In vitro evaluation of the antimicrobial activity of ethanolic extract of Alpinia zerumbet against Escherichia coli and Staphylococcus aureus strains

Abstract

The search for plant-based medicines emerges as a promising alternative to synthetic medicine, standing out for its therapeutic efficacy. Plant extracts, obtained through techniques such as tincturing, have significant pharmacological potential. In the face of the growing challenge of bacterial resistance, which compromises the effectiveness of antibiotics, the relevance of this study lies in the investigation of active compounds from the coastal flora of the state of São Paulo, focusing on “Colônia” (Alpinia zerumbet), a plant widely used by the local population for therapeutic purposes, aiming to contribute to innovation in natural-origin antimicrobial compounds. This study evaluates the antibacterial activity of the species Alpinia zerumbet against Escherichia coli and Staphylococcus aureus strains. Standard strains were used and exposed to different concentrations of ethanolic extracts from various parts of the Colônia plant. Strains were inoculated on Heart Infusion Agar and incubated for 24 hours at 37°C in a bacteriological incubator. These cultures were then transferred to test tubes containing 5 mL of peptone water and incubated for another 24 hours at 37°C. The cultures were adjusted to 1.5 x 10⁸ CFU/mL. The ethanolic extracts were prepared from leaves, flowers, and rhizomes at a 1% concentration. Microdilution tests were conducted in 96-well microplates and incubated for 24 hours at 37°C. Through streak seeding on petri dishes with Heart Infusion Agar, we determined the Minimum Bactericidal Concentration (MBC). Growth inhibition was observed for both S. aureus and E. coli at different ethanolic extract concentrations.