SPECIFIC DESMUTAGENS (ANTIMUTAGENS) IN OREGANO AGAINST A DIETARY CARCINOGEN, TRP-P-2, ARE GALANGIN AND QUERCETIN

This study found two compounds which strongly suppressed the mutagenicity of one of the dietary carcinogens, 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), in oregano (Origanum vulgare). The compounds were purified chromatographically monitoring the suppressing activity with Salmonella typhimurium TA98. An instrumental elucidation identified two flavonoids as 3,5,7-trihydroxy-2-phenyl-4H-1-benzopyran-4-one (galangin) and 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-1-benzopyran-4-one (quercetin). Galangin and quercetin are strong desmutagens that neutralized Trp-P-2 before mutating the bacteria. The amounts of galangin and quercetin required for 50% inhibition against the mutagenicity of 20 ng of Trp-P-2 (IC50) were 0.12 and 0.81 mu g, respectively, while the IC50 of chlorophyll in oregano was 230 mu g. Toward the other mutagens, benzo[alpha]pyrene, 1-nitro-pyrene, 2-(acetylamino)fluorene, and N-methyl-N'-nitro-N-nitrosoguanidine, they were not effective. Galangin and quercetin are the specific desmutagens against the dietary carcinogen Trp-P-2.