Antimalarial activity of methanolic extracts from plants used in Kenyan ethnomedicine and their interactions with chloroquine (CQ) against a CQ-tolerant rodent parasite, in mice.

Methanolic extracts from 15 medicinal plants representing 11 families, used traditionally for malaria treatment in Kenya were screened for their in vivo antimalarial activity in mice against a chloroquine (CQ)-tolerant Plasmodium berghei NK65, either alone or in combination with CQ. The plant parts used ranged from leaves (L), stem bark (SB), root bark (RB), seeds (S) and whole plant (W). When used alone, extracts from 7 plants, Clerodendrum myricoides (RB), Ficus sur (L/SB/RB), Maytenus acuminata (L/RB), Rhamnus prinoides (L/RB), R. staddo (RB), Toddalia asiatica (RB) and Vernonia lasiopus (RB) had statistically significant parasitaemia suppressions of 31.7-59.3%. In combination with CQ, methanolic extracts of Albizia gummifera (SB), F. sur (RB), R. prinoides and R. staddo (L/RB), Caesalpinia volkensii (L), Maytenus senegalensis (L/RB), Withania somnifera (RB), Ekebergia capensis (L/SB), T. asiatica (L/RB) and V. lasiopus (L/SB/RB) gave statistically significant and improved suppressions which ranged from 45.5-85.1%. The fact that these activities were up to 5-fold higher than that of extract alone may suggest synergistic interactions. Remarkable parasitaemia suppression by the extracts, either alone or in combination with CQ mostly resulted into longer mouse survival relative to the controls, in some cases by a further 2 weeks. Plants, which showed significant antimalarial activity including V. lasiopus, T. asiatica, F. sur, R. prinoides and R. staddo warrant further evaluation in the search for novel antimalarial agents against drug-resistant malaria.浜松医科大学学位論文 医博第546号(平成２１年３月１８日