In vitro Antiplasmodial and Antioxidant Activities of Entandrophragma cylindricum (Meliaceae) Extracts

Abstract

Malaria is still regarded as a major global infectious disease in the 21st Century with a high pediatric mortality toll in the developing world. In Africa, malaria is one of the diseases causing the most morbidity and mortality. These past 30 years, malaria parasites especially P. falciparum have rapidly developed resistance to commonly used antimalarial drugs. New, more effective and affordable anti-malarial drugs are needed. Medicinal plants play a key role in the control of malaria, especially where access to modern health services is limited. The aim of this study was to evaluate the antimalarial and antioxidant properties of Entandrophragma cylindricum stem bark extracts. Three types of extracts (methanolic, Ethyl Acetate and aqueous extracts) were prepared and tested on both Chloroquino-Sensitive 3D7 and Chloroquino-Resistant INDO strains of Plasmodium falciparum. These parasite strains were cultivated in vitro by the method of Trager and Jensen. Cultures were maintained in fresh O+ human erythrocytes at 4% haematocrit in complete medium RPMI 1640 supplemented with 0.5% Albumax II at 37°C under reduced O2. The synchronized ring stage development of P. falciparum Pf3D7 and PfINDO strains were incubated in a 96-well microplate for 48h with different concentrations (12.5, 25, 50 and 100 µg/ml) of plant extracts. Zero point four (0.4%) DMSO in RPMI was used as negative control, while Chloroquine (1 nM) was used as positive control and the results were obtained by the microtiter plate based SYBR Green I fluorescence assay. The antioxidant activity was determined by measuring ferric reducing-antioxidant power (FRAP), DPPH radical scavenging, nitric oxide (NO) radical scavenging and ferrous ion-chelating activities. Vitamin C was used as control. Of the extracts tested, the highest antiplasmodial activity was observed with Ethyl Acetate extract against the Chloroquinoresistant Pf INDO strain with IC50 of 16,05 ± 0,35 µg/ml then aqueous extract (16.85± 0,54 µg/ml) and methanol extract (18.93 ± 2.88 µg/ml). The same extract exhibited in vitro antioxidant property in FRAP, DPPH radical scavenging, NO radical scavenging and ferrous ion-chelating assays and can therefore prevent oxidative stress.