2005 Volume 18 Issue 4 Pages 175-182
A subchronic oral toxicity study of dokudami extract, distilled with ethanol from the leaves of dokudami (Houttuynia cordata Thunb.), was conducted. Groups of 10 male and 10 female F344/DuCrj rats were fed dokudami extract at dietary levels of 0, 0.5, 1.5 and 5.0% for 13 weeks. There were no treatment-related adverse effects on body weight, food and water consumption, or on ophthalmology, hematology and urinalysis data. The serum BUN level was significantly increased in the 5.0% female group and remarkable elevation in absolute and relative kidney weights was also found in both sexes receiving 5.0% of dokudami extract. Furthermore, on histopathological assessment, marked mineralization at the cortico-medullary junction of the kidney was observed in the 1.5 and 5.0% female groups and the 5.0% male group. No treatment-related histopathological changes in any other organs/tissues were observed in either sex given 5.0% dokudami extract. Thus, the No-Observed-Adverse-Effect-Level (NOAEL) for dokudami extract was judged to be a dietary level of 1.5% (999 mg/kg body weight/day) for males and 0.5% (350 mg/kg body weight/day) for females under the present experimental conditions.
