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.

COMPARATIVE ASSESSMENT OF TOTAL PHENOLIC CONTENT IN SELECTED MEDICINAL PLANTS.

This study was to compare the total phenolic (TP) content in extracts from eleven plant materials collected at different geographical locations in Kenya, Nigeria, and USA. These plants have been selected because the majority of them are highly pigmented, from yellow to purple, and would therefore have economic value in industries for producing antioxidants and surfactants. Two of them were collected from the industrial and domestic waste outlets. Each analysis was achieved using the Folin-Ciocalteau technique. The order of decreasing phenolic acid content as gallic acid concentration (mg/g dry weight) was Prunus africana (55.14) > Acacia tortilis (42.11) > Khaya grandifoliola (17.54) > Curcuma longa (17.23) > Vernonia amygdalina (14.9)> Russelia equisetiformis (14.03) > Calendula officinalis (7.96) >Phragmites australis (control) (7.09) > Rauwolfia vomitoria (6.69) > Phragmites australis (industrial) (6.21) > Cnidoscolus aconitifolius (5.6). The TP contents of Spartina alterniflora species were below the detection limit.

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.

Antimalarial activity of fractions isolated from Albizia gummifera and Aspilia mossambicensis crude extracts.

To identify the fractions of medicinal plant extracts containing the highest concentration of antimalarial principles, we tested the antimalarial activities of the crude or total extracts and two fractions from Albizia gummifera (Leguminosae) and three fractions from Aspilia mossambicencis (Compositae) against laboratory adapted isolates of Plasmodium falciparum in vitro using the 3H-hypoxanthine uptake assay. Chloroquine was used as a reference antimalarial drug. The mean 50% inhibitory concentrations (IC50s) of A. gummifera total extract and fraction were both <2.2 microg/ml for three P. falciparum isolates while the mean IC50 of A. gummifera f raction-2 was higher (5.0+2.9sd) for the same isolates. Aspilia mossambicensis total extract and fractions-1,4 and 5 had mean IC50 values of 96.6+/-32.5,38.6+/-23.0,142.5+/-79.6 and >1250.0 microg/ml, respectively, against four P. falciparum isolates. These results show that fraction-1 of either A. gummifera or A, mossambicensis had the highest concentration of antimalarial principles. We now plan to concentrate our efforts on these promising fractions in order to isolate pure compounds which could eventually be used to effectively treat malaria.

An effective traditional medicine for bronchial asthma: clinical demonstration and preliminary toxicological evaluation.

This clinical paper reports the investigations conducted on a traditional African anti-asthmatic formulations and evaluates its toxicological and phyto-chemical effects.

Preliminary chemical characterization of pharmacologically active compounds of aqueous extracts of synadenium glaucescens.

A test system based on the use of ion exchanges, gel filtration on Sephadex and extraction with organic solvents is described. This system provides information on the stability, molecular size, charge, and polarity of the pharmacologically active compounds in the aqueous plant extracts. Knowledge of these properties permitted the development of an isolation method for a glucose present in the aqueous extracts of the leaves of S.galucescens, responsible for the inhibition of the electrically induced contractions of a quinea pig ileum.

Detectability and measurability of amoscanate in plasma by TLC and HPLC.

Although amoscanate has been established as a potent antischistosomal drug, its detectability and measurability in biological fluids has been in doubt. Experiments have been carried out to show that these measurements can be made. High pressure liquid chromatographic (HPLC) and thin layer chromatographic (TLC) analyses have been performed on plasma samples incubated with plasma at 37 degrees C. Specific chemical detection methods of functional groups in the molecule were used to establish the identity of the drug on TLC plates, and the results were found to correlate with the HPLC analyses.