2.7. Peters 4-Day Suppressive Test

The in vivo antimalarial activity of Murraya exotica extract (MEE) was assessed using the 4-day suppressive test in the P. berghei-infected mouse model [10]. Mice infected with the P. berghei NK 65 strain served as the reservoir, parasites were maintained by serial blood passage in mice, and the blood stage was stored at −80°C until use. The donor mice were infected with 200 μl of P. berghei parasite inoculum. The parasitized blood of each donor mouse was collected from the tail vein and diluted with 0.9% sodium chloride. ICR mice of both sexes were divided into five groups and each intraperitoneally infected with 0.2 ml of saline suspension containing 1.0 × 10⁷ parasitized erythrocytes (day 0). Three hours after infection, the mice in each group (n = 6) were treated with oral daily doses of 50, 100, 300, or 600 mg/kg body weight of MEE for four consecutive days (test groups 1, 2, 3, and 4, respectively). Positive and negative control groups were treated daily with an oral daily dose of artesunate at 2 mg/kg body weight and 5% sodium carboxymethylcellulose, respectively. The parasitemia of each mouse was determined under light microscope by examination of Giemsa-stained thin blood smears prepared from the mouse tail 4 days (96 hours) post infection [11].