Evaluation of in vitro bioactivity profile of bee propolis extracts delivered by yeast glucan particles

Due to its antibacterial, anticancer and immunomodulatory properties, propolis is widely used in the treatment of various diseases. However, its poor water solubility and bioavailability reduce its effectiveness in vivo. A solution may be found by combining enhanced propolis extraction with loading the extract into a suitable carrier. Here, we investigated glucan particles, obtained from the cell walls of baker's yeast (Saccharomyces cerevisiae), as promising porous carriers capable of increasing the dispersion of propolis and, thereby, its solubility. First, propolis extracts were prepared using a modified sonication method (70 % ethanol at a propolis/ethanol ratio of 1:10); three types of raw propolis differing in source location and year of harvest were used for comparison. Next, lyophilized propolis extracts were loaded into the glucan particles by spray drying and slurry evaporation to ensure the resulting propolis extract content of 10 wt %. ATR-FTIR spectroscopy and SEM confirmed the successful loading into the glucan particles, and UV–VIS spectrophotometry was used to determine encapsulation efficiency. Dissolution tests showed that the loading into glucan particles led to the formation of a supersaturated solution of propolis extract and the enhancement of its dissolution rate. Subsequently, the biological activity of the encapsulated propolis extract was investigated. Overall, the encapsulated propolis extract showed much higher anti-inflammatory, antioxidant and antimicrobial activity than pure propolis. Thus, our results indicate that the combination of propolis extract with glucan particles increases propolis solubility and bioactivity.