Programme de bourses "Echanges Universitaires"

Search for natural products for treating helminth infections

Intestinal helminthiases are a major concern of human and veterinary health in tropical countries. Schistosomiasis affects about 200 million people worldwide, and more than 700 million people live in endemic areas. Schistosomiasis is a considerable health problem in Côte d’Ivoire. Soil-transmitted helminths produce a wide range of symptoms including intestinal manifestations (diarrhoea, abdominal pain), general malaise and weakness that may affect working and learning capacities and impair physical growth. Hookworms cause chronic intestinal blood loss, which is a cause of anaemia. Furthermore, in livestock, gastrointestinal nematode infections are of considerable economic importance.

Since very few drugs available and drug resistance is a main threat there is a need to develop novel anthelminthics. 

Against this background, in the current project, we tested the effectiveness of crude extracts from West African medicinal plants and related phytocompounds for the control of parasitic helminths such as schistosomiasis and hookworms. The studied plants have already shown anthelmintic activity against Haemonchus contortus, a veterinary nematode. These plants are used in human and veterinary ethnomedicine to fight against intestinal worms and associated discomforts.

After selection, the plant parts were collected from forest (South) and savannah (Center and North) of Côte d’Ivoire. The plants were dried (at room temperature), grounded and extracted with ethanol 90% under mechanical stirring during 14 hours. The extracts were filtered, evaporated in a rotavapor (40°C) and lyophilized. 35 crude extracts were tested with a range of dilution from 200 to 20 µg/ml against Schistosoma mansoni (schistosomula and adults), Ancylostoma ceylanicum, Echinostoma caproni and Heligmosomoides polygyrus. For S. mansoni, of the tested extracts, 57 % were active against schistosomula (pictures 1 and 2) after 24, 48 and 72 h; and against adults, 48 %, 60 % and 65%, respectively exhibited activity after 24, 48 and 72 h (pictures 3-5). Against E. caproni (adult), 23 % of the tested extracts showed activity after 24 h, 31 % after 48 h and 46 % after 72 h. Eight extracts were active against both S. mansoni and E. caproni. A. ceylanicum and H. polygyrus were less affected by the extracts. The results of the cytotoxicity assays on the most promising extracts showed that none of them was toxic.

This is the first report of the anthelmintic potency of natural products of Côte d’Ivoire on S. mansoni and E. caproni. Further studies are necessary to isolate and characterize the active components of the extracts.

        Picture 1: Control schistosomula                                   Picture 2: Treated schistosomula

    Picture 3: Control adult S. mansoni           Picture 4-5: Treated adult S. mansoni

This project is a joint activity between Centre Suisse de Recherches Scientifiques, University of Abobo-Adjamé and the Swiss Tropical Institute.

Contacts:

Professor Jennifer Keiser
Unit Helminth Drug Development 
Department of Medical Parasitology and Infection Biology
Swiss Tropical Institute,
CH-4002 Basel, Switzerland
E-Mail: Jennifer.Keiser@unibas.ch  

Docteur Koné Mamidou Witabouna
UFR Sciences de la Nature, Université d’Abobo-Adjamé,
02 BP 801 Abidjan 02, Côte d’Ivoire/
Centre Suisse de Recherches Scientifiques en Côte d’Ivoire,
01 BP 1303 Abidjan 01, Côte d’Ivoire
E-Mail: mamidou.kone@csrs.ci

Partner Institutions

UFR Sciences de la Nature, Université d’Abobo-Adjamé, Côte d’Ivoire
Centre Suisse de Recherches Scientifiques, Côte d’Ivoire
Swiss Tropical Institut, Switzerland

Associated partner

Laboratory of Pharmacognosy and Phytochemistry, University of Geneva, Switzerland

Funded by :

The University Exchange Program of Swiss Agency for Development and Cooperattion (administrated by the KFPE)

The Unit Helminth Drug Development, Swiss Tropical Institut, Switzerland