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The asterriquinones represent a class of ascomycete metabolic products whose significance stems from remarkable and useful pharmacological activities, among those antiretroviral (e.g., against the HI-virus), antitumor, and antidiabetes properties. Recently, the first genetic locus for an asterriquinone, the clustered terrequinone genes tdiA-E, was identified during a genome-wide screen in Aspergillus nidulans for "orphan" natural product biosynthesis loci. Here, we describe overexpression and characterization of TdiB, which catalyzes the reverse prenylation event during terrequinone A biosynthesis, which is the transfer of dimethylallyl diphosphate to carbon atom 2' of the intermediate didemethylasterriquinone D, to yield asterriquinone C-1. TdiB does not depend on the presence of divalent metal cations for catalysis and lacks the canonical prenyl diphosphate binding motif (D/N)DXXD.

This communication describes the first total synthesis of asterriquinone B1, a representative member of a group of anti-tumor metabolites of Aspergillus terreus. The synthesis described herein is potentially applicable to other members of the asterriquinone family.