Evaluation of selected medicinal plants for chemotherapeutic Activities on plasmodium knowlesi and plasmodium berghei
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Date
2010
Authors
Were, Patrick Simiyu
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Malaria is one of the most widespread haemoparasitic diseases in the world, with an
estimated incidence of about 500 million clinical cases annually and a corresponding annual
mortality of up to 2.7 million. The use of conventional antimalarial drugs as a control
strategy for malaria is greatly hampered by drug resistance exhibited by the parasites.
Moreover, about 75% of the population in Africa does not have access to conventional
medicine and therefore resort to traditional medicine (TM) for treating the disease. These TM
suffer from lack of objective diagnosis and paucity of information on pharrnacokinetic
factors such as formulation, toxicity, dosage forms and efficacy. Among the Kenyan
communities living around Ngong Division of Kajiado District, malaria is a common
problem and has been culturally treated using TM. This study was therefore carried out to
determine the efficacy of four selected medicinal plants from Oloolua Forest, Ngong
Division, popularly used by local herbalists in treating malaria. A total of 15 crude extracts
were prepared from Warburgia ugandensis, Zanthoxylum usambarense, Aloe ngongensis and
Ajuga remota and assayed for in vitro activities against Plasmodium berghei and P. knowlesi.
Extracts that displayed high activities were subsequently assayed for curative and
prophylactic activities against P. berghei using the four-day suppressive test in BALB/c
mice. A total of 40 male adult mice were used in the two regimens in which experimental
mice were treated with each extract at a dose rate of 200mg/kg/day being administered
intraperitoneally, while control groups received Phosphate-Buffered Saline at the same rate.
Mean parasitaemia inhibitions and survivorship values were reported as means ± SEM and
compared using one-way analysis of variance (ANOVA) and the student t-test. All p-values
less than 0.05 were considered statistically significant. Significant reductions in parasitaemia
levels from in vitro tests (4 = 19.84,p < 0.05) were observed in treated groups relative to the
controls. Three extracts; chloroformic and methanolic from W ugandensis and aqueous
extraction of Z usambarense displayed significantly high parasitaemia suppression in
chemotherapeutic (F = 9.63, df = 3, 15,P < 0.05) and chemoprophylactic (F = 5.812, df = 3,
15, P < 0.05) assays respectively. The most effective chemotherapeutic agent was the
chloroformic extract with an average parasitaemia suppression of 69%. On the other hand,
the most active prophylactic agent was found to be an aqueous extract from W ugandensis
that produced 67% suppression of parasites in BALB/c mice. The same extract was equally
therapeutic, giving a suppressive value of 65%. In terms of mice survivorship, the aqueous
extract from Z usambarense as well as both methanolic and chioroformic extracts from W
ugandensis significantly increased mean survival times (MST) in treated groups in both
therapeutic (F = 40.462, df= 3, 10,p < 0.000) and prophylactic analyses (F = 67.74, df= 3,
10, p < 0.000). The results indicate that W ugandensis and Z usambarense possess bioactive
antiplasmodial compounds. On the basis of this study, it is recommended that bioactive
substances from W ugandensis and Z usambarense should be identified and characterized as
prime candidates for novel antimalarial drugs
Description
Department of Zoological Sciences, 96p. 2010, RC 159 .A5W4