Antioxidative activity of propolis extract in yeast cells.

The antioxidative activities of propolis and its main phenolic compounds, caffeic acid, p-coumaric acid, ferulic acid, and caffeic acid phenethyl ester, were investigated in the yeast Saccharomyces cerevisiae. After 1 h of exposure of the yeast cells, their intracellular oxidation was measured using 2',7'-dichlorofluorescein. Yeast cells exposed to 96% ethanolic extracts of propolis in DMSO (EEP) showed decreased intracellular oxidation, with no significant differences seen for the individual phenolic compounds. However, cellular uptake was seen only for a moderately polar fraction of EEP (E2) and caffeic acid phenethyl ester. The EEP antioxidative activity thus resulted from this E2 fraction of EEP. The influence of EEP was also investigated at the mitochondrial proteome level, by analyzing its profile after 1 h of exposure of the yeast cells to EEP and E2. Changes in the levels of antioxidative proteins and proteins involved in ATP synthesis were seen.