Effects of the mycotoxin ochratoxin A in a bacterial and a mammalian in vitro mutagenicity test system

• Published in: Archives of toxicology Vol. 77; no. 5; pp. 298 - 304
• Main Authors: FÖLLMANN, Wolfram, LUCAS, Stefanie
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.05.2003; Springer Nature B.V
• Subjects: Animals; Bacteria; Biological and medical sciences; Cells, Cultured; Cricetinae; Cricetulus; Culture Media, Conditioned - pharmacology; Dose-Response Relationship, Drug; Hepatocytes - drug effects; Hepatocytes - metabolism; Hypoxanthine Phosphoribosyltransferase - genetics; Hypoxanthine Phosphoribosyltransferase - metabolism; Male; Medical sciences; Mutagenesis; Mutagenicity Tests; Mutagens - toxicity; Mutation; Mycotoxins - toxicity; Neutral Red - metabolism; Ochratoxins - toxicity; Plant poisons toxicology; Rats; Rats, Wistar; Ribosomal Proteins - drug effects; Ribosomal Proteins - metabolism; Salmonella typhimurium - drug effects; Salmonella typhimurium - genetics; Toxicology; Toxins; Rat; Toxicity; Glycosyltransferases; Mycotoxin; Hypoxanthine phosphoribosyltransferase; Salmonella typhimurium; Ochratoxin A; Hepatocyte; V79-Cell line; Bacteria; Mechanism of action; Enterobacteriaceae; Enzyme; Mutagenicity testing; Transferases; Rodentia; In vitro; Toxin; Vertebrata; Mammalia; Animal; Metabolic activation; Mutagenicity; Pentosyltransferases; HPRT assay
• ISSN: 0340-5761; 1432-0738
• DOI: 10.1007/s00204-002-0423-x

Ochratoxin A (OTA), a mycotoxin produced by several Aspergillus and Penicillium species, is a worldwide contaminant of food and feedstuffs. It is nephrotoxic, immunosuppressive and carcinogenic in several animal species. The mechanism by which OTA acts is not fully understood up to now. Here, OTA was evaluated for mutagenicity in the Salmonella typhimurium assay (Ames assay) and in the HPRT assay with V79 hamster fibroblasts. In the bacterial assay using the strains TA 98, TA 100, TA 1535, TA 1538, TA 102 and TA 104, OTA was not mutagenic at a concentration range from 0.01 to 500 micro M in the presence and absence of an external metabolising enzyme system (rat liver S9 enzyme mix). In V79 fibroblasts, cytotoxicity of OTA was estimated with the neutral red uptake assay. An IC(50) of 11.6 micro M was found in the absence and an IC(50) of 6.4 micro M in the presence of S9 mix. In the subsequent HPRT (hypoxanthine-guanine-phosphoribosyl-transferase) assay with V79 cells the negative result of the bacterial assay was confirmed using OTA in concentrations from 0.1 to 100 micro M. In order to obtain converted OTA metabolites from viable, metabolically competent cells, a preincubation of primary cultured rat hepatocytes with 0.016 to 0.8 micro M OTA was performed. The resulting culture medium, which contained OTA metabolites, was tested in both mutagenicity assays. Again, no mutagenic effect was detected either in the bacterial or in the mammalian test assay. In accordance with several literature data, the present results imply that OTA does not act as direct mutagen. Additionally, the OTA metabolites derived from cultured rat hepatocytes or rat liver S9 mix, also, do not have a mutagenic potency in the test systems used.