Encapsulation of ε-Viniferin into Multi-Lamellar Liposomes: Development of a Rapid, Easy and Cost-Efficient Separation Method to Determine the Encapsulation Efficiency

Abstract

Onion-type multi-lamellar liposomes (MLLs), composed of a mixture of phosphatidylcholine and Tween 80, were analyzed for their ability to encapsulate ε-Viniferin (εVin), a resveratrol dimer. Their encapsulation efficiency (EE) was measured by UV-VIS spectroscopy using three different separation methods—ultracentrifugation, size exclusion chromatography, and a more original and advantageous one, based on adsorption filtration. The adsorption filtration method consists indeed of using syringe filters to retain the molecule of interest, and not the liposomes as usually performed. The process is rapid (less than 10 min), easy to handle, and inexpensive in terms of sample amount (around 2 mg of liposomes) and equipment (one syringe filter is required). Whatever the separation method, a similar EE value was determined, validating the proposed method. A total of 80% ± 4% of εVin was found to be encapsulated leading to a 6.1% payload, roughly twice those reported for resveratrol-loaded liposomes. Finally, the release kinetics of εVin from MLLs was followed for a 77 day period, demonstrating a slow release of the polyphenol.

Trans-ε-Viniferin Encapsulation in Multi-Lamellar Liposomes: Consequences on Pharmacokinetic Parameters, Biodistribution and Glucuronide Formation in Rats

“…The multi-lamellar character was checked by polarized light microscopy. Indeed, the organized structure of MLLs induces birefringence that produces Maltese crosses, as previously observed [48]. Their average size was 247 ± 8 nm as measured by DLS, while their Zeta potential was −47.0 ± 0.4 mV, in accordance with previous results [45,48].…”

“…MLLs were produced as previously described [33,48]. Briefly, P75, Tween 80 and εVin (52.5 wt%, 11.5 wt% and 4 wt% of the final composition, respectively) were first individually solubilized in ethanol before being mixed together.…”

“…The multi-lamellar character of the liposomes was confirmed by polarized light microscopy (Olympus BX51, ×60 and ×100 magnifications, Hamburg, Germany). The encapsulation rate of εVin in MLLs was determined using UV-Vis spectrophotometry and using an adsorption filtration method as previously developed [48]. The liposomes distribution size was established using dynamic light scattering (DLS, Vasco particle size analyzer, Cordouan Technologies Ltd., Pessac, France) with a refractive index of 1.33 and 1.45 for water and liposomes, respectively.…”

“…The encapsulation of εVin was carried out by following the optimized protocol developed previously [48]. The multi-lamellar character was checked by polarized light microscopy.…”

“…Oniontype MLLs, also called spherulites©, are made up of lipid bilayers up to the core of vesicles, contrary to classical MLLs that display a limited number of bilayers and a large water core. Recently, we produced εVin-loaded onions displaying a high encapsulation rate [48], considerably increasing its water solubility, and showing a decreased cytotoxicity of encapsulated εVin on Caco-2 cell line [45].…”