Caracterização química do extrato do epicarpo de Acrocomia aculeata e avaliação das atividades antioxidante e antimicrobiana

Abstract

Acrocomia aculeata, popularly known as macaúba, is an oleaginous palm tree recognized for its great potential in biodiesel production. Despite its high productivity and great potential for waste reuse, the epicarp (shell) is still little explored in relation to its chemical composition and biological activity. In this sense, the objective of this study was to investigate the potential of the macaúba epicarp, an underutilized residue, as a new source of bioactive compounds. To this end, the study performed chemical characterization through the integration of techniques such as imaging mass spectrometry which allowed direct visualization of the spatial distribution of plant tissue compounds, and high-performance liquid chromatography coupled with mass spectrometry which allowed quantification and structural elucidation of the compounds present in the plant extracts. In addition, the study evaluated the antioxidant and antimicrobial potential and performed an in silico prediction for the isolated bioactives. The study identified compounds such as piceatannol, 3,4,5,3′,5′-pentahydroxy-trans-stilbene (PHS) and, in smaller amounts, resveratrol in epicarp extracts through techniques that confirmed the exclusive location of PHS and piceatannol in the fruit epicarp. Extraction with aqueous acetone (Me2CO:H2O) and its EtOAc fraction showed the highest yields of stilbenes and efficiently increases by 51.7 and 68.3%, respectively, the tolerance of Saccharomyces cerevisiae to oxidative stress induced by hydrogen peroxide. Furthermore, the EtOAc fraction showed moderate antibacterial activity against Bacillus subtilis (125 μg/ml), Staphylococcus aureus (125 μg/ml) and methicillin-resistant S. aureus (MRSA) (250 μg/ml). Additionally, it demonstrated significant anticryptococcal activity against three strains of Cryptococcus neoformans with minimum inhibitory concentration ranging from 7.8 to 15.26 μg/ml, with resveratrol and piceatannol by 60 and 70%, respectively, the survival rates of Galleria mellonella larvae infected with C. neoformans H99. In silico analysis indicates low toxicity for piceatannol, PHS and resveratrol, in addition to favorable pharmacokinetic parameters for oral bioavailability. Thus, the study concludes that macaúba epicarp is a valuable source of bioactive compounds with antioxidant and antimicrobial activity.