Antibacterial activity of extracts of Stevia rebaudiana Bertoni against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa

Plants have been an important source of secondary metabolites known for their diverse biological activities; some have been shown to inhibit the development of certain pathogenic microorganisms. Herein, the antimicrobial activity of the carbon tetrachloride, hexane, ethanol, and aqueous extracts of leaves of Stevia rebaudiana Bertoni against Staphylococcus aureus (strain 921), Staphylococcus epidermidis (strains 965, 982, and 735), and Pseudomonas aeruginosa (strains RO3 and RO4) was presented. The antibacterial activity was evaluated using the disk diffusion method, and the minimal inhibitory concentration (MIC) was determined. The results show that, even at the lowest evaluated concentration (1.06 mg/mL), the hexane extract had an inhibitory effect for all the studied microorganisms. The aqueous extract exhibited high inhibition values (84.4%), on S. epidermidis (strain 965). These results indicate that compounds contained in non-polar extracts of S. rebaudiana could be potential candidates as conventional pharmaceutical drugs against bacteria, resistant to conventional antibiotics. Key words: Stevia rebaudiana, antimicrobial properties, plant extracts.