Journal of Inclusion Phenomena and Macrocyclic Chemistry最新文献

Machine Learning (ML) techniques are becoming an integral part of rational drug design and discovery. Data-driven modeling regularly outperforms physics-based models for predicting molecular binding affinities, placing ML as a promising tool. Cyclodextrins are nano-cages used to improve the delivery of insoluble or toxic drugs. Due to chemical similarity to proteins, ML approaches could vastly profit to improve affinity prediction and enhance their carriable drug portfolio. Here we evaluate the performance of three well-known ML methods—Support Vector Regression (SVR), Gaussian Process Regression (GPR), and eXtreme Gradient Boosting (XGB)—to predict the binding affinity of cyclodextrin and known ligands. We perform hyperparameter tuning through Random Search. The results were compatible with the presented literature. We increased our previous prediction performance and present a GPR model to adjust to the data ((R^2) = 0.803) with low prediction errors (RMSE = 1.811 kJ/mol and MAE = 1.201 kJ/mol).

The poor solubility and low stability of rifampicin limited its therapeutic efficacy. One of the common strategies is to form an inclusion complex to address the problems. In this study, acyclic cucurbit[n]uril was used for encapsulation of rifampicin to form an inclusion complex. The inclusion complex was prepared by the kneading method and characterized by DSC, SEM, FT-IR, NMR, PXRD, and UV-Vis spectroscopy. The results confirmed the formation of 1:1 inclusion complex. The drug content was calculated to be 27.35 ± 0.54%. The aqueous solubility of rifampicin was increased 20-fold by complexation with acyclic cucurbit[n]uril. Moreover, the thermo-stability and photo-stability of free rifampicin and inclusion complex were investigated by HPLC. Rifampicin was stabilized by encapsulating the piperazine ring in the cavity of acyclic cucurbit[n]uril. In addition, the MIC of free RIF and RIF‧ACB were determined by using in vitro experiments. It was found that rifampicin complexed by acyclic cucurbit[n]uril exhibited similar antibacterial activities against strain H37Rv to rifampicin alone.

Graphic abstract

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Acyclic cucurbit[n]uril was used to encapsulate rifampicin to form an inclusion complex.

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The aqueous solubility of rifampicin was increased 20-fold by encapsulation with acycliccucurbit[n]uril.

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The thermo-stability and photo-stability of rifampicin was improved by formation ofinclusion complex.

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The antibiotic potency of rifampicin complexed by acyclic cucurbit[n]uril was close to thatof rifampicin alone.

Activated carbon has been reported to act as a catalyst for condensation reactions between glucose molecules. The present study describes the use of activated carbon as a new catalyst for the synthesis of branched cyclodextrins (CDs). Two main methods have been used to synthesize branched CDs: a method using an enzymatic condensation or transfer reaction, and a method using a chemical reaction. However, these methods have problems such as a limited number of the types of branched CDs that can be synthesized that depend on the characteristics of the enzyme, the long reaction time required (several days or more), difficulty in synthesizing branched CD with a high degree of substitution (DS), the need for large quantities of environmentally harmful solvents, and a complicated and costly reaction. Using activated carbon as a catalyst, branched CDs with a high DS could be synthesized within a relatively short time (a few hours), regardless of the type of saccharide in the branched portion. Furthermore, since the reaction was conducted under solvent-free conditions using activated carbon, the amount of solvent used in the production of branched CD could be reduced. The branched β-CDs prepared using the activated carbon catalyst showed high solubility, high solubilization capacity, and low hemolytic activity, similar to the 2-hydroxypropyl-β-CD used for pharmaceuticals. These results indicate that activated carbon is an industrially and environmentally useful catalyst for branched CD syntheses.

Hydroxypyranones form very stable complexes and possess varied uses in medical applications. They are promising chelators for treating iron overload diseases as they form stable complexes with Fe³⁺. A novel tripodal ligand tris[(5-hydroxy-4-oxo-pyran-2-yl)methyl] benzene-1,3,5-tricarboxylate (TBHPY) was synthesized and characterized by several spectroscopic techniques like UV–Vis, FT-IR, ¹HNMR, ¹³CNMR and mass spectrometry. The coordination behavior of the ligand TBHPY was investigated with proton and trivalent metal ions viz., Fe(III), Al(III) and Cr(III) by potentiometric and spectrophotometric methods. The studies revealed four species viz., L³⁻, LH²⁻_, LH₂⁻ and LH₃ for the ligand while ML, MLH and MLH₂ species for all the three metal ion complexes. In addition, only aluminium formed MLH₋₁, MLH₋₂ and MLH₋₃. Quantum mechanical studies at DFT level validated the geometrical, spectroscopic, electronic and photophysical properties of the neutral and deprotonated states of the ligand, and its metal complexes. The ligand showed a scorpio-type geometry with the presence of face-to-face stacking and hydrogen bond, whereas the neutral metal–ligand complexes displayed a distorted octahedral structure.

The effect of conformational flexibility on coordination and bonding of a chelator, [12N3Me5Ox], on the macrocyclic ring 1,5,9-tris(-5-methylene)-1,5,9-triazadodecane and its lanthanide complexes is depicted by synthesis, characterization, and theoretical techniques. The chelator and its complexes were prepared and characterized by physicochemical methods. Each lanthanide complex was eight coordinated with a pseudo-C₃ symmetric distorted dodecahedron geometry. Density functional theory (DFT) studies suggest that Ln³⁺ ions can be easily incorporated into the chelator cavity without changing the basic geometry. Natural bonding orbitals (NBO) and energy decomposition analysis (EDA) indicate that M–L bonds have ~ 70% ionic character. Exciting and diverse behavior was observed when the results of 12N3Me5Ox were compared with 9N3Me5Ox; with the increase in the size of the macrocyclic ring, the covalency of the metal–ligand bond was increased. The luminescence properties of these complexes were different in the solid and solution state. The f–f transitions of the lanthanide were not observed for the complexes. The theoretical results are in good agreement with the experiments.

Crown ethers containing an acridone or an acridine unit are successfully applied opto- and electrochemical cation sensors. The heteroaromatic unit of these macrocycles can be in different forms during the applications, which have a strong influence on the sensing behavior. Moreover, in the case of acridono-macrocycles a prototropic equilibrium takes place upon complexation, which is effected by the physicochemical characteristics. A Pb²⁺-selective acridono-18-crown-6 ether and its 9-phenylacridino-analogue were used as model compounds for comparing the different forms of the heterocyclic units of these sensor molecules. Since in most practical sensor applications of the fluorescent hosts a non-neutral aqueous medium is present, studies on complexation and signaling were carried out from the aspect of the relationship among protonation, coordinating ability, complex stability and tautomeric equilibrium. A strong interdependence among these factors was found and limitations of using unsubstituted acridino- and acridono-sensor molecules in comparison with their 9-substituted-acridino-analogues were discussed. This study will hopefully serve as a useful standpoint for future development of ionophore-based sensors containing an acridone or an acridine unit.

While the world is in search of a vaccine that can cure COVID-19 disease, favipiravir is the most commonly used antiviral drug in the treatment of patients during the pandemic process. In this study, we investigated the host–guest interaction between the popular supramolecule calix[4]arene derivatives and the favipiravir drug by using the DFT (Density Functional Theory) method. The B3LYP hybrid method and 6-31G (d,p) basis set were utilized to determine the optimized structures of the host and guest molecules and their complexes. The negative adsorption energy (∆E) and adsorption enthalpy (∆H) calculated for the complexes formed between calix[4]arene compounds and favipiravir drug molecule mentioned that adsorption of favipiravir molecule was an exothermic process on calix[4]arene structures. On the other hand, among the calixarene derivatives in the study, Gibbs free energy change (∆G) value for the adsorption was only negative on calix[4]arene4 molecule. The infrared spectroscopy (IR) calculations were performed by examining the C=O, O–H and NH₂ vibrational frequencies to see the adsorption behavior in the favipiravir-calix[4]arene complex. After adsorption of the favipiravir molecule, HOMO–LUMO gap values decreased significantly for the structures and therefore electrical conductivity increased proportionally. In addition, sensor response factors, Fermi energy levels and workfunction changes of calix[4]arene derivatives were calculated and examined. Charge transfer between the four calix[4]arene compounds and the favipiravir molecule has occurred after adsorption. This attributes that calix[4]arene derivatives can be used as a well-suited favipiravir sensor (electronic and workfunction) and adsorbent at room temperature. Based on the calculations made to see the solvent effect on the adsorption of favipiravir it was determined that it did not affect the interaction between the drug molecule and the calix[4]arene compound too much and the adsorption energy turned into a slightly less negative value.

This mini review summarizes Vicens’ research on calixdendrimers since 2004.

Making exercise more emotionally rewarding, which is related to the secretion of chemicals like cortisol and serotonin, can be an important way to increase people's continued propensity to exercise regularly, ultimately promoting better public health. This study used a four quadrant circumplex model to understand participants' emotional states during mid-intensity exercise. The study found that participants who exercised with partners and those who exercised solo had different levels of affective valence at different times before, during and after exercise. Solo participants experienced the greatest improvement in affective valence (affect) well after exercise had concluded, while partnered participants experienced the greatest improvement in affective valence during exercise. Solo participants also experienced greater strenuousness (activation) than partnered participants. Both solo and partnered participants experienced improvement in affect vis-à-vis persons who did not exercise at all, indicating that mid-intensity exercise induces positive feelings. The results indicate that the increased perception of sociality through partnered exercise increases positive emotions and decreases fatigue, presenting significant implications for development of programs to encourage regular exercise.

Curcumin (Curcuma longa, [1E,6E]-1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione) has been reported to have anti-inflammatory, antioxidant, antiviral, antifungal, antitumor, and antinociceptive action. In this study, the analgesic efficacy of intravenous curcumin for inflammatory pain was investigated using adult male Sprague-Dawley rats weighing between 200 and 300 g. Curcumin (1, 2.5, 5, and 10 mg/kg) and normal saline solution (0.2 mL) or DMSO (1 %, 0.2 mL) were intravascularly administered, respectively, to each group of five rats 30 s before the formalin test was performed, where phase I and II data were collected. Immunohistochemical analysis was performed to assess the localization of inflammatory cytokines (IL-1β, IL-6, and TNF-α) in the L4–L6 spinal cord of three rats from each of 1 mg/kg, 10 mg/kg and the control (DMSO, 1 %, 0.2 mL) group. It was found that the number of flinching responses were significantly decreased for 1 mg/kg and 10 mg/kg groups in phase I (p < 0.05) compared to the control group. However, there were no significant differences between the curcumin and control groups in phase II. In this phase, appearance of the peak point shifted to the right in the curcumin groups. The sum of the numbers of the responses from phase I and II did not appear to be significantly decreased by the amount of curcumin. As the peak point of the Time Effect Curve for phase I progressed over time over phase II, the mean plaque shifted to the right. The peak at 30 min was significantly delayed more than 10 min in 5 and 10 mg/kg groups compared to the controls. Immunohistochemistry results do not seem to be significantly different in each group except in IL-1β in curcumin 10 mg/kg group.