A Nematode Larval Motility Inhibition Assay for Screening Plant Extracts and Natural Products

Abstract

An in vitro nematode larval motility inhibition assay has been developed to screen plant extracts for anthelmintic activity against the sheep parasite Trichostrongylus colubriformis. The usefulness of this assay was verified by results for extracts of the liverwort Plagiochila stephensoniana and the shrub Pseudowintera colorata. The activity of these extracts was due to 4-hydroxy-3‘-methoxybibenzyl (1) (IC50 0.13 mg/mL) and polygodial (2) (IC50 0.07 mg/mL), respectively. Synthetic analogues of 1 displayed enhanced antiparasitic activity. (Z)-4-Hydroxy-3‘-methoxystilbene (3) had an IC50 of 0.06 mg/mL. The activity of an extract of the tree Phyllocladus aspeniifolius var. alpinus was due to the presence of polyphenolics, since treatment of the extract with polyvinylpolypyrrolidone or polyamide removed the activity. Keywords: Nematodes; anthelmintics; natural products; assay; plant extracts; Trichostrongylus colubriformis