In vivo Efficacy and Toxicity Studies on Erythrina senegalensis and Khaya ivorensis Used as Herbal Remedies for Malaria Prevention in Cameroon

Aim: The study aimed at assessing the in vivo anti-plasmodial activity of aqueous extracts from Erythrina senegalensis and Khaya ivorensis, two plants used traditionally as bark decoctions in Cameroon to prevent and cure malaria.

Methodology: The antiplasmodial activity of aqueous extracts of E. senegalensis and K. ivorensis was investigated using a murine malaria model (Plasmodium berghei / Anopheles stephensi / BALB/c mice), applying a protocol for assessing the prophylactic potential of the remedy. Treatments were administered orally to BALB/c mice for 9 days at doses of 200 and 400 mg/kg/day. Mice were challenged on day 3 of treatment by exposure to P. berghei infected mosquitoes. The impact on parasitaemia was assessed on thin blood smears prepared on day 7 after exposure to infective bites.

The acute toxicity of the plant extracts was tested according to the guidelines of the Organization for Economic Co-operation and Development (OECD guidelines 423).

Results: The plant extracts showed antiplasmodial activity, reducing parasitaemia by 40.4% to 56.3%, according to the extract. In particular, a combination of the two extracts at the dose of 100 mg/kg each provided a reduction of parasitaemia in treated mice by more than 50%, as compared to controls. The extract of E. senegalensis when used alone at 200 mg/kg/day reduced the parasitaemia by 40.3% +/- 7.2%, doubling the dosage increased parasite suppression to 56.3% +/- 5.1%.

Toxicity studies yielded comforting results: up to a dosage of 2000 mg/kg no mortality occurred in treated mice. Also, animals treated during the antiplasmodial experiments did not reveal signs of toxicity and remained in good conditions up to the end of the experiments.

Conclusion: The results suggest that the combination of E. senegalensis and K. ivorensis could be a valid plant combination for the preparation of a standardized, effective and affordable remedy against malaria, in particular for Cameroonian communities with limited access to modern drugs.