In Vivo Antiplasmodial and Antitrypanosomal Efficacy of Extracts of Morinda lucida Benth

The rapid spread of growing resistance to antimalarial medicines is a major constraint to therapeutic control of malaria. Chemotherapy of African trypanosomiases is severely limited by unacceptable toxicity, high cost and inaccessibility of, and increasing parasite resistance to current drugs. Newer and more efficacious drugs are therefore urgently needed for the treatment of these diseases. Aqueous extract of the leaves of Morinda lucida, used traditionally in Nigeria for the treatment of malaria and ailments generally described as “fever”, was evaluated for therapeutic effects in Trypanosoma brucei brucei infection in mice while methanol extract of the root was evaluated for therapeutic potential in Plasmodium berghei infection in mice. At a dose of 400mg/kg, aqueous extract of the leaves completely cleared trypanosomes from circulation within two weeks of treatment. The root extract showed a dose dependent antiplasmodial effect. Percentage suppression of parasitaemia were 56.30, 59.84, 67.72 and 81.80% for doses of 100, 200, 400mg/kg of the extract, and 5mg/kg chloroquine respectively. The mean survival period (days) were 15±0.7, 18±0.5, 19±1, 23±1 and 8±1, for doses of 100, 200, 400mg/kg b.w. of the extract, 5mg/kg chloroquine, and the untreated control respectively. Preliminary phytochemical screening of the root extract showed the presence of alkaloids, phlobotannins, flavonoids and saponins. The LD₅₀ was estimated to be 3800mg/kg b.w. It is concluded that extracts of M. lucida or chemicals therein are potentially useful for the discovery of antimalarial and antisleeping sickness drugs. Acknowledgement: This work was funded by a research grant to Emmanuel O. Ogbadoyi by the Organization for the Prohibition of Chemical Weapons, The Hague.