Insecticidal and Genotoxic Activities of Mint Essential Oils

The essential oils (EOs) extracted from the mint species Mentha pulegium and Mentha spicata, together with their main constituents, pulegone, menthone, and carvone, were tested for insecticidal and genotoxic activities on Drosophila melanogaster . The EOs of both aromatic plants showed strong insecticidal activity, while only the oil of M. spicata exhibited a mutagenic one. Among the constituents studied, the most effective insecticide was found to be pulegone, while the most effective for genotoxic activity was menthone. Data show that both toxic and genotoxic activities of the EOs of the two studied mint plants are not in accordance with those of their main constituents, pulegone, menthone, and carvone. Pulegone is significantly more effective (9 times) as an insecticide, while menthone and carvone are less effective (6 and 2 times, respectively) insecticides when used in their authentic forms, and a mixture of authentic pulegone and menthone, in levels resembling their content in the oil of M. pulegium, showed that the strong toxicity of pulegone is suppressed in the presence of menthone. All the above suggest that synergistic/antagonistic phenomena may be involved that alter the toxicity of the whole EO. Keywords: Mint plants; pennyroyal oil; spearmint oil; essential oils; pulegone; menthone; carvone; insecticides; genotoxicity; Drosophila melanogaster