In vitro antimicrobial activity of 20 selected climber species from the Bignoniaceae family

Abstract

Hydroalcoholic and aqueous extracts of some climber species from the Bignoniaceae family that grow in the north of Argentina were evaluated for in vitro antibacterial activity against Gram-positive and Gram-negative strains. By means of bioautography and disc diffusion methods, it could be determined that all infusions were not active, whereas the hydroalcoholic extracts of seven species were able to inhibit bacterial growth. The minimum inhibitory concentration and minimum bactericidal concentration observed were between 62.5 and 1000 μg gallic acid equivalent (GAE)/mL and between 125 and 1000 μg GAE/mL, respectively. The tested extracts were more active against Gram-positive microorganisms. Time-kill experiments indicated that all extracts have bacteriostatic activity. Phytochemical screening showed the presence of terpenoids, phenols and flavonoids. The amount of phenolic compounds and flavonoids was higher in tinctures when compared with infusions. These results suggest the presence of antibacterial substances in the hydroalcoholic extracts, which could be used for the treatment of infections.

Keywords::

• antimicrobial activity
• Bignoniaceae
• phytomedicine
• time-kill assay

Acknowledgements

The authors thank M.M. Arbo of the IBONE for plant identification; they are grateful to CONICET and Universidad Nacional del Chaco Austral for their financial support.