In vitro and in vivo anti-plasmodial activities of senna occidentalis roots extracts against plasmodium falciparum and plasmodium berghei
Teahton, Julius W.
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Plasmodium is a genus of parasitic protozoa, many of which cause malaria in their host. Five species namely; P. falciparum, P. malarae, P. ovale, P. vivax and P. knowlesi cause human malaria. Malaria due to P. falciparum is one of the most severe public health problems worldwide with an annual estimated 207 million clinical episodes and 627,000 deaths. The use of conventional anti-malarial drugs as treatment for malaria is greatly hindered by drug resistance exhibited by the parasite. Consequently, many people in rural areas have opted for the use of medicinal plants despite the fact that there is no sufficient scientific confirmation of their efficacy. However, studies have suggested that plants contain bioactive compounds which have anti-plasmodial activities. One of such plants is Senna occidentalis (roots) which is been used by herbalist in different parts of Kenya to treat malaria. This study was therefore carried out to determine the in vitro and in vivo anti-plasmodial activities of Senna occidentalis roots from Oloolua Forest against P. falciparum and P. berghei. Aqueous, methanol, and hexane crude extracts were prepared from the roots of S. occideentalis. The in vitro assay using P. falciparum were performed each in triplicate in 96 – wells microtiter flat bottomed plates. All the extracts were subsequently assayed for in vivo (suppressive, curative and prophylactic) activities against P. berghei using a 4-day test in BALB/c mice. A total of 185 mice of both sexes were used in the three regimens in which experimental mice were treated with extracts at dose rates of 1000 mg/kg/day to 200 mg/kg/day for suppressive and 1000 mg/kg/day to 600 mg/kg/day for curative and prophylactic tests respectively being administered orally, while control groups received Phosphate-Buffered Saline and pyrimethamine at 4 mg/kg/day. Mean % parasitaemia and inhibitions were reported as means ± SEM while survivorship values were reported as mean ± SD and compared using one-way analysis of variance (ANOVA) and student t- test. All p-values < 0.05 were considered statistically significant. The results from the in vitro assays revealed that there were no significant differences between the both strains of P. falciparum (W2 – chloroquine resistant and 3D7-chloroquine sensitive strains) amongst the three extracts (p < 0.05). The crude extracts in all regimens showed a dose-dependent reduction in the levels of parasitaemia in the experimental groups of mice relative to the non-treated mice (p < 0.0001). The three extracts displayed significantly high parasitaemia inhibition at a dose rate of 1000 mg/kg/day (p < 0.05) in suppressive, prophylactic and curative tests respectively. The most effective chemotherapeutic agent was the methanolic extract with an average mean percentage inhibition of parasitaemia of 81.84%, 76.18% and 70.18% for suppressive, prophylactic and curative tests respectively. The extracts prolonged the mean survival time in all the experimental groups relative to the non-treated group (p < 0.0001). The results indicate that S. occidentalis roots possess bioactive anti-plasmodial compound. On the basis of this study, it is recommended that further study be undertaken to determine the in vitro and in vivo cytotoxicity effects of S. occidentalis roots extracts on cells and body organs.
- MST-Zoological Sciences