In vivo Antimalarial Activity of Solvents Extracts of Alstonia boonei Stem Bark and Partial Characterization of Most Active Extract(s)

Alstonia boonei, a plant locally called ‘Egbu’ in South Eastern Nigeria is used traditionally in the treatment of malaria in the region. This research was carried out to evaluate in vivo antimalarial activity of different solvents extract (aqueous, methanol and chloroform) of Alstonia boonei against NK-65 Chloroquine sensitive Plasmodium berghei infected mice. A total of 84 mice were inoculated with Plasmodium berghei and left for 7 days for optimum parasitaemia development after which they were screened for malarial parasites using thin blood film. They were then randomly divided into 12 groups of 7 mice per cage. Group 1 serves as negative control, Groups 2-4 animals were administered with aqueous extract at a dose of 150, 250 and 500 mgkg-1 per day for nine days,Groups 5-7 animals were administered with methanol extract at a dose of 150, 250 and 500 mgkg-1 per day for nine days while Groups 8-10 animals were administered with chloroform extract at a dose of 150, 250 and 500 mgkg-1 per day for nine days. Group 11 and 12 were administered with chloroquine and ACT respectively. The antimalarial activity of the different plant extracts was assessed using thin blood films after 3 days, 6 days and 9 days of the extract administration. Results showed that all the extracts had intrinsic antimalarial properties that were both dose dependent and duration dependent. It showed a significant difference (p<0.05) in mean percentage activity and percentage parasitaemia of the extracts when compared with placebo (distilled water), Chloroquine and ACT, with methanol showing highest activity (99.68%) on day 3 at a dose of 500mg/kg followed by aqueous extract (99.03%) at a dose of 250 mg/kg. GCMS results revealed the presence of Di-n-Octyl phthalate; 3-Nitrophthalic acid, bis – (2, ethylhexyl-ester) and Bis – (3, 5, 5-trimethylhexyl) phthalate as possible bioactive compounds presents in the extracts. The present study demonstrated that Alstonia boonei possess strong antimalarial activity with aqueous extracts possessing the highest activity. Thus, supporting the traditional use of the plant for the treatment of malaria.