Antibacterial activity of propolis from two sources in the Basque Country

Propolis has a lot of active ingredients, such as flavonoids and phenolic acids, from different trees and bushes and it shows antifungal, antibacterial and antiviral properties [1].

The aim of this study was to test the antimicrobial activity of ethanol extracted propolis against different in vitro bacteria. The propolis was sourced from two places – Urdaibai and Dima – in the Basque Country. The Minimal Inhibitory Concentration (MIC) of propolis to reduce microbial growth as well as the Minimal Bactericidal Concentration (MBC) were determined. As the presence of ethanol in the propolis extracts can have an additional effect, MICs determinations were also calculated for ethanol.

The method used to determine MIC and MBC for the bacteria was based on the protocol ISO 20776–1:2006 and ISO 20776–2:2007.

The assays were carried out in three bacterial species: Streptococcus mutans (CECT 479), Streptococcus pyogenes (CECT 985) and Staphylococcus aureus (CECT 240). Results showed that ethanol concentration needed for bacterial inhibition was lower than ethanol concentration present in the MICs values of propolis extracts for the different strains. No difference was found in the properties of the propolis from Dima and Urdaibai. In all cases, MIC and MBC values were quite similar, with differences not higher than 1 dilution.

Therefore, our results show that propolis can be used as an inhibitor of bacterial growth, and due to its natural origin it could be an interesting antimicrobial agent.

This study is being extended by the use of Supercritical Fluid Techologies which allows enriched fractions of

the propolis to be obtained without organic solvents.

Reference: [1] Ferreira, F.B.D. (2007) Oral Surg. Oral Med. O. 104:709–716.