In vivo antitrypanosomal effects of stem-bark extracts of Securidaca longipedunculata in rats experimentally infected with Trypanosoma brucei brucei

Abstract

The efficacy of stem-bark extracts of Securidaca longipedunculata against Trypanosoma brucei brucei infected rats was investigated. For curative study, forty adult Wistar rats of both sexes were randomly divided into 8 groups of 5 rats each. Each rat was infected with 10⁶ cells of trypanosomes per ml of blood intraperitoneally (ip). Rats in groups 1 and 2 received the crude methanol extract (CME) at 0.7 and 0.35 mg/kg, respectively. Similarly, rats in groups 3 and 4 received ethyl acetate fraction (EAF) at 0.7 and 0.35 mg/kg, respectively; while 5 and 6 were treated with 0.9 and 0.45 mg/kg of aqueous methanol fraction (AMF), respectively. Rats in groups 7 and 8 were treated with diminazene aceturate (3.5 mg/kg) and phosphate buffered saline, PBS (2 ml/kg), respectively. Four rats (group 9) were neither infected nor treated and served as neutral control. In the prophylactic studies, 25 rats of both sexes were randomly divided into V groups of 5 rats each. Rats in groups I, II, and III were pre-treated with CME at 0.7 mg/kg i.p. for 3, 5 and 7 days, respectively; while group IV received PBS for 7 days and served as negative control. The rats were then individually infected with 10⁶ parasites per ml of blood on days 3, 5 and 7 for groups I, II and III, respectively. Rats in group V were neither treated nor infected and served as neutral control. CME of S. longipedunculata suppressed level of parasitaemia and prolonged the survival period of rats when compared to other groups (P<0.05). Pre-treatment of animals with CME before challenge with the parasite could not prevent infection. Thus, stem-bark extract of S. longipedunculata exhibited some levels of curative antitrypanosomal effect against T. brucei brucei infection in rats despite its low margin of safety.

Keywords: Curative effect, High toxicity, In vivo, Phytochemical screening, Prophylactic effect