Antiprotozoal activity of major constituents from the bioactive fraction of Verbesina encelioides

Shahira M Ezzat,Maha M Salama,Engy A Mahrous,Louis Maes,Cheol-Ho Pan,Essam Abdel-Sattar

doi:10.1080/14786419.2016.1180604

Abstract

The bioactive petroleum ether fraction of Verbesina encelioides, previously studied by the authors, was chosen for the isolation of antiprotozoal metabolites. Pseudotaraxasterol-3β-acetate (1), benzyl 2,6-dimethoxy benzoate (2), 16β-hydroxy-pseudotaraxasterol-3β-palmitate (3) and pseudotaraxasterol (4), in addition to β-sitosterol glucoside (5) and β-sitosterol galactoside (6) were isolated and identified based on one-dimensional and two-dimensional spectral analysis. This is the first report describing (3) and (6) in genus Verbesina. The isolated compounds were tested in vitro against Plasmodium falciparum, Trypanosoma brucei, Trypanosoma cruzi and Leishmania infantum. Cytotoxicity was evaluated on MRC-5 cells. Compound 1 showed moderate to weak activity against L. infantum T. brucei and P. falciparum and was inactive against T. cruzi. Compound 3 showed moderate activity against L. infantum, compound 4 revealed weak activity against T. cruzi, while 5 and 6 were inactive against all tested protozoa. All compounds were non-cytotoxic. The isolated constituents showed less antiprotozoal activity than the crude fraction.

Highlights

Infections caused by protozoa are a major worldwide health problem causing significant morbidity and mortality in Africa, Asia and Latin-America
The authors previously indicated the antiprotozoal potential of the petroleum ether fraction of V. encelioides (IC50: 8.2, 10.1, 9.7 and 4.6 μg/mL against T. cruzi, T. brucei, L. infantum and P. falciparum respectively (Abdel-Sattar et al, 2010)
Our findings indicated that the individual isolated compounds were much less active than the total petroleum ether extract, this might be attributed to the synergistic effect of the compounds in the crude extract rather than acting individually

Summary

Introduction

Infections caused by protozoa are a major worldwide health problem causing significant morbidity and mortality in Africa, Asia and Latin-America. The in vitro activity of the isolated constituents was evaluated against Plasmodium falciparum, Trypanosoma brucei, T. cruzi and Leishmania infantum. The petroleum ether extract of V. encelioides previously studied by the authors indicated antiprotozoal potential (Abdel-Sattar et al, 2010).

Results

Conclusion