Biosynthesis of macrophomic acid: plausible involvement of intermolecular Diels–Alder reaction

Abstract

The biosynthetic precursor of the fungal metabolite macrophomic acid 4 from Macrophoma commelinae has been studied by feeding experiments and enzymatic conversion from the pyrone 3 to 4 in a cell-free system. Based on the experimental data, a biosynthetic pathway for 4 involving an unprecedented intermolecular Diels–Alder reaction is proposed.