Antibacterial and hemolytic activities of Mimosa tenuiflora (Willd) Poir. (Mimosoidea)

Mimosa tenuiflora is a shrub-sized plant native of the Northeast region of Brazil where it is popularly known as “jurema preta” and is widely used in folk medicine, especially the stem bark extract mixtures. Due to its high content of tannins and flavonoids, it is considered to have anti-inflammatory and antimicrobial activity. The antimicrobial activity of the ethanolic extracts of M. tenuiflora (EEMt) was determined by the minimal inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) by means of the broth microdilution technique. The MIC corresponded to the last dilution in which the presence of bacteria was not verified. In order to obtain the MBC, the spread-plating in Mueller Hinton agar (MHA) of the corresponding MIC, MIC×2 and MIC×4 dilutions was performed. The EEMt presented antibacterial activity against S. aureus (ATCC 25.925) and P. aeruginosa (ATCC 25.619) where the MIC and the MBC were 128 and 256 µg/mL, respectively; concentrations inferior to the cytotoxic concentrations for human erythrocytes (A, B and O). For S. aureus (ATCC 25.213), the MIC and the MBC were 512 and 1024 µg/mL, respectively.  As for the E. coli ATCC 8859 and E. coli ATCC 2536 they were 1024 and ˃1024 µg/mL, respectively. It was concluded that the EEMt has a good antibacterial activity, presenting a low toxicity and a better activity against Gram positive strains. However it exhibited a good activity against the P. aeruginosa strain which is a Gram negative microorganism of clinical importance.   Key words: Mimosa tenuiflora, ethanolic extract, antimicrobial activity, hemolytic activity.