In vitro Antitrypanosomal Activity and Phytochemical Screening of Selected Acacia Plant Species Aqueous Methanol Extract

Abstract

Trypanosomiasis has been recognized as a scourge in sub-Saharan Africa for centuries and chemotherapy of the disease still remains unsatisfactory. This study is to explore an alternative source of antitrypanosomal agents from the stem bark of four Acacia species; Acacia nilotica, Acacia sieberiana, Acacia geradii and Acacia hockii. Dried stem bark of each plant was pulverized and extracted with 98% methanol by maceration. Phytochemical screening was carried out followed by in vitro testing of extracts on the motility of Trypanosoma congolense maintained in Ringer solution. Motility assessment of trypanosome was carried out after exposure with varied concentrations of the extracts for 2 hours. Thereafter, infectivity test was carried out using albino mice. Seventy-two mice, divided into twenty-four (24) groups of three animals were each inoculated with 100µl of the mixture containing the varying extract concentrations intraperitoneally. Berenil was used as standard drug control. Establishment of infection and subsequent Parasitaemiawere monitored in the animals for 60 days. The Phytochemical assay revealed the presence of anthraquinones, tannins, glycosides, cardiac glycosides and terpenes in all the extracts. Saponin was only present in Acacia nilotica and Acacia geradii. Incubation of parasites with each of the four acacia species recorded cessation in parasite motility which was concentration dependent. The highest concentration 20 mg/ml showed the highest effect within fifteen (15) minutes of incubation which was similar to the Berenil incubated control. However, lower doses (0.005 and 0.00005) mg/ml did not show difference from the non extract incubated negative control. Incubation of T. congolense with Acacia nilotica, Acacia sieberiana, Acacia geradii and Acacia hockii at 20, 10 and 1 mg/ml inhibited the ability of the parasites to establish infection in the albino mice as compared the standard control drug. The results indicate that the methanolic stem extracts of the four acacia species possess antitrypanosomal activity with potentials for the treatment of trypanosomiasis.