5'-Hydroxyaverantin (HAVN) was isolated from a mold, Emericella heterothallica IFO 30842. Aspergillus parasiticus NIAH-26, a UV-irradiated mutant of A. parasiticus SYS-4, produced neither aflatoxins nor precursors in yeast extract-sucrose (YES) medium. When the postmicrosome (cytosol) fraction of NIAH-26, which had been prepared from the culture in YES medium, was incubated with norsolorinic ac...

A relatively stable enzyme system that converts versiconal hemiacetal acetate to versicolorin A was isolated from the soluble fraction of the homogenized cells of Aspergillus parasiticus ATCC 15517. The cell-free preparation did not require oxygen or oxidized nicotinamide adenine dinucleotide phosphate for activity, nor did it require dithiothreitol, polyclar (polyvinyl pyrrolidone), or glycero...

Biosynthesis of the toxic and carcinogenic aflatoxins (AFs) requires the activity of more than 27 enzymes. The roles in biosynthesis of newly described enzymes are discussed in this review. We suggest that HypC catalyzes the oxidation of norsolorinic acid anthrone; AvfA (AflI), the ring-closure step in formation of hydroxyversicolorone; HypB, the second oxidation step in conversion of O-methyls...

The physiological effects of DL-ethionine and related methionine analogs upon cellular protein synthesis and methyl group transfer to aflatoxin B1 in Aspergillus parasiticus were examined in growing and resting cell systems. The addition of DL-ethionine (0.02 M) to growing mycelia inhibits cellular growth some 37% after 120 h of development. Addition of ethionine before 50 h prevents any aflato...

aflatoxins are carcinogenic metabolites produced by several strains of aspergillus flavus group in food and feed. cluster genes in aflatoxin biosynthesis pathway contain structural, regular and unassigned genes , nor-1 , ver-1 , and omt-1 are structural genes that coding for key enzymes and aflr is a regulatory gene that plays a key role in the production of aflatoxin and is affecting on the st...