Optimization and evaluation of a thermoresponsive ophthalmic in situ gel containing curcumin-loaded albumin nanoparticles

Breaking Barriers: Nanomedicine-Based Drug Delivery for Cataract Treatment

Cataract is a leading cause of blindness globally, and its surgical treatment poses a significant burden on global healthcare. Pharmacologic therapies, including antioxidants and protein aggregation reversal agents, have attracted great attention in the treatment of cataracts in recent years. Due to the anatomical and physiological barriers of the eye, the effectiveness of traditional eye drops for delivering drugs topically to the lens is hindered. The advancements in nanomedicine present novel and promising strategies for addressing challenges in drug delivery to the lens, including the development of nanoparticle formulations that can improve drug penetration into the anterior segment and enable sustained release of medications. This review introduces various cutting-edge drug delivery systems for cataract treatment, highlighting their physicochemical properties and surface engineering for optimal design, thus providing impetus for further innovative research and potential clinical applications of anti-cataract drugs.

Recent Updates on Nanocarriers for Drug Delivery in Posterior Segment Diseases with Emphasis on Diabetic Retinopathy

In recent years, various conventional formulations have been used for the treatment and/or management of ocular medical conditions. Diabetic retinopathy, a microvascular disease of the retina, remains the leading cause of visual disability in patients with diabetes. Currently, for treating diabetic retinopathy, only intraocular, intravitreal, periocular injections, and laser photocoagulation are widely used. Frequent administration of these drugs by injections may lead to serious complications, including retinal detachment and endophthalmitis. Although conventional ophthalmic formulations like eye drops, ointments, and suspensions are available globally, these formulations fail to achieve optimum drug therapeutic profile due to immediate nasolacrimal drainage, rapid tearing, and systemic tearing toxicity of the drugs. To achieve better therapeutic outcomes with prolonged release of the therapeutic agents, nano-drug delivery materials have been investigated. These nanocarriers include nanoparticles, solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), dendrimers, nanofibers, in-situ gel, vesicular carriers, niosomes, and mucoadhesive systems, among others. The nanocarriers carry the potential benefits of site-specific delivery and controlled and sustained drug release profile. In the present article, various nanomaterials explored for treating diabetic retinopathy are reviewed.

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.

Milk Protein-Based Nanohydrogels: Current Status and Applications

Milk proteins are excellent biomaterials for the modification and formulation of food structures as they have good nutritional value; are biodegradable and biocompatible; are regarded as safe for human consumption; possess valuable physical, chemical, and biological functionalities. Hydrogels are three-dimensional, cross-linked networks of polymers capable of absorbing large amounts of water and biological fluids without dissolving and have attained great attraction from researchers due to their small size and high efficiency. Gelation is the primary technique used to synthesize milk protein nanohydrogels, whereas the denaturation, aggregation, and gelation of proteins are of specific significance toward assembling novel nanostructures such as nanohydrogels with various possible applications. These are synthesized by either chemical cross-linking achieved through covalent bonds or physical cross-linking via noncovalent bonds. Milk-protein-based gelling systems can play a variety of functions such as in food nutrition and health, food engineering and processing, and food safety. Therefore, this review highlights the method to prepare milk protein nanohydrogel and its diverse applications in the food industry.

Inherited Retinal Dystrophies: Role of Oxidative Stress and Inflammation in Their Physiopathology and Therapeutic Implications

Inherited retinal dystrophies (IRDs) are a large group of genetically and clinically heterogeneous diseases characterized by the progressive degeneration of the retina, ultimately leading to loss of visual function. Oxidative stress and inflammation play fundamental roles in the physiopathology of these diseases. Photoreceptor cell death induces an inflammatory state in the retina. The activation of several molecular pathways triggers different cellular responses to injury, including the activation of microglia to eliminate debris and recruit inflammatory cells from circulation. Therapeutical options for IRDs are currently limited, although a small number of patients have been successfully treated by gene therapy. Many other therapeutic strategies are being pursued to mitigate the deleterious effects of IRDs associated with oxidative metabolism and/or inflammation, including inhibiting reactive oxygen species’ accumulation and inflammatory responses, and blocking autophagy. Several compounds are being tested in clinical trials, generating great expectations for their implementation. The present review discusses the main death mechanisms that occur in IRDs and the latest therapies that are under investigation.

Bibliometric analysis of articles on nanoemulsion and/or in-situ gel for ocular drug delivery system published during the 2011–2021 period

The bibliometric data were extracted from the Scopus database to investigate the conceptual framework of ocular nanoemulsion and/or in-situ gel drug delivery system using “ocular” AND “nanoemulsion” OR “in-situ gel” keywords. The data were evaluated with RStudio and VOSviewer program.

The results reveal that the publication trends tend to increase continually. India is the most impactful country, and the most constructive institution is Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University. International Journal of Pharmaceutics is the top influential source. Ali A is the most prolific author. The title of the most impactful article was In-situ gelling systems based on Pluronic F127/Pluronic F68 formulations for ocular drug delivery”. “Controlled release” is the most popular keyword.

These results provide insights for stimulating research collaborations and revealing open issues of controlled-release ocular preparation to overcome an ocular barrier and enhance patient compliance.

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.

Recent Advances and Disputes About Curcumin in Retinal Diseases

Curcumin belongs to the group of so-called phytocompounds, biologically active molecules produced by plants exerting a beneficial effect on health. Curcumin shows a wide spectrum of different properties, being an anti-inflammatory, antioxidant, antimicrobial and antimutagenic molecule. The purpose of the review is to examine what literature reported on the characteristics of curcumin, particularly, on the beneficial and controversial aspects of this molecule, aiming for a better therapeutic management of retinal diseases. The retina is a constant target of oxidative stress, this tissue being characterized by cells rich in mitochondria and by vessels and being, obviously, continuously reached from photons affecting its layers. Particularly, the retinal ganglion cells and the photoreceptors are extremely sensitive to oxidative stress damage and it is well known that an imbalance in reactive oxygen species is often involved in several retinal diseases, such as uveitis, age-related macular degeneration, diabetic retinopathy, central serous chorioretinopathy, macular edema, retinal ischemia-reperfusion injury, proliferative vitreoretinopathy, hereditary tapeto-retinal degenerations, and retinal and choroidal tumors. To date, several studies suggest that oral treatment with curcumin is generally well tolerated in humans and, in addition, it seems to have no negative effects: therefore, curcumin is a promising candidate as a retinal disease therapy. Unfortunately, the primary limitation of curcumin is represented by its poor bioavailability, in fact only a minimal fraction of this substance can reach the blood stream in the form of a biologically active compound. However, many steps have been made in several fields. In the future, it is expected that the strategies developed until now to allow curcumin to reach the target tissues in adequate concentrations could be ameliorated and, above all, large in vivo studies on humans are needed to demonstrate the total safety of these compounds and their effectiveness in different eye diseases.

Potential of Stimuli-Responsive In Situ Gel System for Sustained Ocular Drug Delivery: Recent Progress and Contemporary Research

Eyesight is one of the most well-deserved blessings, amid all the five senses in the human body. It captures the raw signals from the outside world to create detailed visual images, granting the ability to witness and gain knowledge about the world. Eyes are exposed directly to the external environment; they are susceptible to the vicissitudes of diseases. The World Health Organization has predicted that the number of individuals affected by eye diseases will rise enormously in the next decades. However, the physical barriers of the eyes and the problems associated with conventional ocular formulations are significant challenges in ophthalmic drug development. This has generated the demand for a sustained ocular drug delivery system, which serves to deliver effective drug concentration at a reduced frequency for consistent therapeutic effect and better patient treatment adherence. Recent advancement in pharmaceutical dosage design has demonstrated that a stimuli-responsive in situ gel system exhibits the favorable characteristics for providing sustained ocular drug delivery and enhanced ocular bioavailability. Stimuli-responsive in situ gels undergo a phase transition (solution-gelation) in response to the ocular environmental temperature, pH, and ions. These stimuli transform the formulation into a gel at the cul de sac to overcome the shortcomings of conventional eye drops, such as rapid nasolacrimal drainage and short contact time with the ocular surface This review highlights the recent successful research outcomes of stimuli-responsive in situ gelling systems in treating in vivo models with glaucoma and various ocular infections. Additionally, it also presents the mechanism, recent development, and safety considerations of stimuli-sensitive in situ gel as the potential sustained ocular delivery system for treating common eye disorders.

Preparation and Evaluation of a Xanthan Gum-Containing Linezolid Ophthalmic Solution for Topical Treatment of Experimental Bacterial Keratitis

PURPOSE

To formulate a xanthan gum-containing linezolid ophthalmic solution (LZD-XG) as a new antibiotic treatment against ocular bacterial infection.

METHODS

LZD-XG was prepared and evaluated for its in vitro/in vivo ocular tolerance, in vitro/in vivo antibacterial activity, and in vivo ocular penetration.

RESULTS

The optimized LZD-XG exhibited good in vitro/in vivo eye tolerance. A prolonged ocular surface residence time of LZD-XG was observed after topical instillation, and the ocular permeation was significantly better for LZD-XG than fora linezolid (LZD) ophthalmic solution. The in vitro antimicrobial activity was significantly better with LZD-XG than with LZD. In vivo evaluation also confirmed a strong therapeutic treatment effect of LZD-XG, as it significantly improved the clinical symptoms, ameliorated the damage of Staphylococcus aureus to ocular tissues, lowered the colony forming unit counts in the cornea, and decreased the myeloperoxidase activity in the cornea.

CONCLUSION

LZD-XG was deemed a viable ophthalmic solution against ocular bacterial infection due to its excellent in vitro and in vivo characterizations.

Ocular Delivery of Polyphenols: Meeting the Unmet Needs

Nature has become one of the main sources of exploration for researchers that search for new potential molecules to be used in therapy. Polyphenols are emerging as a class of compounds that have attracted the attention of pharmaceutical and biomedical scientists. Thanks to their structural peculiarities, polyphenolic compounds are characterized as good scavengers of free radical species. This, among other medicinal effects, permits them to interfere with different molecular pathways that are involved in the inflammatory process. Unfortunately, many compounds of this class possess low solubility in aqueous solvents and low stability. Ocular pathologies are spread worldwide. It is estimated that every individual at least once in their lifetime experiences some kind of eye disorder. Oxidative stress or inflammatory processes are the basic etiological mechanisms of many ocular pathologies. A variety of polyphenolic compounds have been proved to be efficient in suppressing some of the indicators of these pathologies in in vitro and in vivo models. Further application of polyphenolic compounds in ocular therapy lacks an adequate formulation approach. Therefore, more emphasis should be put in advanced delivery strategies that will overcome the limits of the delivery site as well as the ones related to the polyphenols in use. This review analyzes different drug delivery strategies that are employed for the formulation of polyphenolic compounds when used to treat ocular pathologies related to oxidative stress and inflammation.

Curcumin Metabolite Tetrahydrocurcumin in the Treatment of Eye Diseases

Curcumin is one of the most valuable natural products due to its pharmacological activities. However, the low bioavailability of curcumin has long been a problem for its medicinal use. Large studies have been conducted to improve the use of curcumin; among these studies, curcumin metabolites have become a relatively new research focus over the past few years. Additionally, accumulating evidence suggests that curcumin or curcuminoid metabolites have similar or better biological activity than the precursor of curcumin. Recent studies focus on the protective role of plasma tetrahydrocurcumin (THC), a main metabolite of curcumin, against tumors and chronic inflammatory diseases. Nevertheless, studies of THC in eye diseases have not yet been conducted. Since ophthalmic conditions play a crucial role in worldwide public health, the prevention and treatment of ophthalmic diseases are of great concern. Therefore, the present study investigated the antioxidative, anti-inflammatory, antiangiogenic, and neuroprotective effects of THC on four major ocular diseases: age-related cataracts, glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR). While this study aimed to show curcumin as a promising potential solution for eye conditions and discusses the involved mechanistic pathways, further work is required for the clinical application of curcumin.

Advances and limitations of drug delivery systems formulated as eye drops

Topical instillation of eye drops remains the most common and easiest route of ocular drug administration, representing the treatment of choice for many ocular diseases. Nevertheless, low ocular bioavailability of topically applied drug molecules can considerably limit their efficacy. Over the last several decades, numerous drug delivery systems (DDS) have been developed in order to improve drug bioavailability on the ocular surfaces. This review systematically covers the most recent advances of DDS applicable by topical instillation, that have shown better performance in in vivo models compared to standard eye drop formulations. These delivery systems are based on in situ forming gels, nanoparticles and combinations of both. Most of the DDS have been developed using natural or synthetic polymers. Polymers offer many advantageous properties for designing advanced DDS including biocompatibility, gelation properties and/or mucoadhesiveness. However, despite the high number of studies published over the last decade, there are several limitations for clinical translation of DDS. This review article focuses on the recent advances for the development of ocular drug delivery systems. In addtion, the potential challenges for commercialization of new DDS are presented.

Poloxamer Hydrogels for Biomedical Applications

This review article focuses on thermoresponsive hydrogels consisting of poloxamers which are of high interest for biomedical application especially in drug delivery for ophthalmic, injectable, transdermal, and vaginal administration. These hydrogels remain fluid at room temperature but become more viscous gel once they are exposed to body temperature. In this way, the gelling system remains at the topical level for a long time and the drug release is controlled and prolonged. Poloxamers are synthetic triblock copolymers of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO), also commercially known as Pluronics®, Synperonics® or Lutrol®. The different poloxamers cover a range of liquids, pastes, and solids, with molecular weights and ethylene oxide-propylene oxide weight ratios varying from 1100 to 14,000 and 1:9 to 8:2, respectively. Concentrated aqueous solutions of poloxamers form thermoreversible gels. In recent years this type of gel has arouse interest for tissue engineering. Finally, the use of poloxamers as biosurfactants is evaluated since they are able to form micelles in an aqueous environment above a concentration threshold known as critical micelle concentration (CMC). This property is exploited for drug delivery and different therapeutic applications.

Review of Stimuli-Responsive Polymers in Drug Delivery and Textile Application

This review describes some commercially available stimuli-responsive polymers of natural and synthetic origin, and their applications in drug delivery and textiles. The polymers of natural origin such as chitosan, cellulose, albumin, and gelatin are found to show both thermo-responsive and pH-responsive properties and these features of the biopolymers impart sensitivity to act differently under different temperatures and pH conditions. The stimuli-responsive characters of these natural polymers have been discussed in the review, and their respective applications in drug delivery and textile especially for textile-based transdermal therapy have been emphasized. Some practically important thermo-responsive polymers such as pluronic F127 (PF127) and poly(N-isopropylacrylamide) (pNIPAAm) of synthetic origin have been discussed in the review and they are of great importance commercially because of their in situ gel formation capacity. Some pH-responsive synthetic polymers have been discussed depending on their surface charge, and their drug delivery and textile applications have been discussed in this review. The selected stimuli-responsive polymers of synthetic origin are commercially available. Above all, the applications of bio-based or synthetic stimuli-responsive polymers in textile-based transdermal therapy are given special regard apart from their general drug delivery applications. A special insight has been given for stimuli-responsive hydrogel drug delivery systems for textile-based transdermal therapy, which is critical for the treatment of skin disease atopic dermatitis.

Potential Albumin-Based Antioxidant Nanoformulations for Ocular Protection against Oxidative Stress

Amongst various drug administration methods, ophthalmic drug delivery has been a useful way for the treatment of eye-related diseases. However, therapeutic efficacy of ocular therapy for anterior or posterior eye segments through topical administration is considerably challenged by the number of anatomical and physiological barriers in the eyes affecting ocular bioavailability. In this respect, advanced biocompatible nanoformulations make it possible to improve drug delivery to the target sites and enhance ocular bioavailability of ophthalmic medicines. Various ocular diseases have been reported to be related to oxidative stresses in tissues, and polyphenolic compounds have been known for their antioxidant activities in various tissues, including the eyes. Despite drug efficacy, poor water solubility and intrinsic color of the compounds limit the drug’s inclusion into the development of ocular medicine. In the present study, we investigated the antioxidant protectant efficacy of rosmarinic or ursolic acid in the retinal epithelial cells, as compared to those of curcumin, by forming nanospheres with bovine serum albumin. Our results demonstrate that antioxidant-containing nanoformulations provide a significantly higher drug solubility and decreased ROS (reactive oxygen species) production in the retinal epithelial cells. Finally, we also found that albumin-based nanoformulations could improve bioavailability and increase antioxidant activity of rosmarinic or ursolic acid in the retina to be applied as efficient ocular protectant.

Nanostructured lipid carriers-based thermosensitive eye drops for enhanced, sustained delivery of dexamethasone

AIM

Nanostructured lipid carriers in-gel (NLCs-gel) were prepared to enhance and improve the ocular delivery of dexamethasone. Materials & methods: NLCs containing dexamethasone prepared by high-pressure homogenization were characterized and dispersed into thermosensitive gels (Pluronic F127 and F68 as gels material). In vitro drug release studies, ocular irritation tests, ex vivo corneal penetration and drug dynamics of NLCs and NLCs-gel were evaluated in aqueous humor.

RESULTS

NLCs-gel exhibited a rapid sol-gel transition at 34.4°C and presented nano-sized, narrowly distributed particles. Corneal penetration studies revealed steady sustained drug release (Ritger-Peppas); NLCs-gel increased ocular bioavailability by prolonging precorneal retention time and improving corneal permeation.

CONCLUSION

These findings suggest developing NLCs-gel for potential treatment of posterior segment eye diseases.

Preventive Effect of Curcumin Against Chemotherapy-Induced Side-Effects

Cancer is still a severe threat to the health of people worldwide. Chemotherapy is one of main therapeutic approaches to combat cancer. However, chemotherapy only has a limited success with severe side effects, especially causing damage to normal tissues such as bone marrow, gastrointestine, heart, liver, renal, neuron, and auditory tissues, etc. The side-effects limit clinical outcome of chemotherapy and lower patients’ quality of life, and even make many patients discontinue the chemotherapy. Thus, there is a need to explore effective adjuvant strategies to prevent and reduce the chemotherapy-induced side effects. Naturally occurring products provide a rich source for exploring effective adjuvant agents to prevent and reduce the side effects in anticancer chemotherapy. Curcumin is an active compound from natural plant Curcuma longa L., which is widely used as a coloring and flavoring agent in food industry and a herbal medicine in Asian countries for thousands of years to treat vomiting, headache, diarrhea, etc. Modern pharmacological studies have revealed that curcumin has strong antioxidative, anti-microbial, anti-inflammatory and anticancer activities. Growing evidence shows that curcumin is able to prevent carcinogenesis, sensitize cancer cells to chemotherapy, and protect normal cells from chemotherapy-induced damages. In the present article, we review the preventive effect of curcumin against chemotherapy-induced myelosuppression, gastrointestinal toxicity, cardiotoxicity, hepatotoxicity, nephrotoxicity, neurotoxicity, ototoxicity, and genotoxicity, and discuss its action mechanisms.

Resveratrol-Loaded Albumin Nanoparticles with Prolonged Blood Circulation and Improved Biocompatibility for Highly Effective Targeted Pancreatic Tumor Therapy

Human serum albumin (HSA) is an intrinsic protein and important carrier that transports endogenous as well as exogenous substances across cell membranes. Herein, we have designed and prepared resveratrol (RV)-loaded HSA nanoparticles conjugating RGD (arginine-glycine-aspartate) via a polyethylene glycol (PEG) "bridge" (HRP-RGD NPs) for highly effective targeted pancreatic tumor therapy. HRP-RGD NPs possess an average size of 120 ± 2.6 nm with a narrow distribution, a homodisperse spherical shape, a RV encapsulation efficiency of 62.5 ± 4.21%, and a maximum RV release ratio of 58.4.2 ± 2.8% at pH 5.0 and 37 °C. In vitro biocompatibility of RV is improved after coating with HSA and PEG. Confocal fluorescence images show that HRP-RGD NPs have the highest cellular uptake ratio of 47.3 ± 4.6% compared to HRP NPs and HRP-RGD NPs with free RGD blocking, attributing to an RGD-mediated effect. A cell counting kit-8 (CCK-8) assay indicates that HRP-RGD NPs without RV (HP-RGD NPs) have nearly no cytotoxicity, but HRP-RGD NPs are significantly more cytotoxic to PANC-1 cells compared to free RV and HRP NPs in a concentration dependent manner, showing apoptotic morphology. Furthermore, with a formulated PEG and HSA coating, HRP-RGD NPs prolong the blood circulation of RV, increasing approximately 5.43-fold (t1/2). After intravenous injection into tumor-bearing mice, the content of HRP-RGD NPs in tumor tissue was proven to be approximately 3.01- and 8.1-fold higher than that of HRP NPs and free RV, respectively. Based on these results, HRP-RGD NPs were used in an in vivo anti-cancer study and demonstrated the best tumor growth suppression effect of all tested drugs with no relapse, high in vivo biocompatibility, and no significant systemic toxicity over 35 days treatment. These results demonstrate that HRP-RGD NPs with prolonged blood circulation and improved biocompatibility have high anti-cancer effects with promising future applications in cancer therapy.

Curcumin, A Potential Therapeutic Candidate for Anterior Segment Eye Diseases: A Review

Curcumin, the major curcuminoid of the turmeric, has been extensively used in many countries since ancient time for preventing and/or treating a multitude of diseases. This review is to illustrate the researches on the properties of curcumin and its potential therapeutic efficacy in major anterior segment eye diseases. The bio-medical potential of curcumin is restricted because of its low solubility and digestive bioavailability. This review will discuss promising research in improving curcumin bioavailability through structural modification. In vitro and in vivo research made progress in studying the beneficial effects of curcumin on major anterior segment eye diseases, including anti-angiogenesis effect in corneal diseases; anti-inflammation or anti-allergy effects in dry eye disease, conjunctivitis, anterior uveitis; anti-proliferation and pro-apoptosis effects in pterygium; anti-oxidative stress, anti-osmotic stress, anti-lipid peroxidation, pro-apoptosis, regulating calcium homeostasis, sequestrating free radicals, protein modification and degradation effects in cataracts; neuroprotective effects in glaucoma. Curcumin exhibited to be a potent therapeutic candidate for treating those anterior segment eye diseases.

β-Caryophyllene/Hydroxypropyl-β-Cyclodextrin Inclusion Complex Improves Cognitive Deficits in Rats with Vascular Dementia through the Cannabinoid Receptor Type 2 -Mediated Pathway

This work was conducted to prepare β-caryophyllene-hydroxypropyl-β-cyclodextrin inclusion complex (HPβCD/BCP) and investigate its effects and mechanisms on cognitive deficits in vascular dementia (VD) rats. First, HPβCD/BCP was prepared, optimized, characterized, and evaluated. HPβCD/BCP and AM630 were then administered to VD rats to upregulate and downregulate the cannabinoid receptor type 2 (CB2). Results showed that HPβCD/BCP can significantly increase the bioavailability of BCP. Through the Morris water maze test, HPβCD/BCP can attenuate learning and memory deficits in rats. Cerebral blood flow (CBF) monitoring results indicated that HPβCD/BCP can promote the recovery of CBF. Moreover, molecular biology experiments showed that HPβCD/BCP can increase the expression levels of CB2 in brain tissues, particularly the hippocampus and white matter tissues, as well as the expression levels of PI3K and Akt. Overall, the findings demonstrated the protective effects of HPβCD/BCP against cognitive deficits induced by chronic cerebral ischemia and suggested the potential of HPβCD/BCP in the therapy of vascular dementia in the future.

Thermosensitive hydrogel based on chitosan and its derivatives containing medicated nanoparticles for transcorneal administration of 5-fluorouracil

A thermosensitive ophthalmic hydrogel (TSOH) – fluid at 4°C (instillation temperature), semisolid at 35°C (eye temperature), which coupled the dosing accuracy and administration ease of eyedrops with the increased ocular bioavailability of a hydrogel – was prepared by gelling a chitosan hydrochloride (ChHCl) solution (27.8 mg/mL) medicated with 1.25 mg/mL 5-fluorouracil (5-FU) with β-glycerophosphate 0.8 mg/mL. Polymer mixtures, where Ch was partially (10%, 15%, or 20%) replaced by quaternary ammonium–chitosan conjugates (QA-Ch) or thiolated derivatives thereof, were also used to modulate 5-FU-release properties of TSOH. Also, Ch-based nanoparticles (NPs; size after lyophilization and redispersion 341.5±15.2 nm, polydispersity 0.315±0.45, ζ-potential 10.21 mV) medicated with 1.25 mg/mL 5-FU prepared by ionotropic cross-linking of Ch with hyaluronan were introduced into TSOH. The 5-FU binding by TSOH polymers in the sol state was maximum with plain Ch (31.4%) and tended to decrease with increasing QA presence in polymer mixture. 5-FU release from TSOH with or without NPs was diffusion-controlled and linear in √t. The different TSOH polymers were compared on a diffusivity basis by comparing the slopes of √t plots. These showed a general decrease with NP-containing TSOH, which was the most marked with the TSOH, where Ch was 20% replaced by the derivative QA-Ch50. This formulation and that not containing NP were instilled in rabbits and the 5-FU transcorneal penetration was measured by analyzing the aqueous humor. Both TSOH solutions increased the area under the curve (0–8 hours) 3.5 times compared with the plain eyedrops, but maximum concentration for the NP-free TSOH was about 0.65 µg/mL, followed by a slow decline, while the NP-containing one showed a plateau (0.25–0.3 µg/mL) in a time interval of 0.5–7 hours. This is ascribed to the ability of this TSOH to control drug release to a zero order and that of NPs to be internalized by corneal cells.

Novel multifunctional pH-sensitive nanoparticles loaded into microbubbles as drug delivery vehicles for enhanced tumor targeting

This study fabricated novel multifunctional pH-sensitive nanoparticles loaded into microbubbles (PNP-MB) with the combined advantages of two excellent drug delivery vehicles, namely, pH-sensitive nanoparticles and microbubbles. As an antitumor drug, resveratrol (RES) was loaded into acetylated β-cyclodextrin nanoparticles (RES-PNP). The drug-loaded nanoparticles were then encapsulated into the internal space of the microbubbles. The characterization and morphology of this vehicle were investigated through dynamic light scattering and confocal laser scanning microscopy, respectively. In vitro drug release was performed to investigate the pH sensitivity of RES-PNP. The antitumor property of RES-loaded PNP-MB (RES-PNP-MB) was also analyzed in vivo to evaluate the antitumor effect of RES-PNP-MB. Results suggested that PNP exhibited pH sensitivity, and was successfully encapsulated into the microbubbles. RES-PNP-MB exhibit effective tumor growth suppressing in vivo. Therefore, such drug delivery vehicle should be of great attention in tumor therapy.

Application of albumin-based nanoparticles in the management of cancer

Over the past three decades, tremendous progress has been made in cancer prevention and treatment. Despite these advances, a substantial number of cancer cases experience early recurrence and metastases. Thus, the better management of cancer, especially developing more effective drugs for combating cancer cells, is an arduous task. Albumin-based nanoparticles are emerging as a promising approach to replace the traditional way of carrying therapeutic drugs to a tumor site. In this review, we describe the basic knowledge on albumin-based nanoparticles, recent progress of using albumin-based nanoparticles in the diagnosis and treatment of cancer, and the application of nanoparticle albumin bound (Nab) paclitaxel for the treatment of lung, breast and pancreatic cancer. Last but not least, we try to discuss future goals and perspectives in the field of drug delivery research, thereby facilitating the antitumor activity.

Therapeutic Applications of Curcumin Nanoformulations

Curcumin (diferuloylmethane) is a bioactive and major phenolic component of turmeric derived from the rhizomes of curcuma longa linn. For centuries, curcumin has exhibited excellent therapeutic benefits in various diseases. Owing to its anti-oxidant and anti-inflammatory properties, curcumin plays a significant beneficial and pleiotropic regulatory role in various pathological conditions including cancer, cardiovascular disease, Alzheimer's disease, inflammatory disorders, neurological disorders, and so on. Despite such phenomenal advances in medicinal applications, the clinical implication of native curcumin is hindered due to low solubility, physico-chemical instability, poor bioavailability, rapid metabolism, and poor pharmacokinetics. However, these issues can be overcome by utilizing an efficient delivery system. Active scientific research was initiated in 2005 to improve curcumin's pharmacokinetics, systemic bioavailability, and biological activity by encapsulating or by loading curcumin into nanoform(s) (nanoformulations). A significant number of nanoformulations exist that can be translated toward medicinal use upon successful completion of pre-clinical and human clinical trials. Considering this perspective, current review provides an overview of an efficient curcumin nanoformulation for a targeted therapeutic option for various human diseases. In this review article, we discuss the clinical evidence, current status, and future opportunities of curcumin nanoformulation(s) in the field of medicine. In addition, this review presents a concise summary of the actions required to develop curcumin nanoformulations as pharmaceutical or nutraceutical candidates.

Synthesis, characterization, and in vitro evaluation of curcumin-loaded albumin nanoparticles surface-functionalized with glycyrrhetinic acid

We have designed and developed curcumin (Ccn)-loaded albumin nanoparticles (BNPs) surface-functionalized with glycyrrhetinic acid (Ccn-BNP-GA) for GA receptor-mediated targeting. Ccn-BNP-GA was prepared by conjugating GA as a hepatoma cell-specific binding molecule onto the surface of BNPs. Ccn-BNP-GA showed a narrow distribution with an average size of 258.8±6.4 nm, a regularly spherical shape, an entrapment efficiency of 88.55%±5.54%, and drug loading of 25.30%±1.58%. The density of GA as the ligand conjugated to BNPs was 140.48±2.784 μg/g bovine serum albumin. Cytotoxicity assay results indicated that Ccn-BNP-GA was significantly more cytotoxic to HepG2 cells and in a concentration-dependent manner. Ccn-BNP-GA also appeared to be taken up to a greater extent by HepG2 cells than undecorated groups, which might be due to the high affinity of GA for GA receptors on the HepG2 cell surface. These cytotoxicity assay results were corroborated by analysis of cell apoptosis and the cell cycle. Further, Ccn-BNP-GA showed an approximately twofold higher rate of cell apoptosis than the other groups. Moreover, proliferation of HepG2 cells was arrested in G₂/M phase based on cell cycle analysis. These results, which were supported by the GA receptor-mediated endocytosis mechanism, indicate that BNPs surface-functionalized with GA could be used in targeted cancer treatment with high efficacy, sufficient targeting, and reduced toxicity.

Curcumin Inhibits Neuronal Loss in the Retina and Elevates Ca²⁺/Calmodulin-Dependent Protein Kinase II Activity in Diabetic Rats

PURPOSE

To determine whether curcumin offers neuroprotection to minimize the apoptosis of neural cells in the retina of diabetic rats.

METHODS

Streptozotocin (STZ)-induced diabetic rats and control rats were used in this study. A subgroup of STZ-induced diabetic rats were treated with curcumin for 12 weeks. Retinal histology, apoptosis of neural cells in the retina, electroretinograms, and retinal glutamate content were evaluated after 12 weeks. Retinal levels of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), phospho-CaMKII (p-CaMKII), and cleaved caspase-3 were determined by Western blot analysis.

RESULTS

The amplitudes a-wave, b-wave, and oscillatory potential were reduced by diabetes, but curcumin treatment suppressed this reduction of amplitudes. Curcumin also prevented cell loss from the outer nuclear, inner nuclear, and ganglion cell layers. Apoptosis of retinal neurons was detected in diabetic rats. The concentration of glutamate in the retina was higher in diabetic rats, but was significantly reduced in the curcumin-treated group. Furthermore, p-CaMKII and cleaved caspase-3 expression were upregulated in the diabetic retina, but reduced in curcumin-treated rats.

CONCLUSIONS

Curcumin attenuated diabetes-induced apoptosis in retinal neurons by reducing the glutamate level and downregulating CaMKII. Thus, curcumin might be used to prevent neuronal damage in the retina of patients with diabetes mellitus.