Use of medicinal plants for helminth control – in vitro effect of a hydroethanolic extract from Combretum mucronatum leaves on larvae of gastrointestinal nematodes

Abstract text

Combretum mucronatum is a forest liane that is used to treat parasite infections in parts of Western and Central Africa, where these infections are often diagnosed by traditional healers and herbal practitioners. However, anthelmintic properties of C. mucronatum on helminths of human and veterinary importance are insufficiently characterized.

To understand whether C. mucronatum leave extract (CME) can be a potential natural resource for the control of gastrointestinal nematodes, its activity against infectious larvae of parasitic nematodes was tested in vitro.

To this end, the inhibitory activity of hydroethanolic components of C. mucronatum leaves was evaluated by larval migration assays.

Even low concentrations of the CME had an inhibitory effect on the migration of larvae of Ascaris suum (IC50=5.5 µg/ml), Ancylostoma caninum (IC₅₀=19.0 µg/ml) and Trichuris suis (IC₅₀=7.4 µg/ml), whereas inhibition of larvae of Toxocara canis (IC₅₀=310.0 µg/ml) and Toxocara cati (IC₅₀=7249.8 µg/ml) was seen at higher doses only. While larvae of Ostertagia ostertagi (IC₅₀=48.9 µg/ml), Cooperia oncophora (IC₅₀=28.3 µg/ml) and Trichostrongylus colubriformis (IC₅₀=2.1 µg/ml) were highly sensitive to the plant extract, larvae of most other gastrointestinal strongylids were only moderately or slightly affected.

The larval migration assays indicated a high activity of CME against larvae of helminths of genera which contain also classical soil-transmitted nematodes of human health concern. Ongoing qPCR-based assays on the transcription of chemo resistance-inducing and detoxification-related genes may unravel mechanisms underlying this activity. Moreover, in vivo experiments with H. contortus-infected goats treated with different dosages of CME will show whether the extract is suitable for the treatment of H. contortus infections.