Antimicrobial and antioxidant activity of the leaves and flowers of Tabebuia aurea and Cordia glabrata

Abstract

The search for new compounds of plant origin with antimicrobial activity has been the goal of many research groups, due to the increase in the number of microorganisms resistant to antimicrobials. The objective of this study was to evaluate the antimicrobial and antioxidant activity of two plant species, Tabebuia aurea (“paratudo”) and Cordia glabrata (“louro branco”), present in the state of Mato Grosso. The plant material (leaves and flowers) was extracted by maceration in 70% ethanol (Et) and polar hexane (Hex) (non-polar solvent). The determination of the antimicrobial activity was carried out by broth microdilution technique, and the antioxidant potential determined by the DPPH free radical method. In the evaluation of the antibacterial activity, the ethanolic extract of C. glabrata leaves presented better antibacterial potential for Staphylococcus aureus, revealing a minimum inhibitory concentration (MIC) of 125 μg / mL. However, for strains of Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium, all extracts of C. glabrata showed MICs of 2000 μg / mL or higher. The ethanolic and hexanic extracts of T. aurea flowers and leaves did not show promising antibacterial potential for any of the tested strains. In the evaluation of antifungal activity against Candida albicans and Candida parapsilosis, the hexanic extract of C. glabrata leaves presented weak to moderate activity only for the C. albicans strain (MIC = 1000 μg / mL). The remaining extracts of C. glabrata and the extracts of T. aurea were not promising against the tested yeasts, showing inhibitory concentrations equal to or greater than 2000 μg / mL. In the determination of the antioxidant potential, the polar extracts (Et 70%) had a higher capacity to sequester the DPPH radical than the capacity obtained for the apolar extracts (Hex). The tests revealed promising antibacterial activity for Staphylococcus aureus and high antioxidant potential of the hydroethanolic extracts of leaves and flowers of C. glabrata, respectively.

Keywords

• tabebuia aurea, cordia glabrata, extracts, antimicrobial, antioxidant