Acute and Subacute Toxicity Tests of Madder Root, Natural Colorant Extracted From Madder (Rubia Tinctorium), in (C57Bij6 x c3H)F1 Mice

As part of the safety assessment of madder root (MR), a food colorant extracted from madder (Rubia tinctorium), toxicity tests were undertaken using (C57BL/6 x C3H)F1 mice of both sexes. An acute toxicity test was performed by 14-day administration of MR dissolved in distilled water by gavage at doses of 0, 500, 2000, 3500, and 5000 mg/kg body weight to groups of each sex. One male mouse dosed at 5000 mg/kg body weight was dead before the end of the study, indicating that the maximum tolerated dose of MR was between 3500 and 5000 mg/kg body weight. A subacute toxicity test of MR was performed using 62 mice of each sex, mixing their diets with MR at concentrations of 0, 0.3, 0.6, 1.25, 2.5, and 5% for 90 days. All mice tolerated these doses of MR well. The body weight gains of either sex were not affected by the treatment. None of the mice treated with MR showed clinical signs of toxicity. Histopathological examinations showed retention cysts of the kidneys and epidermal vaginal cysts in a few of the treated or control mice. No hyperplastic, preneoplastic, and neoplastic lesions and no pathological findings of toxicity were found. These results suggest that dietary exposure of MR at these doses has no acute or subacute toxic effects on mice.