Abstract

Parasitic diseases are the most common in tropical Africa where climatic and hygienic conditions favor their proliferation. Due to the limitations of synthetic therapy, there is a need to turn back to phytotherapy. Thus, the nematicidal efficacy of methanol/methylene chloride (v/v) extract of stem bark of Rauwolfia vomitoria (Apocynaceae) was tested on Heligmosomoides bakeri, a nematode parasite of Mus musculus. Seventy Swiss white mice of both sexes aged 5 to 6 weeks and weighing between 20 to 25 g were orally infected with a suspension containing about 100 to 110 one week old H. bakeri infective larvae (L₃). After the pre-patent period, infected animals were randomly divided into 7 groups of 10 animals each corresponding to the treatments. Thus, five doses of plant extracts [200, 400, 800, 1600, 3200 mg/kg body weight (bwt)] and a unique dose of 22 mg/kg bwt of albendazole were prepared. The nematicidal activity of the organic plant extracts compared to albendazole was assessed indirectly through faecal egg count reduction (FECR) and directly through total worm count reduction (TWCR). Albendazole served as the positive control while 4% dimethylsulfoxide (DMSO) as placebo. Each animal received for 6 consecutive days a daily dose of 0.7 ml of the organic plant extract according to its weight and group. Albendazole was given as a single dose. R. vomitoria at doses ≥ 1600 mg/kg bwt was active on the adult H. bakeri and reduced significantly (P  0.05) the FEC and TWC of the nematode. The dose of 3200 mg/kg BW showed a high nematicidal activity of 76. 21% FECR and 79.55% TWCR, 7 days post-treatment. These results were similar to those obtained with albendazole, 88.67% and 85.60% respectively for FECR and TWCR. These findings suggest that R. vomitoria is an efficient anthelminthic. However, further studies are required in order to establish its mechanism of action. In addition, toxicological studies should be carried out.

Key words: Methanol/methylene chloride extract, Rauvolfia vomitoria, Albendazole, Heligmosomoides bakeri, Mus musculus.