The Peter’s 4-day suppressive test against Chloroquine sensitive
P. berghei (NK 65) infection in mice was employed [23]. Twenty
albino mice of both sexes were inoculated. They were randomly
grouped with the same number of male and female and four
mice in each group. The animal were then administered
extract daily for 4 consecutive days. On day 1 (D0); heparinized
blood was prepared from the donor mouse as explained earlier,
treatment started 2 h after the mice were infected with the
parasite. Group 1 that served as control was orally administered
with 1 ml/kg body weight of normal saline, Groups 2, 3 and 4
were orally administered with 100, 200 and 300 mg extract/kg
body weight daily respectively, while group 5 was administered
with 5 mg chloroquine/kg body weight orally [23]. On Day 2-4
(D1-D3); the mice were treated again with the same doses and
through the same route as in D0 at interval of 24 h, 48 h and 72 h
post-infection [24]. On the 5th day (D4), blood was collected
from the tail of each mouse and spread on a microscope slide to
make a thin film. The blood films were fixed with methanol for
1 min stained with 3% Giemsa solution for 30 min and examined
microscopically [25]. Eight fields containing 250 erythrocyte and
the number of parasitized erythrocytes were recorded while the
suppression of parasitemia was expressed as percent for each
dose, by comparing the parasitemia in the control group with the
treated one. The mice were observed for signs of toxicity after
treatment for the first 4 (critical) h, then over a period of 24 h,
thereafter daily for 7 days. Mortality occurring at a particular dose
will indicate either to continue administration of subsequent
higher dose or to estimate the LD50 by comparing the mortality
to a fixed LD50 cut-off values provided in the guideline [26].