In vitro acaricidal activity of Crescentia cujete L. fruit pulp against Rhipicephalus microplus

Cattle tick (Rhipicephalus microplus) is an important constraint on livestock production, particularly in tropical and subtropical areas. Synthetic acaricides are the primary method of control this thick. Resistance of R. microplus to synthetic acaricides has given rise to the need of new scientific investigations on alternative ways to control it. The objective of this work was to conduct a chemical investigation of Crescentia cujete L. fruit pulp and to evaluate the acaricide effect on R. microplus larvae of extracts, fractions, and isolated substances from this species. Crescentia cujete is a Bignoniaceae and it is characteristic of tropical climates. Its most distinctive feature is its fruit, which is spherical and gourd-like, with a hard woody shell and gelatinous pulp. The fruit pulp of C. cujete was extracted with ethanol by maceration yielding an extract and a residue. The extract was partitioned giving an ethyl acetate phase (EAF) that was fractionated by chromatographic procedures yielding cinnamic acid and benzoic acid. The remained botanic material from the ethanol extraction was further and successively extracted with ethyl ether and methanol under reflux. The acaricide effect of all extracts and fractions was evaluated against R. microplus using the larval packet test. The best result was observed for the EAF that caused 100% of mortality when a 10% solution was used and with LC₅₀ of 5.9%. Cinnamic acid was also tested showing 63.0% of mortality with LC₅₀ of 6.6% at the same concentrations and time of the experiment. The data obtained in this study provides information related to the chemical nature and the acaricide activity of the C. cujete epicarp that has not been previously reported. This study shows that the ethyl acetate phase of the ethanol extract of C. cujete fruit pulp is a potential alternative control for R. microplus and its activity is in part associated to cinnamic acid, its major compound.