In vitro activity of defatted crude extracts of Solanum pseudocapsicum leaves against Plasmodium falciparum

Abstract

Background: Plasmodium falciparum is the most lethal and major malaria parasite that is widely spread in Africa. It has led to high mortality rate especially in children below the age of 5years and also caused a serious economic and social burden to this region. The lack of an effective vaccine and increase in drug resistance and cost to the currently used antimalarial drugs has complicated malaria therapy and necessitate the search for new effective and affordable alternative antimalarials. Solanum pseudocapsicum commonly called Jerusalem cherry is a plant with a lot of traditional medicinal claims.

Objective: The aim of the study was to screen the methanol and dichloromethane extracts of Solanum pseudocapsicum for their antimalarial activities.

Methods: Extraction was carried out using cold maceration with methanol (polar) and dichloromethane (non polar) solvents after defatting with petroleum ether. Infected blood collected from symptomatic patients was cultivated in vitro in a candle jar set up using RPMI 1640 medium. Monoculture of P. falciparum was established by PCR protocol using P. falciparum specific primers. In vitro antiplasmodial studies involved sub cultivation of already synchronised culture (using 10% sobitol) and further cultivation of the parasite with extracts at concentrations in triplicates on a 96 well micro titre plate using RPMI 1640 supplemented with 15% O+ human serum. The antimalarial effects of the extracts were expressed as mean of percentage inhibition of parasite growth relative to control wells (0μg/ml) and mean values were statistically compared using MS-Excel add in (version 1.11) with those of chloroquine treated control group. Phytochemicals were screened using conventional screening methods.

Results: Phytochemical screening of the 3 extracts revealed the presence of cardiac glycosides, steroid and triterpenes. Tannins were detected in the methanol and dichloromethane extracts while saponins, flavonoids and alkaloids detected in the methanol extract and anthraquinone was absent in all extracts. In vitro antiplasmodial screening shows that the methanol extracts of S. pseudocapsicum leaves had the highest activity with IC50 of 6.31 μg/ml. The dichloromethane fraction of S. pseudocapsicum leaves was moderately active with IC50 of 22.39. Statistical analysis reveals increasing activity with increasing concentration which shows significant antiplasmodial activity at P value ≤ 0.01. The petroleum ether extracts of S. pseudocapsicum leaves were in active with IC50 values greater than 50 μg/ml.

Conclusion: To our knowledge, this is the first report of the antimalarial study of this plant and it is thought that further identification of active constituents through further bioguided assay could lead to possible drug development.