Prophylactic Potentials of Extracts of Alstonia boonei Stem Bark on Chloroquine-Sensitive P. berghei- Induced Malaria in Mice

• O.O Olorunsogo

drug resistance and cross resistance of antimalarials especially plasmodium constitute a great handicap to the eradication of this disease.
Plant decoction that either treats or prevents parasite invasion is highly desirable in developing countries as it will be cost effective and
also readily available for the treatment and prevention of malaria. It was in this regard that we investigated the prophylactic potentials of
the various fractions of the stem bark of Alstonia boonei which is locally used for the treatment of malaria in South Western Nigeria.
Male albino mice were pretreated separately daily with a single dose of Sulfadoxine-Pyrimethamine (SP) (5mg/kg body weight) while
the other groups were pretreated separately with two different doses (200mg/kg body weight and 400mg/kg body weight) of methanol
extracts (ME), n-hexane (HF), chloroform (CF), ethylacetate (EF) and aqueous fractions (AF) of Alstonia boonei stem bark for seven
consecutive days. The animals were then challenged with inoculums of 1x107 chloroquine- sensitive P. berghei infected erythrocyte
intraperitoneally. The results showed a mutual delay in parasitemia with chloroform, n-hexane and aqueous fractions. The mean
percentage suppression of the parasite using SP and the extracts and fractions of Alstonia boonei (ME, HF, CF, EF, AF) on the seventh
day of the experiment were: 100±0.00, 40.22±0.00, 45.45±0.00, 50.00±0.01, 30.46±0.00, and 43.42±0.11 respectively for 200mg/kg
body weight dose and 100±0.00, 67.50±0.11, 80.20±0.00, 96.40±0.01, 62.55±0.02 and 70.20±0.00 respectively for 400mg/kg body
weight dose. These results showed that 200mg CF/kg body weight prevented parasitemia by half the capacity of SP while 400mg CF/kg
body weight was almost as good as SP. The percentage parasitemia also decreased in this order. The packed cell volume (PCV)
increased significantly (p<0.05) in the SP and the 200mg/kg body weight dose CF (48.50±0.02 and 35.01±01) respectively and increased
for all the fractions used for 400mg/kg body weight dose compared with the control. The result showed that chloroform fraction of
Alstonia boonei has promising anitimalarial potential which could be of future importance.

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