Biosynthesis of the bicycloalternarenes, mixed terpenoids of Alternaria alternata

By incorporation of [2-C-13]-mevalonate, [1-C-13]-acetate and [1-C-13]-gluc ose we could reveal that the phytopathogenic fungus Alternaria alternata bi osynthesized the mixed terpenoids bicycloalternarenes via the classic meval onate pathway. The polyketid pathway does not participate in the biosynthes is of bicycloalternarenes, because there is no incorporation of [C-13]-acet ate into the C-ring of these compounds. The labelling pattern in this nonte rpenoid part of bicycloalternarenes after feeding with [1-C-13]-glucose and [U-C-13(6)]-glucose, respectively, allows the assumption that metabolites of the shikimate pathway are involved. (C) 2001 Elsevier Science Ltd. All r ights reserved.