Formulation and characterization of polyphenol-loaded lipid nanocapsules

The purpose of this study was to design and characterize two flavonoid-loaded lipid nanocapsules (LNC) by applying the phase inversion process, and to enhance their apparent solubility and/or the stability. The flavonoid-loaded LNC were characterized by particle size, encapsulation efficiency, drug leakage rates, stability and spectroscopic studies. It was observed that quercetin-loaded LNC30 (3%) and LNC60 (2%) carried a particle size of 30.3 and 55.1 nm, respectively and significant higher entrapment efficiency. Encapsulation of quercetin (QC) in LNC enabled us to increase its apparent aqueous solubility by a factor of 100. And in view of calculations and results, it seems most probable that QC is arranged at this LNC interface between the oil phase and the hydrophilic polyethylene glycol moieties of the surfactant. In addition, colloidal suspensions proved to be stable in term of encapsulation for at least 10 weeks and QC was not oxidised. With simple chemical modification of (-)-epigallocatechin-3-gallate or (-)-EGCG, it was possible to reach very high encapsulation rates (95%). Thus we obtained stable colloidal suspensions of (-)-EGCG in water over 4 weeks while free (-)-EGCG solubilised in water exhibited 100% degradation within 4h. The initial problems (solubility and stability) of these flavonoids were resolved thanks to drug-loaded LNC.