Thiacalixarene Carboxylic Acid Derivatives as Inhibitors of Lysozyme Fibrillation.

Amyloid fibroproliferation leads to organ damage and is associated with a number of neurodegenerative diseases affecting populations worldwide. There are several ways to protect against fibril formation, including inhibition. A variety of organic compounds based on molecular recognition of amino acids within the protein have been proposed for the design of such inhibitors. However, the role of macrocyclic compounds, i.e., thiacalix[4]arenes, in inhibiting fibrillation is still almost unknown. In the present work, the use of water-soluble thiacalix[4]arene derivatives for the inhibition of hen egg-white lysozyme (HEWL) amyloid fibrillation is proposed for the first time. The binding of HEWL by the synthesized thiacalix[4]arenes (logKa = 5.05-5.13, 1:1 stoichiometry) leads to the formation of stable supramolecular systems capable of stabilizing the protein structure and protecting against fibrillation by 29-45%. The macrocycle conformation has little effect on protein binding strength, and the native HEWL secondary structure does not change via interaction. The synthesized compounds are non-toxic to the A549 cell line in the range of 0.5-250 µg/mL. The results obtained may be useful for further investigation of the anti-amyloidogenic role of thiacalix[4]arenes, and also open up future prospects for the creation of new ways to prevent neurodegenerative diseases.

Calix[6]arene dismantles extracellular vesicle biogenesis and metalloproteinases that support pancreatic cancer hallmarks.

Many challenges are faced in pancreatic cancer treatment due to late diagnosis and poor prognosis because of high recurrence and metastasis. Extracellular vesicles (EVs) and matrix metalloproteinases (MMPs), besides acting in intercellular communication, are key players in the cancer cell plasticity responsible for initiating metastasis. Therefore, these entities provide valuable targets for the development of better treatments. In this context, this study aimed to evaluate the potential of calix[6]arene to disturb the release of EVs and the activity of MMPs in pancreatic cancer cells. We found a correlation between the endocytic-associated mediators and the prognosis of pancreatic cancer patients. We observed a more active EV machinery in the pancreatic cancer cell line PANC-1, which was reduced three-fold by treatment with calix[6]arene at subtoxic concentration (5 µM; p ã€ˆ0,001). We observed the modulation of 186 microRNAs (164 miRNAs upregulated and 22 miRNAs downregulated) upon calix[6]arene treatment. Interestingly, some of them as miR-4443 and miR-3909, regulates genes HIF1A e KIF13A that are well known to play a role in transport of vesicles. Furthermore, Calix[6]arene downmodulated matrix metalloproteinases (MMPs) -2 and - 9 and disturbed the viability of pancreatic organoids which recapitulate the cellular heterogeneity, structure, and functions of primary tissues. Our findings shed new insights on calix[6]arene's antitumor mechanism, including its intracellular effects on vesicle production and trafficking, as well as MMP activity, which may harm the tumor microenvironment and contribute to a reduction in cancer cell dissemination, which is one of the challenges associated with high mortality in pancreatic cancer.

Substitution of bridge carbons for sulphur in calix[4]arene-bis-α-hydroxymethylphosphonic acid transformed mobile carrier into ionic channel accompanied with evoked muscle contraction and impaired neurotransmission powered by membrane action of resulting thiocalix[4]arene-bis-α-hydroxymethylphosphonic acid.

The action of calix[4]arenes C-424, C-425 and C-1193 has been investigated on suspended cholesterol/egg phosphatidylcholine lipid bilayer in a voltage-clamp mode. Comparative analysis with the membrane action by calix[4]arene-bis-α-hydroxymethylphosphonic acid (C-99) has shown that the substitution of bridge carbons for sulphur and addition of another methyl group to two alkyl tales in the lower rim of former dipropoxycalix[4]arene C-99 transformed mobile carrier that C-99 created in lipid bilayer (Shatursky et al., 2014) into a transmembrane pore as exposure of the bilayer membrane to sulphur-containing derivative dibutoxythiocalix[4]arene C-1193 resulted in microscopic transmembrane current patterns indicative of a channel-like mode of facilitated diffusion. Within all calix[4]arenes tested a net steady-state voltage-dependent transmembrane current was readily achieved only after addition of calix[4]-arene C-1193. In comparison with the membrane action of C-99 the current induced by calix[4]-arene C-1193 exhibited a much weakened anion selectivity passing slightly more current at positive potentials applied from the side of bilayer membrane to which the calix[4]-arene was added. Testing C-1193 for the membrane action against smooth muscle cells of rat uterus or swine myometrium and synaptosomes of rat brain nerve terminals revealed an increase in intracellular concentration of Ca2+ with reduction of the effective hydrodynamic diameter of the smooth muscle cells and enhanced basal extracellular level of neurotransmitters (glutamate and γ-aminobutyric acid) after C-1193-induced depolarization of the nerve terminals.

Host-Guest-Interaction Enhanced Nitric Oxide Photo-Generation within a Pillar[5]arene Cavity for Antibacterial Gas Therapy.

Supramolecular macrocycles with intrinsic cavities have been widely explored as containers to fabricate versatile functional materials via specific host-guest recognitions. However, relatively few studies have focused on the modulation of guest reactivity within a macrocyclic cavity. Here, we demonstrate the confinement effect of pillar[5]arene with an electron-rich and precise cavity that can dramatically enhance guest photoactivity and nitric oxide (NO) generation upon visible light irradiation. Mechanism studies reveal that it is achieved through increasing the ground state nitro-aromatic torsion angle, suppressing the intersystem crossing relaxation path of the S1 state, and accelerating the isomerization reaction path of guest molecules. This NO-generating system displays broad-spectrum antibacterial, biofilm inhibition, and dispersal activities. Moreover, it can accelerate the healing of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds in vivo.

Calixarene-based cryoprotectants for ice recrystallization inhibition and cell cryopreservation.

The development of new cryoprotectants for cryopreservation of cells has attracted considerable interest. Herein, five calixarene-based CPAs (SC4A, S-S-C4A, S-SO2-C4A, SBAC4A, and CAC4A) were developed, and their IRI activity, DIS property and cryoprotective effect were studied. SBAC4A with a sulphobetaine zwitterion and SC4A with sulfo group modification possessed better cryoprotective effects than the other calixarene-based CPAs, especially for SBAC4A with the enhanced cell viabilities of 16.16 ± 1.78%, 12.60 ± 1.15% and 14.90 ± 1.66% against MCF-7, hucMSCs and A549 cells, respectively. This result provides a supramolecular principle for developing novel CPAs with consideration of the factors of hydrogen bonding, the macromolecular crowding principle and the three-dimensional (3D) structure.

Functionalized Calixarenes as Promising Antibacterial Drugs to Face Antimicrobial Resistance.

Since the discovery of polyphenolic resins 150 years ago, the study of polymeric compounds named calix[n]arene has continued to progress, and those skilled in the art perfectly know now how to modulate this phenolic ring. Consequently, calix[n]arenes are now used in a large range of applications and notably in therapeutic fields. In particular, the calix[4]arene exhibits multiple possibilities for regioselective polyfunctionalization on both of its rims and offers researchers the possibility of precisely tuning the geometry of their structures. Thus, in the crucial research of new antibacterial active ingredients, the design of calixarenes finds its place perfectly. This review provides an overview of the work carried out in this aim towards the development of intrinsically active prodrogues or metallic calixarene complexes. Out of all the work of the community, there are some excellent activities emerging that could potentially place these original structures in a very good position for the development of new active ingredients.

Calix[4]arene-pyrazole conjugates as potential cancer therapeutics.

Tumor selectivity is yet a challenge in chemotherapy-based cancer treatment. A series of calixarenes derivatized at the lower rim with 3-phenyl-1H-pyrazole units with variable upper-rim substituent and conformations of macrocyclic core, alkyl chain length between heterocycle and core, as well as phenolic monomer (5-(4-tert-butylphenyloxy)methoxy-3-phenyl-1H-pyrazole) have been synthesized and characterized in a range of therapeutically relevant cellular models (M-HeLa, MCF7, A-549, PC3, Chang liver, and Wi38) from different target organs/systems. Specific cytotoxicity for M-HeLa cells has been observed in tert-butylcalix[4]arene pyrazoles in 1,3-alternate (compound 7b) and partial cone (compound 7c) conformations with low mutagenicity and haemotoxicity and in vivo toxicity in mice. Compounds 7b,c have induced mitochondrial pathway of apoptosis of M-HeLa cells through caspase-9 activation preceded by the cell cycle arrest at G0/G1 phase. A concomitant overexpression of DNA damage markers in pyrazole-treated M-HeLa cells suggests that calixarene pyrazoles target DNA, which was supported by the presence of interactions between calixarenes and ctDNA at the air-water interface.

An L-arginine-functionalized pillar[5]arene-based supramolecular photosensitizer for synergistically enhanced cancer therapeutic effectiveness.

An L-arginine-functionalized pillar[5]arene-based supramolecular photosensitizer LAP5⊃NBSPD was constructed by host-guest interactions, which could self-assemble into nano-micelles to achieve effective delivery and selective release of LAP5 and NBS in cancer cells. In vitro studies revealed that LAP5⊃NBSPD NPs exhibited excellent cancer cell membrane disruption and ROS generation properties, which provides a novel route for synergistically enhanced cancer therapeutic effectiveness.

Calix[n]arene-based immunogens: A new non-proteic strategy for anti-cocaine vaccine.

Introduction: Cocaine use disorder is a significant public health issue without a current specific approved treatment. Among different approaches to this disorder, it is possible to highlight a promising immunologic strategy in which an immunogenic agent may reduce the reinforcing effects of the drug if they are able to yield sufficient specific antibodies capable to bind cocaine and/or its psychoactive metabolites before entering into the brain. Several carriers have been investigated in the anti-cocaine vaccine development; however, they generally present a very complex chemical structure, which potentially hampers the proper assessment of the coupling efficiency between the hapten units and the protein structure. Objectives: The present study reports the design, synthesis and preclinical evaluation of two novel calix[n]arene-based anti-cocaine immunogens (herein named as V4N2 and V8N2) by the tethering of the hydrolysis-tolerant hapten GNE (15) on calix[4]arene and calix[8]arene moieties. Methods: The preclinical assessment corresponded to the immunogenicity and dose-response evaluation of V4N2 and V8N2. The potential of the produced antibodies to reduce the passage of cocaine analogue through the blood-brain-barrier (BBB), modifying its biodistribution was also investigated. Results: Both calix[n]arene-based immunogens elicited high titers of cocaine antibodies that modified the biodistribution of a cocaine radiolabeled analogue (99mTc-TRODAT-1) and decreased cocaine-induced behavior, according to an animal model. Conclusion: The present results demonstrate the potential of V4N2 and V8N2 as immunogens for the treatment of cocaine use disorder.

A Calixarene Assembly Strategy of Combined Anti-Neuroinflammation and Drug Delivery Functions for Traumatic Brain Injury Therapy.

Excessive inflammatory reaction aggravates brain injury and hinders the recovery of neural function in nervous system diseases. Microglia, as the major players of neuroinflammation, control the progress of the disease. There is an urgent need for effective non-invasive therapy to treat neuroinflammation mediated by microglia. However, the lack of specificity of anti-inflammatory agents and insufficient drug dose penetrating into the brain lesion area are the main problems. Here, we evaluated a series of calixarenes and found that among them the self-assembling architecture of amphiphilic sulfonatocalix[8]arene (SC8A12C) had the most potent ability to suppress neuroinflammation in vitro and in vivo. Moreover, SC8A12C assemblies were internalized into microglia through macropinocytosis. In addition, after applying the SC8A12C assemblies to the exposed brain tissue, we observed that SC8A12C assemblies penetrated into the brain parenchyma and eliminated the inflammatory factor storm, thereby restoring neurobiological functions in a mouse model of traumatic brain injury.

Utilization of pillar[5]arene-based ICT probes embedded into proteins for live-cell imaging and traceable drug delivery.

Three protein microenvironment-sensitive pillar[5]arene-based fluorescent probes (3/4/5C-B) were designed and synthesized based on intramolecular charge transfer (ICT) mechanism. Unlike the majority of micromolecular ICT probes, the aforementioned probes displayed differentiated sensitivity to multiple proteins. The 7-(diethylamino)coumarin-3-formic acid (DCCA) group in the probes was essential for their sensitivity. The presence of a pillar[5]arene group was also crucial as they benefit 3/4/5C-B form complexes with the proteins, although it changed the electron density distribution of the DCCA group. 3/4/5C-B exhibited favorable carrier ability for regorafenib (REG). 4C-B had the best spatial structure for complexation. The 3/4/5C-B-REG complexes would assemble into high drug-loading fluorescent nanoparticles in a physiological environment (pH = 7.4). Such nanoparticles exhibited pH-triggered enrichment ability, which rapidly enriched REG in the acidic environment (pH = 6.0). Moreover, the complexation between 3/4/5C-B and REG maintained the live-cell membrane imaging property of the probes and the excellent targeted anticancer activity of the drug.

Dual-responsive drug release and fluorescence imaging based on disulfide-pillar[4]arene aggregate in cancer cells.

The construction of multistimuli-responsive nanoaggregate has become one of the increasingly significant research topics in supramolecular chemistry. We herein reported the pH- and glutathione dual-responsive supramolecular assemblies fabricated by the disulfide-containing pillar[4]arene and tetraphenylethylene derivatives possessing different alkyl chains in length. Morphological characterization experiments showed the binary supramolecular assemblies formed well-defined nanoparticles, which could facilitate their endocytosis in cells. More remarkably, due to the compact nanostructures and the existence of acidifiable carboxyl group and bioreducible disulfide linkage in pillar[4]arene, the obtained nanoaggregates presented high drug-loading efficiency and sustained drug release behaviors, as well as the targeted fluorescence imaging ability in cancer cells. Thus, it can be envisioned that such microenvironment-adaptable supramolecular nanoassemblies featuring dual stimuli-responsiveness and fluorescence-imaging abilities may be developed as more appealing nanosystems for the therapy of refractory disease.

Targeting Colorectal Cancer Cells with a Functionalised Calix[4]arene Receptor: Biophysical Studies.

Colorectal cancer (CRC) is a disease which is causing a high degree of mortality around the world. The present study reports the antiproliferative impact of the thioacetamide calix[4]arene, CAII receptor on a highly differentiated Caco-2 cell line. This statement is corroborated by the MTT assay results which revealed a reduction in the cell viability with an IC50 value of 19.02 ± 0.04 µM. Microscopic results indicated that at the starting amount of 10 µM of CAII, a decrease in cells confluency can already be observed in addition to changes in cells morphology. Cell metabolic pathway changes were also investigated. 1H NMR findings showed downregulation in lactate, pyruvate, phosphocholine, lipids, and hydroxybutyrate with the upregulation of succinate, indicating a decline in the cells proliferation. Some biochemical alterations in the cells as a result of the CAII treatment were found by Raman spectroscopy.

An application of p-sulfonatocalix[6]arenes to attenuate cardiotoxicity of mitoxantrone in vitro: preparation, characterization and evaluation.

OBJECTIVES: In this study, p-sulfonatocalix[6]arenes (SCA6) was proposed to construct a host-guest complexation to carry mitoxantrone (MIT) to maintain its anti-proliferation effect on HepG2 cells as well as to attenuate cardiotoxicity on H9C2 cells as a nano-size drug delivery system. METHODS: SCA6 binding to MIT evidenced through competitive fluorescence titration method. The complex was characterized using UV-visible, Fourier transform infrared, and proton nuclear magnetic resonance (1H-NMR) spectroscopies and differential scanning calorimetry analysis. The cytotoxicity was examined by a cell counting kit-8 assay on six cells. High content analysis, cell apoptosis and cell cycle experiments were measured to investigate the mechanism of detoxification in H9C2. KEY FINDINGS: The host-guest complexation was formed with a stoichiometry ratio of 1:1. Cytotoxicity study demonstrated that MIT/SCA6 complex could improve the cell viability on H9C2, MCF-7, A549, Hek293 and L02 cells and remained cytotoxicity effect on HepG2 cells. High content analysis showed that MIT/SCA6 complex could enhance the cell viability, mitochondrial mass and mitochondrial membrane potential and ameliorate the nuclear swelling on H9C2 cells. Moreover, the complex were arrested in G0/G1 phase of the cell cycle and same with MIT, while the detoxication was attributed to reducing early apoptosis. CONCLUSIONS: The host-guest complexation between SCA6 and MIT had the ability to attenuate cardiotoxicity and provided a potential strategy for the application of soluble calixarenes in chemotherapy.

A Simple, Rapid, Comparative Evaluation of Multiple Products for Decontamination of Actinide-contaminated Rat Skin Ex Vivo.

ABSTRACT: Decontamination of skin is an important medical countermeasure in order to limit potential internal contamination by radionuclides such as actinides. Minimizing skin surface contamination will ultimately prevent internal contamination and subsequent committed effective dose as well as contamination spreading. The decontamination agents tested on a rat skin ex vivo model ranged from water to hydrogel wound dressings. A surfactant-containing cleansing gel and calixarene nanoemulsion with chelation properties demonstrated marked decontamination efficacies as compared with water or the chelator DTPA. Based on efficacy to remove different actinide physicochemical forms from skin, the results demonstrate that all products can remove the more soluble forms, but a further component of emulsifying or tensioactive action is required for less soluble forms. This indicates that for practical purposes, successful decontamination will depend on identification of the actinide element, the physicochemical form, and possibly the solvent. This study offers a simple, quick, cheap, reproducible screening method for efficacy evaluation of multiple products for removal of a variety of contaminants.

Coassembly of hypoxia-sensitive macrocyclic amphiphiles and extracellular vesicles for targeted kidney injury imaging and therapy.

BACKGROUND: Hypoxia is a major contributor to global kidney diseases. Targeting hypoxia is a promising therapeutic option against both acute kidney injury and chronic kidney disease; however, an effective strategy that can achieve simultaneous targeted kidney hypoxia imaging and therapy has yet to be established. Herein, we fabricated a unique nano-sized hypoxia-sensitive coassembly (Pc/C5A@EVs) via molecular recognition and self-assembly, which is composed of the macrocyclic amphiphile C5A, the commercial dye sulfonated aluminum phthalocyanine (Pc) and mesenchymal stem cell-excreted extracellular vesicles (MSC-EVs). RESULTS: In murine models of unilateral or bilateral ischemia/reperfusion injury, MSC-EVs protected the Pc/C5A complex from immune metabolism, prolonged the circulation time of the complex, and specifically led Pc/C5A to hypoxic kidneys via surface integrin receptor α4ß1 and αLß2, where Pc/C5A released the near-infrared fluorescence of Pc and achieved enhanced hypoxia-sensitive imaging. Meanwhile, the coassembly significantly recovered kidney function by attenuating cell apoptosis, inhibiting the progression of renal fibrosis and reducing tubulointerstitial inflammation. Mechanistically, the Pc/C5A coassembly induced M1-to-M2 macrophage transition by inhibiting the HIF-1α expression in hypoxic renal tubular epithelial cells (TECs) and downstream NF-κB signaling pathway to exert their regenerative effects. CONCLUSION: This synergetic nanoscale coassembly with great translational potential provides a novel strategy for precise kidney hypoxia diagnosis and efficient kidney injury treatment. Furthermore, our strategy of coassembling exogenous macrocyclic receptors with endogenous cell-derived membranous structures may offer a functional platform to address multiple clinical needs.

Structurally screening calixarenes as peptide transport activators.

Calixarenes are reportedly excellent activators that can remarkably improve the transport efficiencies of cell penetrating peptides. We employed eight calixarenes to systematically study the influence of structure on activation efficiency, which revealed that the scaffold, head group, and alkyl chain are all significant factors for activation efficiency by affecting affinities with the peptide and membrane.

Photoactivated Osmium Arene Anticancer Complexes.

Half-sandwich Os-arene complexes exhibit promising anticancer activity, but their photochemistry has hardly been explored. To exploit the photocytotoxicity and photochemistry of Os-arenes, O,O-chelated complexes [Os(η6-p-cymene)(Curc)Cl] (OsCUR-1, Curc = curcumin) and [Os(η6-biphenyl)(Curc)Cl] (OsCUR-2), and N,N-chelated complexes [Os(η6-biphenyl)(dpq)I]PF6 (OsDPQ-2, dpq = pyrazino[2,3-f][1,10]phenanthroline) and [Os(η6-biphenyl)(bpy)I]PF6 (OsBPY-2, bpy = 2,2'-bipyridine), have been investigated. The Os-arene curcumin complexes showed remarkable photocytotoxicity toward a range of cancer cell lines (blue light IC50: 2.6-5.8 µM, photocytotoxicity index PI = 23-34), especially toward cisplatin-resistant cancer cells, but were nontoxic to normal cells. They localized mainly in mitochondria in the dark but translocated to the nucleus upon photoirradiation, generating DNA and mitochondrial damage, which might contribute toward overcoming cisplatin resistance. Mitochondrial damage, apoptosis, ROS generation, DNA damage, angiogenesis inhibition, and colony formation were observed when A549 lung cancer cells were treated with OsCUR-2. The photochemistry of these Os-arene complexes was investigated by a combination of NMR, HPLC-MS, high energy resolution fluorescence detected (HERFD), X-ray adsorption near edge structure (XANES) spectroscopy, total fluorescence yield (TFY) XANES spectra, and theoretical computation. Selective photodissociation of the arene ligand and oxidation of Os(II) to Os(III) occurred under blue light or UVA excitation. This new approach to the design of novel Os-arene complexes as phototherapeutic agents suggests that the novel curcumin complex OsCUR-2, in particular, is a potential candidate for further development as a photosensitizer for anticancer photoactivated chemotherapy (PACT).

Transcriptional control of brain tumor stem cells by a carbohydrate binding protein.

Brain tumor stem cells (BTSCs) and intratumoral heterogeneity represent major challenges in glioblastoma therapy. Here, we report that the LGALS1 gene, encoding the carbohydrate binding protein, galectin1, is a key regulator of BTSCs and glioblastoma resistance to therapy. Genetic deletion of LGALS1 alters BTSC gene expression profiles and results in downregulation of gene sets associated with the mesenchymal subtype of glioblastoma. Using a combination of pharmacological and genetic approaches, we establish that inhibition of LGALS1 signaling in BTSCs impairs self-renewal, suppresses tumorigenesis, prolongs lifespan, and improves glioblastoma response to ionizing radiation in preclinical animal models. Mechanistically, we show that LGALS1 is a direct transcriptional target of STAT3 with its expression robustly regulated by the ligand OSM. Importantly, we establish that galectin1 forms a complex with the transcription factor HOXA5 to reprogram the BTSC transcriptional landscape. Our data unravel an oncogenic signaling pathway by which the galectin1/HOXA5 complex maintains BTSCs and promotes glioblastoma.

Pillar[5]arene-based supramolecular photosensitizer for enhanced hypoxic-tumor therapeutic effectiveness.

A galactose-targeting supramolecular photosensitizer system DOX@GP5⊃NBSPD was constructed based on a host-guest inclusion complex. The supramolecular system could achieve efficient delivery of DOX/NBS and selective release under GSH stimulation. In vitro studies revealed that this supramolecular DOX/NBS co-delivery system exhibited high ROS production and excellent cancer cell damage capability in a hypoxic environment. This strategy can therefore achieve enhanced hypoxic-tumor therapeutic effectiveness by chemo-photodynamic combination.