Structure and stability of warfarin-sodium inclusion complexes formed with permethylated monoamino-β-cyclodextrin

Preparation, solubility, and anti-inflammatory effects of a complex of diphenylcyclopropenone/β-cyclodextrin derivatives as the treatment of alopecia areata

Purpose

To investigate the preparation of inclusion complexes of diphenylcyclopropenone (DPCP)/β-cyclodextrin (β-CD) derivatives using a three-dimensional (3D) ball mill, and verify the inclusion behavior of the solid dispersion. Additionally, we aimed to investigate the effect of DPCP/β-CDs complex formation on the spleens of male C57BL/6 mice in terms of anti-inflammatory effects.

Methods

The inclusion complexes of DPCP with β-CD and hydroxypropyl-β-cyclodextrin (HPβCD) were prepared using a 3D ball mill. Powder X-ray diffraction (PXRD) and Fourier-transform infrared spectroscopy (FT-IR) were used to evaluate the solid-state properties. The solubility of the prepared DPCP/β-CD and HPβCD complexes and the intermolecular interaction between DPCP and β-CD derivatives in solution were assessed using 1H nuclear magnetic resonance (NMR). Furthermore, the anti-inflammatory effects of DPCPs in the prepared DPCP/CD complexes were investigated using spleens from male C57BL/6 mice, with measurement of interferon gamma (IFN-γ) secretion as an endpoint. Additionally, the protective effects of each drug on NIH-3T3 cells exposed to ultraviolet (UV) irradiation were examined.

Results

Solid-state characterization confirmed the formation of inclusion complexes in the 3D ground mixture (3DGM) (DPCP/β-CD = 1/1) and 3DGM (DPCP/HPβCD = 1/1) complexes through PXRD and IR analysis. The solubility of 3DGM (DPCP/β-CD = 1/1) and 3DGM (DPCP/HPβCD = 1/1) was 17.5 μg/mL and 58.4 μg/mL, respectively, indicating higher solubility than that of DPCP alone. NMR analysis of 3DGM samples suggested that DPCP/β-CD and DPCP/HPβCD form inclusion complexes at a molar ratio of 1/1 but with different inclusion modes. Regarding the anti-inflammatory activity of DPCP, 3DGM (DPCP/HPβ-CD) showed anti-inflammatory effects at lower doses compared to 3DGM (DPCP/β-CD) in terms of IFN-γ and NIH-3T3 cells injured by UV irradiation.

Conclusion

We successfully formed inclusion complexes of DPCP/β-CD and DPCP/HPβCD using the 3D ground mixture method. NMR analysis suggested that DPCP/β-CD and DPCP/HPβCD form inclusion complexes at a molar ratio of 1/1 but with different inclusion modes. The anti-inflammatory activity of DPCP was more pronounced in 3DGM (DPCP/HPβCD) at lower doses compared to that in 3DGM (DPCP/β-CD), indicating that the HPβCD derivatives were more effective in enhancing the anti-inflammatory properties of DPCP.

Characterization, Preparation, and Promotion of Plant Growth of 1,3-Diphenylurea/β-Cyclodextrin Derivatives Inclusion Complexes

The study aimed to prepare inclusion complexes of 1,3-diphenylurea (DPU) with β-cyclodextrin (βCD) and 2-hydroxypropyl-β-cyclodextrin (HP-βCD) using a three-dimensional ground mixture (3DGM). Their physicochemical properties, intermolecular interactions, solubilities, and plant growth-promoting activities were investigated on broccoli sprouts. Phase-solubility diagrams indicated the stability constant (Ks) and complexation efficiency (CE) of βCD/DPU were found to be K1/1 = 250 M-1, CE = 2.48× 10-3. The Ks and CEs of HP-βCD/DPU were found to be K1/1 = 427 M-1, CE = 3.93 × 10-3 and K2/1 = 196 M-1, CE = 1.93 × 10-3 respectively. The powder X-ray diffraction results of 3DGM (βCD/DPU = 2/1, HP-βCD/DPU = 2/1) showed that the diffraction peaks originating from the DPU and βCD disappeared, indicating a halo pattern. Differential scanning calorimetry results showed an endothermic peak at 244 °C derived from the melting point of DPU, but the endothermic peak disappeared in the 3DGM (βCD/DPU = 2/1, HP-βCD/DPU = 2/1). Near-infrared absorption spectra showed peak shifts in 3DGM (βCD/DPU and HP-βCD/DPU) at the -CH and -NH groups of DPU and the -OH groups of βCDs and free water. In the dissolution test (after 5 min), the concentration of intact DPU was 0.083 μg/mL. However, the dissolution concentrations of DPU in the 3DGM (βCD/DPU = 1/1), 3DGM (βCD/DPU = 2/1), 3DGM (HP-βCD/DPU = 1/1), and 3DGM (HP-βCD/DPU = 2/1) were 3.27, 3.64, 5.70, and 7.03 μg/mL, respectively, indicating higher solubility than that of the intact DPU. Further, 1H-1H NOESY NMR spectroscopic measurements showed cross-peaks between H-A (7.32 ppm) and H-B (7.12 ppm) of DPU and H-6 (3.79 ppm) in the βCD cavity of the 3DGM (βCD/DPU = 2/1). A cross-peak was also observed among DPU H-A (7.32 ppm), H-B (7.11 ppm), and H-6 (3.78 ppm) in the βCD cavity. The results of the broccoli sprout cultivation experiment showed that 3DGM (βCD/DPU = 1/1), 3DGM (βCD/DPU = 2/1), 3DGM (HP-βCD/DPU = 1/1), and 3DGM (HP-βCD/DPU = 2/1) increased the stem thickness compared with that of the control group (DPU). These results indicated that the βCD/DPU and HP-βCD/DPU inclusion complexes were formed by the three-dimensional mixing and milling method, which enhanced the solubility and plant growth-promoting effects.

Predicting the Prevalence of Alternative Warfarin Tautomers in Solution

Warfarin, a widely used oral anticoagulant, is prescribed as a racemic mixture. Each enantiomer of neutral Warfarin can exist in 20 possible tautomeric states leading to complex pharmacokinetics and uncertainty as to the relevant species under different conditions. Here, the ability of alternative computational approaches to predict the preferred tautomeric form(s) of neutral Warfarin in different solvents is examined. It is shown that varying the method used to estimate the heat of formation in vacuum (direct or via homodesmic reactions), whether entropic corrections were included, and the method used to estimate the free enthalpy of solvation (i.e., PCM, COSMO, or SMD implicit models or explicit solvent) lead to large differences in the predicted rank and relative populations of the tautomers. In this case, only a combination of the enthalpy of formation using homodesmic reactions and explicit solvent to estimate the free enthalpy of solvation yielded results compatible with the available experimental data. The work also suggests that a small but significant subset of the possible Warfarin tautomers are likely to be physiologically relevant.

Molecular interactions of the inclusion complexes of hinokitiol and various cyclodextrins

The aim of this study was to prepare inclusion complexes of hinokitiol (HT)/α-cyclodextrin (α-CD) and HT/β-cyclodextrin (β-CD) by cogrinding and to evaluate the differences in their formation. The physical properties of the preparation were evaluated by Job's plot, phase solubility studies, differential scanning calorimetry, powder X-ray diffraction, solid fluorescence spectra, and infrared absorption spectra. Intermolecular interaction in the solid state was confirmed to be in the ratios HT/α-CD = 1/2 and HT/β-CD = 1/1. Results indicated that the dissolution property of HT was improved by inclusion in the complexes HT/α-CD and HT/β-CD compared with HT crystals. The ¹H-¹H ROESY NMR spectrum of HT/α-CD showed that part of the seven-membered ring of HT and the isopropyl group of HT was linked to the wider edges of the two α-CDs. In HT/β-CD, the seven-membered ring of HT interacted with the narrower edge of β-CD and the isopropyl group of HT interacted with the wider edges. This structure of inclusion complexes was attributed to the difference in the cavity diameter of the CD and was thought to influence the dissolution properties.

Chiral recognition in separation science - an update

Stereospecific recognition of chiral molecules is an important issue in various aspects of life sciences and chemistry including analytical separation sciences. The basis of analytical enantioseparations is the formation of transient diastereomeric complexes driven by hydrogen bonds or ionic, ion-dipole, dipole-dipole, van der Waals as well as π-π interactions. Recently, halogen bonding was also described to contribute to selector-selectand complexation. Besides structure-separation relationships, spectroscopic techniques, especially NMR spectroscopy, as well as X-ray crystallography have contributed to the understanding of the structure of the diastereomeric complexes. Molecular modeling has provided the tool for the visualization of the structures. The present review highlights recent contributions to the understanding of the binding mechanism between chiral selectors and selectands in analytical enantioseparations dating between 2012 and early 2016 including polysaccharide derivatives, cyclodextrins, cyclofructans, macrocyclic glycopeptides, proteins, brush-type selectors, ion-exchangers, polymers, crown ethers, ligand-exchangers, molecular micelles, ionic liquids, metal-organic frameworks and nucleotide-derived selectors. A systematic compilation of all published literature on the various chiral selectors has not been attempted.

Cyclodextrins in capillary electrophoresis: recent developments and new trends

Despite the fact that extensive research in the field of separations by capillary electrophoresis (CE) has been carried out and many reviews have been published in the last years, a specific review on the use and future potential of cyclodextrins (CDs) in CE is not available. This review focuses the attention in the CD-CE topic over the January 2013-February 2014 period (not covered by previous more general CE-reviews). Recent contributions (reviews and research articles) including practical uses (e.g. solute-CD binding constant estimation and further potentials; 19% of publications), developments and applications (mainly chiral and achiral analysis; 38 and 24% of publications, respectively) are summarized in nine comprehensive tables and are commented. Statistics and predictions related to the CD-CE publications are highlighted in order to infer the current and expected research interests. Finally, trends and initiatives on CD-CE attending to real needs or practical criteria are outlined.