BIOSYNTHESIS OF XANTHOFUSIN, A TETRONIC ACID METABOLITE OF FUSICOCCUMSP

Incorporation experiments with [Me-H-2(3)]methionine, [1-C-13]- and [1 ,2-C-13(2)]- acetate showed that the methyl groups of xanthofusin are derived from methionine, and the remaining carbon atoms are derived fr om three intact acetate units. Incorporation of C-13-labelled 1,3-dihy droxy-2,4-dimethylbenzene shows that this is a probable intermediate. Three possible pathways are discussed, namely a triketide origin of xa nthofusin, a route via a tetraketide but with loss of the starter unit and, finally, a route including a triketide with a malonate starter u nit.