Propolis oil extract: quality analysis and evaluation of its antimicrobial activity

Designing propolis products for external use involves determining the optimal form of propolis for the introduction into dermatological pharmaceuticals and cosmetic preparations. As a potent ingredient, propolis oil extract from raw material harvested in Lithuania was analysed. The rheological characteristics, content of phenolic compounds, major compounds and antimicrobial activity of the propolis oil extract are investigated here for the first time. The propolis oil extract was produced by maceration using different solvents, raw material was collected in Lithuania. Solvent mixture with 96% ethanol increased the rheological stability and extracted amount of phenolic compound. High-performance liquid chromatography identified the potent quality markers for Lithuanian propolis, phenylpropanoid vanillin, coumaric acid and ferulic acid. Antimicrobial activity of propolis oil extract was evaluated in experimental studies in vitro, and the minimal concentration of phenolic compounds that inhibited respective microorganisms was determined. The results demonstrate that phenolic compounds have effective antimicrobial activity in propolis oil extract; thus, it can be compatible with the semisolid preparation.