Anti-plasmodial activity of the extracts of some Kenyan medicinal plants.

ETHNOPHARMACOLOGICAL RELEVANCE: The spread of drug resistant Plasmodium falciparum strains necessitates search for alternative newer drugs for use against malaria. Medicinal plants used traditionally in preparation of herbal medicines for malaria are potential source of new anti-malarial drugs. AIM OF THE STUDY: To identify the anti-plasmodial potential of twelve plants used in preparing herbal remedies for malaria in Kilifi and Tharaka districts of Kenya. MATERIALS AND METHODS: Twelve plants used traditionally for anti-malarial therapy in Kilifi and Tharaka districts were extracted with water/methanol yielding twenty-three extracts. The extracts were tested against chloroquine sensitive (NF54) and resistant (ENT30) P. falciparum strains in vitro using (3)Hypoxanthine assay. RESULTS: Seven (30%) extracts showed activity against P. falciparum with IC(50) values below 20 microg/ml. The remaining 16 extracts showed low or no activity. The most active extracts were from Zanthoxylum chalybeum (Rutaceae) with an IC(50) value of 3.65 microg/ml, Cyperus articulatus (Cyperaceae) with 4.84mug/ml, and Cissampelos pareira (Menispermaceae) with 5.85 microg/ml. CONCLUSIONS: This study revealed plants, that are potential sources of anti-malarial compounds. Anti-plasmodial activities of extracts of T. simplicifolia, C. pareira, and C. articulatus are reported for the first time.

Anti-plasmodial activity of the extracts and two sesquiterpenes from Cyperus articulatus.

Two sesquiterpenes, corymbolone and mustakone, isolated from the chloroform extract of the rhizomes of Cyperus articulatus, exhibited significant anti-plasmodial properties. Mustakone was approximately ten times more active than corymbolone against the sensitive strains of the Plasmodium falciparum.

The antiplasmodial activity of spermine alkaloids isolated from Albizia gummifera.

In the present study the methanolic extract of Albizia gummifera was fractionated into various fractions. These fractions were tested against choroquine sensitive (NF54) and resistant (ENT30) strains of Plasmodium falciparum. All other fractions apart from the alkaloidal fraction showed low activity with IC 50 above 3 microg/ml. The alkaloidal fraction exhibited strong activity against NF54 and ENT30 with IC 50 of 0.16+/-0.05 and 0.99+/-0.06 microg/ml, respectively. Five known spermine alkaloids were isolated from the alkaloidal fraction. These alkaloids exhibited activities against NF54 and ENT30 with IC 50 ranging from 0.09+/-0.02 to 0.91+/-0.10 microg/ml. Four of the alkaloids were further evaluated for in vivo activity against rodent malaria parasite Plasmodium berghei. The alkaloids showed percentage chemosuppression of parasitaemia in mice ranging from 43 to 72%. The use of the extracts A. gummifera for treatment of malaria in traditional medicine seems to have a scientific basis.

Anti-plasmodial activity of some Kenyan medicinal plant extracts singly and in combination with chloroquine.

Sixty organic and aqueous extracts of eleven plants used for the control of malaria by local communities in Kisii District, Kenya were screened for in vitro anti-plasmodial activity. The plants selection was based on existing ethnobotanical information and interviews with local communities. The extracts were tested against chloroquine sensitive and resistant laboratory adapted strains of Plasmodium falciparum. The study revealed that 63.6% of the plants were active (IC50 < or = 100 microg/mL). Extracts of four plants, Ekebergia capensis, Stephania abyssinica, Ajuga remota and Clerodendrum myricoides gave IC50 values below 30 microg/mL against both chloroquine sensitive and resistant P. falciparum strains. Combination of extracts of E. capensis and C. myricoides with chloroquine against the multi-drug resistant P. falciparum isolate (V1/S) revealed synergistic effect. The plants which showed activity may be useful as sources for novel anti-plasmodial compounds.

In vitro antiplasmodial activity of some plants used in Kisii, Kenya against malaria and their chloroquine potentiation effects.

Fifty-five organic and aqueous extracts of 11 plants used in malaria therapy in Kisii District, Kenya were tested in vitro against chloroquine (CQ)-sensitive and resistant strains of Plasmodium falciparum. Of the plants tested, 73% were active (IC(50) < 100 microg/ml). Three plants, Vernonia lasiopus, Rhamnus prinoides and Ficus sur afforded extracts with IC(50) values ranging less than 30 microg/ml against both CQ-sensitive and resistant strains. Combination of some extracts with CQ against the multi-drug resistant P. falciparum isolate V1/S revealed some synergistic effect. The plant extracts with low IC(50) values may be used as sources for novel antimalarial compounds to be used alone or in combination with CQ.