Determination of total phenolic and flavonoid contents, radical scavenging potential and antimicrobial activity of ethanolic extract of Quercus persica on Salmonella typhi, Escherichia coli, Staphylococcus epidermidis and Listeria monocytogenes

The aim of this study was to isolate the ethanolic extract of Quercus persica leaves via maceration method and determination of its total phenol content (via Folin-Ciocalteu method), total flavonoid content (via aluminium chloride colorimetric method), antioxidant activity (based on DPPH and ABTS radical scavenging methods), and antimicrobial effect (based on disk diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration procedures). The extract contained 79.21 mg GAE/g phenolic compounds and 35.10 mg QE/g flavonoid compounds. The leaf ethanolic extract of Q. persica had a remarkable antioxidant activity, and it showed 52.60% DPPH free radical scavenging effect and 60.50% ABTS free radical scavenging activity. The extract had a concentration-dependent antimicrobial activity. The highest and lowest inhibition zones were respectively observed for Staphylococcus epidermidis (18.60 mm) and Salmonella typhi (14.80 mm), through disk diffusion agar method, in the presence of 100 mg.ml-1 extract. In well diffusion agar method, the inhibition zones for the above bacterial species were 14.90 mm and 15.10 mm, respectively. Moreover, the minimum inhibitory concentrations for the sensitive species (S. epidermidis) and the resistant bacteria (S. typhi) were 32 and 256 mg.ml-1, respectively. The results of this study show that the leaf ethanolic extract of Q. persica could be used as a naturally bioactive compound to substitute synthetic preservative agents.