Abstract

This study aimed to investigate the antimicrobial action of different methanolic extract fractions from Myracrodruon urundeuva (Anacardiaceae) bark and to evaluate the interaction between the most active fraction and some commercial antibiotics. After methanolic extraction, the extract obtained was submitted to liquid/liquid fractionation using cyclohexane, ethyl acetate, n-butanol and water. All fractions showed antimicrobial action, although the ethyl acetate fraction showed the best antimicrobial activity. This fraction inhibited all tested microorganism (Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Candida albicans and Aspergillus niger) with minimum inhibitory concentration (MIC) values ranging from 0.097 to 0.78 mg/ml. The ethyl acetate fraction showed different effects depending on the kind of antibiotic and bacteria tested. The best interaction was observed with gentamicin which resulted in synergistic results for all tested bacteria (∑FIC values of 0.01 for both S. aureus and B. subtilis and 0.25 for K. pneumoniae and E. coli). In conclusion, Myracrodruon urundeuva bark is a source of antimicrobial compounds able to improve the activity of some antimicrobials, especially gentamicin, erythromycin, tetracycline and ciprofloxacin. The identification of the active compounds and the action mechanisms involved are crucial for the use of this plant in biotechnological preparations.

Key words: Antimicrobial activity, Myracrodruon urundeuva, Caatinga, synergism, pharmaceutical preparations.