Evaluation of the effects of propolis extracts and their constituents against the ticks Rhipicephalus sanguineus, Rhipicephalus microplus and Amblyomma cajennense

Abstract

Propolis is a resinous substance produced by bees Apis mellifera, containing mainly plant exudates and bee waxes. Propolis is important to the bees, as it is responsible for the maintenance of the hive as a sterile environment, acting against bacteria, fungus and even invading larvae. It has been extensively used in alternative medicine. However, few studies have been developed concerning the use of propolis to animal health. Thus, new strategies are of great importance for tick control. Hence, the aim of this project was to determine the activity of crude extracts of Brazilian propolis and their constituents for the control of specific and generalist ticks. Chloroform extracts were prepared from samples of green propolis from Lavras (state of Minas Gerais) and black propolis from Picos (state of Piauí), previously analyzed chemically. The bioassays were carried out in vitro to verify the effectiveness of the extracts using the larval package test. Bioassays-guided isolations were carried out to obtain active constituents presented in the studied samples. The crude extract of the propolis sample from Picos did not show any acaricide activity. On the other hand, the sample of propolis from Lavras showed high activity, and was fractionated by column chromatography in silica gel. A subfraction with acaricide activity was obtained and analyses by high performance liquid chromatography (HPLC) were developed. The majority compounds were isolated using preparative HPLC and identified by means of current spectroscopic analysis in chemistry of natural products (IR, UV, mass and NMR) (2,2-dimethyl-cromene-6-propenoic-dicafeoyl glucoside acid, artepillin-C, baccarin and 2,2-dimethyl-cromene-8-prenyl-6-propenoic acid). Finally, new bioassays were carried out, but no effect was observed testing the isolated compounds. Thus, probably the high acaricidal activity observed in the active subfraction was due to a synergism among the subfraction constituents.