Larvicidal and antimalarial activity of some Zulu medicinal plants
Gardenia thunbergia T.A Sprague, Siphonochilus aethiopicus (Schweif.) B.L Burt, Schotia brachypetala Sond., Acorus calamus L., Withania somnifera (L) Dunal in DC., Elaeodendron transvalense (Burtt Davy) R.H. Archer, Hypoxis hemerocallidea Fisch., C.A. Mey. & Ave-Lall, Vernonia adoensis Sch. Bip. Ex Walp.and Acanthosperum australe (Loefl.) Kuntze are medicinal plants commonly used by traditional healers in South Africa to treat malaria. Aqueous, dichloromethane and methanol extracts of these plants were screened for larvicidal, antioxidant, in vivo antipyretic, and in vitro antiplasmodial activities. The plant extracts either killed or reduced spontaneous movement in Culex quinquefascitus larvae after 24 hours following treatment. Methanol extracts exhibited antioxidant (DPPH, ABTS scavenging, Fe2+ chelating) activity, albeit to varying degree of efficiency. The dichloromethane and methanol extracts significantly (p<=0.05) reduced pyrexia with activity increasing in a concentration dependent manner. The antiplasmodial activity against chloroquine sensitive strain of Plasmodium falciparum (D10) showed that the methanol extracts of G. thunbergia, V. adoensis and the dichloromethane extracts of E. transvalense, A. australe and W. somnifera were active (IC50 of 1.04–5.07µg/ml). The results suggest that these plants contained constituents that could be developed as potent antimalarial drugs (mosquito larvicide, anti-fever and anti-plasmodial). Possibly, the compounds target metabolic pathways common to the C. quinquefascitus larvae and P. falciparum.
Acknowledgement: University of Zululand Research Committee
Medical Research Council, South Africa