Mutagens produced by Alternaria alternata.

Alternariol, alternariol methyl ether and tenuazonic acid, metabolites present in Alternaria alternata cultures, were tested for mutagenicity with Salmonella typhimurium strains TA98 and TA 100. Alternariol methyl ether was weakly mutagenic to strain TA98 (without metabolic activation). Chromatographic separations of A. alternata mycelium extract yielded several fractions mutagenic in the latter system, including the altertoxin I fraction and a purified yellow pigment C20H14O6, which was characterized spectroscopically.