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Antimicrobial and Antioxidant Activity of Propolis from Croatia and Brazil: a Comparative Study

The propolis of honeybee hives which is frequently used in phytomedicine, exhibits a wide spectrum of biological activities. Because plant sources have the biggest influence on the chemical and biological activities, the goal of present study was to compare two different chemotypes of propolis: poplar-type and alecrim-type, taking into the account geographical positions of hives and flora around hives (Croatian and Brazilian source of propolis). The influence of extraction methods (water and 80 vol % ethanol extraction) was also included in study. Ethanol was found to be better solvent for polyphenols than water. The Croatian raw propolis sample was richer in extractable substances and polyphenols than the Brazilian propolis sample. However, water extracted more polyphenols from Brazilian propolis. Comparative antimicrobial activity testing showed differences in inhibition zones of growth, and minimal inhibitory concentrations (MIC) between ethanol extracts from Croatian and Brazilian liophilized propolis. Lower MIC values of Croatian ethanol extract (which indicate more potent antimicrobial activity) was noticed against gram-negative bacterial species (E. coli and P. aeruginosa), as well as against yeast (C. albicans). Ethanolic extracts of propolis samples showed significantly more anti-oxidative activity using DPPH radical scavenging activity assay, as well as using  -carotene bleaching assay. Using electron paramagnetic resonance (EPR) spectroscopy with DPPH as source of electron spin, significant difference between ethanol and water extracts of Croatian and Brazilian propolis samples was found. Interestingly, source of propolis did not has the influence on anti-oxidative activity of propolis using EPR spectroscopy, but extraction method dramatically changes anti-oxidative potency of propolis. As complex mixture, kinetics of propolis extracts were neither kinetics of the first order nor pseudo-first order, what suggesting many different reaction pathways. The comparative study of two geographically and chemically different types of propolis showed interestingly anti-oxidant and antimicrobial differences of extraction method used.

Croatian propolis, Brazilian propolis, Antimicrobial activity, Antioxidant activity

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