Cyclodextrin Drug Carrier Systems

β-Cyclodextrin-derived diallylamine salt: Synthesis and its copolymerizations

A diallyl amine salt monomer bearing a β-CD substituent was cyclopolymerized for the first time. The reaction of 6-O-toluenesulfonyl-β-cyclodextrin [(C6H10O5)6-(C5H7)]-CH2OTs with diallylamine followed by protonation afforded the diallylamine salt monomer [(C6H10O5)6-(C5H7)]-CH2NH+(CH2CH=CH2)2 Cl-] (I). The cyclopolymerization of monomer I and its copolymerization with monomer [Me2N+(CH2CH=CH2)2 Cl-] (II), [-O2CCH2NH+(CH2CH=CH2)2] (III), [H2O3PCH2NH+(CH2CH=CH2)2 Cl-] (IV) or [HO2CCH2CH(CO2H)NH+(CH2CH=CH2)2 Cl-] (V) yielded a series of copolymers having residues of β-CD and glycine or methyl phosphonate or aspartic acid. Terpolymerization in the presence of SO2 afforded polymers with alternating placements of the SO2 units. The solution properties of the pH-responsive polyzwitterions, including their viscosity, were examined. The water-insoluble terpolymer I/V/SO2 with 20 mol% β-CD residues removed the organic micropollutant 2-naphthol from an aqueous system via host/guest complexation. This work paves the way for the possible synthesis of cross-linked polymers that can simultaneously remove organic micropollutants and toxic metal ions (by complexation with the chelating glycine, aspartic acid, and aminomethyl phosphonate ligands) from contaminated aqueous systems.

Cyclodextrin-Induced Suppression of PEG Crystallization from the Melt in a PEG-Peptide Conjugate

The influence of alpha-cyclodextrin (αCD) on PEG crystallization is examined for a peptide-PEG conjugate, YYKLVFF-PEG3k comprising an amyloid peptide YYKLVFF linked to PEG with molar mass 3 kg mol-1. Remarkably, differential scanning calorimetry (DSC) and simultaneous synchrotron small-angle/wide-angle X-ray scattering (SAXS/WAXS) show that crystallization of PEG is suppressed by αCD, provided that the cyclodextrin content is sufficient. A hexagonal mesophase is formed instead. The αCD threading reduces the conformational flexibility of PEG, and hence suppresses crystallization. These results show that addition of cyclodextrins can be used to tune the crystallization of peptide-polymer conjugates and potentially other polymer/biomolecular hybrids.

Copolymerized Polymers Based on Cyclodextrins and Cationic Groups Enhance Therapeutic Effect of Rebamipide in the N-Acetylcysteine-Treated Dry Eye Model

Purpose

We aimed to prepare a β-cyclodextrin (β-CD) polymer using radical polymerization with co-monomers, 6-deoxy-6-(2-methacryloyloxyethylsuccinamide)-β-cyclodextrin (CD-MSAm) and N,N,N-trimethyl-N-(2-hydroxy-3-metacryloyloxopropyl)-ammonium chloride (QA) to design cyclodextrins suitable for use in ophthalmology. In addition, we evaluated their solubility and inclusion properties with rebamipide (REB), a poorly soluble drug, and investigated the usefulness of the β-CD polymer and REB (REB@CDQA) combination in treating dry eye.

Methods

The β-CD polymer (CD-MSAm-co-QA, CDQA) based on CD-MSAm/QA was prepared via radical polymerization, and the usefulness of REB@CDQA in treating dry eye was evaluated using a rabbit treated with N-acetylcysteine (dry eye model).

Results

The solubility of the CDQA powder was higher than that of the β-CD powder, and 80 nm colloids were observed in the CDQA solution. No corneal toxicity was observed in human corneal epithelial cells or rat corneas treated with 0.2% CDQA solution. The levels of REB dissolved in the CDQA solution were higher than those of the β-CD solution. Moreover, the application of the CDQA solution enhanced REB retention in the cornea and attenuated the transcorneal penetration of REB. In addition, instillation of REB@CDQA enhanced the volume of the lacrimal fluid and normalized the reduced mucin levels in the dry eye model. The extent of tear film breakup was attenuated by REB@CDQA instillation.

Conclusion

The CDQA solution enhanced the solubility of REB, and the combination of CDQA and REB enhanced the drug content in the corneal tissue. Moreover, the therapeutic effect on dry eye was higher than that of REB suspensions without CDQA.

Cyclodextrin-Induced Suppression of the Crystallization of Low-Molar-Mass Poly(ethylene glycol)

We examine the effect of alpha-cyclodextrin (αCD) on the crystallization of poly(ethylene glycol) (PEG) [poly(ethylene oxide), PEO] in low-molar-mass polymers, with M w = 1000, 3000, or 6000 g mol-1. Differential scanning calorimetry (DSC) and simultaneous synchrotron small-/wide-angle X-ray scattering (SAXS/WAXS) show that crystallization of PEG is suppressed by αCD, provided that the cyclodextrin content is sufficient. The PEG crystal structure is replaced by a hexagonal mesophase of αCD-threaded polymer chains. The αCD threading reduces the conformational flexibility of PEG and, hence, suppresses crystallization. These findings point to the use of cyclodextrin additives as a powerful means to tune the crystallization of PEG (PEO), which, in turn, will impact bulk properties including biodegradability.

Chemical accuracy for ligand-receptor binding Gibbs energies through multi-level SQM/QM calculations

Calculating the Gibbs energies of binding of ligand-receptor systems with a thermochemical accuracy of ± 1 kcal mol-1 is a challenge to computational approaches. After exploration of the conformational space of the host, ligand and their resulting complexes upon coordination by semi-empirical GFN2 MD and meta-MD simulations, the systematic refinement through a multi-level improvement of binding modes in terms of electronic energies and solvation is able to give Gibbs energies of binding of drug molecules to CB[8] and β-CD macrocyclic receptors with such an accuracy. The accurate treatment of a small number of structures outperforms system-specific force-matching and alchemical transfer model approaches without an extensive sampling and integration.

Efficiency of Encapsulation of Thioflavin T (ThT) into Polar and Nonpolar Environments of Different Bile Salt Aggregates: A Femtosecond Fluorescence Study

The binding of Thioflavin T (ThT) with various bile salts, a potential host molecule, has been analyzed by steady-state and time-resolved fluorescence spectroscopy. A comparative study has been executed to investigate the influence of confinement of different bile salts, namely, sodium cholate (NaCh), sodium taurocholate (NaTC), and sodium deoxycholate (NaDC) on binding and excited state torsional motion of ThT molecules. The changes in absorption and emission properties of probe molecules were found to be sensitive to increasing bile salt concentration in aqueous 0.2 (M) NaCl solutions. The photophysics of ThT mainly depends on hydrophobicity, morphology, and size of bile salt aggregates in solution. In the presence of bile salts, the emission intensity and emission lifetime of ThT increase significantly, indicating encapsulation of dye. Moreover, we have also investigated the effect of the ionic strength of the medium by sodium chloride (NaCl) on the spectroscopic properties of ThT in the restricted surroundings of aqueous bile salts. It is observed that the fluorescence lifetime of ThT in bile salts increases significantly in the presence of NaCl. The encapsulation efficiency of ThT in bile salt aggregates has been assessed by iodide (I-) as an external ionic quencher. We found that NaDC aggregates are more efficient in the modulation of photophysical properties of ThT and also provide better protection efficiency to decrease the nonradiative deactivation processes.

Intracerebroventricular 2-hydroxypropyl-γ-cyclodextrin alleviates hepatic manifestations without distributing to the liver in a murine model of Niemann-Pick disease type C

Niemann-Pick disease type C (NPC) is a lysosomal lipid storage disorder characterized by progressive neurodegeneration and hepatic dysfunction. A cyclic heptasaccharide, 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), is currently under clinical investigation for NPC, but its adverse events remain problematic. We previously identified that a cyclic octasaccharide, 2-hydroxypropyl-γ-cyclodextrin (HP-γ-CD), also ameliorated NPC manifestations with higher biocompatibility than HP-β-CD. However, preclinical studies describing the associations between the biodistribution and pharmacodynamics of these compounds, which are essential for clinical application, are still lacking. Here, we investigated these properties of HP-γ-CD by measuring its organ biodistribution and therapeutic effect after systemic and central administration. The effect of HP-γ-CD on disturbed cholesterol homeostasis appeared within several hours after exposure and persisted for several days in NPC model cells and mice. Tissue distribution indicated that only a small fraction of subcutaneously administered HP-γ-CD rapidly distributed to peripheral organs and contributed to disease amelioration. We found that a subcutaneous dose of HP-γ-CD negligibly ameliorated neurological characteristics because it has limited penetration of the blood-brain barrier; however, an intracerebroventricular microdose unexpectedly attenuated hepatic dysfunction without the detection of HP-γ-CD in the liver. These results demonstrate that central administration of HP-γ-CD can indirectly attenuate peripheral manifestations of NPC.

Self-Inclusion Complexation of Electron-Accepting Guest into Electron-Donating Cyclic Host by Photoexcitation

Self-inclusion complexes consisting of host-guest conjugates are one of the unique supramolecular structures because they form in-state and out-state depending on the external stimuli. Despite many reports of the stimuli-responsive self-inclusion complex formation, study of the structural relaxation from out-state to in-state by photoexcitation has been unexplored. Herein, we report that an electron-donating host and an electron-accepting guest conjugate exhibits the structural relaxation from out-state to in-state by photoexcitation. Formation of the in-state in the excited state resulted in exciplex emission along with the locally excited emission from the out-state. Moreover, this structural relaxation by photoexcitation was suppressed not only by temperature, but also by the presence of guest molecules, resulting in changes in the ratio of the dual emission intensities.

Application of sodium sulfobutylether-β-cyclodextrin based on encapsulation

Sodium Sulfobutylether-β-cyclodextrin (SBE-β-CD) is a derivative of β-cyclodextrin, characterized by its stereo structure, which closely resembles a truncated cone with a hydrophobic internal cavity. The solubility of insoluble substances within the hydrophobic cavity is significantly enhanced, reducing contact between the guest and the environment. Consequently, SBE-β-CD is frequently employed as a co-solvent and stabilizer. As the research progresses, it has been observed that the inclusion of SBE-β-CD is reversible and competitive. Besides, some inclusion complexes undergo distinct physicochemical property alterations compared to the guests. Additionally, certain guests exhibit varying inclusions with SBE-β-CD at different concentrations. These features have contributed to the expanding applications. SBE-β-CD finds widespread application in pharmaceutics as a protective agent and pKa regulator, in pharmaceutical analysis as a chiral substance separator, and in biomedical engineering for encapsulating dyes and modifying sensors. The article will elaborate in detail on the physicochemical properties of SBE-β-CD, encapsulation principles, and factors influencing the formation of inclusion complexes. Furthermore, the review focuses on the application of SBE-β-CD through encapsulation in pharmaceutics, pharmaceutical analysis, and biomedical engineering. Finally, the prospects and potential applications of SBE-β-CD are discussed.

Methamphetamine Removal from Aquatic Environments by Magnetic Microrobots with Cyclodextrin Chiral Recognition Elements

The growing consumption of drugs of abuse together with the inefficiency of the current wastewater treatment plants toward their presence has resulted in an emergent class of pollutants. Thus, the development of alternative approaches to remediate this environmental threat is urgently needed. Microrobots, combining autonomous motion with great tunability for the development of specific tasks, have turned into promising candidates to take on the challenge. Here, hybrid urchin-like hematite (α-Fe2O3) microparticles carrying magnetite (Fe3O4) nanoparticles and surface functionalization with organic β-cyclodextrin (CD) molecules are prepared with the aim of on-the-fly encapsulation of illicit drugs into the linked CD cavities of moving microrobots. The resulting mag-CD microrobots are tested against methamphetamine (MA), proving their ability for the removal of this psychoactive substance. A dramatically enhanced capture of MA from water with active magnetically powered microrobots when compared with static passive CD-modified particles is demonstrated. This work shows the advantages of enhanced mass transfer provided by the externally controlled magnetic navigation in microrobots that together with the versatility of their design is an efficient strategy to clean polluted waters.

Anti-Candida activity and in vitro toxicity screening of antifungals complexed with β-cyclodextrin

The emergence of resistant fungal species and the toxicity of currently available antifungal drugs are relevant issues that require special consideration. Cyclodextrins inclusion complexes could optimize the antimicrobial activity of such drugs and create a controlled release system with few side effects. This study aimed to assess the in vitro toxicity and antifungal effectiveness of nystatin (Nys) and chlorhexidine (Chx) complexed or not with β-cyclodextrin (βCD). First, a drug toxicity screening was performed through the Artemia salina bioassay. Then, the minimum inhibitory concentrations (MICs) against Candida albicans were determined with the broth microdilution test. After MICs determination, the cytotoxicity of the drugs was evaluated through the methyl-thiazolyl-tetrazolium (MTT) and neutral red (NR) assays and through cell morphology analysis. The PROBIT analysis was used to determine the median lethal concentration (LC50), and the cell viability values were submitted to one-way analysis of variance(ANOVA)/Tukey (α = 0.05). Overall, the βCD-complexed antifungals were less toxic against A. salina than their raw forms, suggesting that inclusion complexes can reduce the toxicity of drugs. The MICs obtained were as follows: Nys 0.5 mg/L; Nys:βCD 4 mg/L; Chx 4 mg/L; and Chx:βCD 8 mg/L. Chx showed significant cytotoxicity (MTT: 12.9 ± 9.6%; NR: 10.6 ± 12.5%) and promoted important morphological changes. Cells exposed to the other drugs showed viability above 70% with no cellular damage. These results suggest that antifungals complexed with βCD might be a biocompatible option for the treatment of Candida-related infections.

Supramolecular Synthesis of Star Polymers

Supramolecular polymers, in which monomers are assembled via intermolecular interactions, have been extensively studied. The fusion of supramolecular polymers with conventional polymers has attracted the attention of many researchers. In this review article, the recent progress in the construction of supramolecular star polymers, including regular star polymers and miktoarm star polymers, is discussed. The initial sections briefly provide an overview of the conventional classification and synthesis methods for star polymers. Coordination-driven self-assembly was investigated for the supramolecular synthesis of star polymers. Star polymers with multiple polymer chains radiating from metal-organic polyhedra (MOPs) have also been described. Particular focus has been placed on the synthesis of star polymers featuring supramolecular cores formed through hydrogen-bonding-directed self-assembly. After describing the synthesis of star polymers based on host-guest complexes, the construction of miktoarm star polymers based on the molecular recognition of coordination capsules is detailed.

Critical Assessment of Micellar Surface Charge-Dependent Disaggregation and Reaggregation of a Bis-Indole Self-Aggregate: What Should Be Our Case-Dependent Choice?

"Aggregation-caused quenching" is a deep-seated mechanism and has been widely used by the researchers as the possible basis for new sensor development. Contrast to aggregation, its turn around process, disaggregation, has gained much less consideration so far. Unfortunately, study of the further scope for reaggregation of the disaggregated probe assembly in the same solution, as and when required, is still under the rare category. The central theme of the current study is focused on this aspect. For this purpose, the effects of headgroup charge (cationic, anionic, and nonionic) and polarity of the micelles on the degree of disaggregation and subsequent emission amelioration of a synthesized bis-indole derivative, 3,3'-bisindolyl(phenyl)methane (BIPM), are studied using steady-state and time-resolved spectroscopic techniques. The relative emission yield of BIPM (φf = 0.01) is significantly enhanced in the presence of cetyltrimethylammonium bromide (φf = 0.21) and polyoxyethylene (20) sorbitan monolaurate (φf = 0.24), whereas comparatively less emission enhancement is recorded within the sodium dodecyl sulfate system (φf = 0.07). In contrast, addition of an external biophilic agent, uric acid, causes requenching of the enhanced emission because of the reaggregation of the disaggregated probes. Detailed microscopic and calorimetric studies are also adopted to investigate the disaggregation-reaggregation mechanism of BIPM associations. The study will provide prior insights about the use of suitable micellar systems for the required degree of disaggregation as well as for the modulation of emission efficiency by controlled tuning of the disaggregation-reaggregation equilibrium for similar probe associations in pure aqueous medium avoiding any chemical transformation.

Synthesis and bioevaluation of water-soluble β-cyclodextrin-diterpene acid conjugates

A series of β-cyclodextrin (β-CD)-conjugates were prepared by combining three abietane-type diterpene acids with two azide-functionalized β-CDs via click chemistry, and the antiviral activity against wild-type and omicron SARS-CoV-2 spike pseudovirus as well as the antibacterial activity against Escherichia coli were investigated. All the synthesised conjugates exhibited no significant cytotoxicity to BHK-21-hACE2 cells with cell viability over 80% at concentration of 15 µM. Among the conjugates, the heptavalent β-CD-dehydroabietic acid conjugate 6b exhibited higher anti-SARS-CoV-2 activity against the omicron variant compared to the other conjugates. This study suggested that the multivalent diterpene acid derivatives may have potential application against coronaviruses as entry inhibitors.

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.

Interaction of Cyclodextrins with Amphiphilic Alternating Cooligomers Possessing the Dense Triazole Backbone

The interaction of cyclodextrins (CDs) with structure-controlled polymers is expected to provide significant insights into macromolecular recognition. However, the interaction of CDs with structure-controlled polymers has been an underexamined issue of investigation. Herein, alternating amphiphilic cooligomers (oligoCnAH, where n denotes the carbon number of alkyl groups; n = 4, 8, and 12) were synthesized by copper(I)-catalyzed azide-alkyne cycloaddition polymerization of heterodimers of 4-azido-5-hexynoic acid (AH) derivatives carrying N-alkylamide and t-butyl (tBu) ester side chains, followed by hydrolysis of the tBu ester, to study the interaction of CDs with oligoCnAH by 1H NMR, nuclear Overhauser effect spectroscopy, and pulse-field-gradient spin-echo NMR. These NMR studies indicated that αCD interacted with oligoC4AH, αCD and βCD interacted with oligoC8AH, and all CDs interacted with oligoC12AH. Based on the equilibrium models proposed, the binding constants were evaluated for the binary mixtures, which showed interaction. Comparing the interactions of the CDs/oligoC12AH binary mixtures with those of the binary mixtures of CDs and alternating copolymers of sodium maleate and dodecyl vinyl ether (polyC12M), it is concluded that oligoC12AH forms less stable micelles than does polyC12M presumably because of the lower molecular weight, the hydrophilic amide groups in the side chain, and the longer interval between neighboring C12 groups in oligoC12AH.

Calixarenes and cyclodextrins as off- and on-fluorescence probes for carbazole

Absorption and fluorescence spectra of the nitrogen polycyclic aromatic hydrocarbon carbazole (CZL) were analyzed with native cyclodextrins (CD;α,β,γ); derivatizedCD(hydroxypropyl-β-cyclodextrin,HPCD; methyl-β-cyclodextrin,MeCD) and p-sulfonated calixarenes (SCAn, with n = 6 and 8) macrocycles. The results showed a slight increase in the absorbance ofCZLwithCD, but the mixture ofCZLwithSCAshowed lower absorption than the sum of the individual spectra. Also, changes in fluorescence were observed by adding the macrocycles, quenching withSCA, and significant increases withCD. The higher fluorescence enhancement was withHPCDrationalized as a complex formation with 1:1 stoichiometry, with an average value for the association constant (KA) of (12 ± 1) x 102M-1, and a quantum yield ratio between the complexedCZLand freeCZL(ΦCZL-HPCD/ΦCZL) of (1.56 ± 0.02) at neutral pH and 25.0 °C. These increases in fluorescence were used as an on-fluorescence switch to develop a supramolecular analytical method forCZLin aqueous samples. The best analytical parameters were inHPCD(LOD = 1.41 ± 0.01 ng mL-1). The method was validated in aqueous samples of river and tap water with recoveries between 96%-104%. The proposed supramolecular method is quick, direct, selective and represents an alternative and low-cost analysis method.

Lipid-Based Nanoparticles as Oral Drug Delivery Systems: Overcoming Poor Gastrointestinal Absorption and Enhancing Bioavailability of Peptide and Protein Therapeutics

Delivery and formulation of oral peptide and protein therapeutics have always been a challenge for the pharmaceutical industry. The oral bioavailability of peptide and protein therapeutics mainly relies on their gastrointestinal solubility and permeability which are affected by their poor membrane penetration, high molecular weight and proteolytic (chemical and enzymatic) degradation resulting in limited delivery and therapeutic efficacy. The present review article highlights the challenges and limitations of oral delivery of peptide and protein therapeutics focusing on the application, potential and importance of solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) as lipid-based drug delivery systems (LBDDSs) and their advantages and drawbacks. LBDDSs, due to their lipid-based matrix can encapsulate both lipophilic and hydrophilic drugs, and by reducing the first-pass effect and avoiding proteolytic degradation offer improved drug stability, dissolution rate, absorption, bioavailability and controlled drug release. Furthermore, their small size, high surface area and surface modification increase their mucosal adhesion, tissue-targeted distribution, physiological function and half-life. Properties such as simple preparation, high-scale manufacturing, biodegradability, biocompatibility, prolonged half-life, lower toxicity, lower adverse effects, lipid-based structure, higher drug encapsulation rate and various drug release profile compared to other similar carrier systems makes LBDDSs a promising drug delivery system (DDS). Nevertheless, undesired physicochemical features of peptide and protein drug development and discovery such as plasma stability, membrane permeability and circulation half-life remain a serious challenge which should be addressed in future.

Overcoming barriers with non-covalent interactions: supramolecular recognition of adamantyl cucurbit[n]uril assemblies for medical applications

Adamantane, a staple in medicinal chemistry, recently became a cornerstone of a supramolecular host-guest drug delivery system, ADA/CB[n]. Owing to a good fit between the adamantane cage and the host cavity of the cucurbit[n]uril macrocycle, formed strong inclusion complexes find applications in drug delivery and controlled drug release. Note that the cucurbit[n]uril host is not solely a delivery vehicle of the ADA/CB[n] system but rather influences the bioactivity and bioavailability of drug molecules and can tune drug properties. Namely, as host-guest interactions are capable of changing the intrinsic properties of the guest molecule, inclusion complexes can become more soluble, bioavailable and more resistant to metabolic conditions compared to individual non-complexed molecules. Such synergistic effects have implications for practical bioapplicability of this complex system and provide a new viewpoint to therapy, beyond the traditional single drug molecule approach. By achieving a balance between guest encapsulation and release, the ADA/CB[n] system has also found use beyond just drug delivery, in fields like bioanalytics, sensing assays, bioimaging, etc. Thus, chemosensing in physiological conditions, indicator displacement assays, in vivo diagnostics and hybrid nanostructures are just some recent examples of the ADA/CB[n] applicability, be it for displacements purposes or as cargo vehicles.

Development of nanoparticles based on amphiphilic cyclodextrins for the delivery of active substances

Although amphiphilic cyclodextrin derivatives (ACDs) serve as valuable building blocks for nanomedicine formulations, their widespread production still encounters various challenges, limiting large-scale manufacturing. This work focuses on a robust alternative pathway using mineral base catalysis to transesterify β-cyclodextrin with long-chain vinyl esters, yielding ACD with modular and controlled hydrocarbon chain grafting. ACDs with a wide range of degrees of substitution (DS) were reliably synthesized, as indicated by extensive physicochemical characterization, including MALDI-TOF mass spectrometry. The influence of various factors, including the type of catalyst and the length of the hydrocarbon moiety of the vinyl ester, was studied in detail. ACDs were assessed for their ability to form colloidal suspensions by nanoprecipitation, with or without PEGylated phospholipid. Small-angle X-ray scattering and cryo-electron microscopy revealed the formation of nanoparticles with distinct ultrastructures depending on the DS: an onion-like structure for low and very high DS, and reversed hexagonal organization for DS between 4.5 and 6.1. We confirmed the furtivity of the PEGylated versions of the nanoparticles through complement activation experiments and that they were well tolerated in-vivo on a zebrafish larvae model after intravenous injection. Furthermore, a biodistribution experiment showed that the nanoparticles left the bloodstream within 10 h after injection and were phagocytosed by macrophages.

The Potential of Cyclodextrins as Inhibitors for the BM2 Protein: An In Silico Investigation

The influenza BM2 transmembrane domain (BM2TM), an acid-activated proton channel, is an attractive antiviral target due to its essential roles during influenza virus replication, whereas no effective inhibitors have been reported for BM2. In this study, we draw inspiration from the properties of cyclodextrins (CDs) and hypothesize that CDs of appropriate sizes may possess the potential to act as inhibitors of the BM2TM proton channel. To explore this possibility, molecular dynamics simulations were employed to assess their inhibitory capabilities. Our findings reveal that CD4, CD5, and CD6 are capable of binding to the BM2TM proton channel, resulting in disrupted water networks and reduced hydrogen bond occupancy between H19 and the solvent within the BM2TM channel necessary for proton conduction. Notably, CD4 completely obstructs the BM2TM water channel. Based on these observations, we propose that CD4, CD5, and CD6 individually contribute to diminishing the proton transfer efficiency of the BM2 protein, and CD4 demonstrates promising potential as an inhibitor for the BM2 proton channel.

Targeted Nanoparticles: the Smart Way for the Treatment of Colorectal Cancer

Colorectal cancer (CRC) is a widespread cancer that starts in the digestive tract. It is the third most common cause of cancer deaths around the world. The World Health Organization (WHO) estimates an expected death toll of over 1 million cases annually. The limited therapeutic options as well as the drawbacks of the existing therapies necessitate the development of non-classic treatment approaches. Nanotechnology has led the evolution of valuable drug delivery systems thanks to their ability to control drug release and precisely target a wide variety of cancers. This has also been extended to the treatment of CRC. Herein, we shed light on the pertinent research that has been performed on the potential applications of nanoparticles in the treatment of CRC. The various types of nanoparticles in addition to their properties, applications, targeting approaches, merits, and demerits are discussed. Furthermore, innovative therapies for CRC, including gene therapies and immunotherapies, are also highlighted. Eventually, the research gaps, the clinical potential of such delivery systems, and a future outlook on their development are inspired.

Carboranes as Potent Phenyl Mimetics: A Comparative Study on the Reversal of ABCG2-Mediated Drug Resistance by Carboranylquinazolines and Their Organic Isosteres

Multidrug resistance is a major challenge in clinical cancer therapy. In particular, overexpression of certain ATP-binding cassette (ABC) transporter proteins, like the efflux transporter ABCG2, also known as breast cancer resistance protein (BCRP), has been associated with the development of resistance to applied chemotherapeutic agents in cancer therapies, and therefore targeted inhibition of BCRP-mediated transport might lead to reversal of this (multidrug) resistance (MDR). In a previous study, we have described the introduction of a boron-carbon cluster, namely closo-dicarbadodecaborane or carborane, as an inorganic pharmacophore into a polymethoxylated 2-phenylquinazolin-4-amine backbone. In this work, the scope was extended to the corresponding amide derivatives. As most of the amide derivatives suffered from poor solubility, only the amide derivative QCe and the two amine derivatives DMQCc and DMQCd were further investigated. Carboranes are often considered as sterically demanding phenyl mimetics or isosteres. Therefore, the organic phenyl and sterically demanding adamantyl analogues of the most promising carborane derivatives were also investigated. The studies showed that the previously described DMQCd, a penta-methoxylated N-carboranyl-2-phenylquinazolin-4-amine, was by far superior to its organic analogues in terms of cytotoxicity, inhibition of the human ABCG2 transporter, as well as the ability to reverse BCRP-mediated mitoxantrone resistance in MDCKII-hABCG2 and HT29 colon cancer cells. Our results indicate that DMQCd is a promising candidate for further in vitro as well as in vivo studies in combination therapy for ABCG2-overexpressing cancers.

Development of α-Cyclodextrin-Based Orally Disintegrating Tablets for 4-Phenylbutyrate

Despite major improvements brought about by the introduction of taste-masked formulations of 4-phenylbutyrate (PB), poor compliance remains a significant drawback to treatment for some pediatric and dysphagic patients with urea cycle disorders (UCDs). This study reports on the development of a cyclodextrin (CD)-based orally disintegrating tablet (ODT) formulation for PB as an alternative to existing formulations. This is based on previous reports of the PB taste-masking potential of CDs and the suitability of ODTs for improving compliance in pediatric and dysphagic populations. In preliminary studies, the interactions of PB with α and βCD in the solid state were characterized using X-ray diffraction, scanning electron microscopy, dissolution, and accelerated stability studies. Based on these studies, lyophilized PB-CD solid systems were formulated into ODTs after wet granulation. Evaluation of the ODTs showed that they had adequate physical characteristics, including hardness and friability and good storage stability. Notably, the developed αCD-based ODT for PB had a disintegration time of 28 s and achieved a slightly acidic and agreeable pH (≈5.5) in solution, which is suitable for effective PB-CD complexation and taste masking. The developed formulation could be helpful as an alternative to existing PB formulations, especially for pediatric and dysphagic UCD patients.

Study of Drug Delivery Using Purely Organic Macrocyclic Containers-Cucurbit[7]uril and Pillararene

An impaired immune system is the root of various human ailments provoking the urge to find vehicle-mediated quick delivery of small drug molecules and other vital metabolites to specific tissues and organs. Thus, drug delivery strategies are in need of improvement in therapeutic efficacy. It can be achieved only by increasing the drug-loading capacity, increasing the sustained release of a drug to its target site, easy relocation of drug molecules associated with facile complexation-induced properties of molecular vehicles, and high stimuli-responsive drug administration. Supramolecular drug delivery systems (SDDS) provide a much needed robust yet facile platform for fabricating innovative drug nanocarriers assembled by thermodynamically noncovalent interaction with the tunable framework and above-mentioned properties. Measures of cytotoxicity and biocompatibility are the two main criteria that lie at the root of any promising medicinal applications. This Review features significant advancements in (i) supramolecular host-guest complexation using cucurbit[7]uril (CB[7]), (ii) encapsulation of the drug and its delivery application tailored for CB[7], (iii) self-assembly of supramolecular amphiphiles, (iv) supramolecular guest relay using host-protein nanocavities, (v) pillararene (a unique macrocyclic host)-mediated SDDS for the delivery of smart nanodrugs for siRNA, fluorescent molecules, and insulin for juvenile diabetes. Furthermore, fundamental questions and future hurdles related to smart SDDS based on CB[7] and pillararenes and their future promising breakthrough implementations are also distinctly outlined in this Review.

Folate-Appended Hydroxypropyl-β-Cyclodextrin Induces Autophagic Cell Death in Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) is a heterogenous myeloid neoplasm that remains challenging to treat. Because intensive conventional chemotherapy reduces survival rates in elderly patients, drugs with lower toxicity and fewer side effects are needed urgently. 2-Hydroxypropyl-β-cyclodextrin (HP-β-CyD) is used clinically as a pharmaceutical excipient for poorly water-soluble drugs. Previously, we showed that HP-β-CyD exerts antitumor activity by disrupting cholesterol homeostasis. Recently, we developed folate-conjugated HP-β-CyD (FA-HP-β-CyD) and demonstrated its potential as a new antitumor agent that induces not only apoptosis, but also autophagic cell death; however, we do not know whether FA-HP-β-CyD exerts these effects against AML. Here, we investigated the effects of FA-HP-β-CyD on folate receptor (FR)-expressing AML cells. We found that the cytotoxic activity of FA-HP-β-CyD against AML cells was stronger than that of HP-β-CyD. Also, FA-HP-CyD induced the formation of autophagosomes in AML cell lines. FA-HP-β-CyD increased the inhibitory effects of cytarabine and a BCL-2-selective inhibitor, Venetoclax, which are commonly used treat elderly AML patients. Notably, FA-HP-β-CyD suppressed the proliferation of AML cells in BALB/c nude recombinase-activating gene-2 (Rag-2)/Janus kinase 3 (Jak3) double-deficient mice with AML. These results suggest that FA-HP-β-CyD acts as a potent anticancer agent for AML chemotherapy by regulating autophagy.

Endocytosis inhibitors block SARS-CoV-2 pseudoparticle infection of mink lung epithelium

Introduction

Both spill over and spill back of SARS-CoV-2 virus have been reported on mink farms in Europe and the United States. Zoonosis is a public health concern as dangerous mutated forms of the virus could be introduced into the human population through spillback.

Methods

The purpose of our study was to determine the SARS-CoV-2 entry mechanism using the mink lung epithelial cell line (Mv1Lu) and to block entry with drug inhibitors.

Results

Mv1Lu cells were susceptible to SARS-CoV-2 viral pseudoparticle infection, validating them as a suitable disease model for COVID-19. Inhibitors of TMPRSS2 and of endocytosis, two pathways of viral entry, were tested to identify those that blocked infection. TMPRSS2 inhibitors had minimal impact, which can be explained by the apparent lack of activity of this enzyme in the mink and its localization within the cell, not on the cell surface.

Discussion

Dyngo4a, a small molecule endocytosis inhibitor, significantly reduced infection, supporting the conclusion that the entry of the SARS-CoV-2 virus into Mv1Lu cells occurs primarily through endocytosis. The small molecule inhibitors that were effective in this study could potentially be used therapeutically to prevent SARS-CoV-2 infection in mink populations. This study will facilitate the development of therapeutics to prevent zoonotic transmission of SARS-CoV-2 variants to other animals, including humans.

"On-Off" Switching of Functional Guest Molecules via Exchange of Natural Product Solubilizing Agents

For the development of delivery systems, the solubilization of hydrophobic guest molecules in water is an important yet challenging task. This can be achieved by preparing stable aqueous solutions with a high concentration of guest molecules using a natural product as a solubilizing agent and a mechanochemical high-speed vibration milling apparatus as a solubilizing method. Various solubilizing agent-guest molecule complexes can be obtained via the exchange between solubilizing agents, which enables the "on-off" switching of the properties of functional guest molecules, such as fluorescence intensity, and photodynamic activity. In the exchange method, guest molecules can transfer into cell membranes such as lysosomes and exosomes. Therefore, the exchange method of the solubilizing agents not only creates novel solubilizing agent-guest molecule complexes but also is applied to drug delivery systems.

β-Cyclodextrin Nanophotosensitizers for Redox-Sensitive Delivery of Chlorin e6

The aim of this study is to prepare redox-sensitive nanophotosensitizers for the targeted delivery of chlorin e6 (Ce6) against cervical cancer. For this purpose, Ce6 was conjugated with β-cyclodextrin (bCD) via a disulfide bond, creating nanophotosensitizers that were fabricated for the redox-sensitive delivery of Ce6 against cancer cells. bCD was treated with succinic anhydride to synthesize succinylated bCD (bCDsu). After that, cystamine was attached to the carboxylic end of bCDsu (bCDsu-ss), and the amine end group of bCDsu-ss was conjugated with Ce6 (bCDsu-ss-Ce6). The chemical composition of bCDsu-ss-Ce6 was confirmed with 1H and 13C NMR spectra. bCDsu-ss-Ce6 nanophotosensitizers were fabricated by a dialysis procedure. They formed small particles with an average particle size of 152.0 ± 23.2 nm. The Ce6 release rate from the bCDsu-ss-Ce6 nanophotosensitizers was accelerated by the addition of glutathione (GSH), indicating that the bCDsu-ss-Ce6 nanophotosensitizers have a redox-sensitive photosensitizer delivery capacity. The bCDsu-ss-Ce6 nanophotosensitizers have a low intrinsic cytotoxicity against CCD986Sk human skin fibroblast cells as well as Ce6 alone. However, the bCDsu-ss-Ce6 nanophotosensitizers showed an improved Ce6 uptake ratio, higher reactive oxygen species (ROS) production, and phototoxicity compared to those of Ce6 alone. GSH addition resulted in a higher Ce6 uptake ratio, ROS generation, and phototoxicity than Ce6 alone, indicating that the bCDsu-ss-Ce6 nanophotosensitizers have a redox-sensitive biological activity in vitro against HeLa human cervical cancer cells. In a tumor xenograft model using HeLa cells, the bCDsu-ss-Ce6 nanophotosensitizers efficiently accumulated in the tumor rather than in normal organs. In other words, the fluorescence intensity in tumor tissues was significantly higher than that of other organs, while Ce6 alone did not specifically target tumor tissue. These results indicated a higher anticancer activity of bCDsu-ss-Ce6 nanophotosensitizers, as demonstrated by their efficient inhibition of the growth of tumors in an in vivo animal tumor xenograft study.

Growing Impact of Intramolecular Click Chemistry in Organic Synthesis

Click Chemistry, a modular, rapid, and one of the most reliable tool for the regioselective 1,2,3-triazole forming [3+2] reaction of organic azide and terimal alkyne is widely explored in various emerging domains of research ranging from chemical biology to catalysis and medicinal chemistry to material science. This regioselective reaction from a diverse range of azido-alkyne scaffolds has been well performed in both intermolecular as well as intramolecular fashions. In comparison to the intermolecular metal (Cu/Ru/Ni) variant of 'Click Chemistry', the intramolecular click tool is little addressed. The intramolecular click chemistry is exemplified as a mordern tool of cyclization which involves metal-catalyzed (CuAAC/RuAAC) cyclization, organo-catalyzed cyclization, and thermal-induced topochemical reaction. Thus, we report herein the recent approaches on intramolecular azide-alkyne cycloaddition 'Click Chemistry' with their wide-spread emerging applications in the developement of a diverse range of molecules including fused-heterocycles, well-defined peptidomemics, and macrocyclic architectures of various notable features.

Dextrin-Based Adsorbents Synthesized via a Sustainable Approach for the Removal of Salicylic Acid from Water

Pharmaceuticals such as salicylic acid are commonly detected in wastewater and surface waters, increasing concern for possible harmful effects on humans and the environment. Their difficult removal via conventional treatments raised the need for improved strategies, among which the development of bioderived adsorbents gained interest because of their sustainability and circularity. In this work, biobased cross-linked adsorbents, synthesized via a sustainable approach from starch derivatives, namely beta-cyclodextrins and maltodextrins, were at first characterized via FTIR-ATR, TGA, SEM, and elemental analysis, showing hydrophilic granular morphologies endowed with specific interaction sites and thermal stabilities higher than 300 °C. Subsequently, adsorption tests were carried out, aiming to assess the capabilities of such polymers on the removal of salicylic acid, as a case study, from water. Batch tests showed rapid kinetics of adsorption with a removal of salicylic acid higher than 90% and a maximum adsorption capacity of 17 mg/g. Accordingly, continuous fixed bed adsorption tests confirmed the good interaction between the polymers and salicylic acid, while the recycling of the adsorbents was successfully performed up to four cycles of use.

Tuning the Solution Self-Assembly of a Peptide-PEG (Polyethylene Glycol) Conjugate with α-Cyclodextrin

Cyclodextrins are saccharide ring molecules which act as host cavities that can encapsulate small guest molecules or thread polymer chains. We investigate the influence of alpha-cyclodextrin (αCD) on the aqueous solution self-assembly of a peptide-polymer conjugate YYKLVFF-PEG3K previously studied by our group [Castelletto et al., Polym. Chem., 2010, 1, 453-459]. This conjugate comprises a designed amyloid-forming peptide YYKLVFF that contains the KLVFF sequence from Amyloid β peptide, Aβ16-20, along with two aromatic tyrosine residues to enhance hydrophobicity, as well as polyethylene glycol PEG with molar mass 3 kg mol-1 . The conjugate self-assembles into β-sheet fibrils in aqueous solution. Here we show that complexation with αCD instead generates free-floating nanosheets in aqueous solution (with a β-sheet structure). The nanosheets comprise a bilayer with a hydrophobic peptide core and highly swollen PEG outer layers. The transition from fibrils to nanosheets is driven by an increase in the number of αCD molecules threaded on the PEG chains, as determined by 1 H NMR spectroscopy. These findings point to the use of cyclodextrin additives as a powerful means to tune the solution self-assembly in peptide-polymer conjugates and potentially other polymer/biomolecular hybrids.

Curcumin-sulfobutyl-ether beta cyclodextrin inclusion complex: preparation, spectral characterization, molecular modeling, and antimicrobial activity

Urinary tract infections (UTIs) caused by Gram-negative bacteria E. coli is responsible for 80-90% of uncomplicated cases in women. The increased prevalence of antibiotic resistance has made the management of UTIs more challenging. Plant-derived compounds have long been used to treat various diseases, and constitute an alternative to antibiotic resistance. Curcumin (CUR), a naturally occurring polyphenolic phytoconstituent obtained from Curcuma longa is endowed with diverse medicinal properties. The present study aims to form a complex of CUR with Sulfobutyl ether-β-cyclodextrin (SBEβCD) to overcome the poor solubility and bioavailability of CUR and to evaluate the antimicrobial activity of CUR-SBEβCD. Phase solubility studies and spectral characterization showed the entrapment of CUR in the SBEβCD cavity. In silico docking studies performed to investigate the complexation process of CUR with SBEβCD, revealed that the methoxy group and OH group of CUR interacted with SBEβCD. The cytotoxicity and HET-CAM assays confirmed that CUR-SBEβCD was non-irritant. The prepared complex investigated with the disc diffusion method showed antimicrobial activity with a zone of inhibition (ZOI) of 13 mm against Escherichia coli (E. coli) and 11.5 mm against Staphylococcus aureus (S. aureus) whereas CUR alone did not show any ZOI. It can be concluded that prepared CUR-SBEβCD demonstrated superior antimicrobial activity and therefore can be a promising alternative for the treatment of UTIs.Communicated by Ramaswamy H. Sarma.

Harnessing Pillar[5]arene Host-Guest Complexation To Improve pH Stability and Affect Enzymatic Degradation of the Anticancer Prodrug Capecitabine: A 19 F NMR Study

Cancer is a global health problem, and supramolecular chemotherapy is emerging as a novel strategy to battle the disease. Here, we first evaluated the thermodynamic and kinetic stability of the complexes formed between several water-soluble per-substituted pillar[5]arene derivatives and capecitabine (1), a widely used oral chemotherapeutic prodrug. The exchange rate was studied, for the first time in pillararene chemistry, by the 19 F guest exchange saturation transfer (GEST) NMR technique. Importantly, when we evaluated the effect of complexation on the characteristics of 1, we found that the complexation of 1 with such pillar[5]arene hosts increased capecitabine stability at acidic pH very significantly and slowed its enzymatic degradation by the carboxylesterase enzyme in a manner that depended on the host. These interesting findings could have implications on the clinical use of this heavily used prodrug and might affect the management of cancer patients.

Supramolecular nanomedicines based on host-guest interactions of cyclodextrins

In the biomedical and pharmaceutical fields, cyclodextrin (CD) is undoubtedly one of the most frequently used macrocyclic compounds as the host molecule because it has good biocompatibility and can increase the solubility, bioavailability, and stability of hydrophobic drug guests. In this review, we generalized the unique properties of CDs, CD-related supramolecular nanocarriers, supramolecular controlled release systems, and targeting systems based on CDs, and introduced the paradigms of these nanomedicines. In addition, we also discussed the prospects and challenges of CD-based supramolecular nanomedicines to facilitate the development and clinical translation of these nanomedicines.

Different solubilizing ability of cyclodextrin derivatives for cholesterol in Niemann-Pick disease type C treatment

BACKGROUND

Niemann-Pick disease type C (NPC) is a fatal neurodegenerative disorder caused by abnormal intracellular cholesterol trafficking. Cyclodextrins (CDs), the most promising therapeutic candidates for NPC, but with concerns about ototoxicity, are cyclic oligosaccharides with dual functions of unesterified cholesterol (UC) shuttle and sink that catalytically enhance the bidirectional flux and net efflux of UC, respectively, between the cell membrane and the extracellular acceptors. However, the properties of CDs that regulate these functions and how they could be used to improve treatments for NPC are unclear.

METHODS

We estimated CD-UC complexation for nine CD derivatives derived from native α-, β-, and γ-CD with different cavity sizes, using solubility and molecular docking analyses. The stoichiometry and complexation ability of the resulting complexes were investigated in relation to the therapeutic effectiveness and toxicity of each CD derivative in NPC experimental models.

FINDINGS

We found that shuttle and sink activities of CDs are dependent on cavity size-dependent stoichiometry and substituent-associated stability of CD-UC complexation. The ability of CD derivatives to form 1:1 and 2:1 complexes with UC were correlated with their ability to normalize intracellular cholesterol trafficking serving as shuttle and with their cytotoxicity associated with cellular UC efflux acting as sink, respectively, in NPC model cells. Notably, the ability of CD derivatives to form an inclusion complex with UC was responsible for not only efficacy but ototoxicity, while a representative derivative without this ability negligibly affected auditory function, underscoring its preventability.

CONCLUSIONS

Our findings highlight the importance of strategies for optimizing the molecular structure of CDs to overcome this functional dilemma in the treatment of NPC.

Structural Modification and Biological Activity of Polysaccharides

Natural polysaccharides are macromolecular substances with a wide range of biological activities. The structural modification of polysaccharides by chemical means can enhance their biological activity. This paper reviews the latest research reports on the chemical modification of natural polysaccharides. At present, the modification methods of polysaccharides mainly include sulfation, phosphorylation, carboxymethylation, socialization, methylation and acetylation. The chemical and physical structures of the modified polysaccharides were detected via ultraviolet spectroscopy, FT-IR, high-performance liquid chromatography, ultraviolet spectroscopy, gas chromatography-mass spectrometry, nuclear magnetic resonance and scanning electron microscopy. Modern pharmacological studies have shown that the modified polysaccharide has various biological activities, such as antioxidant, antitumor, immune regulation, antiviral, antibacterial and anticoagulant functions in vitro. This review provides fresh ideas for the research and application of polysaccharide structure modification.

Inclusion of a Catechol-Derived Hydrazinyl-Thiazole (CHT) in β-Cyclodextrin Nanocavity and Its Effect on Antioxidant Activity: A Calorimetric, Spectroscopic and Molecular Docking Approach

The aim of the present research was to obtain a supramolecular complex between a strong antioxidant compound previously reported by our group, in order to extend its antioxidant activity. The formation of the inclusion complex of a catechol hydrazinyl-thiazole derivative (CHT) and β-cyclodextrin in aqueous solution has been investigated using isothermal titration calorimetry (ITC), spectroscopic and theoretical methods. The stoichiometry of this inclusion complex was established to be equimolar (1:1) and its equilibrium constant was determined. An estimation of the thermodynamic parameters of the inclusion complex showed that it is an enthalpy and entropy-driven process. Our observations also show that hydrophobic interactions are the key interactions that prevail in the complex. ¹H NMR spectroscopic method was employed to study the inclusion process in an aqueous solution. Job plots derived from the ¹H NMR spectral data demonstrated 1:1 stoichiometry of the inclusion complex in a liquid state. A 2D NMR spectrum suggests the orientation of the aromatic ring of CHT inside the β-CD cavity. The antiradical activity of the complex was evaluated and compared with free CHT, indicating a delayed activity compared with free CHT. To obtain additional qualitative and visual insight into the particularity of CHT and β-CD interaction, molecular docking calculations have been performed.

Insights into recent preclinical studies on labelled cyclodextrin-based imaging probes: towards a novel oncological era

As malignancies remain one of the major health concerns worldwide, increasing focus has been centered around the application of cyclodextrins (CDs) in cancer imaging and therapy due to their outstanding inclusion forming capability. Albeit the physicochemical properties of CDs were intensively elucidated, the spread of their clinical application is limited by the relative paucity of knowledge about their pharmacokinetic profile, especially biodistribution. Studies applying fluorescently- CDs, or CD-based MRI contrast agents revealed much about pharmacokinetics and diagnostic applications; however, derivatives labelled with positron emitters seem superior molecular probes in the investigation of the route of CDs in biological niche. In vivo imaging based on preclinical tumor-bearing model systems are well-suited to evaluate the whole-body distribution of the two most frequently assessed CDs: randomly methylated β-cyclodextrin (RAMEB), and hydroxypropyl-β-cyclodextrin (HPBCD). Exploiting the firm signaling interaction between cancer-related cyclooxygenase-2, prostaglandin E2 (PGE2) and RAS oncoprotein, radioconjugated, PGE2-affine CDs project the establishment of novel imaging probes and therapeutic agents. Currently, we provide an overview of the preclinical studies on CD pharmacokinetics highlighting the significance of the integration of translational discoveries into human patient care.

Surface Modification of Bi2O3 Nanoparticles with Biotinylated β-Cyclodextrin as a Biocompatible Therapeutic Agent for Anticancer and Antimicrobial Applications

Bismuth oxide nanoparticles with appropriate surface chemistry exhibit many interesting properties that can be utilized in a variety of applications. This paper describes a new route to the surface modification of bismuth oxide nanoparticles (Bi₂O₃ NPs) using functionalized beta-Cyclodextrin (β-CD) as a biocompatible system. The synthesis of Bi₂O₃ NP was done using PVA (poly vinyl alcohol) as the reductant and the Steglich esterification procedure for the functionalization of β-CD with biotin. Ultimately, the Bi₂O₃ NPs are modified using this functionalized β-CD system. The particle size of the synthesized Bi₂O₃ NPs is found to be in the range of 12-16 nm. The modified biocompatible systems were characterized using different characterization techniques such as Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Differential Scanning Calorimetric analysis (DSC). Additionally, the antibacterial and anticancerous effects of the surface-modified Bi₂O₃ NP system were also investigated.

Exploring Receptor Binding Affinities and Hepatic Cell Association of N-Acetyl-d-Galactosamine-Modified β-Cyclodextrin-Based Polyrotaxanes for Liver-Targeted Therapies

Acid-degradable polyrotaxanes (PRXs) containing threading β-cyclodextrins (β-CDs) are promising candidates for therapeutic applications of β-CDs in metabolic diseases with cholesterol overload or imbalance. To improve cellular uptake specificity and efficiency of PRXs in hepatocytes, N-acetyl-d-galactosamine (GalNAc)-modified PRXs were developed to facilitate asialoglycoprotein receptor (ASGR)-mediated endocytosis. Binding affinity studies revealed that the dissociation constant (K_D) values between recombinant ASGR and GalNAc-PRXs decreased with an increase in the number of modified GalNAc units. Additionally, the K_D values for GalNAc-PRXs were smaller than those for GalNAc-modified β-CD and amylose, suggesting that the PRX backbone structure improves the binding affinity with ASGR. However, the intracellular uptake levels of GalNAc-PRXs in HepG2 cells increased with a decrease in the number of modified GalNAc units, which was opposite to the trend observed in the binding affinity study. We found that GalNAc-PRXs had a large number of GalNAc units localized in recycling endosomes, resulting in the low intracellular uptake. The cholesterol-reducing abilities of GalNAc-PRXs were assessed using cholesterol-overloaded HepG2 cells. GalNAc-PRXs with a small number of GalNAc units were demonstrated to show superior cholesterol-reducing effects compared to previously designed acid-degradable PRX and clinically tested β-CD derivatives. Thus, we conclude that GalNAc modification is a promising molecular design for the therapeutic application of β-CD-threaded PRXs in various metabolic diseases with cholesterol overload or imbalance in the liver.

Evaluation of the effects of bupivacaine combined with sugammadex on the duration of the nociceptive blockade in sciatic nerve blocks: a controlled, double-blind animal study

BACKGROUND

Animal and other experimental studies have demonstrated increased block time and quality when α- and β-cyclodextrin drugs are combined with local anesthetics. However, to our knowledge, no study has utilized γ-cyclodextrins in such a combination. In the present study, we used an animal model to evaluate the effects of different doses of the combined administration of γ-cyclodextrin (sugammadex) and bupivacaine on the duration of sciatic nerve blocks in rats.

METHODS

Sciatic nerve blocks were performed with a 0.20 ml mixture in all groups. For the non-experimental groups, this mixture consisted of 0.2 ml saline (Sham group), 0.2 ml sugammadex (Group S), or 0.16 ml bupivacaine 0.5% and 0.04 ml saline (Group B). For the experimental groups, 0.16 ml bupivacaine 0.5% was administered along with 0.01 ml sugammadex and 0.03 ml saline (Group BS1), 0.02 ml sugammadex and 0.02 ml saline (Group BS2), or 0.04 ml sugammadex (Group BS4). Proprioception, nociception, and motor function were evaluated until the sciatic block was completely reversed.

RESULTS

Motor, proprioceptive, and nociceptive blockades occurred within 5 min in all experimental groups. In Group BS4, the duration of the motor, proprioceptive, and nociceptive blockades was significantly increased compared with the other experimental groups. However, in Groups BS1 and BS2, only the duration of the nociceptive blockade was significantly increased.

CONCLUSIONS

The combined administration of sugammadex and bupivacaine for sciatic nerve blocks in rats led to a significant increase in the duration of motor, proprioceptive, and nociceptive blockades.

Cyclodextrin-Calcium Carbonate Micro- to Nano-Particles: Targeting Vaterite Form and Hydrophobic Drug Loading/Release

Tailor-made and designed micro- and nanocarriers can bring significant benefits over their traditional macroscopic counterparts in drug delivery applications. For the successful loading and subsequent release of bioactive compounds, carriers should present a high loading capacity, trigger release mechanisms, biodegradability and biocompatibility. Hydrophobic drug molecules can accumulate in fat tissues, resulting in drawbacks for the patient's recovery. To address these issues, we propose to combine the advantageous features of both host molecules (cyclodextrin) and calcium carbonate (CaCO₃) particles in order to load hydrophobic chemicals. Herein, hybrid cyclodextrin-CaCO₃ micro- to nano-particles have been fabricated by combining Na₂CO₃ solution and CaCl₂ solution in the presence of an additive, namely poly (vinylsulfonic acid) (PVSA) or glycerol (gly). By investigating experimental parameters and keeping the Na₂CO₃ and CaCl₂ concentrations constant (0.33 M), we have evidenced that the PVSA or gly concentration and mixing time have a direct impact on the final cyclodextrine-CaCO₃ particle size. Indeed, by increasing the concentration of PVSA (5 mM to 30 mM) or gly (0.7 mM to 4 mM) or the reaction time (from 10 min to 4 h), particles with a size of 200 nm could be reached. Interestingly, the vaterite or calcite form could also be selected, according to the experimental conditions. We hypothesised that the incorporation of PVSA or gly into the precipitation reaction might reduce the nucleation rate by sequestering Ca²⁺. The obtained particles have been found to keep their crystal structure and surface charge after storage in aqueous media for at least 6 months. In the context of improving the therapeutic benefit of hydrophobic drugs, the developed particles were used to load the hydrophobic drug tocopherol acetate. The resulting particles are biocompatible and highly stable in a physiological environment (pH 7.4, 0.15 M NaCl). A selective release of the cargo is observed in acidic media (pH lower than 5).

Long-Lived States Provide Insights from NMR into the β-Cyclodextrin Drug Assemblies

In the last two decades, extending spin memory in NMR has been used for several purposes. Long-lived states (LLS) or singlet states are one of the first spin memory enhancement techniques used. LLS have the potential to extract structural information and intra- and intermolecular interactions of complex systems other than studying slow phenomenon. The motional regime of β-cyclodextrin (β-CD) drug inclusion complexes generally lies in the intermediate region, where ωτ_c ≈ 1, and the standard methods of studying these interactions, i.e., NOE and chemical shift monitoring, suffer from insufficient output information. The sensitivity of LLS toward the environmental changes is utilized here to gain insights into the drug assemblies formed by β-CD. One can use change in relaxation of LLS to study the structural changes during complexation. The examples of β-CD with the drugs indomethacin, paracetamol, gliclazide, and CI-933 (a precursor 4-methoxybenzamide) were studied. Indomethacin, paracetamol, and 4-methoxybenzamide show strong interaction through the para-substituted benzene ring, unlike gliclazide. Relaxation of LLS in β-CD-drug complexes is modeled using standard Redfield Relaxation Theory. Computational studies performed support the experimental observations. Docking and molecular dynamics simulation provided the explanation of the relaxation properties of these drug molecules.

Optimizing Dacarbazine Therapy: Design of a Laser-Triggered Delivery System Based on β-Cyclodextrin and Plasmonic Gold Nanoparticles

Dacarbazine (DB) is an antineoplastic drug extensively used in cancer therapy. However, present limitations on its performance are related to its low solubility, instability, and non-specificity. To overcome these drawbacks, DB was included in β-cyclodextrin (βCD), which increased its aqueous solubility and stability. This new βCD@DB complex has been associated with plasmonic gold nanoparticles (AuNPs), and polyethylene glycol (PEG) has been added in the process to increase the colloidal stability and biocompatibility. Different techniques revealed that DB allows for a dynamic inclusion into βCD, with an association constant of 80 M^-1 and a degree of solubilization of 0.023, where βCD showed a loading capacity of 16%. The partial exposure of the NH₂ group in the included DB allows its interaction with AuNPs, with a loading efficiency of 99%. The PEG-AuNPs-βCD@DB nanosystem exhibits an optical plasmonic absorption at 525 nm, a surface charge of -29 mV, and an average size of 12 nm. Finally, laser irradiation assays showed that DB can be released from this platform in a controlled manner over time, reaching a concentration of 56 μg/mL (43% of the initially loaded amount), which, added to the previous data, validates its potential for drug delivery applications. Therefore, the novel nanosystem based on βCD, AuNPs, and PEG is a promising candidate as a new nanocarrier for DB.

The Solubility Studies and the Complexation Mechanism Investigations of Biologically Active Spiro[cyclopropane-1,3'-oxindoles] with β-Cyclodextrins

In this work, we first improved the aqueous solubility of biologically active spiro[cyclopropane-1,3′-oxindoles] (SCOs) via their complexation with different β-cyclodextrins (β-CDs) and proposed a possible mechanism of the complex formation. β-CDs significantly increased the water solubility of SCOs (up to fourfold). Moreover, the nature of the substituents in the β-CDs influenced the solubility of the guest molecule (MβCD > SBEβCD > HPβCD). Complexation preferably occurred via the inclusion of aromatic moieties of SCOs into the hydrophobic cavity of β-CDs by the numerous van der Waals contacts and formed stable supramolecular systems. The phase solubility technique and optical microscopy were used to determine the dissociation constants of the complexes (Kc~102 M−1) and reveal a significant decrease in the size of the formed crystals. FTIR-ATR microscopy, PXRD, and 1H-1H ROESY NMR measurements, as well as molecular modeling studies, were carried out to elucidate the host−guest interaction mechanism of the complexation. Additionally, in vitro experiments were carried out and revealed enhancements in the antibacterial activity of SCOs due to their complexation with β-CDs.

Development of silymarin topical formulation: In vitro and ex vivo dermal kinetics of silymarin

Silymarin constituents are extensively investigated in the treatment of skin disorders. The main constituents of silymarin include taxifolin (TX), silychristin (ST), silydianin (SDN), silybin A (SA), silybin B (SB), isosilybin A (ISA) and isosilybin B (ISB). The objective of the present study was to determine in-vitro dermal kinetics of individual silymarin constituents in human skin models and to develop a silymarin topical formulation. In-vitro studies indicate human skin binding of silymarin was in the range of 2.09 to 12.3% and half-life of silymarin constituents was > 15.5 h in epidermal and dermal cells. Topical silymarin cream was prepared using sulfobutylether-β-cyclodextrins as solubilizer and propylene glycol as permeation enhancer. The cream was subjected to ex-vivo human skin permeation studies. In ex-vivo studies, cumulative amount of TX, ST, SDN, SA, SB, ISA and ISB permeated across human cadaver skin at 24 h was 921 ± 13.5, 1992 ± 67.6, 345 ± 39.2, 1089 ± 45.0, 1770 ± 100, 1469 ± 81.5 and 1285 ± 33.1 ng/cm², respectively. The amount TX, ST, SDN, SA, SB, ISA and ISB retained after 24 h was 60.7 ± 8.2, 376 ± 45.5, 72.3 ± 6.9, 66.4 ± 8.0, 208 ± 31.3, 154 ± 12.4 and 102 ± 6.3 ng/mg of human cadaver skin, respectively. The study results demonstrate silymarin topical formulation could deliver significant amount of silymarin constituents into skin. The developed silymarin formulation could be beneficial for treatment or management of a broad spectrum of dermatological disorders.

Synthesis of Novel Pentacyclic Triterpenoid Derivatives that Induce Apoptosis in Cancer Cells through a ROS-dependent, Mitochondrial-Mediated Pathway

Betulinic acid (BA) and oleanolic acid (OA) are plant-derived conjugates found in various medicinal plants that have emerged as potential antitumor agents. Herein, a series of novel BA and OA derivatives were synthesized by conjugation with per-O-methylated-β-cyclodextrin (PM-β-CD), and their anticancer properties against a panel of three human cancer cell lines were evaluated. Two OA-PM-β-CD conjugates (48 and 50) were observed to be the most potent conjugates against the three cell lines (MCF-7, BGC-823, and HL-60), with a 15- to 20-fold decrease in the IC₅₀ values (IC₅₀: 6.06-8.47 μM) compared with their parental conjugate (OA). Annexin V-FITC/propidium iodide staining and Western blot analysis revealed that both conjugates induced apoptosis in HL-60 cells. Additionally, in the representative conjugate 48-treated HL-60 cells, a decrease in mitochondrial membrane potential and subsequent release of cytochrome c into the cytosol were observed, indicating the activation of the intrinsic apoptosis pathway. Furthermore, 48 dramatically induced the generation of reactive oxygen species (ROS) in HL-60 cells, and the corresponding effect could be reversed using the ROS scavenger N-acetylcysteine. Collectively, these results suggest that the novel pentacyclic triterpenoid derivatives trigger the intrinsic apoptotic pathways via the ROS-mediated activation of caspase-3 signaling, inducing cell death in human cancer cells.

2-Hydroxypropyl-β-cyclodextrin mitigates pathological changes in a mouse model of retinal cholesterol dyshomeostasis

CYP46A1 is a CNS-specific enzyme, which eliminates cholesterol from the brain and retina by metabolism to 24-hydroxycholesterol, thus contributing to cholesterol homeostasis in both organs. 2-Hydroxypropyl-β-cyclodextrin (HPCD), a Food and Drug Administration-approved formulation vehicle, is currently being investigated off-label for treatment of various diseases, including retinal diseases. HPCD was shown to lower retinal cholesterol content in mice but had not yet been evaluated for its therapeutic benefits. Herein, we put Cyp46a1^-/- mice on high fat cholesterol-enriched diet from 1 to 14 months of age (control group) and at 12 months of age, started to treat a group of these animals with HPCD until the age of 14 months. We found that as compared with mature and regular chow-fed Cyp46a1^-/- mice, control group had about 6-fold increase in the retinal total cholesterol content, focal cholesterol and lipid deposition in the photoreceptor-Bruch's membrane region, and retinal macrophage activation. In addition, aged animals had cholesterol crystals at the photoreceptor-retinal pigment epithelium interface and changes in the Bruch's membrane ultrastructure. HPCD treatment mitigated all these manifestations of retinal cholesterol dyshomeostasis and altered the abundance of six groups of proteins (genetic information transfer, vesicular transport, and cytoskeletal organization, endocytosis and lysosomal processing, unfolded protein removal, lipid homeostasis, and Wnt signaling). Thus, aged Cyp46a1^-/- mice on high fat cholesterol-enriched diet revealed pathological changes secondary to retinal cholesterol overload and supported further studies of HPCD as a potential therapeutic for age-related macular degeneration and diabetic retinopathy associated with retinal cholesterol dyshomeostasis.

Nanoparticles of folic acid-methyl-β-cyclodextrin (FA-MβCD)/adamantane-albumin exhibit enhanced antitumor activity compared with FA-MβCD alone

Supramolecular drug carriers are a promising approach for delivering anticancer drugs with high blood retention after administration. We previously synthesized folic acid-modified methyl-β-cyclodextrin (FA-MβCD) as an anticancer drug. FA-MβCD has a selective autophagy-mediated antitumor effect on folic acid receptor (FR)-expressing cancer cells. Here, we enhanced the antitumor effect and safety of FA-MβCD by preparing a supramolecular nanoparticle formulation of FA-MβCD via host-guest interactions using an adamantane conjugate with human serum albumin (Ad-HSA). The Ad-HSA/FA-MβCD supramolecular complex prolonged the blood retention of FA-MβCD and improved its antitumor effect and safety after intravenous administration in tumor-bearing mice xenografted with FR-expressing cancer cells. These results suggest that the supramolecular technique using Ad-HSA is a promising approach for the delivery of CD-based anticancer drugs.