Avaliação da atividade antimicrobiana e antioxidante de Praxelis sanctopaulsensis (BL Robins.) RM King & H. Robins

Abstract

Praxelis sanctopaulensis (BL Robins.) RM King & H. Robins is a plant of the Asteraceae family. Plants of this family have been much studied due to their high biological activity. With the increase of microbial resistance, the search for natural antibiotic sources has increased, as well as the search for antioxidants from vegetable sources has increased, due to the increase of diseases caused by oxidative stress. The antimicrobial activity of plant extracts was then carried out on Gram negative bacteria: Escherichia coli, Klebsiella pneumoniae and Salmonella typhi; and Gram positive bacteria: Bacillus subtilis and Staphylococcus aureus. It was also carried out the antioxidant activity by the radical capture methods DPPH and ABTS, and the phenolic and flavonoid content. The extracts of the plant did not present antimicrobial activity for E. coli, the best results for this analysis were for the ethyl acetate fraction that inhibited almost all the bacteria tested. The extracts did not have bactericidal, only bacteriostatic power. The ethyl acetate and butanolic fractions presented better results for antioxidant activity, where the total phenolic content was 526,80 and 426,19 mg EAG g -1 for the two fractions of the aerial parts respectively, 284,40 and 234,97 mg EAG g -1 for flowers. The content of flavonoids was 97.13 and 82.07 mg EQ g -1 for aerial parts and 77.74 and 75.62 mg EQ g -1 for flowers for the two fractions, respectively. For DPPH the IC 50 of the fractions were close, with values of 13.38 and 15.25 μg mL -1 for aerial parts, 10.75 and 15.54 μg mL -1 for the two flower fractions, respectively. For ABTS the results were more satisfactory for the aerial parts with values of 2011.50 and 1724.34 μmol Trolox g -1 of ethyl acetate and butanolic fractions extract. The results obtained through this work show that Praxelis sanctopaulensis presents a great antioxidant potential, with which it is necessary to continue the studies using its extracts to study the other properties that this plant.