Effect of chloroquine, methylene blue and artemether on red cell and hepatic antioxidant defence system in mice infected with Plasmodium yoelii nigeriensis.

Reactive oxygen species are mediators of tissue injury and are involved in malaria infection. In this study, the status of red cell and hepatic oxidative stress and antioxidant defence indices were investigated during Plasmodium yoelii nigeriensis (P. yoelii) infection, and treatment with chloroquine (CQ), methylene blue (MB) or artemether (ART) in mice. P. yoelii infection caused a significant (p < 0.05) increase in oxidative stress as evidenced by the elevated level of malondialdehyde. This was followed by a significant decrease (p < 0.05) in hepatic antioxidant defence indices, viz. reduced glutathione (GSH) and glutathione-S-transferase (GST). Also, the red cell catalase activity was significantly (p < 0.05) lower in malaria infection, while there was no significant difference (p > 0.05) in the superoxide dismutase (SOD) activity of infected mice when compared to untreated normal. Treatment of infected mice with the three antimalarials showed that the drugs suppressed the parasitaemia in the order CQ > ART > MB. CQ, MB and ART treatment of infected mice caused a significant (p < 0.05) increase in the levels of hepatic GSH and GST. Specifically, CQ, MB and ART increased the levels of hepatic GSH by 108, 124 and 98 %, respectively, at day 6. Also, ART treatment of infected mice significantly (p < 0.05) elevated the red cell SOD level by 200 % at day 3. Taken together, the findings suggest that the antimalarial effect of CQ, MB and ART countered the P. yoelii-induced oxidative stress leading to the elevation of enzymatic and non-enzymatic antioxidants in the host system.