Antimalarial activity and toxicity evaluation of Kenyan Hugonia castaneifolia Engl. Teclea nobilis Del. and Turraea mombassana C.DC

The aqueous and methanol extracts of three medicinal plants, Hugonia castaneifolia, Teclea nobilis and Turrae mombassana were evaluated for in vitro antiplasmodial activity against a chloroquine sensitive Plasmodium falciparum strain (D6) and in vivo, against a P. berghei ANKA strain in mice. The extracts were also assessed for cytotoxicity in Vero cell lines and acute toxicity in mice. The water extracts were moderately active with IC50 of 33.07 3g/ml for T. mombassana and 23.92 3g/ml for H. castaneifolia while the methanol extracts of T. mombassana, H. castaneifolia and T. nobilis were highly active in vitro with IC50 of 6.1 3g/ml, 8.86 3g/ml and 8.61 3g/ml respectively. The methanol extract of T. mombassana had the highest chemosupppression followed by the methanol extract of H. castaneifolia in vivo. Aqueous extract of H. casteinofolia was weakly cytotoxic against Vero cells CC50 =22.00 3g/ml. No toxic effect or mortality was observed in mice treated orally with any of the extracts at the highest concentration of 5000mg/kg. These results demonstrate antimalarial potential and safety of the three medicinal plants tested, which are used traditionally for the treatment of malaria in Kenya. Keywords: Antiplasmodial; Malaria; Toxicity; Meliaceae; Rutaceae; Linacea

Microsatellite typing reveals strong genetic structure of Schistosoma mansoni from localities in Kenya

Genetic diversity and population structure of seven populations of Schistosoma mansoni sampled in Kenya were assessed using five microsatellite markers. The mean number of alleles per locus, expected heterozygosity in Hardy-Weinberg equilibrium and pairwise FST values ranged from 5.2 to 10.7, 0.5-0.8 and 3.6-27.3%, respectively. These data reveal that S. mansoni populations in Kenyan have relatively high levels of genetic diversity and is significantly differentiated. Our data combined with information on biogeography support the hypothesis that the strong genetic structure in Kenyan schistosomes is as a result of limited gene flow and large population sizes. Resistance to anthelminthics has not been reported among the Kenyan schistosomes, we hypothesize that this is probably due to the very little gene flow among populations, thereby limiting opportunities for the spread of rare alleles that might confer resistance to the drugs

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 ug/ml. The alkaloidal fraction exhibited strong activity against NF54 and ENT30 with IC 50 of 0.16 ± 0.05 and 0.99 ± 0.06 ug/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 ug/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