Hemiglobin formation in vitro induced by azo dyes and their metabolites

Azo dyes which after reduction by the intestinal flora yield aniline are known as inducers of Heinz bodies after oral intake (J.J.-P. Drake, 1975). The effect of aniline is thought to depend on its metabolic conversion to the known hemiglobin inducers, phenylhydroxylamine and o- and p-aminophenol (A. de Bruin, 1976). The azo dyes used for colouring of foods are reduced in vivo forming sulphonated primary aromatic amines, many of which are of aminonaphthol structure. Such compounds could be potential hemiglobin inducers. This possibility was investigated in vitro by incubating the following azo dyes and their metabolites, with red cells in Krebs-Ringer phosphate solution: Chrysoin S, Scharlach GN, Azorubine, Sunset Yellow FCF, Food Red 17, Orange GGN, Ponceau 4R, Amaranth, Ponceau 6R and Fast Yellow AB. The concentration in the incubate was 0.5 mmol/l and the hemiglobin formation was measured after 1 h. The effect on red cells from pigs was compared with the effect on human red cells. Only the metabolites containing amino and naphthol groups together were active. The activity depended on the number and position of the sulfonic acid groups.