Abstract:
Malaria parasites are increasingly becoming resistant to currently used antimalarial
therapies, therefore there is an urgent need to expand the arsenal of alternative antimalarial
drugs. In addition, it is also important to identify novel antimalarial drug targets. In the current
study, extracts of two plants, Pterocarpus angolensis and Ziziphus mucronata were obtained and their
antimalarial functions were investigated. Furthermore, we explored the capability of the extracts to
inhibit Plasmodium falciparum heat shock protein 70 (Hsp70) function. Heat shock protein 70 (Hsp70)
are molecular chaperones whose function is to facilitate protein folding. Plasmodium falciparum the
main agent of malaria, expresses two cytosol-localized Hsp70s: PfHsp70-1 and PfHsp70-z. The
PfHsp70-z has been reported to be essential for parasite survival, while inhibition of PfHsp70-1
function leads to parasite death. Hence both PfHsp70-1 and PfHsp70-z are potential antimalarial
drug targets. Extracts of P. angolensis and Z. mucronata inhibited the basal ATPase and chaperone
functions of the two parasite Hsp70s. Furthermore, fractions of P. angolensis and Z. mucronata
inhibited P. falciparum 3D7 parasite growth in vitro. The extracts obtained in the current study
exhibited antiplasmodial activity as they killed P. falciparum parasites maintained in vitro. In addition,
the findings further suggest that some of the compounds in P. angolensis and Z. mucronata may target
parasite Hsp70 function.
