isolated. These were sesquiterpenes, three of which, lubimin, hydroxylubimin, and capsidiol, have been described from other Solanaceae. The fourth, 2,3-dihydroxygermacrene, is a new compound with moderate antifungal activity but which is of especial interest as a possible precursor of several phytoalexins in the Solanaceae.