Melatonin-loaded silica coated with hydroxypropyl methylcellulose phthalate for enhanced oral bioavailability: Preparation, and in vitro-in vivo evaluation

Nanosilicon-based vermicompost leachate and Trichoderma harzianum promote the growth of Panax quinquefolius L. cultivated under forests by improving soil enzyme activity

Planting vegetation under forests in agroforestry systems fosters sustainable agricultural development. However, Limited availability of biostimulants for agroforestry and unclear mechanisms of plant growth promotion. This study synthesized and evaluated a novel biostimulant, nanosilicon-based vermicompost leachate (NSVCL), using Panax quinquefolius L. as the research plant species for forest cultivation. Trichoderma harzianum (TH) was chosen to represent a biostimulant with broad-spectrum properties, and its application effects were compared with NSVCL. The regulatory effects of both on the physiological characteristics and rhizosphere soil microenvironment of P. quinquefolius were investigated, with untreated plants serving as controls. Compared to the control, NSVCL and TH increased the dry weight of P. quinquefolius roots 129.33 % and 23.50 %, respectively. NSVCL was applied more effectively than TH. Additionally, NSVCL markedly improved leaf anatomical traits, including palisade and spongy tissue thickness, overall leaf thickness, chloroplast number, and cuticle thickness. Application of NSVCL and TH significantly elevated the net photosynthetic rate (Pn) by 86.55 % and 60.92 %, respectively, and increased total chlorophyll content (TChl) by 24.91 % and 11.76 %. Biostimulants facilitated nutrient uptake and boosted antioxidant enzyme activity in P. quinquefolius. Partial least squares path modeling (PLS-PM) further demonstrated that both NSVCL and TH promoted plant growth by enhancing soil enzyme activity in forest environments. These findings underscore NSVCL's efficacy in improving P. quinquefolius growth under forest conditions and provide a practical foundation for advancing organic forest cultivation and sustainable forest-medicine integration.

Discovering the anti-parasitic activity of melatonin loaded lecithin/chitosan nanoparticles against giardiasis and cryptosporidiosis in Balb/c infected mice

Background

Giardia duodenalis and Cryptosporidium parvum are the primary causes of diarrhea with global attention due to the severe pathophysiological changes leading to mortality. During this study, we explored the biological protozoal contaminants (Giardia and Cryptosporidium spp.) in some areas of the Nile River. Then, we evaluated effectiveness of melatonin (Mel) and melatonin loaded lecithin/chitosan nanoparticles (Mel-LCNPs) against giardiasis and cryptosporidiosis in mice models using parasitological and inflammatory response examination.

Results

The number of positive samples for Cryptosporidium was higher than that for Giardia with percentage of 46.67% and 40.0%, respectively. Prior to treatment, the physical characterization (hydrodynamic size and zeta potential) and in vitro characterization of Mel-LCNPs were carried. Mel-LCNPs revealed a hydrodynamic size of 78.8 nm and a zeta potential of − 27.2 mV. Furthermore, they have powerful antioxidant and anti-inflammatory properties, while displaying minimal anticoagulant and cytotoxic effects during in vivo evaluation. Mel was consistently discharged from nanoparticles in a regulated and enduring manner for 36 h. Moreover, Mel in NPs has an entrapment efficiency (EE) of 33.6% and a drug loading capacity (DLC) of 7.2% and significant reduction (100% and 99.4%, respectively) in the shedding of Giardia cysts and Cryptosporidium oocysts. This reduction was higher than that observed with Mel alone or LCNPs alone on the 14th day post-infection. Moreover, mice of group V, which received Mel-LCNP treatment, exhibited significantly normal levels of interleukin-4 (IL-4) and interferon-gamma (IFN-γ) as well as healthy control mice group (group I).

Conclusion

Mel-LCNPs were highly effective preparations against giardiasis and cryptosporidiosis in Balb/c mice experimentally infected with proved antioxidant, anti-inflammatory, and immunological modulatory characteristics.

Unveiling the synergy: a combined experimental and theoretical study of β-cyclodextrin with melatonin

Melatonin (MT) is a vital hormone controlling biorhythms, and optimizing its release in the human body is crucial. To address MT's unfavorable pharmacokinetics, we explored the inclusion complexes of MT with β-cyclodextrin (β-CD). Nano spray drying was applied to efficiently synthesize these complexes in three molar ratios (MT : β-CD = 1 : 1, 2 : 1, and 1 : 2), reducing reagent use and expediting inclusion. The complex powders were characterized through thermal analyses (TGA and DSC), Fourier transform infrared spectroscopy (FTIR), and in vitro MT release measurements via high-performance liquid chromatography (HPLC). In parallel, computational studies were conducted, examining the stability of MT : β-CD complexes by means of unbiased semi-empirical conformational searches refined by DFT, which produced a distribution of MT : β-CD binding enthalpies. Computational findings highlighted that these complexes are stabilized by specific hydrogen bonds and non-specific dispersive forces, with stronger binding in the 1 : 1 complex, which was corroborated by in vitro release data. Furthermore, the alignment between simulated and experimental FTIR spectra demonstrated the quality of both the structural model and computational methodology, which was crucial to enhance our comprehension of optimizing MT's release for therapeutic applications.

Melatonin Derivative-Conjugated Formulations of Pd(II) and Pt(II) Thiazoline Complexes on Mesoporous Silica to Enhance Cytotoxicity and Apoptosis against HeLa Cells

The search for alternatives to cisplatin has led to the development of new metal complexes where thiazoline derivatives based on platinum(II) and palladium(II) stand out. In this sense, the Pt(II) and Pd(II) complexes coordinated with the thiazoline derivative ligand 2-(3,4-dichlorophenyl)imino-N-(2-thiazolin-2-yl)thiazolidine (TdTn), with formula [PtCl2(TdTn)] and [PdCl2(TdTn)], have previously shown good results against several cancer lines; however, in this work, we have managed to improve their activity by supporting them on mesoporous silica nanoparticles (MSN). The incorporation of metal compounds with a melatonin derivative (5-methoxytryptamine, 5MT), which is a well-known antioxidant and apoptosis inducer in different types of cancer, has been able to increase the cytotoxic activity of both MSN-supported and isolated complexes with only a very low amount (0.35% w/w) of this antioxidant. The covalently functionalized systems that have been synthesized are able to increase selectivity as well as accumulation in HeLa cells. The final materials containing the metal complexes and 5MT (MSN-5MT-PtTdTn and MSN-5MT-PdTdTn) required up to nine times less metal to achieve the same cytotoxic activity than their corresponding non-formulated counterparts did, thus reducing the potential side effects caused by the use of the free metal complexes.

Melatonin delivered in solid lipid nanoparticles ameliorated its neuroprotective effects in cerebral ischemia

The current study explores the potential of melatonin (MLT)-loaded solid lipid nanoparticles (MLT-SLNs) for better neuroprotective effects in ischemic stroke. MLT-SLNs were prepared using lipid matrix of palmityl alcohol with a mixture of surfactants (Tween 40, Span 40, Myrj 52) for stabilizing the lipid matrix. MLT-SLNs were tested for physical and chemical properties, thermal and polymorphic changes, in vitro drug release and in vivo neuroprotective studies in rats using permanent middle cerebral artery occlusion (p-MCAO) model. The optimized MLT-SLNs showed particle size of ∼159 nm, zeta potential of -29.6 mV and high entrapment efficiency ∼92%. Thermal and polymorphic studies showed conversion of crystalline MLT to amorphous form after its entrapment in lipid matrix. MLT-SLNs displayed a sustained release pattern compared to MLT dispersion. MLT-SLNs significantly enhanced the neuroprotective profile of MLT ascertained by reduced brain infarction, recovered behavioral responses, low expression of inflammatory markers and improved oxidation protection in rats. MLT-SLNs also showed reduced hepatotoxicity compared to p-MCAO. From these outcomes, it is evidenced that MLT-SLNs have improved neuroprotection as compared to MLT dispersion and thereby present a promising approach to deliver MLT to the brain for better therapeutic outcomes in ischemic stroke.

The impact of H/D exchange on the thermal and structural properties as well as high-pressure relaxation dynamics of melatonin

In this paper, thermal properties, atomic-scale structure, and molecular dynamics (at ambient and high pressure) of native melatonin (MLT) and its partially-deuterated derivative (MLT-d₂) have been investigated. Based on infrared spectroscopy, it was shown that treating MLT with D₂O causes the replacement of hydrogen atoms attached to the nitrogen by deuterium. The degree of such substitution was very high (> 99%) and the deuterated sample remained stable after exposure to the air as well as during the melting and vitrification processes. Further calorimetric studies revealed the appearance of a peculiar thermal event before the melting of crystalline MLT-d₂, which was assigned by the X-ray diffraction to a local negative thermal expansion of the unit cell. Finally, the high-pressure dielectric experiments indicated a few interesting findings, including the variation in the shape of the structural relaxation peak during compression, the difference in the pressure evolution of the glass transition temperature, and the temperature dependence of activation volume for both MLT species. The variations in these parameters manifest a different impact of the compression/densification on the dynamics of hydrogen and deuterium bonds in the native and partially-deuterated MLT, respectively.

Solid dispersions based on chitosan/hypromellose phthalate blends to modulate pharmaceutical properties of zidovudine

Zidovudine (AZT) has been widely used alone or in combination with other antiretroviral drugs for the treatment of human immunodeficiency virus. Its erratic oral bioavailability necessitates frequent administration of high doses, resulting in severe side effects. In this study, the design of mucoadhesive solid dispersions (SDs) based on chitosan (CS) and hypromellose phthalate (HP) was rationalized as a potential approach to modulate AZT physicochemical and pharmaceutical properties. SDs were prepared at different drug:polymer ratios, using an eco-friendly technique, which avoids the use of organic solvents. Particles with diameter from 56 to 73 µm and negative zeta potentials (-27 to -32 mV) were successfully prepared, achieving high drug content. Infrared spectroscopy revealed interactions between polymers but no interactions between the polymers and AZT. Calorimetry and X-ray diffraction analyses showed that AZT was amorphized into the SDs. The mucoadhesive properties of SDs were evidenced, and the control of AZT release rates from the matrix was achieved, mainly in acid media. The simple, low-cost and scalable technology proposed for production of SDs as a carrier platform for AZT is an innovative approach, and it proved to be a feasible strategy for modulation the physico-chemical, mucoadhesive and release properties of the drug.

Enhanced anti-angiogenic activity of novel melatonin-like agents

Hypoxia-inducible factor-1 (HIF-1) plays an important role in cellular responses to hypoxia, including the transcriptional activation of several genes involved in tumor angiogenesis. Melatonin, also known as N-acetyl-5-methopxytryptamine, is produced naturally by the pineal gland and has anti-angiogenic effects in cancer through its ability to modulate HIF-1α activity. However, the use of melatonin as a therapeutic is limited by its low oral bioavailability and short half-life. Here, we synthesized melatonin-like molecules with enhanced HIF-1α targeting activity and less toxicity and investigated their effects on tumor growth and angiogenesis, as well as the underlying molecular mechanisms. Among melatonin derivatives, N-butyryl-5-methoxytryptamine (NB-5-MT) showed the most potent HIF-1α targeting activity. This molecule was able to (a) reduce the expression of HIF-1α at the protein level, (b) reduce the transcription of HIF-1α target genes, (c) reduce reactive oxygen species (ROS) generation, (d) decrease angiogenesis in vitro and in vivo, and (e) suppress tumor size and metastasis. In addition, NB-5-MT showed improved anti-angiogenic activity compared with melatonin due to its enhanced cellular uptake. NB-5-MT is thus a promising lead for the future development of anticancer compounds with HIF-1α targeting activity. Given that HIF-1α is overexpressed in the majority of human cancers, the melatonin derivative NB-5-MT could represent a novel potent therapeutic agent for cancer.

Melatonin-Loaded Nanocarriers: New Horizons for Therapeutic Applications

The use of nanosized particles has emerged to facilitate selective applications in medicine. Drug-delivery systems represent novel opportunities to provide stricter, focused, and fine-tuned therapy, enhancing the therapeutic efficacy of chemical agents at the molecular level while reducing their toxic effects. Melatonin (N-acetyl-5-methoxytriptamine) is a small indoleamine secreted essentially by the pineal gland during darkness, but also produced by most cells in a non-circadian manner from which it is not released into the blood. Although the therapeutic promise of melatonin is indisputable, aspects regarding optimal dosage, biotransformation and metabolism, route and time of administration, and targeted therapy remain to be examined for proper treatment results. Recently, prolonged release of melatonin has shown greater efficacy and safety when combined with a nanostructured formulation. This review summarizes the role of melatonin incorporated into different nanocarriers (e.g., lipid-based vesicles, polymeric vesicles, non-ionic surfactant-based vesicles, charge carriers in graphene, electro spun nanofibers, silica-based carriers, metallic and non-metallic nanocomposites) as drug delivery system platforms or multilevel determinations in various in vivo and in vitro experimental conditions. Melatonin incorporated into nanosized materials exhibits superior effectiveness in multiple diseases and pathological processes than does free melatonin; thus, such information has functional significance for clinical intervention.

Melatonin in Cancer Treatment: Current Knowledge and Future Opportunities

Melatonin is a pleotropic molecule with numerous biological activities. Epidemiological and experimental studies have documented that melatonin could inhibit different types of cancer in vitro and in vivo. Results showed the involvement of melatonin in different anticancer mechanisms including apoptosis induction, cell proliferation inhibition, reduction in tumor growth and metastases, reduction in the side effects associated with chemotherapy and radiotherapy, decreasing drug resistance in cancer therapy, and augmentation of the therapeutic effects of conventional anticancer therapies. Clinical trials revealed that melatonin is an effective adjuvant drug to all conventional therapies. This review summarized melatonin biosynthesis, availability from natural sources, metabolism, bioavailability, anticancer mechanisms of melatonin, its use in clinical trials, and pharmaceutical formulation. Studies discussed in this review will provide a solid foundation for researchers and physicians to design and develop new therapies to treat and prevent cancer using melatonin.

Toxicology of Blister Agents: Is Melatonin a Potential Therapeutic Option?

Blister or vesicant chemical warfare agents (CWAs) have been widely used in different military conflicts, including World War I and the Iran-Iraq War. However, their mechanism of action is not fully understood. Sulfur and nitrogen mustard exert toxic effects not only through the alkylation of thiol-bearing macromolecules, such as DNA and proteins, but also produce free radicals that can develop direct toxic effects in target organs such as the eyes, skin, and respiratory system. The lack of effective treatments against vesicant CWAs-induced injury makes us consider, in this complex scenario, the use and development of melatonin-based therapeutic strategies. This multifunctional indoleamine could facilitate neutralization of the oxidative stress, modulate the inflammatory response, and prevent the DNA damage, as well as the long-term health consequences mediated by vesicant CWAs-induced epigenetic mechanisms. In this context, it would be essential to develop new galenic formulations for the use of orally and/or topically applied melatonin for the prophylaxis against vesicant CWAs, as well as the development of post-exposure treatments in the near future.

Computational and experimental approaches for chitosan-based nano PECs design: Insights on a deeper comprehension of nanostructure formation

Nanostructured polyelectrolyte complexes (nano PECs) based on biopolymers are an important technological strategy to target drugs to the action and/or absorption site in a more effective way. In this work, computational studies were performed to predict the ionization, spatial arrangement and interaction energies of chitosan (CS), hyaluronic acid (HA), and hypromellose phthalate (HP), for the design of nano PEC carriers for methotrexate (MTX). The optimal pH range (5.0-5.5) for preparing nano PECs was selected by experimental and computational methodologies, favoring the polymers interactions. CS, HA, HP and MTX addition order was also rationalized, maximizing their interactions and MTX entrapment. Spherical nano-sized particles (256-575 nm, by dynamic light scattering measurement) with positive surface charge (+25.5 to +29.2 mV) were successfully prepared. The MTX association efficiency ranged from 20 to 32 %. XRD analyses evidenced the formation of a new material with an organized structure, in relation to raw polymers.

Endogenous Antioxidant Cocktail Loaded Hydrogel for Topical Wound Healing of Burns

The main goal of this work is the study of the skin wound healing efficacy of an antioxidant cocktail consisting of vitamins A, D, E and the endogenous pineal hormone melatonin (MLT), with all of these loaded into a thermosensitive hydrogel delivery system. The resulting formulation was characterized by scanning electron microscopy. The antioxidant efficacy and microbiological activity against Gram positive and Gram negative strains were also assayed. The skin healing efficacy was tested using an in vivo model which included histological evaluation. Furthermore, atomic force microscopy was employed to evaluate the wound healing efficacy of rat skin burns through the determination of its elasticity at the nanoscale using force spectroscopy analysis. The resulting hydrogel exhibited sol state at low temperature and turned into a gel at 30 ± 0.2 °C. The hydrogel containing the antioxidant cocktail showed higher scavenging activity than the hydrogel containing vitamins or MLT, separately. The formulation showed optimal antimicrobial activity. It was comparable to a commercial reference. It was also evidenced that the hydrogel containing the antioxidant cocktail exhibited the strongest healing process in the skin burns of rats, similar to the assayed commercial reference containing silver sulfadiazine. Histological studies confirmed the observed results. Finally, atomic force microscopy demonstrated a similar distribution of Young's modulus values between burned skin treated with the commercial reference and burned skin treated with hydrogel containing the antioxidant cocktail, and all these with healthy skin. The use of an antioxidant cocktail of vitamins and MLT might be a promising treatment for skin wounds for future clinical studies.

Nose-to-Brain Delivery of Antioxidants as a Potential Tool for the Therapy of Neurological Diseases

Oxidative stress has a key role in the pathogenesis of neurodegenerative disorders such as Alzheimer's, Parkinson's, and Huntington's diseases and can be an important cause of the damages in cerebral ischemia. Oxidative stress arises from high levels of reactive oxygen species (ROS). Consequently, on this rational base, antioxidants (many of natural origin) are proposed as potential drugs to prevent ROS noxious actions because they can protect the target tissues from the oxidative stress. However, the potential of antioxidants is limited, owing to the presence of the blood-brain barrier (BBB), which is difficult to cross with a consequent low bioavailability of the drug into the brain after systemic (intravenous, intraperitoneal, oral) administrations. One strategy to improve the delivery of antioxidants to the brain involves the use of the so-called nose-to-brain route, with the administration of the antioxidant in specific nasal formulations and its passage to the central nervous system (CNS) mainly through the olfactory nerve way. In the current literature, many examples show encouraging results in studies carried out in cell cultures and in animal models about the potential neuroprotective effects of antioxidants when administered through the nose. This review concerns the nose-to-brain route for the brain targeting of antioxidants as a potential tool for the therapy of neurological diseases.

A possible use of melatonin in the dental field: Protein adsorption and in vitro cell response on coated titanium

Melatonin (MLT) is widely known for regulating the circadian cycles and has been studied for its role in bone regeneration and inflammation. Its application as a coating for dental implants can condition the local microenvironment, affecting protein deposition on its surface and the cellular and tissue response. Using sol-gel coatings as a release vehicle for MLT, the aim of this work was to assess the potential of this molecule in improving the osseointegration and inflammatory responses of a titanium substrate. The materials obtained were physicochemically characterized (scanning electron microscopy, contact angle, roughness, Fourier-transform infrared spectroscopy, nuclear magnetic resonance, Si release, MLT liberation, and degradation) and studied in vitro with MC3T3-E1 osteoblastic cells and RAW264.7 macrophage cells. Although MLT application led to an increased gene expression of RUNX2 and BMP2 in 10MTL, it did not improve ALP activity. On the other hand, MLT-enriched sol-gel materials presented potential effects in the adsorption of proteins related to inflammation, coagulation and angiogenesis pathways depending on the dosage used. Using LC-MS/MS, protein adsorption patterns were studied after incubation with human serum. Proteins related to the complement systems (CO7, IC1, CO5, CO8A, and CO9) were less adsorbed in materials with MLT; on the other hand, proteins with functions in the coagulation and angiogenesis pathways, such as A2GL and PLMN, showed a significant adsorption pattern.

Hypromellose - A traditional pharmaceutical excipient with modern applications in oral and oromucosal drug delivery

Hydroxypropylmethylcellulose (HPMC), also known as Hypromellose, is a traditional pharmaceutical excipient widely exploited in oral sustained drug release matrix systems. The choice of numerous viscosity grades and molecular weights available from different manufacturers provides a great variability in its physical-chemical properties and is a basis for its broad successful application in pharmaceutical research, development, and manufacturing. The excellent mucoadhesive properties of HPMC predetermine its use in oromucosal delivery systems including mucoadhesive tablets and films. HPMC also possesses desirable properties for formulating amorphous solid dispersions increasing the oral bioavailability of poorly soluble drugs. Printability and electrospinnability of HPMC are promising features for its application in 3D printed drug products and nanofiber-based drug delivery systems. Nanoparticle-based formulations are extensively explored as antigen and protein carriers for the formulation of oral vaccines, and oral delivery of biologicals including insulin, respectively. HPMC, being a traditional pharmaceutical excipient, has an irreplaceable role in the development of new pharmaceutical technologies, and new drug products leading to continuous manufacturing processes, and personalized medicine. This review firstly provides information on the physical-chemical properties of HPMC and a comprehensive overview of its application in traditional oral drug formulations. Secondly, this review focuses on the application of HPMC in modern pharmaceutical technologies including spray drying, hot-melt extrusion, 3D printing, nanoprecipitation and electrospinning leading to the formulation of printlets, nanoparticle-, microparticle-, and nanofiber-based delivery systems for oral and oromucosal application. Hypromellose is an excellent excipient for formulation of classical dosage forms and advanced drug delivery systems. New methods of hypromellose processing include spray draying, hot-melt extrusion, 3D printing, and electrospinning.

Melatonin-Loaded Nanoparticles for Enhanced Antidepressant Effects and HPA Hormone Modulation

Background. The present work aims at formulating the melatonin-loaded nanoparticles (MTNPs) exhibiting the controlled-release and pH-sensitivity to repurpose the use of melatonin in the treatment of depressive-like behaviors and hypothalamus-pituitary-adrenal (HPA) axis dysregulation.Methods. MTNPs were characterized for the size, drug incorporation, andin vitrorelease in the different pH environments. Its merits werein vivotested on the pinealectomized rats presenting the depressive-like behaviors and the abnormal HPA axis activity by calculating the improvement on saccharin preference, swimming immobility time, and the negative feedback of HPA axis.Results. Results revealed that MTNPs showed nanometer size, 15.77% of drug loading, 33.82% of encapsulation efficiency, the different controlled-release profiles in different pH environments (pH 1.2, pH 6.8, and pH 7.4), more sensitivity release in simulated intestinal fluid (pH 7.4) and blood (pH 6.8), and less sensitivity release in simulated gastric fluid (pH 1.2). Furthermore, MTNPs displayed better antidepressant actions in reducing the immobility time of forced swimming test, increasing the preference for saccharin, and sensitizing the blunt negative feedback of HPA axis, when compared to the free melatonin.Conclusions. The controlled-release nanoparticles is shown to be an effective improvement on the dosage form for melatonin, which is worthy of futuristic and complete evaluation.

Synthesis of a New Water-Soluble Melatonin Derivative with Low Toxicity and a Strong Effect on Sleep Aid

A new melatonin sulfonate derivative sodium 4-(3-(2-acetamidoethyl)-5-methoxy-1H-indol-1-yl) butane-1-sulfonate (MLTBS) with higher water solubility (695 times) and lower cytotoxicity than natural melatonin (MLT) was synthesized, yet with the same sleep aid function. The poor solubility of MLT in water has been improved with a simple chemical reaction, which solves the poor solubility of melatonin in water, overcoming the safety problem caused by adding organic reagents such as dimethyl sulfoxide (DMSO) and ethanol to increase the solubility. Moreover, the modified MLT still has the same sleep aid effect as the natural MLT and higher biological safety. As a novel potential drug for sleep aid, the new MLT derivative could also flourish the application and research of this molecule in medicine and biology.

PK-PD based optimal dose and time for orally administered supra-pharmacological dose of melatonin to prevent radiation induced mortality in mice

AIMS

The study reports preclinical pharmacokinetics (PK) and correlation with pharmacological effect at suprapharmacological dose of orally administered melatonin along with time and dose optimization, which have been lacking in earlier reports of radioprotection using melatonin.

METHODS

PK of melatonin in C57BL/6 mice was evaluated after dose of 250 mg/kg using HPLC. Tissue distribution study was conducted in vital organs following oral administration. Plasma total antioxidant capacity (TAC) was determined by ABTS⁺ radical assay and was correlated to plasma concentrations of melatonin. Using the outcomes of PK and Pharmacodynamics (PD), survival study was conducted for optimization of 'drug radiation gap period' (DRGP). Optimal oral dose for radioprotection was determined using survival as an end point.

KEY FINDINGS

PK analysis of melatonin revealed T_max at 5 min with closely spaced another distinct concentration peak at 20 min. Plasma TAC of melatonin showed similar peaks at 5 min and 45 min, with the highest TAC at 45 min. Survival following a lethal (9 Gy) radiation dose was 20% and 40% after 5 and 45 min of melatonin administration, respectively. DRGP for melatonin was thus 45 min, while optimal oral dose ranged from 125 to 250 mg/kg. PK parameters at 250 mg/kg dose were qualitatively similar to low dose of melatonin, thus preventing chances of unexpected toxicity.

SIGNIFICANCE

Survival enhancement at 45 min suggested as probable interval required as 'DRGP'. The optimum oral therapeutic window appears large with no substantial toxicity. The outcomes will be useful in development of radioprotectors as well as other therapeutic applications.

Melatonin loaded with bacterial cellulose nanofiber by Pickering-emulsion solvent evaporation for enhanced dissolution and bioavailability

The objective of the present work aimed to explore the potential of bacterial cellulose (BC) for oral delivery of melatonin (MLT), a natural hormone that faces problems of low solubility and oral bioavailability. BC was hydrolyzed by sulfuric acid followed by the oxidation to prepare bacterial cellulose nanofiber suspension (BCNs). Melatonin-loaded bacterial cellulose nanofiber suspension (MLT-BCNs) was prepared by emulsion solvent evaporation method. The properties of freeze-dried BCs and MLT-BCNs were studied by Fluorescence microscopy (FM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermo gravimetric (TG). The results indicated that the fibers in BCNs became short and thin compared with BC, MLT in MLT-BCNs was uniformly distributed, both BCNs and MLT-BCNs have good thermodynamic stability. The MLT-BCNs showed more rapid dissolution MLT rates compared to the commercially available MLT in SGF and SIF, the dissolution of the cumulative release rate was about 2.1 times of the commercially available MLT. The oral bioavailability of MLT-BCNs in rat was about 2.4 times higher than the commercially available MLT. Thus, MLT-BCNs could act as promising delivery with enhanced dissolution and bioavailability for MLT after oral administration.

Melatonin May Increase Anticancer Potential of Pleiotropic Drugs

Melatonin (N-acetyl-5-methoxytryptamine) is not only a pineal hormone, but also an ubiquitary molecule present in plants and part of our diet. Numerous preclinical and some clinical reports pointed to its multiple beneficial effects including oncostatic properties, and as such, it has become one of the most aspiring goals in cancer prevention/therapy. A link between cancer and inflammation and/or metabolic disorders has been well established and the therapy of these conditions with so-called pleiotropic drugs, which include non-steroidal anti-inflammatory drugs, statins and peroral antidiabetics, modulates a cancer risk too. Adjuvant therapy with melatonin may improve the oncostatic potential of these drugs. Results from preclinical studies are limited though support this hypothesis, which, however, remains to be verified by further research.

Poly(Lactide-Co-Glycolide)-Monomethoxy-Poly-(Polyethylene Glycol) Nanoparticles Loaded with Melatonin Protect Adipose-Derived Stem Cells Transplanted in Infarcted Heart Tissue

Stem cell transplantation is a promising therapeutic strategy for myocardial infarction. However, transplanted cells face low survival rates due to oxidative stress and the inflammatory microenvironment in ischemic heart tissue. Melatonin has been used as a powerful endogenous antioxidant to protect cells from oxidative injury. However, melatonin cannot play a long-lasting effect against the hostile microenvironment. Nano drug delivery carriers have the ability to protect the loaded drug from degradation in physiological environments in a controlled manner, which results in longer effects and decreased side effects. Therefore, we constructed poly(lactide-co-glycolide)-monomethoxy-poly-(polyethylene glycol) (PLGA-mPEG) nanoparticles to encapsulate melatonin. We tested whether the protective effect of melatonin encapsulated by PLGA-mPEG nanoparticles (melatonin nanoparticles [Mel-NPs]) on adipose-derived mesenchymal stem cells (ADSCs) was enhanced compared to that of free melatonin both in vitro and in vivo. In the in vitro study, we found that Mel-NPs reduced formation of the p53- cyclophilin D complex, prevented mitochondrial permeability transition pores from opening, and rescued ADSCs from hypoxia/reoxygenation injury. Moreover, Mel-NPs can achieve higher ADSC survival rates than free melatonin in rat myocardial infarction areas, and the therapeutic effects of ADSCs pretreated with Mel-NPs were more apparent. Hence, the combination of Mel-NPs and stem cell transplantation may be a promising strategy for myocardial infarction therapy. Stem Cells 2018;36:540-550.

Preparation of Melatonin-Loaded Zein Nanoparticles using Supercritical CO2 Antisolvent and in vitro Release Evaluation

In this work, we reported preparation of melatonin-loaded zein nanoparticles using the technique of solution-enhanced dispersion by supercritical CO2 (SEDS) for prolonging the release of melatonin. The influence of pressure, temperature and the ratio of melatonin and zein on the morphology, the particle size and drug loading was investigated. The release profiles of the melatonin-loaded nanoparticles were evaluated. The sizes of the most particles were less than 100 nm at most conditions examined, and the morphology had three types: rod-like, globule, and filament. The maximum drug loading of 6.9% and encapsulation efficiencies of 80.2% were obtained, respectively, under different conditions. The release speed of the melatonin in the nanoparticles is lower than both the pure one and that in the physical mixture. It displayed a near zero-order release which implied that it could be applied as a potential controlled-release drug.

Application of a validated HPLC-PDA method for the determination of melatonin content and its release from poly(lactic acid) nanoparticles

Melatonin is a natural hormone and with the advancement of age its production declines and thereby may result in some neurological disorders. Exogenous administration of melatonin has been suggested as a neuroprotective agent. Due to its low oral bioavailability, the loading of melatonin in polymeric nanoparticles could be an important tool to effectively use exogenous melatonin. The quantification of the incorporated drug within polymeric nanoparticles is an important step in nanoparticles characterization. An analytical method using high performance liquid chromatography equipped with photodiode array detector (HPLC-PDA) was developed and validated for melatonin determination in poly (lactic acid) nanoparticles obtained by a single emulsion-solvent evaporation technique. The melatonin in vitro release profile also was determined by the HPLC method. Mobile phase consisted of acetonitrile: water (65:35, v/v) pumped at a flow rate of 0.9 mL/min, in the isocratic mode and PDA detector was set at 220 nm. The method was validated in terms of the selectivity, linearity, precision, accuracy, robustness, limits of detection and quantification. Analytical curve was linear over the concentration range of 10–100 μg/mL, and limits of detection and quantification were 25.9 ng/mL and 78.7 ng/mL, respectively. The mean recovery for melatonin was 100.47% (RSD = 1.25%, n = 9). In the intra- and inter-assay, the coefficient of variation was less than 2%. Robustness was proved performing changes in mobile phase, column temperature and flow rate. The method was suitable for the determination of melatonin encapsulation efficiency in poly(lactic acid) nanoparticles and for the evaluation of melatonin in vitro release profile.