In vitro Cytotoxicity and Antiplasmodial Activity of Fractions from Anthocleista djalonensis A. Chev. Acetone Root Extract

Aim: Malaria caused by Plasmodium falciparum is one of the killer diseases in Africa today and the uncontrollable spread of drug resistance and limited drugs with therapeutic efficacy makes it necessary to discover agents against this deadly parasite. Traditionally Anthocleista djalonensis root extract is used in the treatment of Malaria in many parts of Africa and has demonstrated to be a source of antiplasmodial agents. This study aims at identifying possible antiplasmodial agents from chromatographic root fractions of Anthocleista djalonensis of the Genatianceae family as well as to evaluate their cytotoxicity against HeLa cells.

Place and Duration of Study: The study was undertaken in the Department of Organic Chemistry, Rhodes University, Grahamstown, South Africa. The duration period was between March and July 2016.

Methodology: The Anthocleista djalonensis roots were collected from Arochukwu, Abia State, Nigeria. The acetone extract was obtained from successive maceration of the methanol crude extract with hexane, ethyl acetate and acetone. The concentration (1-1000 µg/mL range) of the chromatographic fractions from acetone root extract of Anthocleista djalonensis were tested for anti-malarial activity against Plasmodium falciparium (P. falciparum). Cytotoxicity against HeLa cells was also evaluated using Resazurin based assay.

Results: The Five fractions obtained from the chromatographic fractionation of acetone extract labeled A1, A2, A3, A4, and A5 with percentage yield (13.02, 26.66, 24.70, 0.05 and 26.66% respectively) showed excellent anti-plasmodial activity. The anti-malarial bioassay test showed fractions A1, A2, A3, A4 and A5 with IC50 value of 0.0360 ± 0.0100, 8.1299 ± 2.0358, 46.2482 ± 1.2720, 0.0151 ± 0.0010, and 9.8013 ± 0.8171 μg/mL respectively. CC50 values of 44.2010 ± 8.6790, 50.0000 ± 5.6412, 71.6221 ± 2.9600, 36.7212 ± 5.8900 and 0.5132 ± 3.770 μg mL–1 were recorded for fractions A1, A2, A3, A4 and A5 respectively. Fractions were classified as marginally active (A3) showing SI of 1.540 ± 0.0091, partially active (A2 and A5) with SI 6.150 ± 0.0200 and 4.133 ± 0.015 and as active (A1, A4,) exhibiting SI of 1227.805 ± 8.210 and 2431.867 ± 1.589 respectively. A1 and A4 showed SI > 10 and IC50 < 10 ug/mL. Chloroquine, used as a reference anti-malarial drug, tested in parallel had an IC50 of 0.0125 ± 0.0001 µM and was comparable with A1 and A4.

Conclusion: The chromatographic fractions from acetone root extract of Anthocleista djalonensis are potential sources for anti-malarial agents of lead compounds for the development of anti-plasmodial drugs.