The effect of flavonoids on ofloxacin-induced mutagenicity in Euglena gracilis

The antimutagenicity of 14 naturally occurring flavonoids (20 μmol/l) on ofloxacin (43 μmol/l and 86 μmol/l)-induced bleaching (mutagenicity) was studied in Euglena gracilis. The flavonoids chrysin, tectochrysin, chrysin-5-methylether, galangin, galangin-5-methylether, pinocembrin and pinobanksin possess considerable antimutagenic properties against ofloxacin-induced bleaching of E. gracilis. Apigenin and isalpinin had only weak antimutagenic potency. Pinobanksin-5-methylether and pinobanksin-3-acetate showed very weak or no antimutagenic effect. However, kempferol, quercetin-3-methylether and quercetin-3,3′-dimethylether showed co-mutagenic or no antimutagenic effect depending on the concentration of ofloxacin. Two possible modes of action of the flavonoids on ofloxacin-induced bleaching of E. gracilis are discussed.