Encapsulation of complex extracts in beta-cyclodextrin: an application to propolis ethanolic extract

Area of Science:

• Natural Products Chemistry
• Pharmaceutical Sciences
• Supramolecular Chemistry

Background:

• Propolis ethanolic extracts (PE) contain diverse bioactive compounds with limited water solubility.
• Beta-cyclodextrin (beta-CD) is a cyclic oligosaccharide capable of forming inclusion complexes with hydrophobic molecules.

Purpose of the Study:

• To investigate the encapsulation of specific propolis components within beta-CD.
• To enhance the aqueous solubility of propolis ethanolic extracts (PE) using beta-CD.
• To evaluate the impact of molecular structure on encapsulation efficiency and in vitro release.

Main Methods:

• Preparation of PE/beta-CD inclusion complexes via sonication, filtration, and freeze-drying.
• Determination of aqueous solubility using solubility diagrams.
• Quantification of encapsulation efficiencies for different chemical classes of PE constituents.
• Assessment of in vitro solubility in simulated gastric fluid.

Main Results:

• Encapsulation efficiencies varied by chemical class, with higher values for smaller aromatic molecules (9.4-23.3%) and lower values for terpenes (5.0-6.7%), anthraquinones (3.6-8.4%), and flavonoids (4.0-10.7%).
• In vitro solubility in simulated gastric fluid showed an inverse relationship with molecular size, being lower for smaller aromatic compounds.
• Beta-cyclodextrin encapsulation significantly increased the aqueous solubility of propolis constituents.

Conclusions:

• Beta-cyclodextrin (beta-CD) effectively increases the water solubility of propolis ethanolic extracts (PE) constituents.
• The degree of solubility enhancement is dependent on the chemical structure and properties of the encapsulated compounds.
• Release profiles in simulated gastric fluid are influenced by both chemical characteristics and the abundance of propolis compounds within the matrix.