G Mbogning Tayo, T S Nguepnang, H G Tsila, A F Djouela, R J Atiokeng Tatang, J Yondo
Gastrointestinal parasitic infections adversely affect the health and well-being of animals worldwide. The limitations of the efficacy of pharmaceutical anthelmintics underscore the importance of finding alternative approaches to reduce the impact of parasitism on hosts. Investigating the anthelmintic properties of bioactive plants could be one way to contribute to this effort. The present study evaluates in vitro the activity of aqueous and ethanolic extracts of Setaria barbata on the four free-living life stages of Ancylostoma caninum, the primary gastrointestinal nematode of dogs. After preparing the extracts, phytochemical tests were conducted to identify secondary metabolites based on colour and precipitation reactions specific to each metabolite present in the extracts. Serial dilution of the extract allowed us to obtain five test concentrations, which were used for egg embryonation, egg hatching, and larval mortality assays. Fresh eggs, embryonated eggs, and L1 and L2 larvae of A. caninum from a naturally infected dog were incubated for 24 hours with 5 concentrations of Setaria barbata extracts, while the embryonated eggs were incubated for 6 hours. 0.5% DMSO and distilled water were used as negative controls. At the end of this period, the number of non-embryonated eggs, unhatched eggs, and dead L1 and L2 larvae was recorded. Flavonoids, phenolic compounds, and alkaloids were identified in the three extracts of S. barbata. The presence of triterpenes and steroids, however, varied depending on the solvent used for extraction. The extracts proved more effective on embryonated eggs than on fresh eggs; the aqueous macerated extract thus resulted in 100% inhibition of egg hatching at a concentration of 0.625 mg/mL, with the lowest IC₅₀ (0.31 mg/mL). L2-stage larvae were more sensitive to the various extract concentrations than L1-stage larvae. The ethanolic extract caused 100% mortality in L2-stage larvae, with an LC₅₀ of 0.48 mg/mL. Extracts of Setaria barbata contain compounds with bio-ovicidal and bio-larvicidal properties. These extracts could be sprayed in dog kennels and in the wild as a disinfectant to eliminate the pre-infectious forms of gastrointestinal nematodes. Further studies are needed to evaluate the efficacy and safety of these extracts in a complete biological system.