In Vitro Antiplasmodial Activity of an Azadirachta indica Cell Culture Extract

Azadirachta indica A. Juss (neem tree) is used in Nigeria and India to control malaria. Due to the difficulty to obtain secondary metabolites from this plant, this study aimed to evaluate the in vitro antiplasmodial activity of extracts and fractions of A. indica cell culture on chloroquine-resistant Plasmodium falciparum (FCR3) strains. A. indica cell culture was carried on in stirred tank bioreactor. Biomass from this process was extracted with ethanol and subsequently fractionated with different solvents. Ethanolic extract and fractions obtained were tested in bioassays on chloroquine-resistant Plasmodium falciparum (FCR3) strains. Chloroquine was used as positive control. Finally, hexane fraction was analyzed by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry, to tentatively identify some compounds that might be involved in antiplasmodial activity. The extract showed promising activity with a half-maximal (50%) inhibitory concentration (IC50) of 6.14 μg ml−1, which decreased with the time (IC50: 33.64 µg ml−1 for at > 18 months). Some extract fractions showed impressive activity against P. falciparum with IC50 values of 13.66 and 9.80 µg ml−1 for the hexane and dichloromethane fractions at > 18 months, which was higher than that of the crude extract during the same time frame. Also, 16 compounds were partially identified in hexane fraction. This is the first study reporting in vitro antiplasmodial activity of extracts of A. indica obtained by biotechnology way. The in vitro antiplasmodial activity of the A. indica cell culture ethanolic extract was demonstrated, and this extract could be a potential future alternative for treating and controlling malaria.