Influence of Excipients on the Release Kinetics and Antioxidant Activity of Encapsulated Propolis Phenolic Compounds

Propolis is a widely studied natural raw material, the composition of which varies depending on the plant origin, harvest season, geographical area, climate and bee species. This large variety of chemical composition limits the use of propolis extracts in the pharmaceutical industry, which makes it difficult to ensure standardization of the raw material. One of the challenges that limit the modeling of oral pharmaceutical forms with propolis extract is the limited solubility and bioavailability of active compounds. Solid dispersion technology is commonly used in the production of oral capsules. The aim of this study is to evaluate the influence of different materials (HPMC, poloxamer and β-cyclodextrin) on the dissolution kinetics of phenolic compounds of propolis dry extract contained in capsules and their antioxidant activity in vitro. Analysis of the selected formulations showed that the major phenolic compounds detected in the propolis extract were also present in the dissolution medium samples. The auxiliary polymeric materials selected for the capsules formed a prerequisite for the dissolution kinetics profile. The addition of poloxamer and cyclodextrin increased the solubility and dissolution kinetics of hydrophobic propolis compounds in the test media. The addition of HPMC prolonged the dissolution kinetics of propolis active compounds. The antioxidant activity of the tested samples depends on the concentration of active compounds in the receptor medium by both the ABTS and DPPH methods.