Aspergillus rugulosus

In vitro studies of the ring closure reaction on closely related xanthone models result in a c/s-orientation of the hydroxyl and isopropenyl substituents which can be explained by steric clash between the ketone and xanthone carbonyls in the potential intermediate (10) which can be avoided if the ene reaction occurs on the benzophenone intermediate (9). This observation was supported by the isolation of previously known Aspergillus rugulosus metabolites, e.g. arugosin A (12), as co-metabolites of tajixanthone in Aspergillus variecolor. The involvement of anthraquinone intermediates was subsequently... 

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