The antimutagenic effects of methanol extracts of sun dried and freeze dried Houttuynia cordata (HC) using Salmonella typhimurium TA100 in the Ames test system were evaluated. The methanol extract of freeze dried HC showed higher antimutagenic effect against aflatoxin B₁ (AFB₁) than that of sun-dried HC by approx. 10%. Whereas, the inhibitory activity of the methanol extracts of the HC on N-methyl- N'-nitro-N-nitrosoguanidine (MNNG) was somewhat lower compared to AFB₁. The separated fractions from the methanol extract showed strong antimutagenic activities both in chloroform and aqueous fractions against AFB₁. However, in case of MNNG, the aqueous fraction exhibited antimutagenic effect while the chloroform fraction did not show the antimutagenic activities. From this results, the lipid soluble (chloroform) fraction from the methanol extract of HC exhibited strong antimutagenic effect on AFB₁ which is an indirect mutagen, but not on MNNG which is a direct mutagen, however, the aqueous fraction from the methanol extract of HC showed strong antimutagenic effects both on AFB₁ and MNNG. The aqueous fraction of HC which generally be prepared as a folk medicine or tea proved to have the antimutagenic activity in this study. (Cancer Prev Res 10, 67-72, 2005)

Keywords: Houttuynia cordata Thunb, Aqueous fraction, Antimutagenicity, Ames test