Studies in the biosynthesis of fungal metabolites. 2. The biosynthesis of alternariol and its relation to other fungal phenols

The mode of biosynthesis of certain types of fungal phenols involves the condensation of acetate units (for a review see Birch, 1957).How- ever, the biosynthesis of alternariol, CL4H,005 (I), a metabolite of Alternaria tenui8 auct.(Raistrick, Stickings & Thomas, 1953), was of particular interest since, in addition to its rarity among known fungal products as a diphenyl derivative, it appeared to constitute a classical example of the acetate hypothesis.Thus it can in theory be derived solely by the head-to-tail condensation of seven acetate units without requiring additional stages involving oxidation, reduction, decarboxylation, etc. Anaother example of a fungal phenol, ex- clusively derived from acetate, is the key substance orsellinic acid, C8H804 (II), isolated from Chaeto- * Part 1: Chaplen & Thomas (1960).