In Vitro Study on the Effect of Treatment with Picralima nitida Seed Extract on Haemozoin Formation in Plasmodium berghei Infected Mice

Haemozoin is among the targets in malaria medication and some antimalarials are known to inhibit this compound as the mechanism of their actions. The essence of this experiment is to determine the inhibitory effect of seed extract of Picralima nitida on β-haemozin. Seeds of this plant were collected, identified and were extracted using ethanol. Plasmodium berghei was cultured from blood of infected mice and cultures at the ring stage (12 to18 h) with parasitemia of about 5% were used. Different concentrations of the extract (80 μg/mL, 160 μg/mL, 240 μg/mL, 320 μg/mL and 400 μg/mL) dissolved with 3 % tween 80 were used for the assay. Parasitized red blood culture treated with chloroquine at 10 μg/mL was used as standard control while untreated parasitized red blood cell culture was used as positive control. Various concentrations of haemin standard dissolved in DMSO (Dimethyl Sulfoxide) were used to get a standard plot for the extrapolation of the amount of haemozoin formed. At various time intervals (0 h, 18 h, 24 h, and 30 h) spread over approximately 30 h, the cultures were harvested and haemozoin contents measured spectrophotometrically. The results of the haemozoin formation assay showed that at 18 and 30 hours time interval, all the test groups had significant (p < 0.05) decrease in haemozoin concentration compared to the positive control (culture without treatment) while at 24 hour time interval, cultures treated with 240 μg/ml and 400 μg/ml of the extract showed non-significant (p > 0.05) decrease in haemozoin concentration. When compared with the standard control and haemin solution at the various time intervals (18, 24 and 30 hours), all test groups had significant (p < 0.05) increase in haemozoin concentration. Therefore, the extract of Picralima nitida was observed to inhibit the formation of haemozoin in malaria parasite in a non dose-dependent fashion.