Biosynthesis of multicolosic acid, a polyketide metabolite from Penicillium multicolor: occurrence of large 18O-induced β-isotope shifts in 13C n.m.r. spectra

Abstract

Fermentation of Penicillium multicolor under an atmosphere containing ¹⁸O₂ produces multicolosic acid (1) whose methylated derivative (2) displays both α-isotope shifts and unusually large β-isotope shifts in its ¹³C n.m.r. spectra; the results define the origins of all oxygens of (1) and provide information about its formation from an aromatic polyketide precursor, 6-pentylresorcylate (3).