Mutagenicity of commercial Monascus fermentation products and the role of citrinin contamination

Pigments produced as secondary metabolites by various isolates of moulds be longing to the genus Monascus have been used traditionally as colorants in Oriental food. Modern food industry has rediscovered these moulds as promis ing source for natural colorants. However, recent studies evidence that one of the secondary metabolites produced by Monascus is identical in structur e to the mycotoxin citrinin. Thus, a sensitive HPLC method was developed to analyse these food colorants for contamination with citrinin. The mycotoxi n could be detected in all the commercial Monascus samples at concentration s varying between 0.2 to 17.1 mu g/g. In addition, the mutagenicity of comm ercial Monascus samples applying Salmonella-microsome assay and Salmonella- hepatocyte-assay was investigated and compared to the results obtained with citrinin. Citrinin and two Monascus extracts induced a positive dose depen ding mutagenic response in the Salmonella-hepatocyte-assay applying strain TA-98. However, no mutagenicity could be detected in the Salmonella-microso me assay, neither with nor without S9-mix, for citrinin and Monascus extrac ts, applying TA-98, TA-100, TA-1535, TA-1538 and TA-97. These findings prov ide further evidence that citrinin requires complex cellular biotransformat ion to exert mutagenicity. (C) 1999 Elsevier Science B.V. All rights reserv ed.