Progress toward a biosynthetic rationale of the aflatoxin pathway

Abstract

Specifically-labeled samples of averufin have been synthesized and incorporated intact into aflatoxin B 1, versicolorin A and versiconal acetate as determined by NMR spectroscopy. [1- 13 C]-Hexanoic acid has been shown to be utilized as the primer of the pathway while a group of alternative starters was found to be degraded to acetate prior to incorporation. The correct structure of nidurufin has been established and it and its 2’-epimer, pseudonidurufin, in labeled form have failed to be utilized in aflatoxin biosynthesis under two experimental protocols. [1- 18 0.5 - 13 C]-Averufin, however, was observed to label versiconal acetate in such a way that the acetyl carbonyl bore 80% of the original 180-label. A biogenetic scheme is proposed to account for these findings that is supported in the cationic regime by preliminary model studies. © 1986 IUPAC