Antimicrobial activity of Lobelia brasiliensis A.O.S.Vieira & G.J.Sheph.: A preliminary study

Lobelia brasiliensis A.O.S.Vieira & G.J.Sheph . is endemic to the Federal District, and classified as rare in its natural habitat. This species predominantly occurs in wetland areas ( veredas ), being considered a bioindicator of water presence in the region. Although several Lobelia species have been extensively investigated regarding their phytochemical composition and potential pharmacological properties, L. brasiliensis remains poorly studied, with limited data available in scientific literature. Among the species of the genus, antimicrobial activities have been reported, which motivated the present study to evaluate the antimicrobial activity of L. brasiliensis . The assay was conducted after partitioning the crude hexane extract (He0) into five fractions according to their polarity. The antimicrobial activity was evaluated using the broth microdilution method [ 1 ] against Escherichia coli , Staphylococcus aureus , and Mycobacterium smegmatis . The extract and fractions were diluted in DMSO. The assays were conducted in volumes ranging from 0.1 to 0.2 mL, with concentrations varying from 0.03125 to 1 mg/mL (maximum concentration), by using the microdilution technique. None of the samples inhibited the bacterial growth of S. aureus and E. coli , even in the highest tested concentration. However, the hexane extract was able to inhibit M. smegmatis growth at concentrations higher than 0.5 mg/mL. These findings suggest promising prospects for antimicrobial agents derived from this plant species. Additional studies are required to confirm this activity, as well as against other bacterial species. Funding University of Brasília (UnB), National Council for Scientific and Technological Development (CNPq), and Federal District Research Support Foundation (FAPDF). Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany