Secondary metabolites by chemical screening, 42 - Cladospirones B to I from Sphaeropsidales sp F-24 ' 707 by variation of culture conditions

Variation of the culture conditions - static surface cultures in particular - of the fungus Sphaeropsidales sp. (strain F-24'707), which produces clad ospirone bisepoxide (1), led to the isolation of eight new spirobisnaphthal enes - the cladospirones B to I (8-15) -together with seven known represent atives of this class of secondary metabolites. Cladospirones C (9) and D (1 1) show antibiotic activity against bacteria and algae. The structures of c ladospirone B (8) and E (12) were confirmed by X-ray structure analysis. Cl adospirones C (9) and G to I (10, 14-15) represent new members of the spiro bis-naphthalene family, thanks to their hydroxylation patterns. Moreover, t hey underline the extraordinary status of this interesting class of compoun ds as the most diverse secondary metabolites, allowing for their small numb er of carbon atoms, described to date. Almost all possible permutations of stereochemistry and oxygen substitution pattern on the C-10 skeleton are pr oduced by different fungi.