Tuesday, March 10, 2009

Encapsulation Used to Increase Propolis Solubility in Water

Encapsulation of Complex Extracts in β-cyclodextrin: An Application to Propolis Ethanolic Extract
Journal of Microencapsulation, 6 March 2009

Propolis ethanolic extracts (PE) are rather complicated mixtures of bioactive compounds belonging to several chemical classes. The potential use of β-cyclodextrin (β-CD) cavity for the incorporation of specific PE components, aiming to increase their solubility in water, was studied in a Greek propolis, which was rich in polyphenols and terpenes.

The PE/β-CD inclusion complexes were prepared by sonication of PE suspensions in aqueous solutions of β-CD, followed by filtration and freeze-drying. The aqueous solubility of PE in the presence of β-CD was studied by the construction of solubility diagrams and by determining the fraction of PE constituents that was dissolved in water.

Encapsulation efficiencies were found to be higher (9.4-23.3%) for relatively small aromatic molecules like cinnamic and benzoic acid derivatives and lower for terpenic acids (5.0-6.7%), anthraquinones (3.6-8.4%) and flavonoids (4.0-10.7%). The respective in vitro solubilities in simulated gastric fluid followed an opposite trend, being lower for the relatively small aromatic molecules.

It is concluded that the encapsulation in β-CD may increase the solubility of PE constituents in a manner related to their structure, while the amount of substances released will depend both on their chemical properties and on their relative abundance in the matrix.

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