UV mutagenesis and enzyme inhibitors as tools to elucidate the late biosynthesis of the spirobisnaphthalenes

The metabolite pattern of UV mutants of the spirobisnaphthalene producing f ungus F-24'707 by TLC and HPLC analysis has been investigated. Mutants with differences in colony morphology or colour compared to the parent strain w ere isolated. Cultivation in shaking flasks and P flasks showed differences in the metabolite pattern of some of the strains. Furthermore, enzyme inhi bitors were used to block the spirobisnaphthalene biosynthesis of the paren t strain at different steps. Feeding of precursors and intermediates of cla dospirone bisepoxide (15) led to a two-fold increase of the production of 1 5. From these data and preceding biosynthetic studies we deduced a general pathway for the biosynthesis of all spirobisnaphthalenes of the fungus F-24 '707. This enables us to present the hypothesis that all bisnaphthalenes de scribed so far are produced using a common pathway with only a few intermed iates as central branching points. (C) 2000 Elsevier Science Ltd. All right s reserved.