In vitro ovicidal and adulticidal activities of crude extracts and fractions of Rosa abyssinica Lindley and Justicia schimperiana (Hochst. Ex Nees) T. Anders against Fasciola species

Abstract

The increasing emergence of triclabendazole resistance in Fasciola species necessitates the exploration of alternative control strategies. This study evaluated the in vitro ovicidal and adulticidal activity of crude extract (80% methanol) and solvent fractions (aqueous, ethyl acetate and n-hexane) of the leaves of Rosa abyssinica Lindley and Justicia schimperiana (Hochst. Ex Nees) against Fasciola species. Egg hatch inhibition and adult worm anti-motility assays were performed at different concentrations, and preliminary phytochemical screening was conducted to identify major secondary metabolites. The results demonstrated that all tested phytochemicals were present in the crude extracts and most fractions of both plants, except phenolics and glycosides, which were not detected in the ethyl acetate (JSEF) and n-hexane (JSNF) fractions of J. schimperiana. Moreover, in both the egg hatch inhibition and adult worm anti-motility assays, all extracts exhibited varying degrees of activity. The highest efficacy was observed in the R. abyssinica aqueous fraction (RAAF), which achieved 76.4% egg hatch inhibition (at 8 mg/mL) and 100% worm motility inhibition (death) at 240 minutes (at 15 mg/mL). In addition, egg hatch assay observations also indicated that the RAAF induced egg degeneration, complete developmental inhibition and delayed embryonic development. In conclusion, these findings demonstrate that R. abyssinica and J. schimperiana have activity against Fasciola species, with RAAF revealing the most potent effects. Therefore, the observed anthelmintic potential suggests that these plants warrant further investigation for the possible development of plant-based fasciolicidal agents.