Antioxidant defense system induced by cysteine-stabilized peptide fraction of aqueous extract of &ITMorinda lucida&IT leaf in selected tissues of &ITPlasmodium&IT &ITberghei&IT-infected mice

OBJECTIVE: This study evaluated the responses of some antioxidant parameters in selected tissues of Plasmodium berghei-infected mice treated with cysteine-stabilized peptide fraction (CSPF) of aqueous extract of Morinda lucida leaf.& para;& para;METHODS: Fifty-six mice were randomly divided into seven groups. Group A (normal control) was uninfected and received 5% dimethyl sulfoxide (DMSO). Mice in Groups B (negative control), C, D, E and F were inoculated with P. berghei NK65 and were administered with 5% DMSO and 15.63, 31.25, 61.5 and 125 mg/kg body weight of CSPF respectively. Group G animals, were also inoculated with P. berghei NK65, and received 20 mg/kg body weight of chloroquine. The administration lasted for three days, after which malondialdehyde (MDA) concentration and various antioxidant parameters in selected tissues of mice were determined on days 4 and 8 post-inoculation.& para;& para;RESULTS: The results revealed that MDA concentration was significantly increased (P < 0.05) in the tissues of the negative control and chloroquine-treated groups. The increased MDA concentration was reduced by CSPF in a dose-dependent manner, which was significant (P < 0.05) at higher doses. The activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase and the concentration of reduced glutathione were significantly reduced (P < 0.05) in the tissues of the negative control animals compared to the normal controls. This observed reduction in the negative control animals was reverted in a dose-dependent manner in infected animals given CSPF, even to the range of the normal controls at highest dose, as did chloroquine.& para;& para;CONCLUSION: The results suggest that CSPF of M. lucida leaf extract may induce the antioxidant defense system in vivo against Plasmodium species infection.