| Summary: | Background: Medicinal plants displaying both antimalarial and immunomodulatory mechanisms of action are better candidates for antimalarial drug development. The effects of aqueous leaf and stem bark extracts of Nauclea latifolia and Morinda lucida, and leaf extracts of Lawsonia inermis, Chromolaena odorataandTithonia diversifoliaon malaria immune responses and Plasmodium parasite were studied. Methods: Inbred balb/c mice were treated with all extracts individually at 100 mg/kg. Initial cytokines measurements were determined from plasma samples of mice before exposure to plant extracts. Mice were treated for 3 days, and then infected with Plasmodium chabaudi chabaudi. Plasma samples were further collected on 3, 5, and 7 days post-infection and pro-inflammatory cytokines (IL-6, IFN-ɤ, IL-12p70 and TNF-α), Chemokine (MCP-1) and anti-inflammatory cytokine (IL-10) were quantified using flow cytometry. Extracts Percentage Chemoprophylaxis was determined. Results: After treatment, M. lucida stem bark extract significantly stimulated both pro-inflammatory and anti-inflammatory cytokines, with percentage immunomodulatory activity of 69.6%, 87.2%, 38.3%, 81.4% and 45.0% for IL-6, MCP-1, IL-10, IL-12p70 and TNF-α respectively. On day 3 post-infection, N.latifolia stem bark extract significantly produced higher pro-inflammatory (IL-6, IL-12 and TNF-α) and anti-inflammatory (IL-10) cytokines when compared to control. M. lucida stem bark extract group further displayed lower values of IL-6, MCP-1, IFN-ɤ and TFN-α when compared to control at 3-day post-infection. T. diversifolia and L. inermis displayed delayed inflammatory responses. All extracts suppressed parasitaemia, and the highest percentage chemoprophylaxis of 71.9% and 70.5% was observed in N. latifolia and M. lucida stem barks treated groups. Conclusion: These suggest that the plants have immunomodulatory and antiplasmodial potentials and a few of them can be exploited as antimalarial drug candidates and adjuvants.
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