Immunoregulatory properties of n-hexane extract of Osmundastrum cinnamomeum in treatment of Plasmodium berghei infection in mice
Malaria control is threatened by the emergence of drug-resistant parasites and there is an urgent need for the development of antimalarial agents with novel mechanisms of actions. This study evaluated the anti-plasmodial and immune-modulatory activities of N-hexane leaf extract of Osmundastrum cinnamomeum in a mice model. Chloroquineresistant Plasmodium berghei infected mice were separated into six treatment groups and treated orally with 0, 50, 100, 200 and 400 mg/kg of extract, water and combination of dihydroartemisinin/ piperaquine (DHAP), respectively. Parasitological activities and survival rates were monitored for 30 days’ post infection. Phytochemical composition of O. cinnamomeum was analysed by gas chromatography-mass spectrometry (GC-MS) methods. Levels of TNF-α and IL-10 were assessed using enzyme-linked immunosorbent assay (ELISA). Leaf extract of O. cinnamomeum is rich in terpenoids, saponins and cardiac glycosides. The extract showed significant (p<0.05) antiplasmodial effect in the treated groups relative to parasitemia (23.68 %) in the untreated control on day 13. Parasitaemia was significantly higher in the DHAP group (9.83 %) on day 30 compared to extract treatment of 50 mg/kg (2.09 %) and 100 mg/kg (1.83 %). Significantly low level of TNF-α (28.82 pg/ml) and conversely, high expression of IL-10 (79.04 pg/ml) were recorded in the 50 mg/kg test group. There was a significantly higher survival rate of animals in the same group (50 mg/kg). In conclusion O. cinnamomeum demonstrated potential activity to suppress parasite and also prime the immune system against malaria infection in mice. Therefore, O. cinnamomeum may be used as a potential adjunctive therapy in the treatment of malaria infection.
Keywords: Osmundastrum cinnamomeum, Plasmodium berghei, Immunomodulation, Inflammatory cytokines