Effect of walnut leaves on oxidative stress caused by murine cerebral malaria

Following the infection of mice by the Plasmodium parasite, a significant increase in oxidative stress occurs within the brain. This oxidative stress is further intensified as the parasite proliferates, leading to an imbalance in the body's oxidant and antioxidant systems. As a result, the affected mice experience various health issues stemming from this disruption. Previous research has indicated that the leaves of Juglans regia, commonly known as walnut, possess protective properties that can mitigate brain damage caused by the Plasmodium parasite. These leaves inhibit the parasite's reproduction and restore normal brain functions in the affected mice.

In the current study, we investigated the impact of J. regia leaves on oxidative stress and cellular damage associated with cerebral malaria infection in a murine model.

The extract of leaves from Juglans regia was prepared using methanol as the solvent. Thirty female C57BL/6 mice, weighing 20 to 25 grams and aged 9 to 12 weeks, were organized into six distinct groups for the experiment (labeled G1 through G6). On day 9, following the initiation of the infection protocol, all mice were euthanized, and their brains were harvested for further analysis. The primary focus of this study was to assess the degree of oxidative stress present in the brain tissue and measure the activities of various antioxidant enzymes. To quantify levels of inducible nitric oxide synthase (iNOS), the Enzyme-Linked Immunosorbent Assay (ELISA) technique and immunohistochemistry assay were employed, providing a sensitive and specific means of detecting this enzyme's concentration in the brain tissue samples.

The study findings revealed that the heightened levels of free radicals in the brain, induced by the infection with Plasmodium berghei, were effectively eliminated following a daily treatment regimen with JRLE. This treatment resulted in notable reductions in the concentration of key oxidative stress markers, including nitric oxide (NO), malondialdehyde (MDA), and hydrogen peroxide (H₂O₂), in the groups of mice that received JRLE compared to those that remained infected. Moreover, the administration of JRLE appeared to play a protective role against oxidative stress by enhancing the activities of several crucial antioxidant enzymes. Specifically, there was a marked increase in the activity levels of catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), and total antioxidant capacity (TAC) in the treated groups. Interestingly, although the treatment significantly increased the expression levels of inducible nitric oxide synthase (iNOS), the subsequent administration of JRLE effectively mitigated this increase.

This comprehensive evaluation aimed to clarify the potential protective effects of J. regia leaf extract concerning oxidative stress and its related neurological implications induced by P. berghei infection. Therefore, these plant leaves are an alternative source of new antioxidants and antimalarial agents.