LAUSR

portuguesO objetivo deste trabalho foi avaliar o efeito das condicoes de extracao sobre os compostos bioativos, bem como sobre a atividade antioxidante e atividade antimicrobiana do extrato com maior caracteristica antioxidante. Os extratos foram obtidos pelo metodo convencional e extracao assistida por ultrassom, variando a temperatura (20oC, 40oC e 60oC). Foram quantificados os fenolicos totais, flavonoides totais, a atividade antimicrobiana, e atividade antioxidante pelos metodos DPPH, FRAP, e ORAC. Os metodos de extracao convencional e ultrassom influenciaram no teor de fenolicos em todas as temperaturas testadas. Os flavonoides nao sofreram influencia dos metodos de extracao. A atividade antioxidante (DPPH) foi superior no metodo ultrassom nas temperaturas de 40°C e 60°C, entretanto pelo metodo FRAP os melhores resultados foram na extracao convencional. Os metodos convencional e ultrassom nao influenciaram no IC50 nas temperaturas de 20oC e 40oC, mas a atividade antioxidante pelo metodo ORAC sofreu influencia dos metodos em todas as temperaturas. O extrato obtido a 60°C pelo metodo ultrassom possui elevada acao antimicrobiana frente a cepas de Salmonella sp., Escherichia coli, e Staphylococcus aureus. A extracao assistida por ultrassom pode ser considerada adequada para obtencao de extratos de marcela, que sao ricos em compostos bioativos com alta atividade antioxidante. Palavras-chave: ultrassom; compostos bioativos; antioxidantes naturais; Achyrocline satureioides EnglishThe aim of this study was to evaluate the effect of extraction conditions on bioactive compounds, as well as on antioxidant activity, and the antimicrobial activity of the extracts with the highest antioxidant characteristics. The extracts were obtained by conventional method and ultrasound-assisted extraction at various temperatures (20°C, 40°C and 60°C). Total phenolics, total flavonoids, antimicrobial activity and antioxidant activity were quantified by the methods of DPPH, FRAP, and ORAC, respectively. The conventional extraction method and ultrasound method influenced the phenolic content at all the tested temperatures. Flavonoids were not influenced by extraction methods. The antioxidant activity (DPPH) was highest in the ultrasonic method at temperatures of 40°C and 60°C; however, in the case of the FRAP method the best results were for the conventional extraction method. The conventional and ultrasonic methods did not influence the IC50 at temperatures of 20°C and 40°C, but using ORAC the antioxidant activity was influenced by the methods at all temperatures. The extract obtained at 60°C by the ultrasound method had high antimicrobial action in relation to the strains of Salmonella sp., Escherichia coli, and Staphylococcus aureus. Extraction ultrasonic-assisted can be considered adequate to obtain extracts of marcela, which are rich in bioactive compounds with high antioxidant activity. Key words: ultrasound; bioactive compounds; natural antioxidant; Achyrocline satureioides