The Aqueous Extract of Quercus robur L. (Fagaceae) Shows Promising Antibacterial Activity against Klebsiella pneumoniae"

Abstract

 Introduction: Quercus robur L. shows anti-inflammatory, antimicrobial, antioxidative and astringent activity, and contains the following chemical compounds: flavonoids, tannins, phytoncide, phlobaphenes and phloroglucinol. Method: This study was designed as an experimental in vitro study on microorganisms. Chopped plant material was extracted using solvent (aqua) at room temperature and then left to dry in vacuum evaporators. We examined cytotoxic effects of different concentrations (10-1000µg/ml) of Quercus robur L. on Klebsiella pneumoniae. Examination of antimicrobial activity of the extract was performed using disc diffusion method on Mueller-Hinton outpoured agar in a Petri dish. As the control, we used discs with Gentamicin. Results were obtained by measuring the inhibition zone diameter.
Results: Our results revealed that the decrease of the extract concentration (from 1000µg/ml to 10µg/ml) of Quercus robur L. showed significantly lower cytotoxicity (p<0.05) on brine shrimp larvae. We demonstrated a strong positive correlation (r=0.959, p<0.05) between aqueous extract concentrations of Quercus robur L. and the number of dead larvae (Artemia salina L.). Additionally, aqueous extract of Quercus robur L. has shown effective antimicrobial activity on tested K. pneumoniae. Antibacterial activity of Quercus robur L. aqueous extract against Klebsiella pneumoniae was found at concentration of 1mg/mL. Maximum inhibition zone diameter was 15.40mm.
Conclusion: Our study provides evidence that Q. robur cortex extract showed promising antibacterial activity against K. pneumoniae.