Inclusion Complexes Research Articles

Cyclodextrin Dimers Functionalized with Biotin as Nanocapsules for Active Doxorubicin Delivery Against MCF-7 Breast Cell Line.

Cyclodextrin dimers have been investigated as potential nanocapsules of biomolecules. The presence of two cavities can improve the stability of inclusion complexes, working as a hydrophilic sandwich of poorly water-soluble species. Here, we designed new β- and γ-cyclodextrin dimers functionalized with biotin as a targeting unit and tested the new bioconjugates as doxorubicin delivery systems in cancer cells. Biotin can recognize the Sodium-dependent Multivitamin Transporter (SMVT) receptor, encoded by the Solute Carrier Family 5 Member 6 (SLC5A6) gene and improve the uptake of drugs. We evaluated the expression of the SLC5A6 transcript in human cell lines to select the best cell model (MCF-7) for the in vitro studies. Furthermore, in the cell lines, we investigated the transcript levels of genes correlated to biotin cell availability, Holocarboxylase Synthetase (or HCS encoded by HLCS gene) and Biotinidase (encoded by BTD gene) enzymes. Moreover, the expression of ATP Binding Cassette Subfamily G Member 2 transporter (encoded by ABCG2 gene), which may play a role in doxorubicin resistance, has been investigated. The antiproliferative activity of the doxorubicin complexes with the dimers has been determined to study the effect of the biotin moiety on the cytotoxicity in MCF-7 cancer cells.

DEVELOPMENT AND EVALUATION OF CYCLODEXTRIN NANOSPONGES-BASED TOPICAL FORMULATION OF TAZAROTENE

Objective: Tazarotene is used as a topical retinoid for the treatment of acne, psoriasis and sun-damaged skin. But its topical formulation has many side effects, including itching, burning, dryness, redness, stinging, rash blistering, skin discoloration, peeling at the site of application and low bioavailability. The present study focuses on the reduction of side effects and enhancement of solubility and topical bioavailability of tazarotene by using cyclodextrin-based nanosponges. Methods: Nanosponge of tazarotene were prepared by lyophilization method. The physiochemical characterization of plain nanosponges and drug-loaded nanosponges were performed using Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and X-ray Diffractometer (XRD) studies. The drug-loaded nanosponges were incorporated into a carpool-based gel formulation. The prepared formulation was evaluated for viscosity, dissolution and stability. FTIR, DSC and XRD studies confirmed the formation of inclusion complex of tazarotene with nanosponges. Results: The particle size of the drug-loaded nanosponges was found to be in the range of 156.72 to 163.48 nm. Transmission Electron Microscopy (TEM) images revealed the regular spherical shape of both the nanosponges that are unaffected even after drug encapsulation. The pH of the gel formulations was found to be in the range of 5.86 to 6.46. The gel formulation resulted in the diffusion of drug in controlled manner for up to 24 h. The in vitro dissolution studies revealed that nanosponges-based topical formulation had better results than the marketed product. Conclusion: Thus, the study showed that nanosponge-based gel formulation can be a possible alternative to conventional formulations of tazarotene with enhanced bioavailability and skin retention characteristics for topical application.

Chalcogen Bond-Driven Alkylations: Selenoxide-Pillar[5]arene As A Recyclable Catalyst For Displacement Reactions In Water.

A novel strategy to catalyze alkylation reactions through chalcogen bond interaction using a supramolecular structure is presented herein. Utilizing just 1.0 mol% of selenoxide-pillar[5]arene (P[5]SeO) as the catalyst we achieved efficient catalysis in the cyanation of benzyl bromide in water. Our approach demonstrated high efficiency and effectiveness, with the results supported by designed control experiments and theoretical models, highlighting the catalytic effect of the pillar[5]arene through noncovalent interactions. Quantum-chemical calculations (ωB97X-D/def2-TZVP@SMD) pointed out that the catalyzed cyanation reaction followed an SN2-like mechanism, with energy barriers (ΔH‡) ranging from 16.7 to 18.2 kcal mol-1, exhibiting dissociative character depending on the para-substituent. 1H NMR analysis revealed that P[5]SeO acted as a catalyst through inclusion complex formation, facilitating the transfer of the electrophilic substrate to the aqueous solution for nucleophilic displacement. Our reaction protocol proved applicable to various substrates, including aromatic and alpha-carbonyl derivatives. The use of sodium azide as the nucleophile was also feasible. Importantly, our method allowed scalability, and the catalyst P[5]SeO could be recovered and reused effectively for multiple reaction cycles, showcasing sustainability.

Screening and inclusion of luteolin for β-cyclodextrin: molecular simulations and experiments

In this study, we first established a guest small molecule screening mechanism by molecular simulation, and then screened lignans from 10 polyphenolic compounds to identify the most suitable guest molecule for encapsulation with β-cyclodextrin (β-CD). Subsequently, the subject-guest interactions and encapsulation mechanisms of lignans with β-CD, 2-hydroxypropyl-cyclodextrin (HP-β-CD) and 2,6-dimethyl-cyclodextrin (DM-β-CD) were investigated using a combination of molecular simulation and experimental methods, respectively. Molecular simulations were performed to calculate the microstructural parameters, including solubility parameters, binding energies, and mean square displacements. The simulation results demonstrated that DM-β-CD exhibited the strongest interaction with luteolin and formed the most stable inclusion complex. The inclusion complexes of luteolin with the three cyclodextrins were prepared by freeze-drying method, and the formation of the inclusion complexes was demonstrated using infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and ultraviolet-visible spectroscopy (UV). Phase solubility studies confirmed the formation of 1:1 stoichiometric inclusion complexes of lignans with cyclodextrins. Furthermore, 2,2-diphenyl-1-pyridine hydrazine (DPPH) free radical scavenging experiments demonstrated that the inclusion complexes exhibited enhanced antioxidant capacity. In light of these findings, it can be concluded that among the three cyclodextrins, DM-β-CD was optimally encapsulated with luteolin.

Deep Eutectic Solvents for Next-generation Cyclodextrin Science

Abstract In cyclodextrin science, water has been almost exclusively employed as solvent, and this imposes non-negligible limitations to the scope of applications. Accordingly, deep eutectic solvents, constructed from hydrogen-bonding donors and acceptors, have been attracting much interest as important substitutes of water. This review comprehensively covers chemical and physicochemical features of cyclodextrins in these eco-friendly solvents. In one category, cyclodextrins or their derivatives are dissolved as solutes in conventional deep eutectic solvents. All of α-, β-, and γ-cyclodextrins efficiently form inclusion complexes with various guest molecules, exactly as observed in water. Notably, chemically modified cyclodextrins (e.g., 2-hydroxypropyl-cyclodextrins) form still more stable inclusion complexes than native cyclodextrins. Alternatively, deep eutectic solvents are prepared by combining cyclodextrins with other hydrogen-bonding components. The cyclodextrin units in these mixtures also form inclusion complexes with guest molecules. It has been proposed that enhanced flexibility of cylindrical structures of cyclodextrins allows effective induced-fit to stabilize inclusion complexes. The applications of these systems widely range from catalysis for organic synthesis to extraction, analysis, pharmaceutics, and many other fields. High solubilities of CDs and various chemicals in these solvents guarantee high productivity of target transformation, and unprecedentedly novel functions are promising for these unique systems.

Enhancing orofacial pain relief: α-phellandrene complexed with hydroxypropyl-β-cyclodextrin mitigates orofacial nociception in rodents.

Orofacial pain affects 10-15% of adults and can severely impact quality of life. Despite ongoing treatment challenges, monoterpene alpha-phellandrene (PHE) shows potential therapeutic benefits. This study aimed to develop and evaluate an inclusion complex of PHE with hydroxypropyl-beta-cyclodextrin (PHE-HPβCD) for treating orofacial pain. The PHE-HPβCD complex was created using physical mixing and characterized by differential scanning calorimetry (DSC) and high-performance liquid chromatography (HPLC) to determine encapsulation efficiency. The complex exhibited a 70.45% encapsulation efficiency. Male Swiss mice were used in models of orofacial pain induced by formalin, cinnamaldehyde, glutamate, and corneal nociception by hypertonic saline. Additionally, cytokine levels (TNF-α and IL-1β) were measured in the upper lip tissue of mice subjected to the formalin model. Both PHE and PHE-HPβCD showed significant antinociceptive effects at a 50mg/kg dose during formalin-induced pain, reducing both neurogenic and inflammatory phases of pain. PHE-HPβCD also reduced TNF-α and IL-1β levels. For cinnamaldehyde and glutamate-induced nociception, both treatments reduced pain behavior, but only PHE-HPβCD decreased eye wipes in corneal nociception. These results suggest that PHE, especially in complexed form, alleviates orofacial pain by potentially modulating pain-related receptors (TRPA1 and TRPV1), mediators, like glutamate, and reducing pro-inflammatory cytokines. Further research is needed to explore the precise mechanisms of PHE in chronic orofacial pain models, but the study indicates promising avenues for new pain treatments.

Exploring the interaction of curcumin with β-cyclodextrin and its binding with DNA: A combined spectroscopic and molecular docking study

At present, a major effort in biophysical studies has been paid towards exploring the interactions and release of therapeutic payloads to the specific site leaving behind healthy cells unaffected and hence, lower the drug-induced toxicity. For the purpose, interaction of β-bound CUR with calf thymus DNA (ctDNA) has been examined intensely using a series of biophysical methods like absorption, steady state fluorescence emission, and circular dichroism together with molecular docking study. The experimental analysis divulge that CUR interacts with both β–CD (although with different molar ratio) and DNA. However, the binding affinity of CUR with the target (DNA) is higher than it does with the β–CD. When β–CD-carried (10 mM) CUR (μM) (inclusion complex) comes near DNA (15–372 μM), CUR gets out from β–CD's void and approaches to binds with the DNA. The relocation of the probe occurred due to competitive binding of the CUR between β–CD and the DNA. The present investigation may provide a simple yet probable route for the transfer of encapsulated therapeutic payload of β–CD to the most relevant biomolecular target DNA.

Baicalin nanofiber membranes: A comprehensive study on preparation, characterization, and antimicrobial pharmacological activities

Baicalin is a natural active ingredient known for its medicinal properties and a broad spectrum of pharmacological activities, including antimicrobial, antioxidant, antiviral, and anticancer effects. However, its application is hindered by its poor water-solubility. In this study, we aimed to enhance the water solubility of baicalin by embedding it within the hydrophobic cavity of hydroxypropyl-β-cyclodextrin through supramolecular assembly to form inclusion complexes. The inclusion complexes were subsequently processed into nanofiber membranes suitable for application on skin and wounds using coaxial electrostatic spinning. The inclusion complexes and nanofiber membranes were analyzed and characterized using high-performance liquid chromatography (HPLC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The combined results from XRD, FT-IR, and TGA confirmed that baicalin successfully formed inclusion complexes with cyclodextrin, resulting in an increase in water solubility from 0.0170 mg/mL to 8.9600 mg/mL, representing a 527-fold enhancement. Additionally, the inclusion complexes demonstrated superior antimicrobial activity against E. coli, S. aureus and C. albicans, as well as higher free radical scavenging rates compared to native baicalin. After the inclusion complexes were transformed into nanofiber membranes via coaxial electrospinning, their properties remained unchanged, and they continued to exhibit excellent antimicrobial and antioxidant activities. In the in vitro release assay, nearly 90% of the drug (baicalin) was released from the nanofiber membranes over a period of time, indicating sustained release. Furthermore, the molecular docking mechanism of baicalin and cyclodextrin was elucidated through molecular docking simulations, establishing a theoretical foundation for the synthesis of inclusion complexes in the computational studies. This study reports the successful fabrication of water-soluble, antimicrobial nanofiber membranes containing bioavailable baicalin, which have potential clinical applications in the development of wound dressings and drug delivery systems utilizing plant-extracted bioactive compounds.

Parallel (competitive) reactions of micelle formation and cyclodextrin–surfactant inclusion complex formation in aqueous solution: A consequence of the Gibbs–Duhem equation—invariance of the mass action law and the possibility of determining the equilibrium constant of the inclusion complex

The Gibbs–Duhem equation results in the independence between the standard Gibbs free energy of micelle formation and the standard Gibbs free energy of monocomponent surfactant’s and cyclodextrin’s (CD’s) inclusion complex formation in aqueous solution. The experimental data show that the surfactant’s critical micellar concentration increases in the presence of CD. At a constant temperature, the standard Gibbs free energy of micelle formation remains constant, irrespective of the presence of parallel competitive processes such as inclusion complex formation. This indicates that the critical micellar concentration remains unchanged at the corresponding concentration scale. As a result, the equilibrium constant for surfactant–CD inclusion complex formation can be determined by changing the critical micellar concentration in the presence and absence of CD. A graphical method for determining the equilibrium constant of the inclusion complex is also presented. An analytical approach for analyzing the influence of the formation of the inclusion complex with CD on the formation of the binary mixed micellar pseudophase is presented. Suppose that different values exist for the equilibrium constants of the formation of the inclusion complex for two surfactants from their binary mixture. In this case, there is a change in the initial mole fraction from the initial mixture of surfactants, which should be considered when applying the regular solution theory protocol when determining the parameters of a binary mixed micelle in the presence of CD.

β-Cyclodextrin Derivatives Bind Aromatic Side Chains of the Cyclic Peptide Lanreotide

Cyclodextrin complexation has a potential to modulate the physicochemical properties of peptide drugs. The ability of peptides to form an inclusion complex can be influenced by factors such as size, amino acid sequence of peptide and the size and charge of the cyclodextrin cavity. In this study, the inclusion complexes of cyclic peptide drug lanreotide acetate with two common β-cyclodextrin derivatives, Sulfobutyl ether β-CD (SBEβ-CD) and hydroxypropyl β-CD (HPβ-CD) were investigated. NMR spectroscopy was used to examine the interaction between β-cyclodextrin derivatives and specific residues of lanreotide. It was observed that the hydrophobic side chain of aromatic residues in the lanreotide sequence can be fit into the cavity of both β-cyclodextrin derivatives. Additionally, NMR revealed a lower diffusion coefficient and higher hydrodynamic radius of complex, indicative of binding to the cavities. Each aromatic residue was individually studied by substituting alanine in lanreotide to measure its association binding with both β-cyclodextrin derivatives. The alanine-substitute study indicated a stronger binding of SBEβ-CD to Lanreotide compared to HPβ-CD. Docking studies suggested that the 1:1 inclusion complex is more favorable than higher order complexes due to the steric hindrance and size considerations. The docking analysis indicated the stable conformation of all three aromatic side chains with both β-cyclodextrin derivatives, SBEβ-CDand HPβ-CD.

Chitosan-grafted Cyclodextrin via Click Chemistry as an Encapsulating Agent to Enhance the Antibacterial Activity of Thymol

Introduction: This paper aimed to investigate, for the first time, the possibility of increasing the antibacterial activities of thymol (TH) by developing an encapsulating agent based on chitosan-grafted cyclodextrin. For this purpose, β-cyclodextrin was monosubstituted at position 6 via propargyl bromide, and chitosan’s amine groups were converted to azide functions. After alkylation and diazotization reactions, the grafting of β-cyclodextrin onto the chitosan (CSβCD) was realized via click chemistry alkyne–azide cycloaddition. Methods: The incorporation of TH into chitosan-grafted β-cyclodextrin (TH/CS-βCD) was performed by the freeze-drying method, and the encapsulation efficiency was investigated based on various mass ratios (TH:CS-βCD). The optimized inclusion complex was then thoroughly examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Results: The antibacterial activity was assessed against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis using broth-microdilution assay. Fourier transform infrared spectroscopy analysis demonstrated the successful grafting of β-cyclodextrin onto chitosan since the optimum mass ratio between TH and CS-βCD was 1:8 (w:w), corresponding to 78 ± 3.42% of encapsulation efficiency, while SEM, XRD, TGA and DSC confirmed the establishment of TH/CS-βCD inclusion complexes. Conclusion: The in vitro investigation showed that TH/CS-βCD exhibited higher antibacterial properties compared to TH in free form.

In Situ Gelling Eye Drops of Tacrolimus with Improved Ocular Delivery and Therapeutic Efficacy.

In situ gelling eye drops of tacrolimus (FK506 Gel) were developed to address the formulation challenge of tacrolimus for anterior ocular inflammatory diseases. Both in silico and in vitro investigations were conducted to screen a suitable cyclodextrin species to increase the drug solubility. Guanosine was employed as the gelator and combined with inclusion complexes of tacrolimus in the presence of borate anions to obtain FK506 Gel, which gelated when came into contact with cations in tear fluid and led to the formation of a nanofibrous hydrogel. The versatility of our design to improve the solubility and ocular retention of the hydrophobic drug was demonstrated in vivo with coumarin 6 as a model drug. A mouse dry eye model was used to evaluate the therapeutic effects of FK506 Gel, which, in combination with the biocompatibility study, suggested that FK506 Gel served as a superior treatment for anterior ocular inflammatory diseases.

Recent Advances in Cyclodextrin-Based Nanoscale Drug Delivery Systems.

Cyclodextrins (CDs) belong to a class of cyclic oligosaccharides characterized by their toroidal shape consisting of glucose units linked via α-1,4-glycosidic bonds. This distinctive toroidal shape exhibits a dual nature, comprising a hydrophobic interior and a hydrophilic exterior, making CDs highly versatile in various pharmaceutical products. They serve multiple roles: they act as solubilizers, stabilizers, controlled release promoters, enhancers of drug bioavailability, and effective means of masking undesirable tastes and odors. Taking advantage of these inherent benefits, CDs have been integrated into numerous nanoscale drug delivery systems. The resulting nanomaterials exploit the exceptional properties of CDs, including their ability to solubilize hydrophobic drugs for substantial drug loading, engage in supramolecular complexation for engineered nanomaterials, increase bioavailability for improved therapeutic efficacy, stabilize labile drugs, and exhibit biocompatibility and versatility. This paper compiles recent studies on CD functional nanoscale drug delivery platforms. First, we described the physicochemical and toxicological aspects of CDs, CD/drug inclusion complexation, and their impact on improving drug bioavailability. We then summarized applications for CD-functional nano delivery systems based on polymeric, hybrid, lipid-based nanoparticles, and CD-based nanofibers. Particular interest was in the targeted applications and the function of the CD molecules used. In most applications, CD molecules were used for drug solubilization and loading, while in some studies, CD molecules were employed for supramolecular complexation to construct nanoscale drug delivery systems. Finally, the review concludes with a thoughtful consideration of the current challenges and outlook.

Sulfonated Hydroxyaryl-Tetrazines with Increased pKa for Accelerated Bioorthogonal Click-to-Release Reactions in Cells.

Bioorthogonal reactions that enable switching molecular functions by breaking chemical bonds have gained prominence, with the tetrazine-mediated cleavage of trans-cyclooctene caged compounds (click-to-release) being particularly noteworthy for its high versatility, biocompatibility, and fast reaction rates. Despite several recent advances, the development of highly reactive tetrazines enabling quantitative elimination from trans-cyclooctene linkers remains challenging. In this study, we present the synthesis and application of sulfo-tetrazines, a class of derivatives featuring phenolic hydroxyl groups with increased acidity constants (pKa). This unique property leads to accelerated elimination and complete release of the caged molecules within minutes. Moreover, the inclusion of sulfonate groups provides a valuable synthetic handle, enabling further derivatization into sulfonamides, modified with diverse substituents. Significantly, we demonstrate the utility of sulfo-tetrazines in efficiently activating fluorogenic compounds and prodrugs in living cells, offering exciting prospects for their application in bioorthogonal chemistry.

Evaluation of All-Atom and Martini 3 Coarse-Grained Force Fields from the Structural Investigation of Nitroxide Spin Probes and Their Confinement in Beta-Cyclodextrin.

Nitroxide radicals have found wide applications as spin labels or probes, and their guest-host interactions with cyclodextrins exhibit enhanced applications in electron spin resonance (ESR) spectroscopy and imaging due to improved biostability toward reducing agents. Although the computational prediction of the guest-host binding has become increasingly common for small ligands, molecular simulations regarding the conformational preferences of hosted spin probes have not been conducted. Here we present molecular dynamics simulations at an atomistic level for a set of four TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl) spin probes and thereafter develop coarse-grained models compatible with the recent version of the Martini force field (v 3.0) to tackle their encapsulation in the cavity of β-cyclodextrin (βCD) for which experimental ESR data are available. The results indicate that the atomistic descriptions perform well in relation to the structural parameters derived from X-ray diffraction as well as hydrogen bonding and hydrogen patterns and predict that the guest-host complexation is hydrophobically driven by the presence of a methyl group pair of the spin probe at the cavity center of βCD. The spin probe mobility at the binding site reveals the nitroxide group orientation toward the secondary rim of the cyclodextrin and the alternating presence of the two methyl group pairs inside the cavity, features in agreement with the experimental behavior of the ESR parameters. The coarse-grained parameterizations of TEMPO probes and βCD rely on optimizing the bonded and nonbonded parameters with references to the atomistic simulation results, and they are capable of recovering the orientation and location of the spin probe inside the cyclodextrin cavity predicted by the atomistic guest-host complexes. The results suggest the cyclodextrin host-guest system as a powerful validation suite to evaluate new coarse-grained parameterizations of small ligands and future extensions to functionalized cyclodextrins in inclusion complexes.

Probing Host‐Guest Inclusion Complex of DHP with β‐CD in Augmenting Bioavailability to Boost Biochemical Applications Optimized by Physicochemical and Molecular Docking

AbstractThis research aims to develop the inclusion complex of 2, 4‐diamino‐6‐hydroxypyrimidine (DHP) with β‐cyclodextrin (β‐CD) using an inclusion process, and to investigate the effect of inclusion on the photo stability and bioactivity of DHP. The formation of DHP‐β‐CD inclusion complex has been examined by means of physicochemical as well as spectroscopic techniques (1H NMR, FT‐IR, PXRD and SEM) suggesting the successful inclusion of the DHP molecule into the β‐CD cavity. The 1 : 1 stoichiometry of the inclusion complex was validated through Job's plot. β‐CD displayed a fairly strong affinity (Ka =889.67 M−1) for DHP, indicating that the binding process is thermodynamically feasible. A molecular docking study speculated the most preferred orientation of DHP molecule within the binding pocket of β‐CD cavity. The photostability of DHP was found to improve on complexation with β‐CD. In vitro antibacterial activity test demonstrated that the DHP‐β‐CD inclusion complex displayed better activity than pure DHP. DHP‐β‐CD inclusion complex (IC50 =240.04 μM) also exhibited relatively significant in vitro cytotoxic activity than pure DHP towards the human kidney cancer cell line (ACHN). These results reveals that the inclusion of DHP using β‐CD could lead to stabilization of DHP and efficient display of its bioactivity.

Computational and experimental analysis of Luteolin-β-cyclodextrin supramolecular complexes: Insights into conformational dynamics and phase solubility

Investigating the structural stability of poorly-soluble luteolin (LuT) after encapsulation within cyclodextrins (CDs) is crucial for unlocking the therapeutic potential of LuT bioactive molecule. Herein, native and modified β-CD were employed to investigate LuT inclusion complex formation. Molecular mechanics (MM) and quantum mechanics (QM) were utilized for structural dynamics analysis. Microsecond timescale MD simulations yielded insights into LuT-CD interactions. The binding affinity between LuT and selected β-CDs was assessed by calculating the binding free energy using MM-PBSA and umbrella sampling simulations. The MM-PBSA results indicated that Heptakis-O-(2-hydroxypropyl)-β-CD (HP-β-CD) (−82.59+/-11.67 kJ/mol) and Di-O-methyl-β-CD (DM-β-CD) (−54.01+/-11.07 kJ/mol) exhibited good binding affinity for LuT. Subsequently, derivative screening of HP-β-CD revealed that only 2-HP-β-CD (HP-β-CD-1)/LuT (−21.38 kJ/mol) displayed a superior binding free energy (obtained from umbrella sampling) than HP-β-CD/LuT (−16.55 kJ/mol) inclusion complex. We conducted QM calculations on the top three inclusion complexes namelly HP-β-CD, DM-β-CD, and HP-β-CD-1 employing wB97X-D/6–311 + G(d,p) model chemistry to strengthen the MM results. The computational analysis aligns with experimental findings (phase solubility analysis), validating HP-β-CD-1 as most effective cavitand molecule for improving the solubility of LuT. This study offers critical structural insights for developing novel HP-β-CD derivatives with enhanced host capacity to encapsulate guest molecules efficiently.

Complexation of telmisartan with cyclodextrins as a tool of solubility enhancement: A comparative analysis of influence of the cyclodextrin type and method of solid dispersion preparation

Cardiovascular telmisartan (TMS) was complexed with modified cyclodextrins (CD) aiming at improvement of its poor solubility which results into low bioavailability. Inclusion complexes with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and sulfobutylether-β-cyclodextrin (SBE-β-CD) in liquid and solid state was evaluated for first time. Phase solubility isotherm diagrams of TMS versus the CD concentration were plotted in a buffer pH 7.4. It was found that TMS/CD complexes are formed in solution in an equimolar stoichiometric ratio of 1:1. The aqueous solubility of TMS with the addition of 0.05 mol·L−1 HP-β-CD increased by 23 times and was 38.9·10−5 mol·L−1, and the presence of the same amount of SBE-β-CD in solution increased the solubility of the drug by 7 times, reaching a value of 12.6·10−5 mol·L−1.The binding constants were found to 468 and 114 L·mol−1 for HP-β-CD and SBE-β-CD, respectively. Novel solid forms of TMS with both CDs were prepared using the grinding and evaporation approaches. Successful formation of supramolecular TMS/HP-β-CD and TMS/SBE-β-CD solid complexes was confirmed by FTIR, PXRD, DSC, TGA and SEM. The residual crystallinity of all obtained solid dispersions of TMS/CD did not exceed 10 %. Supersaturation was observed during the dissolution of all the solid complexes. The grinding technique was found to be more advantageous as it ensured the biggest improvement of the drug maximum concentration in the aqueous solution: the TMS solubility in the TMS/HP-β-CD(gr) and TMS/SBE-β-CD(gr) solid complexes increased by 27 and 33 times, respectively. Besides, polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG) were tested as crystallization inhibitors. Addition of 1 wt% PVP as a stabilizer is a promising approach for the preparation of TMS pharmaceutical formulations with improved bioavailability.

Evaluation of β‐ and γ‐Cyclodextrins as Promising Bisoprolol Drug Carriers: Docking, Molecular Dynamics and MM‐PBSA1 Free‐Energy Calculations*

AbstractIn this research work, the binding mechanism of Bisoprolol (BIS) drug into the beta‐cyclodextrin (β‐CD) and gamma‐cyclodextrin (γ‐CD) nanopores were investigated using docking, molecular dynamics (MD) simulations, and MM‐PBSA free energy calculations. Also, we assessed the energetic aspects within the BIS‐CDs complex under different thermal conditions in four stages from 298 to 334 K, which includes mammalian body temperature in order to approximate physiological conditions. The computational results reveal that the encapsulation of the BIS into the cavities of CDs is reinforced by hydrogen bonds (HBs) and van der Waals (vdW) interactions in the aqueous phase. The stability of the inclusion complexes of β and γ‐CD with BIS was confirmed by evaluating system stability, flexibility, dynamic and thermodynamic properties at all temperature steps. Next, we analyzed the degree of complexation between BIS and CDs at four different temperatures. The findings revealed that the degree of complexation is decreased as the temperature is increased. The translational movement of the drug to the outside of the CDs cavity increased in the temperature range of 310 to 334 K in γ‐CD more than β‐CD. The β‐CD complex exhibits greater stability compared to the γ‐CD complex in the aqueous medium. The MM‐PBSA free energy approach also confirms more binding affinity of BIS drug into the β‐CD cavity. keywords: Bisoprolol, β‐cyclodextrin, γ‐cyclodextrin, Molecular dynamics, MM‐PBSA free energy.

Accessible Trail Tourism: Trail Accessibility and Difficulty Rating Approach Designed for Individuals, Including With Mobility Impairments

ABSTRACTThis study introduces a novel approach to trail accessibility and difficulty rating tailored specifically for individuals, including those with mobility impairments, aiming to promote accessible trail tourism. Grounded in theoretical frameworks of inclusive outdoor recreation, equality, and complex adaptive systems, the proposed rating system incorporates criteria addressing physical access, terrain challenges, and amenities to accommodate diverse user needs. This study employed a sensor technology, called wheeled instrumentation sensor package (WISP) within the framework of the high‐efficiency trail assessment process (HETAP) to develop a new quantitatively based trail classification scheme. A case study trail and two hypothetical synthetic data trails were used to demonstrate both the trail wheelchair accessibility binary classification approach and the proposed trail difficulty classification approach. This research pioneers trail accessibility and difficulty rating and underscores the importance of integrating accessibility considerations into trail management practices to create truly inclusive outdoor recreational experiences.