Evaluation of the in vitro antimalarial and malaria prophylactic activity of eight Ficus species

AG Bwalya; P Phiri; M Kaiser; D Tasdemir

doi:10.1055/s-0031-1282139

Planta Medica, Table of Contents

Evaluation of the in vitro antimalarial and malaria prophylactic activity of eight Ficus species

AG Bwalya ¹, P Phiri ², M Kaiser ³, D Tasdemir ¹

¹Centre for Pharmacognosy and Phytotherapy, School of Pharmacy, University of London, London WC1N 1AX, UK
²School of Mathematics and Natural Sciences, Copperbelt University, P.O Box 21692 Kitwe, Zambia
³Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, CH-4002 Basel, Switzerland

Abstract

Malaria is a serious health problem in Africa, where approximately 250 million new cases and one million deaths are recorded per year [1]. The absence of long-term prophylaxis and the emerging resistance to the current therapies highlights the necessity of new drugs for its eradication and control. Liver stage malaria parasites show an absolute requirement for type-II fatty acid biosynthesis (FAS-II) [2], rendering this pathway a good target for causal prophylaxis. In Zambia, the genus Ficus is traditionally used against malaria [3]. Hence, we collected the leaves, barks and roots of eight Zambian Ficus species and screened their crude methanol (CR-Me) extracts for in vitro activity against the multi-drug-resistant Plasmodium falciparum strain K1 using a modified [3H]-hypoxanthine incorporation assay. Malaria prophylactic potential of the extracts was also evaluated against three recombinant FAS-II elongation enzymes, FabI, FabG and FabZ, by spectrophotometric assays. All CR-Me extracts were active against P. falciparum, with F. ovata Vahl bark exhibiting the best activity (IC₅₀ 4.76µg/ml). Most of the root extracts, particularly F. sycomorus L. subsp. gnaphalocarpa (Miq.) C.C. Berg potently inhibited FabZ (96.6% inhibition at 1µg/ml). The CR-Me extracts were then subjected to solvent partitioning to yield n-hexane, CHCl₃and aq. MeOH subextracts. Remarkable antiplasmodial potency was observed in CHCl₃ subextracts of four species (IC₅₀ <2µg/ml). The leaf and root aq-MeOH subextracts were active against FabI and FabZ enzymes with inhibition rates >90% at 1µg/ml. This is the first screening of Zambian Ficus species for antimalarial potential and our results justify their traditional use.

Acknowledgement: UK Commonwealth Scholarship Commission and the Rick-Cannell Travel Fund of the School of Pharmacy are acknowledged for funding.

References: 1. World Health Organization (WHO) (2009) Fact sheet on Malaria WHO, Geneva, Switzerland.

2. Vaughan AM et al. (2008) Cell Microbiol 11: 506–520.

3. Fowler DG (2007) Zambian Plants: Their vernacular names and uses. Royal Botanical Gardens. Kew, UK.