BIOSYNTHESIS OF TRICHOTHECENE MYCOTOXINS: IDENTIFICATION OF ISOTRICHODIOL AS A POST-TRICHODIENE INTERMEDIATE

Article abstract of DOI:10.1016/0031-9422(91)83621-Q

When cultures of Fusarium culmorum CMI 14764 were treated with the furanocoumarin xanthotoxin, trichothecene biosynthesis was suppressed, and large amounts of trichodiene accumulated, along with the smaller amounts of 12,13-epoxytrichothec-9-ene (EPT) and isotrichodermin.Trichodiene was shown to be a precursor of the trichothecene mycotoxins in F. culmorum, and when large amounts of trichodiene were supplied, a new trichodiene metabolite isotrichodiol was found to accumulate.This compound, 12,13-epoxy-2α,11α-dihydroxytrichodiene, was shown to be a biosyntheticprecursor of the trichothecenes, and represents the first demonstrated post-trichodiene intermediate in the pathway to trichothecenes.Slow, acid-catalysed cyclization of isotrichodiol to EPT was demonstrated, but the rapid in vivo incorporation into EPT points to an enzyme-catalysed process in the fungus.The biosynthesis of oxygenated trichothecenes such as 3-acetyldeoxynivalenol in F. culmorum appears to require further 3-hydroxylation to isotrichotriol prior to cyclization. Key Word Index - Fusarium culmorum; mycotoxin; trichothecene; biosynthesis; isotrichodiol.