Evaluation Of Mutagenic And Antimutagenic Effects Of Three Flavonoids By Mouse Lymphoma Assay

Quercetin, kaempferol and genistein are three common flavonoids in human diets. Because of their biological activities, they have been widely used as materials for drug and healthy food. Recent researches indicated that these flavonoids might have some mutagenic and antimutagenic effects at the different doses. In this study, mutagenic and/or antimutagenic effects of quercetin, kaempferol, genistein were tested by mouse lymphoma assay (MLA) for two purposes. One is to provide safety evidence for further use of these flavonoids for drug and healthy food, and to accumulate data for further use of MLA in evaluating the safety of raw materials for drug and healthy food. And the other is to validate the feasibility of application of MLA to detect antimutagenic effects and broaden its application field.In the mutation assay, L5178Y mouse lymphoma cells were exposed respectively to quercetin (at concentrations 10, 20, 30, 40, 50 μg/ml). kaempferol (at concentrations 20, 35, 50, 65, 80 μg/ml) and genistein (at concentrations 5, 10, 15, 20 μg/ml) for 3 hours without S9 metabolic activation. Determination of cytotoxicity, plating efficiency and mutant frequency were performed using the microwell method. The results showed that cytotoxicity of quercetin, kaempferol and genistein for L5178Y cells increased dose-dependently. Mutant frequencies (MF) induced by quercetin at concentrations ≥40 μg/ml and genistein at concentrations ≥15 μg/ml were both twice higher than spontaneous mutant frequency at tk locus in L5178Y cells, and the MF increases were dose related.In the antimutation assay, L5178Y mouse lymphoma cells were exposed respectively to quercetin or genistein (at concentrations 0.625, 1.25, 2.5, 5, 10ug/ml) simultaneously with 0.5 jig/ml MMC for 3 hours without S9. Determination of cytotoxicity, plating efficiency and mutant frequency were also performed as that in the mutation assay. The results showed that simultaneous treatment with genistein at concentration 0.625 u.g/ml effectively reduced mutant frequency induced by MMC at tk locus in L5178Y cells, but quercetin ranging from 0.625 to 10 u.g/ml failed to exert such antimutagenic effect.This study indicated that quercetin, kaempferol and genistein with a higher dose range had relatively strong cytotoxicity, and that quercetin and genistein could induce tk gene mutation in L5178Y cells. Therefore, the safety evaluation of these flavonoids as drug and healthy food materials needs further studies. This study also showed that simultaneous treatment with genistein had an inhibitory effect on genotoxic MMC, but quercetin had no such inhibitory effect. Success of application of MLA to detect antimutagenic effect of genistein indicated this assay might have a broad prospect in detecting antimutagen.