Fitoquímica e prospecção de princípios ativos em resíduos madeireiros de swietenia macrophylla king

Abstract

Despite the emergence of synthetic materials, wood continues to be widely used by various industrial sectors, which, on the other hand, end up generating large volumes of wood waste. Residues that are usually not appreciated during processing and most often are from species without chemical knowledge reported in the literature, due to scarcity. In this context, seeking to add value to the residues discarded after the mechanical processing of logging activities, the present work presents studies focused on the chemical investigation of the residues of Swietenia macrophylla King (mahogany). It is worth mentioning that the opportunity to carry out chemical studies with a native species, not endemic in Brazil, arose from the donation of a mahogany window frame belonging to an abandoned building that is more than 30 years old, since it is located in an ecosystem threatened. After the technological studies and the manufacture of small objects with the species, some pieces were donated to the Natural Products Chemistry Laboratory, where they were crushed, ground and submitted to cold extraction with hexane and methanol to obtain the crude extracts. Column chromatography with different stationary phases (cellulose, florisil®, sephadex LH-20 and 70-230 and 230-400 mesh silica gel) was used to fractionate the extracts and obtain the secondary metabolites. Phytochemical studies with S. macrophylla revealed three new limonoids with a phragmalin skeleton (11-acetoxy-1”α-hydroxy-swietenitin K, 11-acetoxy-1”β-hydroxy-swietenitin K and 11-acetoxy-swietenitin K). In addition, 16 known substances belonging to the triterpene class were also isolated (cycloeucalenol, cycloeucalenone, cycloartenol, 24-methylene-cycloartan-3β-ol; cycloart-23-en-3β-25-diol, cycloeucalenol ester, α and β- amyrins), steroids (β-sitosterol, stigmasterol, β-sitosterol ester and sitosterol 3-O-β-D-glucopyranoside), benzaldehyde derivatives (2,4-dihydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde and 3,4-dihydroxyacetophenone) and a coumarin (scoporone). The structures of the substances were proposed based on 1D and 2D nuclear magnetic resonance (NMR) analyses, high and low resolution mass spectra and comparison with literature data. Considering the biological potential of the classes of isolated substances, bioassays were carried out against the nymphs of Bemesia tabaci (insecticide) and against the strains of Candida albicans, Candida krusei and Cryptococcus gattii (fungicide). From these tests, the phragmalin limonoids stood out with 54 and 52% of mortality among the substances tested in the insecticide test. In the antifungal assay, the most active compound was 3-O-β-D-glucopyranoside with a MIC of 40 µg/mL for Candida albicans and 160 µg/mL for Candida krusei and Cryptococcus gattii.