Evaluation of the Antiplasmodial Activity of the Aqueous and n-hexane fractions of Citrullus lanatus leaf in Plasmodium berghei beghei infected Mice

Abstract

There is still high morbidity and mortality from malaria in Sub-Saharan Africa and Nigeria. Reports of the emergence of resistance to  artemisinin combination therapy, will aggravate the situation. This study evaluated the in vivo antiplasmodial activities of aqueous and n- hexane fractions of Citrullus lanatus leaf extracts in mice infected with Plasmodium berghei berghei. Median lethal-dose (LD50) of the  extracts were determined using Lorke’s method. The antiplasmodial activity was investigated using three standard methods: a 4-day  suppressive, curative and prophylactic tests. Tests groups were administered three graded doses (50, 100 and 200 mg/kg) of the extracts.  Chloroquine (5 mg/kg) and pyrimethamine (1.2 mg/kg) were used as positive controls while normal saline (10 mL/kg) was the negative  control. Preliminary phytochemical screening revealed the presence of alkaloids, saponins, flavonoids, tannins, phytosterols, reducing sugars and phenolic compounds. The antimalarial activity of both fractions showed significant (p < 0.05) dose-dependent reductions in  parasitaemia compared to the negative control. For suppressive test, the aqueous and nhexane fractions of Citrullus lanatus at their  highest doses (200 mg/kg), gave maximum of 90.95% & 74.07% chemo-suppression respectively comparable to 94.65% for chloroquine.  For curative test, the aqueous fractions showed significant (p < 0.002) schizonticidal activity at all doses. The prophylactic effect of the n- hexane fraction showed significant reductions in parasitaemia (p < 0.05) at all doses. This result demonstrates that the leaf of Citrullus  lanatus possesses significant antiplasmodial activity and is safe for the ethnomedicinal management of malaria.