Evaluation of methanol root extract of securidaca longipedunculata for antitrypanosomal activity in vitro and in vivo

Abstract

Securidaca longipedunculata is a medicinal plant used in different parts of Africa for treatment of various ailments including sleeping sickness in Northern Nigeria. On this basis, the methanol root extract of S. longipedunculata was investigated for antitrypanosomal effect to determine a possible rationale for this purpose. Acute toxicity was investigated orally and intraperitoneally (IP) to determine the LD50. Trypanocidal activity was evaluated in vitro and in vivo. The extract was given orally for nine days at the doses of 200, 300 and 400 mg/kg. Then, the effects on haematology, Alanine Aminotransferase (ALT), Aspartate aminotransferase (AST) and weight gain were investigated. The minimum inhibitory concentrations (MICs) of the extract and diminazene aceturate (DA), a standard trypanocidal drug, were 5 μg/ml and 2.1 μg/ml, respectively. For In vivo study, the extract was well tolerated orally up to 5000 mg/kg, therefore oral LD50 was not determined. Meanwhile, the IP LD50 was 3.3 mg/kg. The extract significantly decreased parasitaemia at the dose of 400 mg/kg for six days of post-treatment. There was also significant decrease in parasitaemia on day 9 post-treatment in all the extract treated groups. However, parasitaemia cleared by day 3 post-treatment in the DA-treated group. The extract at all doses significantly increased packed cell volume (PCV) on day 7 and 14 post-infection. The extract also significantly improved weight gain at all doses used on day 7 and 14. The serum levels of ALT and AST were significantly decreased at the extract dose of 400 mg/kg. Our study suggests promising trypanocidal activity especially in vitro, giving some level of credence to the traditional use of the plant in Northern Nigeria for the treatment of sleeping sickness.