Improved stability and skin penetration through glycethosomes loaded with glycyrrhetinic acid.

OBJECTIVE: In recent years, glycyrrhetinic acid (GA) has been popularly used in cosmetics because of its anti-inflammatory and anti-oxidant effects. However, due to the poor water solubility of GA and the barrier effect of human skin, the penetration of GA through the skin may be hindered. Liposomes are a common delivery system for functional compounds in cosmetics. Nonetheless, the stability and transdermal effect of traditional liposomes are limited. The aim of this work was to prepare a new liposome system that contained glycerol and ethanol to enhance the stability of the vesicles and promote the penetration of GA into the skin. METHODS: The glycethosomes were prepared by ethanol injection and sonication method. The effects of different concentrations of glycerol and ethanol on the particle size, polydispersity (PDI), entrapment efficiency (EE), stability and rheological properties of vesicles were evaluated. Lipophilic and hydrophilic fluorescent probes were used to investigate the microviscosity of vesicles. In vitro permeation tests were performed with pig skin in Franz cells and the concentration of GA in different skin layers was determined by high-performance liquid chromatography (HPLC). The ability of different vesicles to induce lipid extraction and fluidization was analysed by using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). RESULTS: When glycerol was 50% and ethanol was 25%, the obtained glycethosomes had the smallest particle size and the best stability with a mean particle size of 94.5 nm, PDI 0.216 and 99.8% EE. Fluorescence probe studies indicated that the microviscosity of glycethosomes was the largest when the concentration of glycerol and ethanol was 50% and 25%, which was consistent with the storage stability of glycethosomes. It was found that the glycethosomes had the best transdermal effect and the total skin permeation percentage of GA was 20.67%, while those of ethosomes, glycerosomes, liposomes and dispersion were 10.56%, 9.38%, 7.78% and 5.02%, respectively. And glycethosomes had effectively lipid extraction and fluidization effect on the skin stratum corneum. CONCLUSION: Compared with other traditional liposomes, glycethosomes can significantly improve the stability of vesicles and the transdermal effect of GA. Glycethosomes is promising vesicles for the delivery of GA.

OBJECTIF: Ces dernières années, l'acide glycyrrhétinique (AG) a souvent été utilisé dans le domaine des cosmétiques en raison de ses effets anti-inflammatoires et anti-oxydants. Cependant, la faible solubilité de l'AG dans l'eau et l'effet barrière de la peau humaine peuvent entraver la pénétration de l'AG à travers la peau. Les liposomes sont fréquemment utilisés comme système d'administration pour les composés fonctionnels dans les cosmétiques, mais la stabilité et l'effet transdermique des liposomes traditionnels demeurent limités. Ce travail a eu pour but de préparer un nouveau système liposomal à base de glycérol et d'éthanol pour améliorer la stabilité des vésicules et favoriser la pénétration de l'AG à travers la peau. MÉTHODES: Les glycéthosomes ont été préparés par injection d'éthanol et suivant une méthode de sonication. Les effets des différentes concentrations de glycérol et d'éthanol sur la taille des particules, la polydispersité (PDI), l'efficacité de capture (entrapment efficiency, EE), la stabilité et les propriétés rhéologiques des vésicules ont été évalués. Des sondes fluorescentes lipophiles et hydrophiles ont été utilisées pour étudier la microviscosité des vésicules. Des tests de perméation in vitro ont été réalisés avec de la peau de porc dans des cellules de Franz, et la concentration d'AG dans différentes couches cutanées a été déterminée par chromatographie en phase liquide à haute performance (CLHP). La capacité des différentes vésicules à induire une extraction lipidique et une fluidisation a été analysée à l'aide d'une spectroscopie infrarouge à réflectance totale atténuée et transformée de Fourier (TR-FTIR). RÉSULTATS: Avec des proportions de 50 % de glycérol et de 25 % d'éthanol, les glycéthosomes obtenus avaient la plus petite taille de particules et la meilleure stabilité avec une taille moyenne de particules de 94,5 nm, une PDI de 0,216 et une efficacité de capture de 99,8 %. Les études par sonde de fluorescence ont indiqué que la microviscosité des glycéthosomes était à son pic lorsque les concentrations de glycérol et d'éthanol s'élevaient respectivement à 50 % et 25 %, soit des proportions cohérentes avec la stabilité de conservation des glycéthosomes. Les glycéthosomes ont présenté le meilleur effet transdermique, et le pourcentage total de perméation cutanée de l'AG était de 20,67 %, tandis que ce pourcentage s'élevait, pour les éthosomes, les glycérosomes, les liposomes et la dispersion, à respectivement 10,56 %, 9,38 %, 7,78 % et 5,02 %. Les glycéthosomes ont aussi eu un effet efficace sur la couche cornée de la peau en ce qui concerne l'extraction des lipides et la fluidisation. CONCLUSION: Comparés aux liposomes traditionnels, les glycéthosomes peuvent améliorer de façon significative la stabilité des vésicules et l'effet transdermique de l'AG. Les glycéthosomes semblent ainsi constituer des vésicules prometteuses pour l'administration d'AG.

Prevention of Hypercholesterolemia with "Liposomes in Microspheres" Composite Carriers: A Promising Approach for Intestinal-Targeted Oral Delivery of Astaxanthin.

Cardiovascular diseases are caused by hypercholesterolemia. Astaxanthin (AST) has been reported to exhibit antioxidant and anti-inflammatory properties. However, its bioavailability is poor because of low solubility and instability. In order to improve the bioavailability of AST, we developed an intestinal-responsive composite carrier termed as "liposomes in micropheres" incorporating N-succinyl-chitosan (NSC)-poly(ethylene glycol) (PEG) liposomes that functionalized by neonatal Fc receptors (FcRn) into hydrogels of sodium alginate (SA) and carboxymethyl chitosan (CMCS). In the AST NSC/HSA-PEG liposomes@SA/CMCS microspheres, the AST's encapsulation efficiency (EE) was 96.26% (w/w) and its loading capacity (LC) was 6.47% (w/w). AST NSC/HSA-PEG liposomes had stability in the gastric conditions and achieved long-term release of AST in intestinal conditions. Then, AST NSC/HSA-PEG liposomes@SA/CMCS bind to intestinal epithelial cell targets by the neonatal Fc receptor. In vitro permeation studies show that there was a 4-fold increase of AST NSC/HSA-PEG liposomes@SA/CMCS in AST permeation across the intestinal epithelium. Subsequent in vivo experiments demonstrated that the composite carrier exhibited a remarkable mucoadhesive capacity, allowing for extended intestinal retention of up to 12 h, and it displayed deep penetration through the mucus layer, efficiently entering the intestinal villi epithelial cells, and enhancing the absorption of AST and its bioavailability in vivo. And oral administration of AST NSC/HSA-PEG liposomes@SA/CMCS could effectively prevent hypercholesterolemia caused by a high-fat, high-cholesterol diet (HFHCD). These advancements highlight the potential of NSC/HSA-PEG liposomes@SA/CMCS composite carriers for targeted and oral uptake of hydrophobic bioactives.

Development and characterization of ultrastable emulsion gels based on synergistic interactions of xanthan and sodium stearoyl lactylate.

Emulsion gels with the mixtures of low-molecular-weight emulsifier (LME) and polymer have attracted much attention in food; however, the LME-polymer interactions in emulsion system are complex and unclear. Here, the interactions between SSL and xanthan in emulsions and the mechanisms of stabilizing emulsions were investigated by using tensiometry, zeta potential, Fourier transform infrared spectroscopy (FTIR), confocal laser scanning microscopy (CLSM), cryo-scanning electron microscopy (cryo-SEM) and rheology. SSL was more efficiently adsorbed on the oil-water interface than xanthan. Interestingly, the honeycomb structure was formed in emulsion gels, which firmly immobilized oil droplets. Furthermore, electrostatic repulsion and hydrophobic interactions between xanthan and SSL facilitated the efficient bonding at interface and in bulk. Both linear and nonlinear rheology strongly supported the fact that the interactions between xanthan and SSL enhanced gel-like viscoelastic structure of emulsion gels. This structure endows excellent stability of emulsion gels under high temperature storage, sealed conditions and pH change.