In vitro lousicidal activity and phytochemical screening of methanolic extract of Brucea antidysenterica seed against Bovicola ovis in West Shewa Zone

Abstract

Lice are a common ectoparasite of sheep and have been identified as one of the leading causes of sheep production constraints and skin quality deterioration in Ethiopia. Despite the fact that Brucea antidysenterica has been traditionally used to treat ectoparasite infestations in Ethiopia, its efficacy has not been validated experimentally in the laboratory. Therefore, this study aimed to determine the lousicidal activity of B. antidysenterica against Bovicola ovis in vitro and to screen the phytochemical constituents of the extract. Brucea antidysenterica seed was collected, dried under shade, powdered, and macerated with 99.8% methanol. The phytochemical constituents of the extract were screened using different tests, such as the foam test, the ferric chloride test, Liebermann’s assay, the Bate-Smith and Metcalf assay, the hydrochloric acid test, the Libermann-Burchard test, and the Salkowski test. Adult lice were collected from sheep and identified under a stereomicroscope. An in vitro adult immersion test was started within an hour of lice collection. The extract was checked for its lousicidal activities with 200, 100, 50, 25, 12.5, and 6.25 mg/ml concentrations at different time intervals within 24 hrs. As positive and negative controls, 0.1% diazinon and 0.5% tween 20 were used, respectively. All tests were conducted in triplicate. Flavonoids, glycosides, saponins, phlobatannis, steroids, and tannins were detected in the extract of B. antidysenterica seed, but phenols and phytosterols were not. At 24 hours post-exposure, higher concentrations of the extract, 200, 100, 50, and 25 mg/ml, showed strong lousicidal activities similar to 0.1% diazinon. However, the lower concentration of the extract, 6.25 mg/ml, showed moderate activity. A significant increase in lice mortality started 30 min after post-exposure with 200, 100, and 50 mg/ml concentrations, while after 2 hrs post-exposure with 25 and 12.5 mg/ml concentrations of the extract and diazinon compared to the negative control. The extract's efficacy increased with increasing time after exposure and concentration. Methanolic seed extract of B. antidysenterica had shown a good killing effect on B. ovis, suggesting that it could be used as a future alternative to treat lice infestation