Antimalarial compounds of Homalolepis suffruticosa (Simaroubaceae)

Many of the species in the Simaroubaceae family have been used in folk medicine and some of them have had had their biological effects demonstrated. For example, the species Homalolepis cedron, belonging to the Homalolepis genus, is widely used as antimalarial by members of a quilombola community in the Amazonia, an endemic region with a high incidence of malaria. In this family, as well as in the genus concerned, some classes of biologically promising compounds have been found, such as: triterpenes, quassinoids and alkaloids. Thus, the aim of this work was to isolate the chemical compounds of the species Homalolepis suffruticosa, as well as to test the antimalarial activity of the isolated compounds. Roots of the plant species were collected in Araguari-MG, dried at room temperature, grinded and extracted succsessivily with hexane and methanol. The methanolic extract was fractionated by column chromatography and preparative thin layer chromatography, both on silica gel. The structural determination of the compounds isolated was based on spectroscopic data including 1D (1H and 13C) and 2D NMR (1H-1H-COOSY, 1H-1H-NOESY, HSQC and HMBC) and high resolution mass spectroscopy (HRESI-MS). In vitro antimalarial testing of the samples was performed in culture of chloroquine resistant Plasmodium falciparum W2 clone by the determination of the parasite enzyme lactate dehydrogenase (PfLDH method)5. Results led to the dentification of an new triterpene called Milemaronol (1), together with other known compounds, such as chaparrinone (2), scopoletin (3), cantin-6-one (4) and 5-methoxycantin-6-one (5), and the triterpenes eurylene (6), hispidol A (7), hispidol B (8), nilocytine (9), α-dihydronylocytine (10) and teurylene (12). In conclusion, the phytochemical study of the species Homalolepis suffruticosa led to the isolation of a new triterpene together with other eleven known compounds. Antimalarial testing of the compounds isolated from the plant species roots showed that 2 and 5 were very active against P. falciparum clone W2, with IC50 values of 0.067 e 0.0548 µg/mL respectively. This results were close to that one of chloroquine (standard antimalarial drug). Compounds 1, 9 and 12 were also active against P. falciparum clone W2, with IC50 values ranging from 4.9 to 10.8 µg/mL. All of antimalarial results presented here are unpublished in the literature.