METHODS AND RESULTS: On the basis of the LD50 values against D. farinae, 3'-methoxyacetophenone (0.41 μg/cm(2)) was 89.9 times more toxic than DEET (36.87 μg/cm(2)), followed by 4'-methoxyacetophenone (0.52 μg/cm(2)), 2'-methoxyacetophenone (0.75 μg/cm(2)), 2'-Hydroxy-5'-methoxyacetophenone (1.03 μg/cm(2)), 2'-hydroxy-4'-methoxyacetophenone (1.29 μg/cm(2)), acetophenone (1.48 μg/cm(2)), 2'-hydroxyacetophenone (1.74 μg/cm(2)), 2',5'-dimethoxyacetophenone (1.87 μg/cm(2)), 2',4'-dimethoxyacetophenone (2.10 μg/cm(2)), and benzyl benzoate (9.92 μg/cm(2)). In regard to structure-activity relationships between acaricidal activity and functional radicals (hydroxyl and methoxy groups) on the acetophenone skeleton, a monomethoxy group (2'-, 3'-, and 4'-methoxyacetone) on the acetophenone skeleton was more toxic than were the other groups (2',4'- and 2',5'-dimethoxyacetophenone, 2'- and 4'-hydroxyacetophenone, 2'-hydroxy-4'-methoxyacetophenone, 2'-Hydroxy-5'-methoxyacetophenone, and 4'-hydroxy-3'-methoxyacetophenone). CONCLUSIONS: These results indicated that acaricidal activity against three mite species changed with the introduction of functional radicals (hydroxyl and methoxy groups) onto the acetophenone skeleton. |