Anthelmintic screening of phytomedicines using <i>Haemonchus placei</i> adult motility assay

Abstract

Background: The leaf extract of S. mombin was previously shown to be active against gastrointestinal nematodes (egg and infective larvae) in sheep.

Objective: To examine S. mombin extracts against adult H. placei, a cattle parasite and optimise the adult worm motility assay.

Materials and Method: Levamisole hydrochloride was used to optimise incubation time in the assay protocol. Adult worms (ten) were incubated, in duplicate, with standard drug solutions in either phosphate-buffered saline, pH 7.4 (PBS-7.4) or normal saline (NS) for 3h. Worms were afterwards examined and classified as dead or paralysed. The activities of three S. mombin leaf extracts (AH-H01, AH-A02, AH-W03) were investigated and median lethal concentration (LC₅₀) was estimated by sigmoidal curve-fitting analysis.

Results: Three hours incubation time was found optimal. Significantly, NS was better than PBS-7.4 in solvating plant extracts, which gave LC₅₀ values of (AH-H01; 104 mg/mL), (AH-A02; 30.5 mg/mL) and (AH-W03; 56.27 mg/mL) respectively.

Conclusion: S. mombin extracts are active against adult H. placei and the optimised assay enhanced sample throughput in anthelmintic phytomedicine screening.

Keywords: Screening assay, Heamonchus placei, Anthelminitics, Spondias mombin, Plant extracts