Estudo químico e biológico de Strycnhos amazonica

Abstract

The Strychnos genus, the main of the Loganiaceae family, is distributed in tropical regions, principally on Africa, Asia, Central and Sourth America .It is well known for its toxic properties, wich led to the isolation a wide variety of indole alkaloids with diverse biological properties and medicinal application. In addition to the use in the manufacture of curare the Strychnos genus is important in ethnopharmacology due to antimalarial, aphrodisiac, tonic, and anti-anemic effects for American species.However, the most studied biological activities are anticonvulsants and relaxing. In this study, was performed a phytochemical and biological studies on the leaves and stem of the species Strychnos amazonica Krukoff. From the hexane extracts of the leaves and stem were obtained, respectively, as binary mixtures, the pentacyclic tritepenes, friedelin and friedelanol and the steroids, sitosterol and stigmasterol. Conventional methodology for obtaining alkaloids led to isolation of strictosidine from leaves and 17-O-methylakagerine along with its derivative named 4-hidroxi-metileno-17-O-methylakagerine, from core of the stem. However, the presence of impurities evidenced in the NMR spectra indicate further analysis for confirmation of the proposed structure of this derivative.The identification of compounds was done by spectroscopic techniques, especially, 1H NMR, HSQC and HMBC MS, and comparison with the literature data. Theoretical studies were performed on 17-Omethyl- akagerine alkaloids and strictosidine, where optimization geometric data obtained by DFT calculation (bond distances and angles) are presented and compared to experimental data (angles provided by coupling constants and X-ray data for similar molecules). Antimicrobial tests performed with methanol extracts of leaves, bark and heartwood, and the isolated alkaloids, showed significant activity of the samples, especially the alkaloid 17-O-methyl-akagerine against Candida albicans, confirming the great pharmacological potential of this species.