Isolation and characterization of zearalenone sulfate produced by Fusarium spp.

A water-soluble compound related to zearalenone was isolated from a culture of Fusarium graminearum 30 grown in rice. The structure of the novel metabolite was determined to be zearalenone-4-sulfate on the basis of fast-atom-bombardment mass spectrometry, proton nuclear magnetic resonance, UV spectroscopy, and by chemical and enzymatic reactions. Strains representing Fusarium equiseti, Fusarium sambucinum, and Fusarium roseum produced the sulfate conjugate as well. In the rat uterus enlargement bioassay, the metabolite or its hydrolysis product was found to retain the estrogenic activity characteristic of zearalenone. Natural occurrence of this novel metabolite might be significant because analytical methods devised for zearalenone in grain cannot detect the conjugate but the conjugate retains the biological properties of the mycotoxin when ingested by animals.