Toxicity of Atractylon and Atractylenolide III Identified inAtractylodes ovataRhizome toDermatophagoides farinaeandDermatophagoides pteronyssinus

Abstract

The acaricidal activity of materials derived from rhizome of Atractylodes ovata (Atractylodesmacrocephala) toward adult Dermatophagoides farinae and Dermatophagoides pteronyssinus was examined using fabric-circle residual contact and vapor-phase toxicity bioassays. Results were compared with those of the currently used acaricides: benzyl benzoate, dibutyl phthalate, and N,N-diethyl-m-toluamide (Deet). The active principles of A. ovata rhizome were identified as the sesquiterpenoids, atractylenolide III (1) and atractylon (2), by spectroscopic analysis. In fabric-circle residual contact bioassays with adult D. farinae, atractylenolide III (LD₅₀, 103.3 mg/m²) and atractylon (136.2 mg/m²) were five and four times more toxic than Deet and 1.7- and 1.3-fold more active than dibutyl phthalate, respectively, based on 24 h LD₅₀ values. These compounds were less toxic than benzyl benzoate (LD₅₀, 45.8 mg/m²). Against adult D. pteronyssinus, atractylenolide III (LD₅₀, 73.8 mg/m²) and atractylon (72.1 mg/m²) were eight times more active than Deet and 2.5-fold more toxic than dibutyl phthalate. These compounds were slightly less effective than benzyl benzoate (LD₅₀, 46.0 mg/m²). In vapor-phase toxicity tests with both mite species, atractylenolide III and atractylon were effective in closed but not in open containers. These results indicate that the effect of these sesquiterpenoids was largely a result of action in the vapor phase. Naturally occurring atractylenolide III and atractylon merit further study as potential house dust mite control agents or leads because of their great activity as a fumigant. Keywords: Botanical acaricide; natural fumigant; Dermatophagoides farinae; Dermatophagoides pteronyssinus; Atractylodes ovata; atractylenolide III; atractylon