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Membrane-bound enzyme complex of extrinsic tenase (VIIa/TF) is believed to be the primary activator of blood clotting in vivo . This complex (where factor VIIa (FVIIa) is a catalytically active part and tissue factor (TF) is its essential cofactor) activates its primary substrate factor X (FX) leading to factor Xa (FXa) (‘a’ stands for ‘activated’). Both FX and FXa are able to bind to phospholipid membrane and, therefore, are distributed between solution and membrane surface. As a result, two possible mechanisms of substrate delivery to the extrinsic tenase exist: via lateral diffusion on the membrane surface or directly from the solution. Determination of the predominant pathway of substrate delivery is an important key to understanding the precise reaction mechanism. Here we construct a mechanism-driven computational model of FX activation by extrinsic tenase on the surface of phospholipid vesicles of different size. We show that experimentally observed dependence of the tenase activity on the phospholipid concentration could be obtained only if the substrate (FX) is membrane-bound. For correct experimental data description it is also necessary to take into account the dependence of FX/FXa membrane binding parameters (equilibrium dissociation constant and the number of phospholipid molecules per bound FX/FXa) on the membrane curvature. The model predicts that small vesicles promote activation of FX by the extrinsic tenase significantly better than large vesicles (with the same overall phospholipid, factors VIIa, X and TF concentrations in the solution). [ABSTRACT FROM AUTHOR]

New three-dimensionally-structured hybrid phospholipid vesicles, able to load clotrimazole in a high amount (10 mg/mL), were obtained for the first time in this work by significantly reducing the amount of water (≤10%), which was replaced with a mixture of glycerol and ethanol (≈90%). A pre-formulation study was carried out to evaluate the effect of both the composition of the hydrating medium and the concentration of the phospholipid on the physico-chemical properties of hybrid vesicles. Four different three-dimensionally-structured hybrid vesicles were selected as ideal systems for the topical application of clotrimazole. An extensive physico-chemical characterization performed using transmission electron microscopy (TEM), cryogenic transmission electron microscopy (cryo-TEM), 31P-NMR, and small-angle X-ray scattering (SAXS) displayed the formation of small, multi-, and unilamellar vesicles very close to each other, and was capable of forming a three-dimensional network, which stabilized the dispersion. Additionally, the dilution of the dispersion with water reduced the interactions between vesicles, leading to the formation of single unilamellar vesicles. The evaluation of the in vitro percutaneous delivery of clotrimazole showed an improved drug deposition in the skin strata provided by the three-dimensionally-structured vesicles with respect to the commercial cream (Canesten®) used as a reference. Hybrid vesicles were highly biocompatible and showed a significant antifungal activity in vitro, greater than the commercial cream Canesten®. The antimycotic efficacy of formulations was confirmed by the reduced proliferation of the yeast cells at the site of infection in vivo. In light of these results, clotrimazole-loaded, three-dimensionally-structured hybrid vesicles appear to be one of the most innovative and promising formulations for the treatment of candidiasis infections.

Global health is under attack by increasingly-frequent pandemics of viral origin. Antimicrobial peptides are a valuable tool to combat pathogenic microorganisms. Previous studies from our group have shown that the membrane-lytic region of turbot (Scophthalmus maximus) NK-lysine short peptide (Nkl71⁻100) exerts an anti-protozoal activity, probably due to membrane rupture. In addition, NK-lysine protein is highly expressed in zebrafish in response to viral infections. In this work several biophysical methods, such as vesicle aggregation, leakage and fluorescence anisotropy, are employed to investigate the interaction of Nkl71⁻100 with different glycerophospholipid vesicles. At acidic pH, Nkl71⁻100 preferably interacts with phosphatidylserine (PS), disrupts PS membranes, and allows the content leakage from vesicles. Furthermore, Nkl71⁻100 exerts strong antiviral activity against spring viremia of carp virus (SVCV) by inhibiting not only the binding of viral particles to host cells, but also the fusion of virus and cell membranes, which requires a low pH context. Such antiviral activity seems to be related to the important role that PS plays in these steps of the replication cycle of SVCV, a feature that is shared by other families of virus-comprising members with health and veterinary relevance. Consequently, Nkl71⁻100 is shown as a promising broad-spectrum antiviral candidate.

The present study aimed at developing a new vesicular formulation capable of promoting the protective effect of ascorbic acid and tocopherol against intestinal oxidative stress damage, and their efficacy in intestinal wound healing upon oral administration. A pH-dependent copolymer (Eudragit® L100), a water-soluble prebiotic fibre (Nutriose® FM06), a phospholipid mixture (Lipoid S75), and two natural antioxidants (ascorbic acid and tocopherol) were combined to fabricate eudragit-nutriosomes by a simple, solvent-free procedure. The vesicles were spherical and oligolamellar, with some multicompartment structures in Eudragit-nutriosomes, small in size (~100 nm), with highly negative zeta potential. The effect of Eudragit® and Nutriose® on the stability on storage and in simulated gastrointestinal fluids were confirmed by the Turbiscan® technology and in vitro studies, respectively. Eudragit-nutriosomes exhibited a protective effect against H2O2-induced oxidative stress, and a proliferative effect in Caco-2 cells, as they provided the closure of the scratched area after 96 h of incubation.

Quercetin is a flavonoid with high antioxidant capacity that provides beneficial biological effects. However, the absorption rate of quercetin in the gastrointestinal tract is low but encapsulated lipid matrices, such as liposomes, can be useful to enhance its bioavailability. In this study, quercetin-loaded liposome dispersions were produced by ethanol injection and 12 mM of phospholipid encapsulating 0.3% molar quercetin was suitable to evaluate physicochemical stability. The Langmuir monolayer technique indicated that it was possible to encapsulate a maximum of 0.3% molar quercetin in liposomes. Quercetin-loaded liposome dispersions presented a mean hydrodynamic diameter of 264 nm and a zeta potential of −17 mV, which is typical for small unilamellar vesicles produced by ethanol injection. Sucrose was used as the lyoprotectant (mass sucrose: phospholipid ratio, 4:1), and the encapsulated quercetin had not degraded after 100 days of storage. In addition, the lyophilized liposomes presented a low propensity for water adsorption and low hygroscopicity. Such behavior is considered highly suitable for stability in dried foods. [ABSTRACT FROM AUTHOR]

Nanoparticulate systems with an uncharged hydrophilic surface may have a great potential in mucosal drug delivery. In the present study liposomes were coated with hydrophobically modified hydroxyethyl cellulose (HM-HEC) to create a sterically stabilized liposomal system with an uncharged surface. The aim was to clarify the influence of the amount of hydrophobic modification of HEC and the length of the hydrophobic moiety, on the stability of the system and on the release properties. HM-HEC with different degrees of hydrophobic modification (1 and 2 mol%) and hydrophobic groups with different chain lengths (C8, C12, C16) were included in the study, as well as fluid phase and gel phase liposomes. Both types of liposomes were successfully coated with HM-HEC containing 1 mol% of hydrophobic groups, while 2 mol% did not work for the intended pharmaceutical applications. The polymer coated gel phase liposomes were stable (size, zeta potential, leakage) for 24 weeks at 4 °C, with no differences between the C8 and C16 HM-HEC coating. For the fluid phase liposomes a size increase was observed after 24 weeks at 4 °C for all formulations; the C8 HM-HEC coated liposomes increased the most. No differences in the leakage during storage at 4 °C or in the release at 35 °C were observed between the fluid phase formulations. To conclude; HM-HEC with a shorter hydrophobic chain length resulted in a less stable product for the fluid phase liposomes, while no influence of the chain length was observed for the gel phase liposomes (1 mol% HM). [ABSTRACT FROM AUTHOR]

In this study, the active components of grape pomaces were first extracted by maceration in ethanol and propylene glycol, then in extra virgin olive oil. The main components of the hydrophilic extractive solutions were flavonoids, while monounsaturated fatty acids were the most abundant constituents of the extractive oil, with high levels of oleic acid, which were identified by HPLC/DAD and GC/MS, respectively. The hydrophilic extractive solutions and the lipophilic extractive oil were used to prepare phospholipid vesicles, avoiding the energetically and economically expensive steps required to obtain solid matrixes or pure compounds. The obtained grape bioactive enriched penetration enhancer containing vesicles (PEVs) were multilamellar, around 200 nm in size, and more viscous than the corresponding solutions. The antioxidant activity, evaluated by the Folin-Ciocalteu and DPPH assays, was potentiated when the extractive solutions were loaded in PEVs. Further, the grape enriched PEVs were able to ensure an optimal protection against oxidative stress in an ex vivo human erythrocytes-based model. [ABSTRACT FROM AUTHOR]

The objective of this study was to obtain and characterise curcumin-loaded proliposomes by the method of coating of micronised sucrose. Proliposomes incorporating curcumin were characterised in terms of coating, morphology, crystallinity, solubility and water sorption. The powders showed a good capacity to preserve curcumin, as after 60 days of storage about 80% of the initial amount of curcumin was preserved. The water adsorption on the proliposomes was very low, as was the hygroscopicity (3.4%). The evaluation of the capacity of the multilamellar liposomes produced by the hydration of phospholipid powders to preserve encapsulated curcumin was assessed. Liposome dispersions were produced with different thickeners, and the best results of average size (around 800 nm) and curcumin preservation (72% after 30 days of storage) were obtained with xanthan gum and guar gum. These results evidenced the coating of micronised sucrose is a promising technique to produce liposomes to be incorporated into food. [ABSTRACT FROM AUTHOR]

Introduction: Vaccination requires innovation to provide effective protection. Traditional vaccines have several drawbacks, which can be overcome with advanced technologies and different administration routes. Over the past 10  years, a significant amount of research has focussed on the delivery of antigens into liposomes due to their dual role as antigen-carrying systems and vaccine adjuvants able to increase the immunogenicity of the carried antigen., Areas Covered: This review encompasses the progress made over the last 10  years with liposome-based vaccines designed for minimally or noninvasive administration, filling the gaps in previous reviews and providing insights on composition, administration routes, results achieved, and Technology Readiness Level of the most recent formulations., Expert Opinion: Liposome-based vaccines administered through minimally or noninvasive routes are expected to improve efficacy and complacency of vaccination programs. However, the translation from lab-scale production to large-scale production and collaborations with hospitals, research centers, and companies are needed to allow new products to enter the market and improve the vaccination programs in the future.

Background: The nanoincorporation of the extract of Citrus limon (L.) Osbeck var. pompia into liposomes was aimed at improving its antioxidant and antibacterial effects. Methods: The extract of the rind of Citrus limon (L.) Osbeck var. pompia was obtained by maceration in ethanol, evaporation, and freeze-drying. The extract phytochemical fingerprint was obtained by HPLC and mass spectrometry, and it was determined that gallic acid, neohesperidin, eriocitrin, and neoeriocitrin were the most abundant components. The freeze-dried extract was loaded in liposomes, glycerosomes, and penetration-enhancer-containing vesicles prepared with propylene glycol (PG-PEVs). Results: Capability of the vesicles of improving efficacy of the extract in counteracting oxidative stress was studied in vitro in keratinocytes, along with antimicrobial activity against planktonic cultures of Streptococcus mutans, Lactobacillus acidophilus, and Streptococcus sanguinis. Conclusion: Results showed that the vesicles, especially glycerosomes and PG-PEVs, prevented oxidative damage and cell death, and inhibited bacterial proliferation.

In this study, 1 wt% lecithin (-), chitosan (+), and λ-carrageenan (-) were prepared to manufacture multiple-layered liposomes with optimal formulations developed in a previous study by using layer-by-layer electrostatic deposition. We observed their particle size, ζ-potential, sedimentation behavior, and microstructure for 6 weeks. Multiple-layered liposomes were quenched with calcein to evaluate stability in terms of factors such as encapsulation efficiency and released amount of calcein. The particle size of multi-layered liposomes increased with storage periods and the ζ-potential of multiple-layered liposomes gained a neutral charge. Interestingly, negatively charged layered liposomes were smaller than positively charged layered liposomes and showed a lower polydispersity index. Moreover, the ζ-potential did not apparently change compared to positively charged layered liposomes. For the calcein release study, multiple-layered liposomes significantly sustained quenched calcein more than that observed using non-layered liposomes. This study showed that it was possible to increase the thickness of the liposome surface and to manipulate its charge using chitosan and λ-carrageenan through electrostatic deposition. Results showed that manufacturing negatively charged multiple-layer (over 4-layer) liposomes with charged biopolymer improved the physicochemical stability of liposomes. [ABSTRACT FROM AUTHOR]

Rifampicin loaded glycerosomes, vesicles composed of phospholipids, glycerol and water, were combined with trimethyl chitosan chloride (TMC) to prepare TMC-glycerosomes or, alternatively, with sodium hyaluronate (HY) to obtain HY-glycerosomes. These new hybrid nanovesicles were tested as carriers for pulmonary delivery of rifampicin. Glycerosomes without polymers were also prepared and characterized. All vesicles were similar: they were spherical, multilamellar and able to incorporate good amount of rifampicin (EE% ∼ 55%). The addition of the polymers to the formulations allowed an increase of mean diameter. All the glycerosomes, in particular HY-glycerosomes, were able to deliver the drug to the furthest stages of the Next Generation Impactor and the aptitude of the vesicles to be nebulized was always higher than that of drug dispersion. Rifampicin nanoincorporation in vesicles reduced the in vitro drug toxicity on A549 cells, as well as increased its efficacy against Staphylococcus aureus . Finally, the in vivo biodistribution and accumulation, evaluated after intra-tracheal administration to rats, confirmed the improvement of rifampicin accumulation in lungs. [ABSTRACT FROM AUTHOR]

Clusters of negatively charged liposomes encapsulated with glucose oxidase were prepared in the presence of Ca2+ and used to catalyze the oxidation of glucose in an external loop airlift bubble column. The clusters exhibited higher catalytic activity compared to nonclustered glucose oxidase-containing liposomes (GOLs) when the liposome membranes were incorporated with cholesterol. The clusters were structurally altered in shear flow to give sufficient interfacial area accessible to glucose. The reactivity of GOL clusters could be modulated on the basis of lipid composition of the membranes which affected the mode of interaction among liposomes through Ca2+. Part of GOL clusters could be separated from the reaction mixture by centrifugation, which would be advantageous for reusing liposomal catalysts. The liposome clusters can be the platforms to regulate the catalytic performance of glucose oxidase in the airlift. [ABSTRACT FROM AUTHOR]

We have systematically investigated the effect of various alkali metal ions with negatively charged phospholipid membranes. Size distributions of large unilamellar vesicles have been confirmed using dynamic light scattering. Zeta potential and effective charges per vesicle in the presence of various alkali metal ions have been estimated from the measured electrophoretic mobility. We have determined the intrinsic binding constant from the zeta potential using electrostatic double layer theory. The reasonable and consistent value of the intrinsic binding constant of Na + , found at moderate NaCl concentration (10–100 mM), indicates that the Gouy–Chapman theory cannot be applied for very high (> 100 mM) and very low (< 10 mM) electrolyte concentrations. The isothermal titration calorimetry study has revealed that the net binding heat of interaction of the negatively charged vesicles with monovalent alkali metal ions is small and comparable to those obtained from neutral phosphatidylcholine vesicles. The overall endothermic response of binding heat suggests that interaction is primarily entropy driven. The entropy gain might arise due to the release of water molecules from the hydration layer vicinity of the membranes. Therefore, the partition model which does not include the electrostatic contribution suffices to describe the interaction. The binding constant of Na + (2.4 ± 0.1 M − 1 ), obtained from the ITC, is in agreement with that estimated from the zeta potential (~ 2.0 M − 1 ) at moderate salt concentrations. Our results suggest that hydration dynamics may play a vital role in the membrane solution interface which strongly affects the ion–membrane interaction. [ABSTRACT FROM AUTHOR]

Liquorice extract, obtained by percolation in ethanol of Glycyrrhiza glabra L. roots, was incorporated in liposomes and hyalurosomes, new phospholipid-sodium hyaluronate vesicles, and their protective effect against oxidative stress skin damages was probed. As a comparison, raw glycyrrhizin was also tested. All the vesicles were small in size (≤100 nm), with a highly negative zeta potential ensuring long-term stability, and able to incorporate a high amount of the extract. In vitro tests showed that the liquorice extract loaded in vesicles was able to scavenge DPPH free radical (80% inhibition) and to protect 3T3 fibroblasts against H 2 O 2 -induced oxidative stress, restoring the normal conditions. By contrast, glycyrrhizin showed poor antioxidant activity, and was not able to efficiently counteract the oxidative effect of H 2 O 2 . In addition, the incorporation of the liquorice extract into the vesicular systems promoted the proliferation and migration of 3T3 fibroblasts, favouring the closure of the scratched area. In vivo anti-inflammatory tests on mice confirmed the ability of the proposed nanosystems to improve the local efficacy of the extract, favouring the re-epitelization process. [ABSTRACT FROM AUTHOR]

In the present work new highly biocompatible nanovesicles were developed using polyanion sodium hyaluronate to form polymer immobilized vesicles, so called hyalurosomes. Curcumin, at high concentration was loaded into hyalurosomes and physico-chemical properties and in vitro/in vivo performances of the formulations were compared to those of liposomes having the same lipid and drug content. Vesicles were prepared by direct addition of dispersion containing the polysaccharide sodium hyaluronate and the polyphenol curcumin to a commercial mixture of soy phospholipids, thus avoiding the use of organic solvents. An extensive study was carried out on the physico-chemical features and properties of curcumin-loaded hyalurosomes and liposomes. Cryogenic transmission electron microscopy and small-angle X-ray scattering showed that vesicles were spherical, uni- or oligolamellar and small in size (112–220 nm). The in vitro percutaneous curcumin delivery studies on intact skin showed an improved ability of hyalurosomes to favour a fast drug deposition in the whole skin. Hyalurosomes as well as liposomes were biocompatible, protected in vitro human keratinocytes from oxidative stress damages and promoted tissue remodelling through cellular proliferation and migration. Moreover, in vivo tests underlined a good effectiveness of curcumin-loaded hyalurosomes to counteract 12-O-tetradecanoilphorbol (TPA)-produced inflammation and injuries, diminishing oedema formation, myeloperoxydase activity and providing an extensive skin reepithelization. Thanks to the one-step and environmentally-friendly preparation method, component biocompatibility and safety, good in vitro and in vivo performances, the hyalurosomes appear as promising nanocarriers for cosmetic and pharmaceutical applications. [ABSTRACT FROM AUTHOR]

According to circular economy, wine-making by-products represent a fascinating biomass, which can be used for the sustainable exploitation of polyphenols and the development of new nanotechnological health-promoting products. In this study, polyphenols contained in the grape pomace were extracted by maceration with ethanol in an easy and low dissipative way. The obtained extract, rich in malvidin-3-glucoside, quercetin, procyanidin B2 and gallic acid, was incorporated into phospholipid vesicles tailored for intestinal delivery. To improve their performances, vesicles were enriched with gelatine or a maltodextrin (Nutriose®), or their combination (gelatine-liposomes, nutriosomes and gelatine-nutriosomes). The small (~147 nm) and negatively charged (~ −50 mV) vesicles were stable at different pH values mimicking saliva (6.75), gastric (1.20) and intestinal (7.00) environments. Vesicles effectively protected intestinal cells (Caco-2) from the oxidative stress and promoted the biofilm formation by probiotic bacteria. A preliminary evaluation of the vesicle feasibility at industrial levels was also performed, analysing the economic and energetic costs needed for their production. • Valorization of grape pomace by the extraction of the main polyphenols • Incorporation of the extract into innovative phospholipid vesicles • Evaluation of the stability of the extract containing vesicles at different pHs • Protective effect of vesicles against oxidative stress induced in intestinal cells • Probiotic effect of formulations on gut microbiota [ABSTRACT FROM AUTHOR]

Background: To achieve a target-based drug delivery with minimal side effects, novel drug delivery systems are being continuously explored. Vesicular systems are one such system that can ameliorate the bioavailability of the encapsulated drug by delivering the drug at the targeted site and can minimize the side effect., Objective: The objective of this patent review is to provide a vivid description of glycerosomes and their applications. Glycerosomes are sphere-shaped versatile vesicles consisting of one or more phospholipid bilayers similar to liposomes but contain a high concentration of glycerol, which modifies the liposome bilayer fluidity. Glycerosomes can encapsulate both hydrophobic and hydrophilic drugs, which makes them the promising vehicle in the field of drug delivery., Conclusion: Most of the glycerosome formulations prepared were targeted for topical delivery and in particular, a cutaneous route where they have shown promising results. These vesicles are biocompatible and due to the high glycerol concentration, they have improved spreadability and penetrability. It is therefore imperative to explore the other topical routes such as ocular, vaginal, nasal, and rectal for delivery of drugs., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The aim of this work was to formulate Santolina insularis essential oil-loaded nanocarriers, namely Penetration Enhancer containing Vesicles (PEVs), evaluate the physico-chemical features and stability, and gain insights into their ability to deliver the oil to the skin. S. insularis essential oil was obtained by steam distillation, and was predominantly composed of terpenes, the most abundant being β-phellandrene (22.6%), myrcene (11.4%) and curcumenes (12.1%). Vesicles were prepared using phosphatidylcholine, and ethylene or propylene glycol were added to the water phase (10% (v/v)) to improve vesicle performances as delivery systems. Vesicles were deeply characterized by light scattering, cryogenic transmission electron microscopy and small/wide-angle X-ray scattering, the results showing polyhedral, faceted, unilamellar vesicles of ∼115 nm in size. The presence of the glycols improved vesicle stability under accelerated ageing conditions, without changes in size or migration phenomena (e.g. sedimentation and creaming). Confocal laser scanning microscopy images of pig skin treated with S. insularis formulations displayed a penetration ability of PEVs greater than that of control liposomes. Moreover, all formulations showed a marked in vitro biocompatibility in human keratinocytes. These findings suggest that the nanoformulation may be of value in enhancing the delivery of S. insularis essential oil to the skin, where it can exert its biological activities. [ABSTRACT FROM AUTHOR]

We study the wetting properties of very small droplets of salty aqueous suspensions of unilamellar liposomes of DMPC (dimyristoylphosphatidylcholine), situated on SiO 2 – glass surfaces with different levels of hydrophobicity. We evaluated two different measures of hydrophobicity of solid surfaces - receding contact angles and the thickness of wetting films trapped between an air bubble and the solid surface at different levels of hydrophobicity. We established a good correlation between methods which differ significantly in measurement difficulty and experimental setup. We also reveal details of the mechanism of wetting of different surfaces by the DMPC liposome suspension. Hydrophilic surfaces with water contact angles in the range of 0° to 35° are readily hydrophobized by the liposomes and only showed corresponding contact angles in the range 27°−43°. For same range of surface hydrophobicities, there was a clear reduction of the thickness of the wetting films between the surface and a bubble, reaching a minimum in the 35°−40° range. At higher levels of hydrophobicity both pure water and the liposome suspension show similar contact angles, and the thickness of wetting films between a bubble and those surfaces increases in parallel. Our analysis showed that the only force able to stabilize the film under these experimental conditions is steric repulsion. The latter suggests that nanobubbles adsorbed on hydrophobic parts of the surface, and coated with a DMPC layer, may be the cause of the 40−70 nm thickness of wetting films we observe. [ABSTRACT FROM AUTHOR]

Here we ask the following: 1) what is the CO2 permeability (PCO2) of unilamellar liposomes composed of L-α-phosphatidylcholine (PC)/L-α-phosphatidylserine (PS) = 4:1 and containing cholesterol (Chol) at levels often occurring in biologic membranes (50 mol%), and 2) does incorporation of the CO2 channel aquaporin (AQP)1 cause a significant increase in membrane PCO2? Presently, a drastic discrepancy exists between the answers to these two questions obtained from mass-spectrometric 18O-exchange measurements (Chol reduces PCO2 100-fold, AQP1 increases PCO2 10-fold) vs. from stopped-flow approaches observing CO2 uptake (no effects of either Chol or AQP1). A novel theory of CO2 uptake by vesicles predicts that in a stopped-flow apparatus this fast process can only be resolved temporally and interpreted quantitatively, if 1) a very low CO2 partial pressure (pCO2) is used (e.g., 18 mmHg), and 2) intravesicular carbonic anhydrase (CA) activity is precisely known. With these prerequisites fulfilled, we find by stopped-flow that 1) Chol-containing vesicles possess a PCO2 = 0.01cm/s, and Chol-free vesicles exhibit ~1 cm/s, and 2) the PCO2 of 0.01 cm/s is increased ≥10-fold by AQP1. Both results agree with previous mass-spectrometric results and thus resolve the apparent discrepancy between the two techniques. We confirm that biologic membranes have an intrinsically low PCO2 that can be raised when functionally necessary by incorporating protein-gas channels such as AQP1. [ABSTRACT FROM AUTHOR]

CYP11A1 hydroxylates vitamin D3 producing 20 S -hydroxyvitamin D3 [20(OH)D3] and 20 S ,23-dihydroxyvitamin D3 [20,23(OH) 2 D3] as the major and most characterized metabolites. Both display immuno-regulatory and anti-cancer properties while being non-calcemic. A previous study indicated 20(OH)D3 can be metabolized by rat CYP24A1 to products including 20 S ,24-dihydroxyvitamin D3 [20,24(OH) 2 D3] and 20 S ,25-dihydroxyvitamin D3, with both producing greater inhibition of melanoma colony formation than 20(OH)D3. The aim of this study was to characterize the ability of rat and human CYP24A1 to metabolize 20(OH)D3 and 20,23(OH) 2 D3. Both isoforms metabolized 20(OH)D3 to the same dihydroxyvitamin D species with no secondary metabolites being observed. Hydroxylation at C24 produced both enantiomers of 20,24(OH) 2 D3. For rat CYP24A1 the preferred initial site of hydroxylation was at C24 whereas the human enzyme preferred C25. 20,23(OH) 2 D3 was initially metabolized to 20 S ,23,24-trihydroxyvitamin D3 and 20 S ,23,25-trihydroxyvitamin D3 by rat and human CYP24A1 as determined by NMR, with both isoforms showing a preference for initial hydroxylation at C25. CYP24A1 was able to further oxidize these metabolites in a series of reactions which included the cleavage of C23-C24 bond, as indicated by high resolution mass spectrometry of the products, analogous to the catabolism of 1,25(OH) 2 D3 via the C24-oxidation pathway. Similar catalytic efficiencies were observed for the metabolism of 20(OH)D3 and 20,23(OH) 2 D3 by human CYP24A1 and were lower than for the metabolism of 1,25(OH) 2 D3. We conclude that rat and human CYP24A1 metabolizes 20(OH)D3 producing only dihydroxyvitamin D3 species as products which retain biological activity, whereas 20,23(OH) 2 D3 undergoes multiple oxidations which include cleavage of the side chain. [ABSTRACT FROM AUTHOR]

Biocompatible quercetin nanovesicles were developed by coating polyethylene glycol-containing vesicles with chitosan and nutriose, aimed at targeting the colon. Uncoated and coated vesicles were prepared using hydrogenated soy phosphatidylcholine and quercetin, a potent natural anti-inflammatory and antioxidant drug. Physicochemical characterization was carried out by light scattering, cryogenic microscopy and X-ray scattering, the results showing that vesicles were predominantly multilamellar and around 130 nm in size. The in vitro release of quercetin was investigated under different pH conditions simulating the environment of the gastrointestinal tract, and confirmed that the chitosan/nutriose coating improved the gastric resistance of vesicles, making them a potential carrier system for colon delivery. The preferential localization of fluorescent vesicles in the intestine was demonstrated using the In Vivo FX PRO Imaging System. Above all, a marked amelioration of symptoms of 2,4,6-trinitrobenzenesulfonic acid-induced colitis was observed in animals treated with quercetin-loaded coated vesicles, favoring the restoration of physiological conditions. Therefore, quercetin-loaded chitosan/nutriose-coated vesicles can represent a valuable therapeutic tool for the treatment of chronic intestinal inflammatory diseases, and presumably a preventive system, due to the synergic action of antioxidant quercetin and beneficial prebiotic effects of the chitosan/nutriose complex. [ABSTRACT FROM AUTHOR]