Assessment of the antimutagenic effects of aqueous extracts from herbal medicines against N-Alkyl-N-nitrosoureas-induced mutagenicity using the umu test

Carcinogenic N-methyl-N-nitrosourea (MNU) has been reported to be formed in vivo and suspected to be a causative agent for human cancer. Therefore, for cancer chemoprevention it is important to find compounds which inhibit N-alkyl-N-nitrosoureas-induced mutagenicity. The inhibitory effect of plant extracts against MNU mutagenicity was evaluated using the umu test. Among thirty aqueous extracts, derived from medicinal plants, seventeen extracts inhibited N-alkyl-N-nitrosoureas-induced mutagenicity using Salmonella typhimurium TA1535/pSK1002. Nine aqueous extracts; Astragalus Root, Bupleurum Root, Cimicifuga Rhizome, Cnidium Rhizome, Glycyrrhiza, Paony Root, Polygonatum Rhizome, Poria Sclerotium, and Processed Ginger, moderately inhibited N-alkyl-N-nitrosoureas-induced mutagenicity (IC₅₀ > 7.0 mg/mL), and eight aqueous extracts; Cinnamon Bark, Cinnamon Twig, Dodder Seed, Malaytea Scurfpea Fruit, Phellodendron Bark, Prunella Spike, Scisandra Fruit, and Suberect spatholobus Stem strongly inhibited N-alkyl-N-nitrosoureas-induced mutagenicity (IC₅₀ < 7.0 mg/mL) in Salmonella typhimurium TA1535/pSK1002. An aqueous extract from Suberect spatholobus Stem showed the most potent antimutagenic effects against N-alkyl-N-nitrosoureas.