Malonate as a biosynthetic intermediate in Penicillium urticae.

We have briefly proposed (1) the general theory that “acetate-derived” aromatic metabolites arise ana.logously to fatty acids, by repeated condensation of malonyl coenzyme A units with an acyl coenzyme A “starter,” citing in support our own work on the 6-methylsalicylic acid of Penicillium urticae and the prior report of Bentley and Keil (2) on penicillic acid. A number of subsequent publication& and private communications of work in progress, seem to confirm the generality of this theory, and here we report in detail our work on the simultaneous incorporation of malonate into phenols, fatty acids, and isoprenoid compounds by P. u&cue. 6-Methylsalicylic acid was chosen as representing the “acetate-derived” phenols of P. urticae since it is the first to appear in cultures and is indeed the parent substance of most of the other phenols. Oleic and palmitic acids were selected as representative of fatty acids since together with linoleic acid they predominate in the saponifiable lipids. As a representative isoprenoid compound, ergosterol was chosen as it predominates in the nonsaponifiable lipids, and pure material for dilution is readily available.