Synthetic organic food colouring agents and their degraded products: effects on human and rat cholinesterases

AbstractMost synthetic coloured additives are carcinogenic, teratogenic and cause allergic reactions. In this study, the effects of synthetic azo dyes (sunset yellow FCF and carmoisine), as well as their degraded products (sulphanilic acid and naphthionic acid), on both true and pseudo-cholinesterases (ChEs) are studied. The results indicate that the synthetic azo dyes and their degraded products inhibit both human true and pseudo-ChE activities in vitro. The concentration of coloured additive that cause 50% inhibition (IC50) and enzyme inhibitor dissociation constant (Ki) show that sunset yellow FCF produces greater inhibition of both true and pseudo-ChEs than does carmoisine and sulphanilic acid, while naphthionic acid produces greater inhibition of pseudo-ChE only. Ki indicates that the affinity of sulphanilic acid for both true and pseudo-ChEs is higher than the other three inhibitors. Inhibition of both true and pseudo-ChEs by sunset yellow FCF is of mixed (competitive and non-competitive) type, but ...