A labeling study to elucidate the biosynthesis of 4-(4-hydroxyphenyl)-butan-2-one (raspberry ketone) by Nidula niveo-tomentosa.

Submerged cells of the basidiomycete Nidula niveo-tomentosa, a microbial producer of 4-(4-hydroxyphenyl)-butan-2-one, were supplemented with (13)C-labeled L-phenylalanines and with [1-(13)C]glucose. Labeled transformation products were detected by a novel method of analyzing stable isotope-labeled metabolites, gas chromatography (GC) coupled to an atomic emission detector, and by GC-mass spectrometry. A benzoate moiety was side chain elongated according to the poly-beta-keto scheme. The presence of an acetyl coenzyme A-carboxylase inhibitor shifted the spectrum of products to benzyl compounds. Hence, the fungal pathway differs from the one established for plant tissues.