Abstract
Increased resistance of malaria parasite to first line antimalarial drugs has led to the search for alternatives in the management of malaria. This study evaluated the anti-plasmodial and immunomodulatory effect of dichloromethane plant extract of Stachytarpheta jamaicensis in Plasmodium berghei infected mice. Chloroquine-resistant Plasmodium berghei infected mice were separated into five treatment groups (200 mg/Kg, 400 mg/Kg, and 600 mg/Kg) with a negative control (given distilled water only) and a positive control (treated with Piperaquine-Dihydro-artemisinin), a standard drug. The plant extracts and the standard drugs were administered orally. Parasitological examinations and survival rates of the animals were monitored for 30 days, post infection. Phytochemical screening of the plant extract was performed using the standard method. Enzyme-linked immunosorbent assay was carried out to ascertain the immunomodulatory potential of the plant extract. Leaf extract of S. jamaicensis revealed the presence of alkaloids only. The extract showed significant (P < 0.05) antiplasmodial effect on Day 11 post-infection and at 200 mg/kg dose mediated parasite clearance and improved survival throughout the study. The intense and sustained TGF-β level stimulated by S. jamaicensis at 200 mg/kg dose may have translated into the prolonged survival observed in the mice. S. jamaicensis modulated both pro and anti-inflammatory responses in early and late infections, thus preventing pathological outcomes associated with excessive expression of the pro-inflammatory (IFN-γ) and anti-inflammatory (TGF-β) cytokines. S. jamaicensis may therefore be explored as alternatives for development of novel antimalarial and immunomodulatory candidates.