Study Of The Antimicrobial Activity Of Tecoma Stans (L.) Ex Kunth (Bignoniaceae)

Antimicrobial resistance has become a significant concern worldwide. In the present work was performed the phytochemical screening of ethanol extract and fractions of Tecoma stans flowers, and evaluated the antimicrobial potential by a broth microdilution assay against 10 isolates of clinical interest. Also was assessed the interaction of combinations of T. stans samples with commercial antimicrobials. The samples of T. stans demonstrated antibacterial activity and fungistatic potential against Proteus mirabilis, Proteus vulgaris, Staphylococcus aureus, Streptococcus mutans, and Candida infanticola, especially the ethanol extract and the dichloromethane and ethyl acetate fractions, with Minimal Inhibitory Concentration values (MIC 2000 - 500 mu g/mL). The combination of T. stans samples with antimicrobials showed synergistic and additive effects. In combinations classified as synergistic interaction, was observed that MIC for the antimicrobial in combination with the samples of T. stans was reduced by 2 to 7 times compared to the MIC for the antimicrobial when used alone. The best results were found for the combination of the ethanol extract with amoxicillin against P. mirabilis, and the ethanol extract and the dichloromethane fraction with tetracycline against S. aureus. Tests of combinations of extract and fractions of T. stans with antimicrobials are unprecedented, making these results promising. In the phytochemical characterization, it was possible to observe the presence of some phenolic compounds, which may justify the antimicrobial potential of T. stans. It is important to highlight the identification of new antimicrobial agents, some of which may be present in the unexplored flora of Brazil.