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Changes in Acaricidal Potency by Introducing Functional Radicals and an Acaricidal Constituent Isolated from Schizonepeta tenuifolia

Yang, Ji-Yeon, Lee, Hoi-Seon
Journal of agricultural and food chemistry 2013 v.61 no.47 pp. 11511-11516
Schizonepeta, benzyl benzoate, bioassays, chromatography, cotton fabric, dust, free radicals, lethal dose 50, mites, nuclear magnetic resonance spectroscopy, oils
The acaricidal potential of an active constituent isolated from Schizonepeta tenuifolia oil and its structurally related derivatives was evaluated using filter paper and impregnated cotton fabric disk bioassays against house dust and stored food mites. The acaricidal constituent of S. tenuifolia oil was isolated by chromatographic techniques and identified as 2-isopropyl-5-methylcyclohexanone by GC-MS, ¹H-, and ¹³C NMR spectra. 2-Isopropyl-5-methylcyclohexanone was a potent acaricide against house dust and stored food mites, based on the LD₅₀ values from the filter paper and impregnated cotton fabric disk bioassays, followed by 4-isopropylcyclohexanone, 2-isopropylidene-5-methylcyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, and benzyl benzoate. Furthermore, 4-isopropylcyclohexanone and 2-isopropyl-5-methylcyclohexanone, which were introduced on the isopropyl (C₃H₇) functional radical of the cyclohexanone skeleton, had the highest acaricidal potency. These results indicate that S. tenuifolia oil and 2-isopropyl-5-methylcyclohexanone structural analogues could be effective natural acaricides for managing house dust and stored food mites.