Estudo químico e avaliação dos potenciais antitumoral e antibacteriano dos exudatos de Myracrodruon urundeuva

Abstract

Myracrodruon urundeuva Allemão (Anacardiaceae), popularly known as Aroeira, is a plant traditionally known for its medicinal properties. It is commonly found in Mato Grosso do Sul and other regions of Brazil. Studies on the chemical composition of M. urundeuva have been conducted with the seeds, essential oil from the leaves, and primarily with the bark of the trunk. These studies report the presence of tannins, chalcones, mono- and sesquiterpenes, alkenylphenols, and other phenolic derivatives. However, there are no reports on the chemical study or the biological properties of the trunk bark exudate of this species, which is used by peasants as a tonic. Therefore, the aim of this study was to conduct a chemical study of the trunk bark exudate of M. urundeuva, aiming at the isolation and structural elucidation of the major constituents, particularly those that may present some biological potential. The exudate was extracted with ethanol and then partitioned with hexane, CH2Cl2, and AcOEt to obtain the resulting phases. The ethanolic extract and/or obtained phases were evaluated for their mutagenic, cytotoxic, and antibacterial potentials, where the extract showed no mutagenic activity, in addition to showing cytotoxic activity, with selectivity for kidney, liver, and breast carcinomas (GI50 values between 30-34 µg/mL) and moderate activity against Gram-negative bacteria E. coli (MIC ≥ 500 µg/mL). Due to the high yield, the hexane phase was selected for the chemical study, and this phase was subjected to fractionation through silica gel 60 column chromatography (70-230 and 230-400 mesh), leading to the isolation of the triterpenes: cycloartenone (1), 24-methylenecycloartenone (2), cycloeucalenone (3), 24-methylenepollinastanone (4), cycloeucalenol (5), and 24- methylenepollinastanol (6). The structural determination of these substances was carried out by the acquisition, analysis, and interpretation of 1H and 13C NMR data. Subsequently, compound 1-6 were also subjected to assays for evaluation of antibacterial activity, and showed weak activity (MIC ≥ 500 µg/mL). Compound 1, 2, 3, 4, and 6 are being described for the first time in the genus Myracrodruon, also being the first report of the occurrence of 3, 4, and 6 in Anacardiaceae. The occurrence of this class of compound exclusively in the exudates of M. urundeuva suggests a compartmentalization of this class of compound in this plant species. The results obtained so far revealed the importance in continue isolation and characterization of the chemical constituents of the exudate of M. urundeuva in order to justify the potential bioactivity presented by the ethanolic extract.