Amine-containing donepezil analogues as potent acetylcholinesterase inhibitors with increased polarity.

Functional dyspepsia (FD) is a gastrointestinal disorder characterized by postprandial fullness, upper abdominal bloating, and early satiation. Peripheral acetylcholinesterase (AChE) inhibitors such as acotiamide have shown efficacy in FD treatment, but their limited affinity towards the enzyme has hindered their effectiveness. Conversely, AChE inhibitors developed for Alzheimer's disease have high potency but exhibit strong central activity, making them unsuitable for FD treatment. In this study, we developed potent AChE inhibitors based on a donepezil and a phthalimide scaffold that contain additional amine groups. Our compounds demonstrate IC50 values in the low to mid-nanomolar range. Computational modelling was employed to determine important molecular interactions with AChE. The compounds show low membrane permeability, which indicates a significantly reduced central activity. These findings suggest that the developed inhibitors could potentially serve as promising treatments for functional dyspepsia.

pH-Responsive Micellar Nanoparticles for the Delivery of a Self-Amplifying ROS-Activatable Prodrug.

The objective of this study is to enhance the therapeutic efficacy of the anticancer drug, camptothecin (CPT) via a nanoparticle (NP) formulation using a novel amphiphilic biopolymer. We have designed a dimeric prodrug of CPT with the ability to self-amplify and respond to reactive oxygen species (ROS). For this, we incorporated the intracellular ROS generator cinnamaldehyde into a ROS-cleavable thioacetal (TA) linker to obtain the dimeric prodrug of CPT (DCPT(TA)). For its efficient NP delivery, a pH-responsive block copolymer of acetalated dextran and poly(2-ethyl-2-oxazoline) (AcDex-b-PEOz) was synthesized. The amphiphilic feature of the block copolymer enables its self-assembly into micellar NPs and results in high prodrug loading capacity and a rapid release of the prodrug under acidic conditions. Upon cellular uptake by HeLa cells, DCPT(TA)-loaded micellar NPs induce intracellular ROS generation, resulting in accelerated prodrug activation and enhanced cytotoxicity. These results indicate that this system holds significant potential as an effective prodrug delivery strategy in anticancer treatment.

Dual-Responsive Enzyme-Polysaccharide Conjugate as a Nanocarrier System for Enzyme Prodrug Therapy.

Biopolymer-based drug delivery systems have gained considerable attention in the field of nanomedicine. In this study, a protein-polysaccharide conjugate was synthesized by covalent conjugation of the enzyme horseradish peroxidase (HRP) with acetalated dextran (AcDex) via a thiol exchange reaction. The resulting bioconjugate shows a dual-responsive behavior in acidic and reductive environments to achieve a controlled release of drugs. The self-assembly of this amphiphilic HRP-AcDex conjugate allows the encapsulation of prodrug indole-3-acetic acid (IAA) into the hydrophobic polysaccharide core. Under slightly acidic conditions, the acetalated polysaccharide reverts to its native hydrophilic form, which triggers the disassembly of micellar nanoparticles and the release of the encapsulated prodrug. The conjugated HRP further activates the prodrug by oxidation of IAA into cytotoxic radicals, which leads to cellular apoptosis. The results indicate that the HRP-AcDex conjugate in combination with IAA has great potential to be used as a novel enzyme prodrug therapy for cancer treatment.

Protein-based Nanoparticles: From Drug Delivery to Imaging, Nanocatalysis and Protein Therapy.

Proteins and enzymes are versatile biomaterials for a wide range of medical applications due to their high specificity for receptors and substrates, high degradability, low toxicity, and overall good biocompatibility. Protein nanoparticles are formed by the arrangement of several native or modified proteins into nanometer-sized assemblies. In this review, we will focus on artificial nanoparticle systems, where proteins are the main structural element and not just an encapsulated payload. While under natural conditions, only certain proteins form defined aggregates and nanoparticles, chemical modifications or a change in the physical environment can further extend the pool of available building blocks. This allows the assembly of many globular proteins and even enzymes. These advances in preparation methods led to the emergence of new generations of nanosystems that extend beyond transport vehicles to diverse applications, from multifunctional drug delivery to imaging, nanocatalysis and protein therapy.

Attenuation of Cigarette-Smoke-Induced Oxidative Stress, Senescence, and Inflammation by Berberine-Loaded Liquid Crystalline Nanoparticles: In Vitro Study in 16HBE and RAW264.7 Cells.

Cigarette smoke is considered a primary risk factor for chronic obstructive pulmonary disease. Numerous toxicants present in cigarette smoke are known to induce oxidative stress and airway inflammation that further exacerbate disease progression. Generally, the broncho-epithelial cells and alveolar macrophages exposed to cigarette smoke release massive amounts of oxidative stress and inflammation mediators. Chronic exposure of cigarette smoke leads to premature senescence of airway epithelial cells. This impairs cellular function and ultimately leads to the progression of chronic lung diseases. Therefore, an ideal therapeutic candidate should prevent disease progression by controlling oxidative stress, inflammation, and senescence during the initial stage of damage. In our study, we explored if berberine (an alkaloid)-loaded liquid crystalline nanoparticles (berberine-LCNs)-based treatment to human broncho-epithelial cells and macrophage inhibits oxidative stress, inflammation, and senescence induced by cigarette-smoke extract. The developed berberine-LCNs were found to have favourable physiochemical parameters, such as high entrapment efficiency and sustained in vitro release. The cellular-assay observations revealed that berberine-LCNs showed potent antioxidant activity by suppressing the generation of reactive oxygen species in both broncho-epithelial cells (16HBE) and macrophages (RAW264.7), and modulating the genes involved in inflammation and oxidative stress. Similarly, in 16HBE cells, berberine-LCNs inhibited the cigarette smoke-induced senescence as revealed by X-gal staining, gene expression of CDKN1A (p21), and immunofluorescent staining of p21. Further in-depth mechanistic investigations into antioxidative, anti-inflammatory, and antisenescence research will diversify the current findings of berberine as a promising therapeutic approach for inflammatory lung diseases caused by cigarette smoking.

Nanoparticulate strategies for the delivery of miRNA mimics and inhibitors in anticancer therapy and its potential utility in oral submucous fibrosis.

MicroRNAs (miRNAs) are naturally occurring noncoding RNAs with multiple functionalities. They are dysregulated in several conditions and can serve as disease biomarkers, therapeutic targets and therapeutic agents. Translation of miRNA therapeutics to the clinic poses several challenges related to the safe and effective delivery of these agents to the site of action. Nanoparticulate carriers hold promise in this area by enhancing targeting efficiency and reducing off-target effects. This paper reviews recent advances in the delivery strategies of miRNAs in anticancer therapy, with a focus on lipid-based, polymeric, inorganic platforms, cell membrane-derived vesicles and bacterial minicells. Additionally, this review explores the potentiality of miRNAs in the treatment of oral submucous fibrosis, a potentially premalignant condition of the oral cavity with no definitive treatment to date.

Treatment of chronic airway diseases using nutraceuticals: Mechanistic insight.

Respiratory diseases, both acute and chronic, are reported to be the leading cause of morbidity and mortality, affecting millions of people globally, leading to high socio-economic burden for the society in the recent decades. Chronic inflammation and decline in lung function are the common symptoms of respiratory diseases. The current treatment strategies revolve around using appropriate anti-inflammatory agents and bronchodilators. A range of anti-inflammatory agents and bronchodilators are currently available in the market; however, the usage of such medications is limited due to the potential for various adverse effects. To cope with this issue, researchers have been exploring various novel, alternative therapeutic strategies that are safe and effective to treat respiratory diseases. Several studies have been reported on the possible links between food and food-derived products in combating various chronic inflammatory diseases. Nutraceuticals are examples of such food-derived products which are gaining much interest in terms of its usage for the well-being and better human health. As a consequence, intensive research is currently aimed at identifying novel nutraceuticals, and there is an emerging notion that nutraceuticals can have a positive impact in various respiratory diseases. In this review, we discuss the efficacy of nutraceuticals in altering the various cellular and molecular mechanisms involved in mitigating the symptoms of respiratory diseases.

Targeting respiratory diseases using miRNA inhibitor based nanotherapeutics: Current status and future perspectives.

MicroRNAs (miRNAs) play a fundamental role in the developmental and physiological processes that occur in both animals and plants. AntagomiRs are synthetic antagonists of miRNA, which prevent the target mRNA from suppression. Therapeutic approaches that modulate miRNAs have immense potential in the treatment of chronic respiratory disorders. However, the successful delivery of miRNAs/antagomiRs to the lungs remains a major challenge in clinical applications. A range of materials, namely, polymer nanoparticles, lipid nanocapsules and inorganic nanoparticles, has shown promising results for intracellular delivery of miRNA in chronic respiratory disorders. This review discusses the current understanding of miRNA biology, the biological roles of antagomiRs in chronic respiratory disease and the recent advances in the therapeutic utilization of antagomiRs as disease biomarkers. Furthermore our review provides a common platform to debate on the nature of antagomiRs and also addresses the viewpoint on the new generation of delivery systems that target antagomiRs in respiratory diseases.

Metal-organic frameworks as protective matrices for peptide therapeutics.

An increasing number of peptide drugs have been identified or synthesized in recent decades, and they have played an important role in disease treatments and scientific research. Peptide drugs have become emerging candidates in the pharmaceutical market, despite some inherent disadvantages that have hindered their further development (i.e., they are chemically and physically unstable). Considering that cold-storage conditions are not easily accessible, particularly in developing countries, it remains a significant challenge to find a facile way to enhance the stability of peptide drugs. In this study, we developed an efficient and facile strategy to provide peptide drugs a strong protection against harsh conditions by biomineralizing metal-organic frameworks (MOFs) around the peptide drugs. Our results showed that the peptides released from MOFs retained their structures and full biological activities after being exposed to high temperatures, repeated freeze-thaw cycles and enzyme degradation. This study provides an alternative method for the storage of biopharmaceuticals and for enhancing their stability under ambient conditions.

Plants derived therapeutic strategies targeting chronic respiratory diseases: Chemical and immunological perspective.

The apparent predicament of the representative chemotherapy for managing respiratory distress calls for an obligatory deliberation for identifying the pharmaceuticals that effectively counter the contemporary intricacies associated with target disease. Multiple, complex regulatory pathways manifest chronic pulmonary disorders, which require chemotherapeutics that produce composite inhibitory effect. The cost effective natural product based molecules hold a high fervor to meet the prospects posed by current respiratory-distress therapy by sparing the tedious drug design and development archetypes, present a robust standing for the possible replacement of the fading practice of poly-pharmacology, and ensure the subversion of a potential disease relapse. This study summarizes the experimental evidences on natural products moieties and their components that illustrates therapeutic efficacy on respiratory disorders.

Asymmetric Disulfanylbenzamides as Irreversible and Selective Inhibitors of Staphylococcus aureus Sortase A.

Staphylococcus aureus is one of the most frequent causes of nosocomial and community-acquired infections, with drug-resistant strains being responsible for tens of thousands of deaths per year. S. aureus sortase A inhibitors are designed to interfere with virulence determinants. We have identified disulfanylbenzamides as a new class of potent inhibitors against sortase A that act by covalent modification of the active-site cysteine. A broad series of derivatives were synthesized to derive structure-activity relationships (SAR). In vitro and in silico methods allowed the experimentally observed binding affinities and selectivities to be rationalized. The most active compounds were found to have single-digit micromolar Ki values and caused up to a 66 % reduction of S. aureus fibrinogen attachment at an effective inhibitor concentration of 10 µM. This new molecule class exhibited minimal cytotoxicity, low bacterial growth inhibition and impaired sortase-mediated adherence of S. aureus cells.

Cellular signalling pathways mediating the pathogenesis of chronic inflammatory respiratory diseases: an update.

Respiratory disorders, especially non-communicable, chronic inflammatory diseases, are amongst the leading causes of mortality and morbidity worldwide. Respiratory diseases involve multiple pulmonary components, including airways and lungs that lead to their abnormal physiological functioning. Several signaling pathways have been reported to play an important role in the pathophysiology of respiratory diseases. These pathways, in addition, become the compounding factors contributing to the clinical outcomes in respiratory diseases. A range of signaling components such as Notch, Hedgehog, Wingless/Wnt, bone morphogenetic proteins, epidermal growth factor and fibroblast growth factor is primarily employed by these pathways in the eventual cascade of events. The different aberrations in such cell-signaling processes trigger the onset of respiratory diseases making the conventional therapeutic modalities ineffective. These challenges have prompted us to explore novel and effective approaches for the prevention and/or treatment of respiratory diseases. In this review, we have attempted to deliberate on the current literature describing the role of major cell signaling pathways in the pathogenesis of pulmonary diseases and discuss promising advances in the field of therapeutics that could lead to novel clinical therapies capable of preventing or reversing pulmonary vascular pathology in such patients.

Receptor-mediated Uptake of Folic Acid-functionalized Dextran Nanoparticles for Applications in Photodynamic Therapy.

In photodynamic therapy (PDT), photosensitizers and light are used to cause photochemically induced cell death. The selectivity and the effectiveness of the phototoxicity in cancer can be increased by a specific uptake of the photosensitizer into tumor cells. A promising target for this goal is the folic acid receptor α (FRα), which is overexpressed on the surface of many tumor cells and mediates an endocytotic uptake. Here, we describe a polysaccharide-based nanoparticle system suitable for targeted uptake and its photochemical and photobiological characterization. The photosensitizer 5, 10, 15, 20-tetraphenyl-21H, 23H-porphyrine (TPP) was encapsulated in spermine- and acetal-modified dextran (SpAcDex) nanoparticles and conjugated with folic acid (FA) on the surface [SpAcDex(TPP)-FA]. The particles are successfully taken up by human HeLa-KB cells, and a light-induced cytotoxicity is observable. An excess of free folate as the competitor for the FRα-mediated uptake inhibits the phototoxicity. In conclusion, folate-modified SpAcDex particles are a promising drug delivery system for a tumor cell targeted photodynamic therapy.

Double stimuli-responsive polysaccharide block copolymers as green macrosurfactants for near-infrared photodynamic therapy.

The NIR absorbing photosensitizer phthalocyanine zinc (PC(Zn)) was stabilized in aqueous media as water-dispersible nanoparticles with a reduction- and pH-responsive full polysaccharide block copolymer. A cellular uptake and also photo switchable intracellular activity of the cargo upon irradiation at wavelengths in the near infrared region were shown. The block copolymer was synthesized by applying a copper-free click strategy based on a thiol exchange reaction, creating an amphiphilic double-stimuli-responsive mixed disulfide. The dual-sensitive polysaccharide micelles represent a non-toxic and biodegradable green macrosurfactant for the delivery of phthalocyanine zinc. By encapsulation into micellar nanoparticles, the bioavailability of PC(Zn) increased significantly, enabling smart photodynamic therapy for future applications in cancer-related diseases.

Protein-Based Nanoparticles for the Delivery of Enzymes with Antibacterial Activity.

Proteins represent a versatile biopolymer material for the preparation of nanoparticles due to their biocompatibility, biodegradability, and low immunogenicity. This study presents a protein-based nanoparticle system consisting of high surface PEGylated lysozyme polyethylene glycol-modified lysozyme (LYZmPEG ). This protein modification leads to a solubility switch, which allows a nanoparticle preparation using a mild double emulsion method without the need of surfactants. The method allows the encapsulation of large hydrophilic payloads inside of the protein-based nanoparticle system. Native lysozyme (LYZ) was chosen as payload because of its innate activity as natural antibiotic. The mild particle preparation procedure retains the structure and activity of the enzyme which was successfully tested against the gram-positive bacteria strain M. Luteus. In comparison, the particle system shows no toxicity to human cells. This first report of a full protein-based particle material for the transport of large hydrophilic payloads opens up new therapeutic applications for biopolymer-based delivery systems.

Surface Modification of Polysaccharide-Based Nanoparticles with PEG and Dextran and the Effects on Immune Cell Binding and Stimulatory Characteristics.

Surface modifications of nanoparticles can alter their physical and biological properties significantly. They effect particle aggregation, circulation times, and cellular uptake. This is particularly critical for the interaction with primary immune cells due to their important role in particle processing. We can show that the introduction of a hydrophilic PEG layer on the surface of the polysaccharide-based nanoparticles prevents unwanted aggregation under physiological conditions and decreases unspecific cell uptake in different primary immune cell types. The opposite effect can be observed with a parallel-performed introduction of a layer of low molecular weight dextran (3.5 and 5 kDa) on the particle surface (DEXylation) that encourages the nanoparticle uptake by antigen-presenting cells like macrophages and dendritic cells. Binding of DEXylated particles to these immune cells results in an upregulation of surface maturation markers and elevated production of proinflammatory cytokines, reflecting cell activation. Hence, DEXylated particles can potentially be used for passive targeting of antigen presenting cells with inherent adjuvant function for future immunotherapeutic applications.

Development of Novel Peptide-Based Michael Acceptors Targeting Rhodesain and Falcipain-2 for the Treatment of Neglected Tropical Diseases (NTDs).

This paper describes the development of a class of peptide-based inhibitors as novel antitrypanosomal and antimalarial agents. The inhibitors are based on a characteristic peptide sequence for the inhibition of the cysteine proteases rhodesain of Trypanosoma brucei rhodesiense and falcipain-2 of Plasmodium falciparum. We exploited the reactivity of novel unsaturated electrophilic functions such as vinyl-sulfones, -ketones, -esters, and -nitriles. The Michael acceptors inhibited both rhodesain and falcipain-2, at nanomolar and micromolar levels, respectively. In particular, the vinyl ketone 3b has emerged as a potent rhodesain inhibitor (k2nd = 67 × 106 M-1 min-1), endowed with a picomolar binding affinity (Ki = 38 pM), coupled with a single-digit micromolar activity against Trypanosoma brucei brucei (EC50 = 2.97 µM), thus being considered as a novel lead compound for the discovery of novel effective antitrypanosomal agents.

Amphiphilic Polysaccharide Block Copolymers for pH-Responsive Micellar Nanoparticles.

A full polysaccharide amphiphilic block copolymer was prepared from end group-functionalized dextrans using copper-mediated azide-alkyne click chemistry. Sufficient modification of the reducing end in both blocks was achieved by microwave-enhanced reductive amination in a borate-buffer/methanol solvent system. The combination of a hydrophilic dextran block with a hydrophobic acetalated dextran block results in an amphiphilic structure that turns water-soluble upon acid treatment. The material has a low critical micelle concentration and self-assembles in water to spherical micellar nanoparticles. The formed nanoparticles have a narrow size distribution below 70 nm in diameter and disassemble in slightly acidic conditions. The amphiphilic polysaccharide system shows low toxicity and can stabilize the hydrophobic model drug curcumin in aqueous solutions over extended time periods.