BIOSYNTHESIS OF THE TRICHOTHECENE 3-ACETYLDEOXYNIVALENOL - IS ISOTRICHODERMIN A BIOSYNTHETIC PRECURSOR

3-Acetyldeoxynivalenol is the major trichothecene produced by the fung us Fusarium culmorum, The first proven tricyclic intermediate in the b iosynthesis of 3-acetyldeoxynivalenol has been shown by in vivo studie s to be isotrichodermin, a natural metabolite of F. culmorum, Indeed, the feeding of ring-deuterated isotrichodermin resulted in ring-deuter ated 3-acetyldeoxynivalenol as shown by NMR studies, In this work, we have shown that the 3-acetyl group of isotrichodermin is mostly lost i n its metabolism to 3-acetyldeoxynivalenol. We have shown by two diffe rent approaches that the deacetylation occurs at an early step after t he first oxygenation step at C-15, Derivatives of isotrichodermin lack ing the 3-acetyl such as 3-deacetyl isotrichodermin or 3-oxo-12, 13-ep oxytrichothec-9-ene are not precursors to 3-acetyldeoxynivalenol. The role of this acetyl exchange mechanism is not clear presently.