Acaricidal activity of tonka bean extracts. Synthesis and structure-activity relationships of bioactive derivatives.

The acaricidal effects of tonka bean, Dipterix odorata, extracts were investigated on Dermatophagoides pteronyssinus, the European house dust mite, and compared with benzyl benzoate as a standard acaricidal compound. A cyclohexane extract was the most effective, with an EC(50) = 0.075 g/m(2) after a 24 h period, as compared with benzyl benzoate (0.025 g/m(2)). Bioassay-guided fractionation of this extract led to the isolation of coumarin (1). Pharmacomodulation of this compound led us to test 20 analogues (2-21), which were either synthesized or purchased.