Antibacterial and modulatory effect of Stryphnodendron rotundifolium.

CONTEXT: Stryphnodendron rotundifolium Mart. (Leguminosae), a tree in Northeast Brazil (Chapada do Araripe), is used in popular medicine to treat different processes such as inflammation and infectious diseases, mainly caused by bacterial pathogens. OBJECTIVE: This study determined the modulatory and antimicrobial activity of the hydroethanol extract of dried stem bark, the most used form of this natural product, as a remedy by the traditional communities, against standard and clinical isolates of Escherichia coli and Staphylococcus aureus. MATERIAL AND METHODS: The antibacterial and modulatory activities of the hydroalcoholic extract from the leaves were obtained by maceration/hydrodistillation method and assayed by microdilution. RESULTS: In the microbiological assays, growth inhibition was demonstrated by this extract against the bacterial strains tested, with minimal inhibitory concentration (MIC) values of 512 µg/mL. However, when a subinhibitory concentration (MIC/8 = 64 µg/mL) was combined with conventional antimicrobial drugs (gentamicin, kanamycin, amikacin and neomycin), the extract showed a potentiating effect, reducing the MIC for all drugs assayed in a range between 312.5 and 2.4 µg/mL. CONCLUSIONS: We indicate that the extract of S. rotundifolium showed potential synergistic antibiotic activity. With the results obtained, these extracts proved to be a promising source of antibacterial and modulatory agents.