Isolamento de Alcaloides e atividades biológicas de espécies de Lauraceae da Amazônia

Abstract

Lauraceae is a plant family that has large number of species with pantropical distribution concentrated in river forests of Asia and the Americas. Chemically, it is characterized by the presence of metabolites with pronounced biological activities, such as flavonoids, lignoids and especially the alkaloids, which have great diversity of chemical structures. This study aimed at isolating Lauraceae species of alkaloids using a spectrometric scanning strategy associated with phytochemicals classic experiments and production of chemical and biological assays with extracts, fractions and isolated alkaloid alkaloids. In the preliminary analysis of this research were prospected leaves and branches of 16 species belonging to 09 different genera of this family. Of these, 07 were selected because they have favorable profile to the presence of alkaloids: Aniba ferrea, Aniba panurensis, Aniba guianensis, Aniba parviflora, Licaria martiniana, Licaria canella angustata and Ocotea leucoxylon. The botanical material was extracted in ethanol. Were tested 03 methodologies for alkaloids extraction. Five unpublished alkaloids have been isolated in these species: ocockyptina (from O. leucoxylon), laurotetanina and reticulin (from A. ferrea) and two indole alkaloids from A. panurensis. Their structures were identified by a set of spectral data (MS) and spectroscopy (1H-NMR, 13C and two-dimensional). For the kidnapping of free radicals we used the methods DPPH • and ABTS • +. The extracts of the branches of A. ferrea, A. parviflora and A. martiniana demonstrated high capacity scavenger of DPPH • (IC50 12.18 mg/mL, 13.23 mg/mL and 14.09 mg/mL, respectively). For the cation radical ABTS • +, the extracts of L. martiniana branches, A. panurensis and A. ferrea were the most outstanding (IC50 9.45 mg/mL, 11.05 mg/mL and 14.14 μg/mL, respectively). In the antimicrobial activity by agar diffusion was found that both the extract of the leaves of A. panurensis branches expressed significant activity with MIC ranging from 2.5 to 0.6 mg/mL. The highest percentage of inhibition in the cytotoxicity assay was observed for the extract of the stems of A. panurensis which reduced 94.65% of the cells belonging to the MRC5 line. The alkaloid fractions tested for the three activities, from the branches of A. panurensis showed relevant activity in the kidnapping of ABTS • + and antimicrobial test facing the strains of two Gram-positive. The indole alkaloid m/z 273 isolated from A. panurensis expressed considerable antimicrobial activity against four Gram-positive bacteria with MIC 0.6 mg/mL confirming the activity observed in the extracts and alkaloid fractions of this species. The profile of antioxidant activity, antimicrobial and cytotoxic alkaloid involving fractions being reported for the first time in this work.