Novel lutein loaded lipid nanoparticles on porcine corneal distribution

Applications of Nanotechnology-mediated Herbal Nanosystems for Ophthalmic Drug

In recent years, herbal nanomedicines have gained tremendous popularity for novel drug discovery. Nanotechnology has provided several advances in the healthcare sector, emerging several novel nanocarriers that potentiate the bioavailability and therapeutic efficacy of the herbal drug. The recent advances in nanotechnology with accelerated strategies of ophthalmic nanosystems have paved a new path for overcoming the limitations associated with ocular drug delivery systems, such as low bioavailability, poor absorption, stability, and precorneal drug loss. Ophthalmic drug delivery is challenging due to anatomical and physiological barriers. Due to the presence of these barriers, the herbal drug entry into the eyes can be affected when administered by following multiple routes, i.e., topical, injectables, or systemic. However, the advancement of nanotechnology with intelligent systems enables the herbal active constituent to successfully entrap within the system, which is usually difficult to reach employing conventional herbal formulations. Herbal-loaded nanocarrier drug delivery systems demonstrated enhanced herbal drug permeation and prolonged herbal drug delivery. In this current manuscript, an extensive search is conducted for original research papers using databases Viz., PubMed, Google Scholar, Science Direct, Web of Science, etc. Further painstaking efforts are made to compile and update the novel herbal nanocarriers such as liposomes, polymeric nanoparticles, solid lipid nanoparticles, nanostructure lipid carriers, micelles, niosomes, nanoemulsions, dendrimers, etc., which are mostly used for ophthalmic drug delivery system. This article presents a comprehensive survey of diverse applications used for the preventative measures and treatment therapy of varied eye disorders. Further, this article highlights the recent findings that the innovators are exclusively working on ophthalmic nanosystems for herbal drug delivery systems. The nanocarriers are promising drug delivery systems that enable an effective and supreme therapeutic potential circumventing the limitations associated with conventional ocular drug delivery systems. The nanotechnology-based approach is useful to encapsulate the herbal bioactive and prevent them from degradation and therefore providing them for controlled and sustained release with enhanced herbal drug permeation. Extensive research is still being carried out in the field of herbal nanotechnology to design an ophthalmic nanosystem with improved biopharmaceutical properties.

Lipid Nanoparticles: An Effective Tool to Improve the Bioavailability of Nutraceuticals

Nano-range bioactive colloidal carrier systems are envisaged to overcome the challenges associated with treatments of numerous diseases. Lipid nanoparticles (LNPs), one of the extensively investigated drug delivery systems, not only improve pharmacokinetic parameters, transportation, and chemical stability of encapsulated compounds but also provide efficient targeting and reduce the risk of toxicity. Over the last decades, nature-derived polyphenols, vitamins, antioxidants, dietary supplements, and herbs have received more attention due to their remarkable biological and pharmacological health and medical benefits. However, their poor aqueous solubility, compromised stability, insufficient absorption, and accelerated elimination impede research in the nutraceutical sector. Owing to the possibilities offered by various LNPs, their ability to accommodate both hydrophilic and hydrophobic molecules and the availability of various preparation methods suitable for sensitive molecules, loading natural fragile molecules into LNPs offers a promising solution. The primary objective of this work is to explore the synergy between nature and nanotechnology, encompassing a wide range of research aimed at encapsulating natural therapeutic molecules within LNPs.

Nanoscale Delivery Systems of Lutein: An Updated Review from a Pharmaceutical Perspective

Carotenoids are natural lipid-soluble pigments that produce yellow to red colors in plants as well as providing bright coloration in vegetables and fruits. Lutein belongs to the xanthophyll subgroup of the carotenoid family, which plays an essential role in photosynthesis and photoprotection in nature. In the human body, lutein, together with its isomer zeaxanthin and its metabolite meso-zeaxanthin, accumulates in the macula of the eye retina, which is responsible for central, high-resolution, and color vision. As a bioactive phytochemical, lutein has essential physiological functions, providing photoprotection against damaging blue light, along with the neutralization of oxidants and the preservation of the structural and functional integrity of cellular membranes. As a potent antioxidant and anti-inflammatory agent, lutein unfortunately has a low bioavailability because of its lipophilicity and a low stability as a result of its conjugated double bonds. In order to enhance lutein stability and bioavailability and achieve its controlled delivery to a target, nanoscale delivery systems, which have great potential for the delivery of bioactive compounds, are starting to be employed. The current review highlights the advantages and innovations associated with incorporating lutein within promising nanoscale delivery systems, such as liposomes, nanoemulsions, polymer nanoparticles, and polymer–lipid hybrid nanoparticles, as well as their unique physiochemical properties.

Recent Developments of Nanostructures for the Ocular Delivery of Natural Compounds

Ocular disorders comprising various diseases of the anterior and posterior segments are considered as the main reasons for blindness. Natural products have been identified as potential treatments for ocular diseases due to their anti-oxidative, antiangiogenic, and anti-inflammatory effects. Unfortunately, most of these beneficial compounds are characterised by low solubility which results in low bioavailability and rapid systemic clearance thus requiring frequent administration or requiring high doses, which hinders their therapeutic applications. Additionally, the therapeutic efficiency of ocular drug delivery as a popular route of drug administration for the treatment of ocular diseases is restricted by various anatomical and physiological barriers. Recently, nanotechnology-based strategies including polymeric nanoparticles, micelles, nanofibers, dendrimers, lipid nanoparticles, liposomes, and niosomes have emerged as promising approaches to overcome limitations and enhance ocular drug bioavailability by effective delivery to the target sites. This review provides an overview of nano-drug delivery systems of natural compounds such as thymoquinone, catechin, epigallocatechin gallate, curcumin, berberine, pilocarpine, genistein, resveratrol, quercetin, naringenin, lutein, kaempferol, baicalin, and tetrandrine for ocular applications. This approach involves increasing drug concentration in the carriers to enhance drug movement into and through the ocular barriers.

Comparative Efficiency of Lutein and Astaxanthin in the Protection of Human Corneal Epithelial Cells In Vitro from Blue-Violet Light Photo-Oxidative Damage

The aim of this study was to compare in vitro the protective and antioxidant properties of lutein and astaxanthin on human primary corneal epithelial cells (HCE-F). To this purpose, HCE-F cells were irradiated with a blue-violet light lamp (415–420 nm) at different energies (20 to 80 J/cm2). Lutein and astaxanthin (50 to 250 μM) were added to HCE-F right before blue-violet light irradiation at 50 J/cm2. Viability was evaluated by the CKK-8 assay while the production of reactive oxygen species (ROS) by the H2DCF-DA assay. Results have shown that the viability of HCE-F cells decreased at light energies from 20 J/cm2 to 80 J/cm2, while ROS production increased at 50 and 80 J/cm2. The presence of lutein or astaxanthin protected the cells from phototoxicity, with lutein slightly more efficient than astaxanthin also on the blunting of ROS, prevention of apoptotic cell death and modulation of the Nrf-2 pathway. The association of lutein and astaxanthin did not give a significant advantage over the use of lutein alone. Taken together, these results suggest that the association of lutein and astaxanthin might be useful to protect cells of the ocular surface from short (lutein) and longer (astaxanthin) wavelengths, as these are the most damaging radiations hitting the eye from many different LED screens and solar light.

Lipid Nanoparticles for the Posterior Eye Segment

This review highlights the application of lipid nanoparticles (Solid Lipid Nanoparticles, Nanostructured Lipid Carriers, or Lipid Drug Conjugates) as effective drug carriers for pathologies affecting the posterior ocular segment. Eye anatomy and the most relevant diseases affecting the posterior segment will be summarized. Moreover, preparation methods and different types and subtypes of lipid nanoparticles will also be reviewed. Lipid nanoparticles used as carriers to deliver drugs to the posterior eye segment as well as their administration routes, pharmaceutical forms and ocular distribution will be discussed emphasizing the different targeting strategies most recently employed for ocular drug delivery.

Preparation and characterization of lutein loaded folate conjugated polymeric nanoparticles

AIM

To prepare and characterise lutein-loaded polylactide-co-glycolide-polyethylene glycol-folate (PLGA-PEG-FOLATE) nanoparticles and evaluate enhanced uptake in SK-N-BE(2) cells.

METHODS

Nanoparticles were prepared using O/W emulsion solvent evaporation and characterised using DLS, SEM, DSC, FTIR and in-vitro release. Lutein-uptake in SK-N-BE(2) cells was determined using flow-cytometry, confocal-microscopy and HPLC. Control was lutein PLGA nanoparticles.

RESULTS

The size of lutein-loaded PLGA and PLGA-PEG-FOLATE nanoparticles were 189.6 ± 18.79 nm and 188.0 ± 4.06 nm, respectively. Lutein entrapment was ∼61%(w/w) and ∼73%(w/w) for PLGA and PLGA-PEG-FOLATE nanoparticles, respectively. DSC and FTIR confirmed encapsulation of lutein into nanoparticles. Cellular uptake studies showed ∼1.6 and ∼2-fold enhanced uptake of lutein from PLGA-PEG-FOLATE nanoparticles compared to PLGA nanoparticles and lutein, respectively. Cumulative release of lutein was higher in PLGA nanoparticles (100% (w/w) within 24 h) compared to PLGA-PEG-FOLATE nanoparticles (∼80% (w/w) in 48 h).

CONCLUSION

Lutein-loaded PLGA-PEG-FOLATE nanoparticles could be a potential treatment for hypoxic ischaemic encephalopathy.

Nutraceutical approach to enhance lutein bioavailability via nanodelivery systems

Lutein, a potent dietary carotenoid, has considerable biological activity and confers protection against age-related macular degeneration. Its bioavailability following consumption, however, depends on its rate of degradation. Nanodelivery systems with improved efficacy and stability are currently being developed to increase the bioavailability of lutein. This review examines nutraceutical approaches used in the development of such nanodelivery systems. It describes the methods of lutein preparation, the characteristics of various delivery systems, and the lutein delivery profile. In order to enhance lutein loading, provide electrostatic stabilization, and achieve the controlled release of lutein, adjuvants such as dextran moieties, whey proteins, medium-chain triglycerides, and chitosan polymers can be used to effectively reduce the particle size (< 70 nm) and improve encapsulation efficiency (to 99.5%). The improved bioavailability of lutein via nanocrystals incorporated into rapidly dissolving films for oral consumption is a new area of exploratory research. This review aims to provide clarity about current research aimed at enhancing the bioavailability of lutein through the development of nanodelivery systems.

Carotenoid-loaded nanocarriers: A comprehensive review

Carotenoids retain plenty of health benefits and attracting much attention recently, but they have less resistance to processing stresses, easily oxidized and chemically unstable. Additionally, their application in food and pharmaceuticals are restricted due to some limitations such as poor bioavailability, less solubility and quick release. Nanoencapsulation techniques can be used to protect the carotenoids and to uphold their original characteristics during processing, storage and digestion, improve their physiochemical properties and enhance their health promoting effects. The importance of nanocarriers in foods and pharmaceuticals cannot be denied. This review comprehensively covers recent advances in nanoencapsulation of carotenoids with biopolymeric nanocarriers (polysaccharides and proteins), and lipid-based nanocarriers, their functionalities, aptness and innovative developments in preparation strategies. Furthermore, the present state of the art encapsulation of different carotenoids via biopolymeric and lipid-based nanocarriers have been enclosed and tabulated well. Nanoencapsulation has a vast range of applications for protection of carotenoids. Polysaccharides in combination with different proteins can offer a great avenue to achieve the desired formulation for encapsulation of carotenoids by using different nanoencapsulation strategies. In terms of lipid based nanocarriers, solid lipid nanoparticles and nanostructure lipid carriers are proving as the encouraging candidates for entrapment of carotenoids. Additionally, nanoliposomes and nanoemulsion are also promising and novel-vehicles for the protection of carotenoids against challenging aspects as well as offering an effectual controlled release on the targeted sites. In the future, further studies could be conducted for exploring the application of nanoencapsulated systems in food and gastrointestinal tract (GIT) for industrial applications.

Ophthalmic Nanosystems with Antioxidants for the Prevention and Treatment of Eye Diseases

Oxidative stress may induce a series of pathophysiological modifications that are directly involved in the development of ophthalmic diseases like age-related cataract, macular degeneration or diabetic retinopathy, considered to be responsible for the majority of vision loss cases. Although various treatment options for eye diseases are available, multiple factors could limit their efficacy. Recently, the accelerated development of ophthalmic nanosystems has provided new possibilities for overcoming the limitations of existing ocular drug delivery methods. This review evaluates the current status of ophthalmic nanosystems loaded with antioxidants for the prevention and treatment of several eye diseases.

Stability, Cytotoxicity, and Retinal Pigment Epithelial Cell Binding of Hyaluronic Acid-Coated PLGA Nanoparticles Encapsulating Lutein

The application of lutein was limited due to water insolubility and susceptible to heat and light degradation. In this study, hyaluronic acid (HA)-coated PLGA nanoparticles encapsulating lutein were fabricated by a solvent displacement method to improve the physicochemical properties and the stability of lutein. A biphasic release profile of lutein was observed, following zero-order release kinetics. The physical stability of lutein stored at 4°C, 30°C, and 40°C for 30 days was enhanced when lutein was encapsulated in the nanoparticles. The degradation of lutein in PLGA NPs coated with HA was fitted to a second-order kinetic model. The rate constant increased with increasing storage temperature. The activation energy of lutein-NPs was 63.26 kJ/mol. The half-lives of lutein in PLGA-NPs were about 49, 4, and 2 days at a storage temperature of 4°C, 30°C, and 40°C, respectively. The results suggested that lutein-NPs should be stored at 4°C to prevent physical and chemical degradation. The photodegradation of lutein in NPs followed a second-order kinetic model. The rate constant was 0.0155 mg^-1 ml day^-1. Cell viability study revealed that HA-coated PLGA nanoparticles encapsulating lutein did not show toxicity against retinal pigment epithelial cells (ARPE-19). The NPs bound ARPE-19 cells in a time- and a dose-dependent manner. The binding efficiency of lutein-NPs decreased at higher concentrations, suggesting that the NPs might reach binding saturation capacity. In conclusion, HA-coated PLGA nanoparticles could be used to deliver lutein and improved physicochemical property of lutein. Graphical abstract ᅟ.

Physicochemical Properties of Lutein-Loaded Microcapsules and Their Uptake via Caco-2 Monolayers

Lutein is one of the most important carotenoids that can be utilized in foods as a natural pigment and nutraceutical ingredient to improve eye health. However, its utilization is limited due to its poor solubility. Chemically, the highly unsaturated structure of lutein makes it extremely susceptible to light, oxygen, heat, and pro-oxidants and therefore easily oxidized, decomposed or dissociated. In this study, we aimed to imbed natural lutein to improve its storage stability and enhance its water dispersibility. As two commonly studied water-soluble and water-insoluble food-grade surfactants, lecithin and sodium caseinate (NaCas) were chosen as the wall materials, and lutein-loaded lecithin microcapsules and NaCas microcapsules were prepared, the results revealed the lutein-loaded NaCas microcapsules not only exhibited better solubility and stability than those of lutein-loaded lecithin microcapsules, but also were more stable when stored at 4 °C, 25 °C, 37 °C. Moreover, the lutein-loaded NaCas microcapsules were more easily absorbed by the intestinal Caco-2 cells than natural lutein. Considering the dispersibility, stability and cell absorption effect, the NaCas-based microparticle is a potential carrier for lutein.

Computer-Aided Formulation Design for a Highly Soluble Lutein-Cyclodextrin Multiple-Component Delivery System

Cyclodextrin (CD) complexation is widely used for the solubilization of poorly soluble drugs in the pharmaceutical industry. Current research was to develop a highly soluble lutein-cyclodextrin multiple-component delivery system (lutein-CD-MCDS) by combined modeling and experimental approaches. Both phase solubility diagram and molecular dynamics (MD) simulation results revealed that the interactions between lutein and CDs were very weak, which confirmed the insignificant solubility improvement of lutein-CD binary system. On the basis of theoretical calculation and preliminary CD studies, lutein-CD-MCDS was developed with over 400-fold solubility improvement after formulation screening. MD simulation indicated that the auxiliary polymers of TWEEN 80 and poloxamer 188 in the lutein-CD-MCDS introduced bridged interaction between lutein and γ-CD to increase the solubility, dissolution rate, and stability of the complex. The lutein-CD-MCDS was characterized by in vitro dissolution test, differential scanning colorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and powder X-ray diffraction (PXRD). Moreover, lutein-CD-MCDS had significantly higher uptake in Caco-2 cells than free lutein. The relative bioavailability of the lutein-CD-MCDS increased to 6.6-fold compared to pure lutein, and to 1.2-fold compared with commercial lutein soft capsules. In conclusion, the highly soluble lutein-CD-MCDS with significant improvement in both the solubility and bioavailability was developed and characterized by combined modeling and experimental approaches. Our research indicates that computer-aided formulation design is a promising approach for future formulation development.

Cyclodextrins and topical drug delivery to the anterior and posterior segments of the eye

It is generally believed that it is virtually impossible to obtain therapeutic drug concentrations in the posterior segment of the eye after topical application of aqueous, low viscosity eye drops. Thus, intravitreal drug injections and drug implants are currently used to treat diseases in the posterior segment such as macular edema. Here it is described how, through proper analysis of the drug permeation barriers and application of well-known pharmaceutical excipients, aqueous eye drops are designed that can deliver lipophilic drugs to the posterior segment as well as how such eye drops can maintain high drug concentrations in the anterior segment. Through stepwise optimization, eye drops containing solid drug/cyclodextrin complex microparticles with a mean diameter of 2-4μm, dissolved drug/cyclodextrin complex nanoparticles and dissolved drug molecules in an aqueous eye drop media of low viscosity were designed. After administration of the eye drops the microparticles slowly dissolved and maintained close to saturated drug concentrations in the aqueous tear fluid for several hours. Studies in rabbits and clinical evaluations in humans, using dorzolamide and dexamethasone as sample drugs, show that the eye drops deliver significant amounts of drugs to both the posterior segment and anterior segment of the eye. Clinical studies indicate that the eye drops can replace intravitreal injections and implants that are currently used to treat ophthalmic diseases and decrease frequency of drug administration, both of which can improve patient compliance.

Topical ophthalmic lipid nanoparticle formulations (SLN, NLC) of indomethacin for delivery to the posterior segment ocular tissues

PURPOSE

The objective of the present study was to formulate indomethacin (IN)-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) and to investigate their potential use in topical ocular delivery.

METHODS

IN SLNs (0.1% w/v) and NLCs (0.8% w/v) were prepared, characterized and evaluated. Their in vitro release and flux profiles across the cornea and sclera-choroid-RPE (trans-SCR) tissues and in vivo ocular tissue distribution were assessed. Furthermore, chitosan chloride (CS) (mol. wt.<200kDa), a cationic and water-soluble penetration enhancer, was used to modify the surface of the SLNs, and its effect was investigated through in vitro transmembrane penetration and in vivo distribution tissue studies.

RESULTS

For the IN-SLNs, IN-CS-SLNs and IN-NLCs, the particle size was 226±5, 265±8, and 227±11nm, respectively; the zeta potential was -22±0.8, 27±1.2, and -12.2±2.3mV, respectively; the polydispersity index (PDI) was 0.17, 0.30, and 0.23, respectively; and the entrapment efficiency (EE) was 81±0.9, 91.5±3.2 and 99.8±0.2%, respectively. The surface modification of the SLNs with CS increased the ocular penetration of IN. The NLCs maintained significantly higher IN concentrations in all ocular tissues tested compared to the other formulations evaluated in vivo.

CONCLUSION

The results suggest that lipid-based particulate systems can serve as viable vehicles for ocular delivery. The NLC formulations demonstrated increased drug loading capability, entrapment and delivery to anterior and posterior segment ocular tissues.