ANTIPLASMODIAL ACTIVITY OF EXTRACTS OF CROTON MACROSTACHYUS (EUPHORBIACEAE) AGAINST PLASMODIUM FALCIPARUM (D6) AND PLASMODIUM BERGHEI (ANKA)

Abstract

Medicinal plants have been used to cure malaria and parasitic diseases for centuries. This study was aimed at determining the effects of Croton macrostachyus (Euphorbiaceae) extracts in vitro using chloroquine sensitive Plasmodium falciparum (STRAIN D6) and in vivo using Plasmodium berghei (STRAIN: ANKA). Chemical analysis of the plant included extraction using methanol, ethyl acetate, butanol and water. Thin Layer chromatography and Column chromatography was used for chemical analysis of extracts. Structural elucidation was carried out using nuclear magnetic resonance (NMR) spectroscopy and Infrared(IR) spectroscopy . The in vitro study for P. falciparum included a growth inhibition assay and the minimum inhibitory concentration (IC50) was determined. An in vivo assay was carried out using BALB/c mice with P. berhgei (STRAIN ANKA). Thin blood films were prepared to determine the percent suppression of parasitaemia (PSP). An immunoprophylaxis assay was carried out to test the efficacy of the extracts as immune boosters. An acute toxicity experiment was carried out to determine the effect of the extract in clean, untreated BALB/c mice. Analysis for the in vitro study was done by Chemosen program to obtain a concentration-response data for a linear regression analysis. For the in vivo and immunoprophylaxis assays, analysis of variance (ANOVA) and tukey’s test was used to analyze significance differences among and between mice treatment groups. Chemical analysis was carried out at The University of Eastern Africa, Baraton and University of Chicago, USA. The bioassays were carried out at the Kenya Medical Research Institute. The in vitro IC50 were recorded as chloroquine (0.346±0.047), artemether (2.895±0.628), ethyl acetate extract (52.838±8.581), methanol extract (14.230±9.450) aqueous extract (43.446±2.218)butanol extract (26.163±5.487), pure compound F5(3.259±1.274) and pure compound F52(22.286±1.338). The in vivo treatment assay showed percent suppression of parasitaemia for ethyl acetate extract positive control (87.64±1.264), 500mg/kg(81.71±0.728), 250mg/kg(81.71±0.728) and 100mg/kg (61.82±0.571). The methanol extract showed percent suppression of parasitaemia for positive control (97.22±0.225), 500mg/kg(68.14±0.670), 250mg/kg (33.61±0.609) and 100mg/kg (27.44±0.443). The aqueous extract results were for positive control, 99.20±0.156, 500mg/kg, 71.85±0.447, 250mg/kg, 44.23±0.064 and 100mg/kg 24.36±0.447. The butanol extract give results for positive control as 100±0.000, 500mg/kg as 80.44±1.259, 250mg/kg as 60.66±0.445 and 100mg/kg as 72.69±0.306. The immunoprophylaxis or immune booster study showed that parasites were suppressed in the ethyl acetate experiment by chloroquine as 98.85±0.248, 500mg/kg as 99.88±0.058, 250mg/kg as 93.96±0.343 and 100mg/kg as 74.02±1.236. Using the methanol extract, percent suppression for the chloroquine control was 98.51±0.478, 500mg/kg was 83.04±0.635, 250mg/kg was 64.84±1.143 and 100mg/kg was 56.89±1.143. The butanol extract give percent parasitaemia for chloroquine control as 99.40±0.016, 500mg/kg as 92.07±0.294, 250mg/kg as 83.66±1.068 and 100mg/kg as 83.66±1.068. C. macrostachyus extract can serve as viable pharmaceutical agents for treatment and prophylaxis of malaria.