In Vitro Antiplasmodial Activity of Flower Extracts From Combretum Leprosum Mart (Mofumbo)

Abstract

Malaria is the cause of hundreds of thousands of deaths per year, besides putting billions of people at risk of developing disease. When it comes to its therapy, the drugs used currently are losing its efficacy due to increase in the frequency of resistant strains of the parasite, highlighting the importance for the search of new classes of molecules presenting antiplasmodial activity. In the present work, the antiplasmodial activities of five extracts (crude, hexane, chloroform, ethyl acetate and methanol) from the flowers of Combretum leprosum are assessed. The method employed for obtaining the extracts was silica gel column chromatography, and the techniques used for the analysis of antiplasmodial activity (IC 50 ) and citotoxicity (MLD 50 ) were ELISA and MTT respectively, where a selectivity index was calculated after the obtaining of these two values. The extract presenting the highest antiplasmodial activity was the chloroform extract (IC 50 = 3.97 µg/mL), however, this extract also presented the higher cytotoxicity (MLD 50 = 18.12 µg/mL), and therefore the extract presenting the best overall activity was the methanolic extract (IS = 18.97 IntrodutionOver 3 billion people are estimated to be at risk of being infected with malaria and therefore developing disease, and according to latest estimates, hundreds of thousands of deaths caused by it occurred in each year of this millennium (WHO, 2014). The world region that suffers the heaviest burden is Africa, where the great majority of cases of malaria occur, mainly in children under the age of five (WHO, 2014). The disease is caused by parasitic protozoa of the genus Plasmodium, of which five species are known to infect humans: P. falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi (COX, 2010). The parasite life cycle begins when a female mosquito of Anopheles genus bites a human and releases the sporozoites from its salivary glands to the dermis, where they reach the avascular tissue and then a percentage of them migrates and enters the blood vessels, making their way to the liver, where they undergo cellular modifications and perform rounds of asexual replication (ALY; VAUGHAN; KAPPE, 2009).After leaving the liver, the parasite begins other cycles of asexual replication inside red blood cells, using molecules and cellular structures of the host cells to survive, grow and reproduce, generating thousands of merozoites and causing the characteristic symptoms of the disease (TILLEY; DIXON; KIRK, 2011). When it comes to its chemotherapy, most of the cases of uncomplicated malaria are treated currently by the use of ACT's drugs, although is already known that these drugs are losing its efficacy due to the increase in frequency of resistant strains (VISSER; VUGT; GROBUSCH, 2014), which highlights the importance for the search of new molecules bearing antiplasmodial activity.Plants have been used during millennia by humanity, and pharmacological studies of medicinal plants yielded useful molecules in the treatment of various diseases, includ...

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