Production of aflatoxins and other fluorescent metabolites by strains of Aspergillus flavus isolated from staple foods and their toxicity to rats

Abstract

Forty strains of Aspergillus flavus isolated from food marketed in Thailand between 1967 and 1969 were re-isolated for toxicological characterization. Approximately 92% produced aflatoxin B 1 or aflatoxins B 1 and B 2 . In acute toxicity tests in weanling male Wistar rats, 87.5% of the orally intubated chloroform extracts (CEX) of the isolates caused at least one death in test groups of five rats, compared with 38% of the ip-administered petroleum ether-insoluble (PEI) fractions. Twenty-four unidentified compounds were produced in varying amounts by eighteen strains of A. flavus. These compounds, detected as blue and green fluorescent spots on thin-layer chromatograms, may have modified the toxic effect of the aflatoxins. The histopathological changes caused by the CEX and PEI fractions were similar, the main ones being haemorrhagic necrosis of the liver and kidney, congestion of pulmonary vessels and hypercellularity of the alveolar septa of the lung, hydropic degeneration of the cardiac muscle and lymphocytic depletion of the spleen.