Comparative studies of genotoxicity and anti-plasmodial activities of stem and leaf extracts of Alstonia boonei (De Wild) in malaria-infected mice

Abstract

Drug resistance in malaria infection is a serious public health challenge. Thus, scientific search for alternative treatment measures among the local medicinal plants is exigent. We therefore investigated the anti-plasmodial efficacy and genotoxicity of the methanolic leaf and stem extracts of Alstonia plant at varying concentration (200 mg/kg, 400 mg/kg and 600 mg/kg) in mice infected with chloroquine sensitive Plasmodium berghei. The phytochemical screening of the extract revealed that leaf sample contained significantly higher secondary metabolites, except saponins (p<0.05). Anti-plasmodial activities of the two extracts were duration and dose- dependent. Stem bark extract showed higher curative potential with inhibition rate of 56.71% at 400 mg/kg whereas, leaf extract was efficient at 600mg/kg with 52.15% inhibition rate. Stem bark extract at 400 mg/kg improved the enzymatic activities of the mice; it lowered serum ALT (6.88±4.42) and increased liver ALT (41.07±5.56). Similarly, 400 mg/kg leaf extract showed highest AST (70.65±4.00) and ALT (44.65±7.83) activities in the kidney and liver respectively. Analysis of genotoxicity revealed that micronucleus and abnormal (binucleated, notched and blebbed) were prevalent among the experimental mice which increased significantly (p<0.05) at all concentrations except at 600mg/kg leaf extract. Therefore, this present study indicates that both leaf and stem bark extracts of A. boonei possess anti-plasmodial activity and are less genotoxic when compared with standard drug.

Keywords: Genotoxicity; Plasmodium berghei; metabolites; micronucleus; blebbed; standard drug