Brazilian Cerrado Qualea grandiflora Mart. Leaves Exhibit Antiplasmodial and Trypanocidal Activities In vitro

BACKGROUND: The rapid spread of drug-resistant strains of protozoan parasites required the urgent need for new effective drugs. Natural products offer a variety of chemical structures, which make them a valuable source of lead compounds for the development of such new drugs. Cerrado is the second largest biome in Brazil and has the richest flora of all the world savannahs. We selected Qualea grandiflora, a plant species known for its proprieties in folk medicine and its antibacterial activity. OBJECTIVE: However, its antiprotozoal activity was not yet explored. MATERIALS AND METHODS: We investigated the activities of fractions from the ethyl acetate extract of Q. grandiflora leaves against human life forms of Plasmodium falciparum, Trypanosoma cruzi, and Trypanosoma brucei gambiense, and for its cytotoxicity upon the rat L6-myoblast cell line. Ten fractions were produced by ethyl acetate:hexane chromatography. RESULTS AND CONCLUSION: The fractions showed no cytotoxicity against L-6 cells (IC(50) > 100 μg/mL) and no hemolysis propriety. Three fractions had a moderate activity against P. falciparum, anyone was active against T. cruzi but four fractions demonstrated a high activity against bloodstream forms of T. brucei gambiense (8.0< IC(50) <15 μg/mL). Identification and characterization of the active compounds are currently under investigation. SUMMARY: Qualea grandiflora is an endemic tree of the Brazilian Cerrado, which presents medicinal properties. Ten fractions of the ethyl acetate extract of Q. grandiflora leaves were assessed against Plasmodium falciparum, Trypanosoma Cruzi, and Trypanosoma brucei gambiense. No fraction showed relevant cytotoxicity and hemolysis activity. All the fractions presented antiplasmodial and trypanocidal activities. Three fractions with moderate antiplasmodial activity (49< IC(50) <56 μg/mL). Four fractions with high activity against bloodstream forms of T. brucei gambiense (8.0< IC(50) <15 μg/mL). [Image: see text] Abbreviations used: CQ: Chloroquine, DMSO: Dimethyl sulfoxide, HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, HMI: Modified Iscove's medium, IC(50): Concentration inhibiting 50% of parasite growth, IC(90): Concentration inhibiting 90% of parasite growth, MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, RPMI: Roswell Park Memorial Institute, SD: Standard deviation, SI: Ratio of cytotoxicity to biological activity − TC(50)/IC(50), TC(50): Concentration causing 50% of cell growth inhibition, TC(90): Concentration causing 90% of cell growth inhibition, TLC: Thin-layer chromatography