Intestinal Absorption of Polymeric Derivatives of the Food Dyes Sunset Yellow and Tartrazine in Rats

Abstract1. Absorption and metabolism of 14C-labelled sunset yellow (FD & C Yellow No. 6), tartrazine (FD & C Yellow No. 5) and high molecular weight polymeric derivatives of the two azo dyes were compared in rats.2. A trace to 1.5% of unchanged monomeric dyes was excreted in urine and bile during the first 24 h after dosing. No unchanged dye was absorbed after administration of the polymeric derivatives.3. In animals dosed with sunset yellow and its polymer derivative, absorption of the azo-bound cleavage product 1-amino-2-naphthol-6-sulphonicacid was 8.5 and 6.9%, respectively, while absorption of the cleavage product sulphanilic acid was 37.4 and O%, respectively.4. In animals dosed with tartrazine and its polymer derivative, absorption of the cleavage product aminopyrazolone and its metabolites was 4.0 and 4.6%, respectiveiy.5. Azo bond cleavage did not appear to be decreased in the polymer derivatives. However, the sulphanilic acid moiety of both dyes remained attached to the polymer backbone, resulting in a 95% decrease in sulphanilic acid ab- sorption with polymeric tartrazine.6. Decreased absorption of unchanged dyes and certain metabolites with the stable, non-absorbed polymeric derivatives may be significant in developing non-sensitizing substitutes for these two commonly used food colourants.