Antioxidant defense system induced by cysteine-stabilized peptide fraction of aqueous extract of Morinda lucida leaf in selected tissues of Plasmodium berghei-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.

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.

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.

CONCLUSION

The results suggest that CSPF of M. lucida leaf extract may induce the antioxidant defense system in vivo against Plasmodium species infection.