An intermediary role for the tremorgenic mycotoxin TR-2 in the biosynthesis of verruculogen.

14C-Labelled compound TR-2, a tremorgenic mycotoxin, was administered to Penicillium raistrickii in submerged fermentation. Half of the added radiolabel was taken up by the fungus during the 60 h incubation period and the secondary metabolites subsequently isolated, principally verruculogen but also fumitremorgin B, were found to be radiolabelled. The efficiency of biosynthetic incorporation of TR-2 into verruculogen within the mycelium was at least 35%, demonstrating for the first time an intermediary role for TR-2. Fumitremorgin B was also TR-2-derived but may not be an important intermediate in verruculogen biosynthesis.