Extrato de Senecio brasiliensis: obtenção e avaliação das atividades antioxidante e antimicrobiana

Abstract

Senecio brasilienses is a species native to Brazil popularly known as "Maria mole," belonging to the Asteraceae family. Plants of the genus Senecio present many bioactive compounds, including phenolic compounds and alkaloids. The study of bioactive plants has aroused the interest of cosmetic, pharmaceutical, and food industries, as they are natural sources of antioxidant compounds capable of replacing synthetic antioxidants, in addition to being used as herbal medicines or as active ingredients in medications. The objective of this work was to obtain extracts from the aerial parts (leaves and stem) of S. brasiliensis using different extraction solvents: ethanol 99% (v/v), ethanol and water 40/60 (v/v), hexane, chloroform, and ethyl acetate, as well as evaluating the extracts for total phenolic content and antioxidant activity. The extract with the highest phenolic content and antioxidant activity was evaluated for antimicrobial potential against gram-positive and gram-negative bacteria. The total phenolic content of the extracts was quantified by assays with the Folin-Ciocalteu reagent, and the antioxidant activity was evaluated by the DPPH, FRAP, and ABTS methods. Extraction with ethyl acetate resulted in the highest content of total phenolic compounds (55.57 mg EAG/g of extract). This extract also showed the highest ability to scavenge DPPH (10.53 μmol of Trolox equivalent/g) and ABTS (21160 mM of Trolox equivalent/g) radicals, as well as the high ferric ionreducing antioxidant power (1977.08 mM of ferrous sulfate/g of extract). The extract obtained with ethyl acetate showed bactericidal activity against gram-positive (Staphylococcus aureus and Listeria monocytogenes) and gram-negative (Salmonella enterica Typhimurium and Escherichia coli) bacteria with a minimum bactericidal concentration (MBC) of 15 mg/mL. The ethyl acetate extract of S. brasiliensis has a high content of phenolic compounds, high antioxidant potential, and antimicrobial potential against gram-positive and gram-negative bacteria. The results suggest that this extract could be a promising alternative for bacterial control. Further studies are essential for evaluating cytotoxicity and the presence of alkaloids in the extract.