Assessment of hepatoprotective effect of extracts of Alstonia boonei leaf in isoniazid and rifampicin co-treated rats

Anti-tuberculosis drugs, rifampicin and isoniazid, in their mode of action can generate toxic reactive metabolites upon oxidative bio-activation of the parent compound by the cytochrome P₄₅₀monooxygenase system leading to liver injury. Currently, there is increased awareness of the benefits in the use of medicinal plants in the management of various oxidative stress-related diseases. This study therefore evaluated the hepatoprotective effect of aqueous and ethanol extracts of <em>Alstonia boonei </em>leaf in rats co-treated with isoniazid (INH) and rifampicin (RIF). Sets of albino Wistar rats were placed into eight groups. The animals in each group (except the normal control) were orally co-treated with isoniazid (200mg/Kg) and rifampicin (200mg/Kg).The results revealed that the INH+RIF co-treated rats significantly (p&lt;0.05) increased the activities of liver function enzymes (ALT, AST and ALP) when compared with the normal control. There were significantly high levels (p&lt;0.05) of malondialdehyde (MDA) and low levels of reduced glutathione (GSH) in the INH + RIF co-treated groups in contrast to the control. However, administration of extracts of <em>A. boonei</em> (250mg/kg and 500mg/kg doses) protected the animals against various degrees of oxidative damage, particularly in the aqueous extract treated rats. A similar trend was observed in the silymarin and vitamin E treated rats which showed normal levels of these parameters. The overall results from this study suggest that the aqueous extract of <em>A. boonei</em> leaf showed better hepatoprotective ability in contrast to the ethanol extract.