Mycotoxins produced from fungi isolated from foodstuffs and soil: comparison of toxicity in fibroblasts and rat feeding tests

Abstract

Thirty-nine isolates of fungi obtained from foodstuffs and soil samples from various parts of the world have been identified. The isolates were grown on a solid rice medium, and extracts were prepared with 50% aqueous methanol. The extracts were examined for toxicity in the following systems: (i) cytotoxicity to cultured normal human diploid skin fibroblasts (proliferating and nonproliferating) and mouse fibroblasts; (ii) skin toxicity after topical application on rats; and (iii) rat feeding tests in which rats were examined for death, overt pathological effects including congestion and hemorrhage of tissues, weight loss, food refusal, and uterine growth. Sixteen culture extracts were highly toxic as indicated by death, congestion and hemorrhage of tissues, and net weight loss. One half of the isolates were highly cytotoxic (50% lethal concentration, 0.01 to 5 micrograms/ml) as indicated by the ability to cause death and disintegration of 3T3 Swiss mouse fibroblasts and human diploid skin fibroblasts during 3 to 4 days in culture. The remainder were moderately cytotoxic (50% lethal concentration, 5 to 250 micrograms/ml). Four culture extracts were highly toxic by some clinical criteria but did not cause congestion and hemorrhage of tissues and were weakly cytotoxic (50% lethal concentration, 250 to 5,000 micrograms/ml). Six culture extracts exhibited moderate toxicity (weight loss only) and low cytotoxicity (50% lethal concentration, 3,000 to 50,000 micrograms/ml). Four culture extracts caused uterine enlargement as the major clinical sign, suggesting the presence of zearalenone. Eleven culture extracts were weakly cytotoxic and caused no major clinical signs, except skin toxicity in two extracts.(ABSTRACT TRUNCATED AT 250 WORDS)