Abstract

Propolis is a natural product widely consumed in folk medicine. The present study was carried out to investigate the antibacterial activity of Jordanian propolis, collected from two locations with two different dominant floras (Type1; Pine trees and Type ll; Oak trees). Zones of inhibition and minimum inhibitory concentrations (MICs) were determined on methicillin resistant Staphylococcus aureus (MRSA), multidrug resistant Escherichia coli and standard strains of both bacteria. Propolis Type I and Type II showed antibacterial activity against MRSA (MIC 4.69 and 18.75 µg ml^-1, respectively). Crude propolis from Type I showed higher antibacterial activity than Type II against the tested bacteria. Three pure phenolic compounds (three flavonoids) namely, pinobanksin-3-O-acetate, pinocemberin and chrysin, were isolated from fractions I-2 and I-4, and screened in vitro for antibacterial activity. Pinobanksin-3-O-acetate and pinocembrin exhibited antibacterial activity especially against MRSA, while chrysin was only active against standard S. aureus. This is the first report that shows in vitro antibacterial activity of isolated flavonoids from Jordanian propolis against standard and resistant strains of E. coli and MRSA.Overall, results of this study highlight the important role of propolis botanical source on the antibacterial activity of such natural material which might affect its medical applications.

Key words: Antibacterial activity, human pathogens, flavonoids, propolis, methicillin resistant Staphylococcus aureus, Escherichia coli.

Abbreviation

MICs, Minimum inhibitory concentrations; MRSA, methicillin resistant Staphylococcus aureus; TLC, thin layer chromatography; MDR, multi drug resistance; CC, column chromatography