Potencial antibacteriano e citotóxico de espécies da família Asteraceae e seus efeitos na associação com ampicilina

Abstract

Antimicrobial resistance jeopardizes the effectiveness of preventing and treating infections. The association of natural compounds with antimicrobial activity to these antibiotics is an alternative to increase the spectrum of action, aiming to reduce adverse damage caused by synthetic compounds. The objective of this work was to determine the antibacterial activity of extracts and fractions of plant species of the Asteraceae family and to evaluate the association with antibiotics. In partnership with the Chemistry Department of the State University of Maringá, crude extracts and fractions of the plants Pterocaulon alopecuroides (PA), Stevia leptophylla (SL), Vernonanthura cuneifolia (VC), Vernonanthura discolor (VD) and Austroeupatorium inulaefolium (AI) were obtained., which were tested for four different bacteria: Staphylococcus aureus, Bacillus cereus, Escherichia coli and Salmonella. at a concentration of 10 mg/mL using the methodology for determining the Minimum Inhibitory Concentration (MIC) by microdilution and the Minimum Bactericidal Concentration (MBC) by subculture in Mueller Hinton agar (MH). MIC demonstrated antibacterial potential against gram-positive bacteria. Subsequently, the microorganisms were submitted to the disk diffusion test on MH agar plates, using ampicillin 10 μg alone and the extract + ampicillin (10 μL+10 μg). The inhibition halos induced by the ethyl acetate fraction of VC, SL and PA, AI crude extract and hexane fraction of PA showed a significant increase for S. aureus and B. cereus. The crude extract and ethyl acetate fraction of VC demonstrated synergism combined with the antibiotic ampicillin in the checkerboard test, characterized by its isobolograms and a FICI of 0.025 and 0.200, respectively. Finally, the toxicity test was performed for the extracts with Artemia salina, where they demonstrated lethality of 100% at the concentration of 2mg/mL, and the extract of PA in the dichloromethane fraction did not demonstrate lethality at the concentration of 1mg/mL, standing out from the others that did not present lethality from 0.5mg/mL. Thus, it was observed that plant species of the Asteraceae family studied have antibacterial activity, with emphasis on P. alopecuroides.