P16: Potent carcinogenicity of madder-color-related alizarin and rubiadin in a rat medium-term multi-organ bioassay

Madder color (MC), a food coloring extracted from roots of Rubia tinctorum L. and used in Japan, proved to have carcinogenic potential on the rat kidney and liver. In addition, madder root is reported to induce DNA adducts in the kidney, liver and large intestine (Westendorf et al., 1998). MC is composed of some anthraquinones including lucidin-3-O-primeveroside (LuP) and alizarin (Alz). To clarify which component is responsible for carcinogenicity, a rat medium-term multi-organ carcinogenesis bioassay was performed, mainly focusing on the kidney, liver and large intestine. Male 6-week-old F344 rats receiving 5 different carcinogens were fed a diet containing either 0.008% or 0.04% of Alz or rubiadin (Rub), a metabolite of LuP, for 23 weeks. In the kidney, 0.04% Rub increased the incidences of atypical tubules and hyperplasias significantly (p These results indicate the kidney as a carcinogenic target of both Rub and Alz, the carcinogenic potential of the latter being weaker. Rub may also target liver and large intestine, suggesting that Rub plays a major role in MC-induced carcinogenicity.