Abstract

Iwalewa EO, Roland T, Aduloju BO, Ologe MO, Adepiti AO, Odediran SA, Iwalewa OJ, Obuotor EM and Olawuni JI

Drug combinations represent current treatment strategies in the management of malaria. Nitric oxide (NO) has been proposed to inhibit Plasmodium growth due to its parasite-scavenging activity thus the effects of various combinations of an NO inducer - anthraquinone (25-100 mg/kg, ANT), an NO donor - sodium nitroprusside (0.5 mg/kg, SNP) and NO inhibitor -nitro-L-arginine methyl ester (40 mg/kg, L-NAME) and their combination drugs were evaluated using the antimalarial curative model in Plasmodium berghei-infected mice. Chloroquine (10 mg/kg, CQ) and distilled water were employed as the positive and negative controls, respectively. The plasma concentrations of nitric oxide in infected mice treated with ANT, SNP and L-NAME were determined spectrophotometrically. A significant (P < 0.05) decrease in the parasitaemia of ANT-treated groups at 50 and 100 mg/kg as well as L-NAME were observed. The result of this study showed the combinations of SNP and ANT (100 mg/kg), L-NAME and ANT, CQ and its combination with SNP and L-NAME were effective as they exhibited significant (p < 0.05) decreases in parasitaemia throughout the period of treatment justifying their antimalarial activity. However, SNP, the combinations of SNP plus ANT (25 and 50 mg/kg), SNP plus L-NAME were not effective as significant increases (P<0.05) in parasitaemia were observed. ANT and CQ demonstrated antiparasitic effect, which may be attributable to nitric oxide. Combinations of the ANT, L-NAME and CQ elicited increases in nitric oxide release, reduced parasitaemia while SNP released no significant amount of nitric oxide.