Actividad antimicrobiana in vitro de los extractos de Tithonia diversifolia (Hemsl) A. Gray (botón de oro) y de Ageratum conyzoides L. (marrubio)

Introduction: Tithonia diversifolia (Hemsl) A. Gray and Ageratum conyzoides L. have been traditionally used in Colombia to treat a variety of diseases, but there is little scientific information validating their use. Objectives: Evaluate the antimicrobial activity of extracts obtained from the aerial parts of T. diversifolia and A. conyzoides against Escherichia coli, Staphylococcus aureus and Candida guilliermondii. Methods: Aerial parts of the two plants were collected in the rural area of the municipalities of Barbosa, Entrerríos and San Pedro de los Milagros in Antioquia, Colombia. Taxonomic identification was conducted at the herbarium of the University of Antioquia. The plant material was dehydrated by convection at room temperature. Extraction was performed by maceration at room temperature for 24 hours, using ethanol, ethyl acetate and hexane as solvents. The solvent was recovered at reduced pressure and 40 °C, and the procedure was repeated three times for each solvent. Tests were performed for sensitivity, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in vitro. A standard antibiotic (ampicillin) was used as positive control. Results: The bacterium S. aureus showed sensitivity to the T. diversifolia extracts at a 2 % concentration obtained with ethanol and ethyl acetate (3.66 and 3.32 mm in radius, respectively). Both extracts had an MIC and MBC of 0.01 g/ml. Conclusions: T. diversifolia extracts obtained with ethanol and ethyl acetate have potential bactericidal activity against S. aureus.