Abstract
The present study aimed to develop and optimize liposome formulation for the colonic delivery of biologically active compounds. A strategy to facilitate such targeting is to formulate liposomes with a polymer coating sensitive to the pH shifts in the gastrointestinal tract. To this end, liposomes encapsulating curcumin—chosen as the biologically active compound model—and coated with the pH-responsive polymer Eudragit S100 were prepared and characterized. Curcumin was encapsulated into small unilamellar vesicles (SUVs) by the micelle-to-vesicle transition method (MVT) in a simple and organic solvent-free way. Curcumin-loaded liposomes were coated with Eudragit S100 by a fast and easily scalable pH-driven method. The prepared liposomes were evaluated for size, surface morphology, entrapment efficiency, stability, in vitro drug release, and curcumin antioxidant activity. In particular, curcumin-loaded liposomes displayed size lower than 100 nm, encapsulation efficiency of 98%, high stability at both 4 °C and 25 °C, high in vitro antioxidant activity, and a cumulative release that was completed within 200 min. A good Eudragit S100 coating which did not alter the properties of the curcumin-loaded liposomes was obtained. The present work therefore provides a fast and solvent-free method to prepare pH-responsive polymer-coated liposomes for the colonic delivery of biologically active compounds.
Highlights
Curcumin is a polyphenol isolated from the rhizome of Curcuma longa, a plant originally fromSoutheast Asia, widely used as a spice and as a remedy in popular medicine
In this work, mixed micelles were formed by sonication of a thin lipid–cholesterol–curcumin film added to a high-critical micellar concentration (CMC) detergent solution of sodium cholate
Due to their great hydrophobicity, curcumin molecules are expected to remain trapped within the lipid bilayer region of the mixed micelles during the procedure, similar to other hydrophobic molecules [18,19]
Summary
Curcumin is a polyphenol isolated from the rhizome of Curcuma longa, a plant originally fromSoutheast Asia, widely used as a spice and as a remedy in popular medicine. Molecules 2018, 23, 739 its antioxidant, anti-inflammatory, antiamyloid, antidiabetic, anti-cystic fibrosis, and antimicrobial properties [1,2]. The interest in this molecule has undergone a tremendous increase since its anticarcinogenic activity emerged, demonstrating its effectiveness through multiple mechanisms of action at various stages of the disease development [3,4]. Curcumin shows a very poor bioavailability in vivo, due to its low aqueous solubility and instability, rapid metabolism, and clearance, that definitely limits its use both as a nutraceutical and as a drug [4]. A very popular and promising approach exploits the loading of curcumin into phospholipid-based liposomes. Several drug-loaded liposomes are currently in clinical use [10]
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