Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 13 1 2021 02 10 98 103 Carlos Padilla Department of Microbiology, Faculty of Health Sciences, University of Talca, Talca, Chile Olga Lobos Department of Microbiology, Faculty of Health Sciences, University of Talca, Talca, Chile Patricia Poblete-Tapia Department of Microbiology, Faculty of Health Sciences, University of Talca, Talca, Chile Verónica Carrasco-Sánchez Department of Microbiology, Faculty of Health Sciences, University of Talca, Talca, Chile 2020 09 26 2021 01 03 Background and Objectives: Haplopappus multifolius Phil. Ex Reiche and Haplopappus taeda Reiche are medicinal shrubs native to Chile and are popularly known as "Bailahuén". Regularly, this plant is used for liver, digestive and renal affections, as well as colds and the cleaning of infected wounds. The aim of the study was to identify the responsible compounds for the antimicrobial activity of H. multifolius and H. taeda. Materials and Methods: Infusions and ethanolic extracts of H. taeda and H. multifolius were analysed by thin-layer chromatography bioautography (TLC-B) to determine the compounds responsible for the antimicrobial activity against Gram-positive and Gram-negative bacterial strains and yeasts of Bailahuén. Finally, the minimum inhibitory concentration (MIC) of pure compounds isolated was determinate. Results: Extract of Bailahuén had activity only against Gram-positive bacterial strains and this activity was associated with aesculetin, 18-acetoxy-cis-cleroda-3,13E-dien-15-oic acid and aromadendrin-7-methyl ether compounds. Conclusion: H. multifolius and H. taeda have antibacterial capacity on different species of Gram-positive bacteria pathogenic for humans. https://ijm.tums.ac.ir/index.php/ijm/article/view/2793 https://ijm.tums.ac.ir/index.php/ijm/article/download/2793/1321