Chemical Properties and Antioxidant and Antimicrobial Activities of Slovenian Propolis by Ana Mavri*, Helena Abramovic ˇ , Tomaz ˇ Polak, Jasna Bertoncelj, Polona Jamnik, Sonja Smole Moz ˇina, and Barbara Jers ˇek Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana (phone: þ 386-1-3203729; fax: þ 386-1-2566296; e-mail: ana.kramar@bf.uni-lj.si) The chemical composition as well as the antioxidant and antimicrobial activities of two EtOH extracts of propolis (PEEs) from Slovenia were determined. EtOH was used as extracting solvent at 70 and 96%, providing the extracts PEE70 and PEE96, respectively. The extraction with 70% EtOH was more efficient than that with 96% EtOH, as the PEE70 was richer in total phenolic compounds than the PEE96. The Slovenian propolis was characterized by different phenolic acids and flavonoids. The PEE96 was slightly richer in three specific compounds, i.e., caffeic acid, ferulic acid, and luteolin, while all other substances detected showed higher contents in the PEE70. The PEE70 showed a stronger reducing power and ability to scavenge free radicals and metal ions than the PEE96. Both PEEs were in the main more effective against Gram-positive bacteria than against fungi and Gram-negative bacteria like Salmonella and Escherichia coli, with the exception of Campylobacter. The PEE96 decreased the intracellular oxidation in Saccharomyces cerevisiae in a dose-dependent manner. The antimicrobial activities and antioxidant properties were related to the total phenolic contents. The two PEEs have the potential for use as natural antimicrobial and antioxidant additives in foods. Introduction. – Propolis, also known as bee glue, is produced by honey bees from plant resins that are mixed with beeswax and products of the bee salivary glands. In temperate zones, the main source of propolis is from poplar buds. Propolis has different functions in beehives, such as the maintenance of their structure, prevention of growth of microorganisms, and prevention of decomposition of intruders; therefore, propolis also prevents the spread of diseases. Propolis has been used since ancient times, when it was a traditional remedy in folk medicine [1 – 3]. The composition of propolis is very complex, with more than 300 constituents having been identified, which vary according to the geographic region and collection season. In general, propolis is composed of wax, resins, vegetable balsams, essential and aromatic oils, pollen, amino acids, sugars, and various other components, including organic debris [1] [4] [5] . The composition, biological activities, and therapeutic uses of propolis have promoted great interest in recent decades. A variety of biological activities, like antiviral, antimicrobial, antioxidant, and antitumor activities, have been associated mainly with the phenolic compounds found in propolis, including flavonoids, phenolic acids, and their esters [1] [3]. Propolis is also rich in inorganic elements that might be involved in fundamental enzymatic systems and, therefore, might contribute to its biological activities [3][4][6][7]. CHEMISTRY & BIODIVERSITY – Vol. 9 (2012) 1545 # 2012 Verlag Helvetica Chimica Acta AG, Zürich