In vitro acaricide activity of Ocotea aciphylla (Nees) Mez. (Lauraceae) extracts and identification of the compounds from the active fractions

The in vitro acaricide activity of hexane, ethyl acetate and ethanol extracts of Ocotea aciphylla leaves was investigated by means of an immersion tests using Rhipicephalus (Boophilus) microplus engorged females and larvae. All extracts were shown effective against the different stages of the parasite, and the ethanol extract (50 mg/mL concentration) was the most active (more than 90% efficacy in both assays). The ethanolic extract was fractionated using column chromatography with silica gel as stationary phase to furnish several fractions that were tested against larvae of R. (B.) microplus. Three fractions showed high acaricidal activity (50 mg/mL), causing between 84.2% and 100% mortality of the larvae. The anticholinesterase effect of these fractions was determined spectrophotometrically using a microtiter assay. The chemical investigation of the active fractions led to the characterization of terpenoids (cadalene 1 and squalene 2), a phenylpropanoid (dillapiole 3) and a phenolic mixture containing five proanthocyanidins (4-8) and a flavonoid(vitexin-2”-O-rhamnoside 9). Our findings suggest that the O. aciphylla has potent acaricidal activity in vitro against R. (B.) microplus, and that different secondary metabolites are responsible for this effect.