Study of the solubility, photostability and structure of inclusion complexes of carvedilol with β-cyclodextrin and (2-hydroxypropyl)-β-cyclodextrin

Characterization and Crystal Structural Analysis of Novel Carvedilol Adipate and Succinate Ethanol-Solvated Salts

Two ethanol-solvated adipate and succinate salts of carvedilol (CVD), a Biopharmaceutics Classification System class 2 drug, were synthesized by crystallizing ethanol with adipic acid (ADP) and succinic acid (SUA). Proton transfer from ADP and SUA to CVD and the presence of ethanol in the two novel compounds were confirmed using powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and single-crystal X-ray diffraction measurements. The two novel ethanol-solvated salts exhibited enhanced solubility and dissolution rates compared with pure carvedilol in phosphate buffer (pH 6.8). Additionally, the morphologies and attachment energies of the two novel compounds and pure CVD were calculated based on their single-crystal structures, revealing a correlation between attachment energy and dissolution rate.

Sulfo-butyl ether β-cyclodextrin inclusion complexes of bosutinib: in silico, in vitro and in vivo evaluation in attenuating the fast-fed variability

Bosutinib (BOS) is a BCS class IV drug that shows low oral bioavailability and high fast-fed variability. Various pharmaceutical formulations have been explored thus far in order to improve its bioavailability while avoiding fast-fed variability. In the present study, we explored cyclodextrin (CD) complexation strategy to overcome the aforementioned disadvantages associated with BOS. CD complexation is a simple, versatile and economic approach that enables formation of inclusion complexes, thereby improving aqueous solubility while nullifying pH-dependent solubility and fast-fed variability for poorly soluble drugs. Initially, we performed molecular dynamics and docking studies to select appropriate CD derivative. The results of in silico studies revealed that sulfo-butyl ether β-cyclodextrin (SBE-CD) offered superior binding affinity with BOS. Further, Job's plot revealed that 1:1 stoichiometry of BOS and CD resulted in enhancement of BOS solubility up to ~ 132.6-folds. In vitro release studies in bio-relevant media (fasted and fed state simulated gastric and intestinal fluids) revealed higher drug release while overcoming its pH-dependent solubility. In vitro studies on K562 cells demonstrated a 1.83-fold enhancement in cytotoxicity due to enhanced ROS production and G2/M phase arrest.In vivo pharmacokinetic studies in Sprague-Dawley rats revealed insignificant fast-fed variability with AUCfast/fed 0.9493 and Cmaxfast/fed 0.8291 being closer to 1 in comparison with BOS. Hence, we conclude that SBE-CD complexation could be a promising approach in diminishing fast-fed variability of BOS.

Encapsulation and Biological Activity of Hesperetin Derivatives with HP-β-CD

The encapsulation of insoluble compounds can help improve their solubility and activity. The effects of cyclodextrin encapsulation on hesperetin's derivatives (HHSB, HIN, and HTSC) and the physicochemical properties of the formed complexes were determined using various analytical techniques. The antioxidant (DPPH•, ABTS•+ scavenging, and Fe2+-chelating ability), cytotoxic, and antibacterial activities were also investigated. The inclusion systems were prepared using mechanical and co-evaporation methods using a molar ratio compound: HP-β-CD = 1:1. The identification of solid systems confirmed the formation of two inclusion complexes at hesperetin (CV) and HHSB (mech). The identification of systems of hesperetin and its derivatives with HP-β-CD in solutions at pHs 3.6, 6.5, and 8.5 and at various temperatures (25, 37 and 60 °C) confirmed the effect of cyclodextrin on their solubility. In the DPPH• and ABTS•+ assay, pure compounds were characterized by higher antioxidant activity than the complexes. In the FRAP study, all hesperetin and HHSB complexes and HTSC-HP-β-CD (mech) were characterized by higher values of antioxidant activity than pure compounds. The results obtained from cytotoxic activity tests show that for most of the systems tested, cytotoxicity increased with the concentration of the chemical, with the exception of HP-β-CD. All systems inhibited Escherichia coli and Staphylococcus aureus.

Reduced Graphene Oxide as a Platform for the Immobilization of Amino-Cyclodextrins

In the present work, we reported on a method to combine amino β-cyclodextrins (CD1) with reduced graphene oxide (obtained by the electrochemical reduction of graphene oxide, erGO) to produce a glassy carbon electrode (GCE) modified with both CD1 and erGO (CD1-erGO/GCE). This procedure avoids the use of organic solvents such as hydrazine or long reaction times and high temperatures. The material combining both CD1 and erGO (CD1-erGO/GCE) was characterized by SEM, ATR-FTIR, Raman, XPS, and electrochemical techniques. As proof-of-concept, the determination of the pesticide carbendazim was carried out. The spectroscopic measurements, especially XPS, proved that CD1 was covalently attached to the surface of the erGO/GCE electrode. The attachment of cyclodextrin at the reduced graphene oxide produced an increase in the electrochemical behavior of the electrode. The cyclodextrin-functionalized reduced graphene oxide, CD1-erGO/GCE, showed a larger sensitivity (1.01 μA/μM) and a lower limit of detection for carbendazim (LOD = 0.50 μM) compared with the non-functionalized material, erGO/GCE, (sensitivity = 0.63 μA/μM and LOD = 4.32 μM, respectively). Overall, the results of the present work show that this simple method is suitable to attach cyclodextrins to graphene oxide, maintaining their inclusion abilities.

Supersaturation maintenance of carvedilol and chlorthalidone by cyclodextrin derivatives: Pronounced crystallization inhibition ability of methylated cyclodextrin

Cyclodextrin (CD) is used to solubilize poorly water-soluble drugs by inclusion complex formation. In this study, we investigated the effect of CD derivatives on stabilizing the supersaturation by inhibiting the crystallization of two poorly water-soluble drugs, carvedilol (CVD) and chlorthalidone (CLT). The phase solubility test showed that β-CD and γ-CD derivatives enhanced the solubility of CVD to a greater extent, whereas the solubility of CLT was enhanced more by β-CD derivatives. The solubilization efficacy of CD derivatives was dependent on the size fitness between the drug molecule and the CD cavity. In the drug crystallization induction time measurement, the same initial drug supersaturation ratio (S) was employed in all the CD solutions, and the methylated CD derivatives greatly outperformed unmethylated CD derivatives in stabilizing the supersaturation of both CVD and CLT. The crystallization inhibition strength of CD derivatives was strongly affected by the CD derivative substituent. Moreover, the calculated logarithm of octanol/water partition coefficients (log P) of CD derivatives showed a good correlation with drug crystallization inhibition ability. Thus, the high hydrophobicity of methylated CD plays an essential role in inhibiting crystallization. These findings can provide a valuable guide for selecting appropriate stabilizing agents for drug-supersaturation formulations.

The challenge of flavonoid/cyclodextrin complexation in a complex matrix of the quercetin, luteolin, and 3-O-methylquercetin

The complexation of herbal constituents with cyclodextrin has been a useful tool to improve their aqueous solubility. However, the simultaneous complexation of these compounds still lacks detailed studies. The present study investigated the multicomplexation of quercetin (QCT), luteolin (LUT), and 3-O-methylquercetin (3OMQ) with (2-hydroxypropyl)-β-cyclodextrin (HPβCD), when they are simultaneously contained in a flavonoid-enriched fraction (FEF) of Achyrocline satureioides. The phase-solubility diagram revealed a linear correlation between the flavonoids solubility and the HPβCD concentration, demonstrating the formation of complexes with a 1:1 stoichiometric ratio, which was confirmed by ESI-MS. Negative ΔG⁰ values indicated that complexation was spontaneous. Flavonoids/HPβCD interactions were evidenced by FT-IR, DSC, SEM, and 1D and 2D NMR. The last one showed the formation of inclusion complexes by insertion of the B-ring of the flavonoids into the cavity of HPβCD. Unexpectedly, the FEF/HPβCD complex showed a radical scavenger potential lower than the FEF. The HPLC analysis revealed that the complex contained different flavonoid ratio than the fraction. Thus, the antioxidant capacity of the samples was demonstrated to be related to the ratio among the flavonoids, rather than to the total flavonoids. These new findings are very useful for developing herbal cyclodextrin-based products from A. satureioides or other herbal products.

Enhanced Antioxidant, Antiviral, and Anticancer Activities of the Extract of Fermented Egyptian Rice Bran Complexed with Hydroxypropyl-β-cyclodextrin

Egyptian rice bran was fermented with baker's yeast, and released phenolics were extracted with aqueous methanol to give fermented rice bran extract (FRBE). The analysis of the FRBE with ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry revealed 21 compounds, mainly phenolic acids and flavonoids. The FRBE was then complexed with (2-hydroxypropyl)-β-cyclodextrin (HPβCD) via noncovalent host-guest inclusion complexation using the thin-film hydration technique to improve the hydrophilicity and bioactivity of the FRBE. The formation of the inclusion complex was confirmed using HPLC, ¹H NMR, FT-IR, and a phase solubility study. In addition, the biological activities of the complex were investigated. The FRBE/HPβCD inclusion complex had more pronounced antioxidant, antiviral, and anticancer activities compared to free FRBE. These findings warrant the future investigation of potential medical applications of FRBE.

Parietin Cyclodextrin-Inclusion Complex as an Effective Formulation for Bacterial Photoinactivation

Multidrug resistance in pathogenic bacteria has become a significant public health concern. As an alternative therapeutic option, antimicrobial photodynamic therapy (aPDT) can successfully eradicate antibiotic-resistant bacteria with a lower probability of developing resistance or systemic toxicity commonly associated with the standard antibiotic treatment. Parietin (PTN), also termed physcion, a natural anthraquinone, is a promising photosensitizer somewhat underrepresented in aPDT because of its poor water solubility and potential to aggregate in the biological environment. This study investigated whether the complexation of PTN with (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) could increase its solubility, enhance its photophysical properties, and improve its phototoxicity against bacteria. At first, the solubilization behavior and complexation constant of the PTN/HP-β-CD inclusion complexes were evaluated by the phase solubility method. Then, the formation and physicochemical properties of PTN/HP-β-CD complexes were analyzed and confirmed in various ways. At the same time, the photodynamic activity was assessed by the uric acid method. The blue light-mediated photodegradation of PTN in its free and complexed forms were compared. Complexation of PTN increased the aqueous solubility 28-fold and the photostability compared to free PTN. PTN/HP-β-CD complexes reduce the bacterial viability of Staphylococcus saprophyticus and Escherichia coli by > 4.8 log and > 1.0 log after irradiation, respectively. Overall, the low solubility, aggregation potential, and photoinstability of PTN were overcome by its complexation in HP-β-CD, potentially opening up new opportunities for treating infections caused by multidrug-resistant bacteria.

Formulation and Characterization Studies of Inclusion Complexes of Voriconazole for Possible Ocular Application

In our study Voriconazole (VOR) was selected as an active agent to be used for the treatment of ocular fungal infections. To overcome low aqueous solubility of VOR, inclusion complexes with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD), hydroxypropyl-cyclodextrin (HP-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD) hydroxypropyl-γ-cyclodextrin (HP-γ-CD), methyl-β-cyclodextrin (M-β-CD) and sulfabutylether-β-cyclodextrin (SBE-β-CD) were formulated. Characterization studies revealed that inclusion complexes were formulated successfully with lyophilization method. Aqueous solubility of VOR was enhanced up to 86 fold with the formation of the inclusion complexes. MTT analyses results revealed the safety of the complexes on 3T3 mouse fibroblast cell lines while Microbroth Dilution Method revealed the remarkable antifungal activities of the complexes. Analyses results revealed that inclusion complexes will overcome the poor ocular bioavailability of VOR resulting in efficient treatment of severe ocular fungal infections.

Cyclodextrin Complexation as a Way of Increasing the Aqueous Solubility and Stability of Carvedilol

We studied the effect of several CDs on carvedilol's solubility and chemical stability in various aqueous media. Our present results show that it is possible to achieve a carvedilol concentration of 5 mg/mL (12.3 mM) in the presence of 5 eq of γCD or RAMEB in an aqueous medium with an acceptable acid pH (between 3.5 and 4.7). Carvedilol formed 1:1 inclusion complexes but those with RAMEB appear to be stronger (K = 317 M-1 at 298 K) than that with γCD (K = 225 M-1 at 298 K). The complexation of carvedilol by RAMEB significantly increased the drug's photochemical stability in aqueous solution. These results might constitute a first step towards the development of a novel oral formulation of carvedilol.

Molecular encapsulation of andrographolide in 2-hydroxypropyl-β-cyclodextrin cavity: synthesis, characterization, pharmacokinetic and in vitro antiviral activity analysis against SARS-CoV-2

In present investigation, AND-2-HyP-β-CYD (Andrographolide-2-Hydroxypropyl-β-cyclodextrin) complex was synthesized and characterized for antiviral and pharmacokinetic profile. The linear host-guest relation suggested synthesis of a 1:1 complex of AND with 2-HyP-β-CYD by inclusion mode. The Kc, stability constant of the two phase system of AND with 2-HyP-β-CYD computed to be 38.60 x 10⁻³M. ¹H NMR spectrum of AND indicated the presence of triplet at 6.63-ppm which was up-fielded in AND-2-HyP-β-CYD complex at 6.60-ppm (doublet) confirmed the insertion of AND in cavity of 2-HyP-β-CYD through lactone ring. AND-2-HyP-β-CYD complex exhibited the IC₅₀ of 0.1-μg.mL⁻¹ (E gene) and 0.29-μg.mL⁻¹ (N gene) against SARS-CoV-2 infected Vero6 cells. Moreover, a 1.5-fold increment in extent of absorption of AND was noticed post complexation. The bioavailability was estimated to be 15.87 ± 3.84% and 23.84 ± 5.46%, respectively for AND and AND-2-HyP-β-CYD complex. AND-2-HyP-β-CYD complex may be a prospective candidate for further studies to evolve as a clinically viable formulation against SARS-CoV-2.

Erlotinib complexation with randomly methylated β-cyclodextrin improves drug solubility, intestinal permeability, and therapeutic efficacy in non-small cell lung cancer

The purpose of this study was to investigate the impact of anticancer drug erlotinib-randomly methylated-β-cyclodextrin complex (ERL-RAMEB CD) on drug solubility and dissolution rate. Phase solubility study showed erlotinib displayed maximum solubility in RAMEB CD solution and the stability constant (K_c) was calculated to be 370 ± 16 M^-1. The optimal formulation was obtained with ERL-RAMEB CD in a 1:1 molar ratio using the co-lyophilization technique. Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM) verified the inclusion of complex formation. In vitro dissolution study confirmed ERL-RAMEB CD as a favorable approach to increase drug dissolution with a 1.5-fold increase than free ERL at 1 h. An improved dissolution with ∼88.4% drug release at 1 h was observed, in comparison with Erlotinib with ∼58.7% release in 45 min. The in vitro cytotoxicity results indicated that the ERL-RAMEB CD inclusion complex reduced cell viability than free erlotinib. Caco-2 cell uptake that is indicative of drug intestinal permeability resulted in a 5-fold higher uptake of ERL-RAMEB CD inclusion complex than the ERL solution. Hence, ERL-RAMEB CD complexation displays a strong potential to increase dissolution and permeability of erlotinib leading eventually to enhanced oral bioavailability.

Electrospun poly (vinyl alcohol) nanofibers incorporating caffeic acid/cyclodextrins through the supramolecular assembly for antibacterial activity

Here, we prepared the solid inclusion complexes between Caffeic acid (CA) and Cyclodextrins (β- and γ-CDs) (CA/CDs) that were effectively embedded into Poly (vinyl alcohol) (PVA) electrospun nanofibers via electrospinning technique to enhanced solubility and antibacterial activity. In tested Cyclodextrins are β-and γ-CDs with CA in the ratio of 1:1 resulting in the formation of CA/CDs by co-precipitation method. The physical properties of CA/CDs were examined by FT-IR, UV, and Raman Spectroscopy. The phase solubility test showed a much higher solubility of CA due to inclusion complexes (ICs). Furthermore, CA/β-CD and CA/γ-CD perfected achieved 0.70:1 and 0.80:1 the molar ratio of ICs, confirmed by NMR studies. The fiber size distribution, average diameter, and morphology features were evaluated by SEM analysis. The dissolution profile of PVA/CA and PVA/CA/CDs were tested within 150 min, resulting in CA dissolved in PVA/CA/CDs slightly higher than PVA/CA nanofibers due to enhanced solubility of ICs. Moreover, PVA/CA/CDs exhibit high antibacterial activity against gram-positive bacteria of E-Coli and gram-negative bacteria of S. aureus. Finally, these results suggest that PVA/CA/CDs may be promising materials for active food packaging applications.

The mechanism of bensulfuron-methyl complexation with β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin and effect on soil adsorption and bio-activity

In this work, the inclusion complexes of hydrophobic herbicide bensulfuron-methyl (BSM) with β-cyclodextrin (β-CD) and (2-hydroxypropyl)-β-CD (2-HP-β-CD) were prepared and characterized. Phase solubility study showed that both β-CD and 2-HP-β-CD increased the solubility of BSM. Three-dimensional structures of the inclusion complexes were simulated by the molecular docking method. The docking results indicated that guest BSM could enter into the cavities of host CDs, folded, and centrally aligned inside the inclusion complexes. The benzene ring of the guest molecule was close to the wide rim of the host molecules; the pyrimidine ring and side chains of the guest molecule were oriented toward the narrow rim of the host molecule. The inclusion complexes were successfully prepared by the coprecipitation method. The physiochemical characterization data of 1H NMR, FT-IR, XRD, and DSC showed that the guest and host molecules were well included. BSM had lower soil adsorption and higher herbicidal activity in the complexation form with β-CD or 2-HP-β-CD than in the pure form. The present study provides an approach to develop a novel CDs-based formulation for hydrophobic herbicides.

Preparation and Characterization of Butachlor/(2-Hydroxypropyl)-β-cyclodextrin Inclusion Complex: Improve Soil Mobility and Herbicidal Activity and Decrease Fish Toxicity

A water-soluble inclusion complex for butachlor was prepared by complexation with (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD). Phase solubility results indicated a 1:1 stoichiometric ratio with an apparent stability constant of 864.3 M^-1 in the obtained solid complex. The formation of the complex was confirmed by ¹H nuclear magnetic resonance, Fourier transform infrared, and differential scanning calorimetry spectra. Coupled with the molecular docking results, butachlor was considered to be completely included in HP-β-CD cavity. Butachlor complexation with HP-β-CD decreased its adsorption capacity and enhanced its mobility in soil. The inclusion complex displayed better herbicidal activities than free butachlor. The 96 h median lethal concentration values of the inclusion complex and free butachlor was 2.30 and 0.65 mg L^-1, respectively, for zebrafish, indicating that the complexation could significantly reduce toxicity to fishes. The present study provides an approach to develop environment-friendly formulations using CDs for herbicides.

Preparation, characterization and antimicrobial activity of inclusion complex of biochanin A with (2-hydroxypropyl)-β-cyclodextrin

Objectives

An inclusion complex of biochanin A (BCA) with (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) was prepared in the ethanol solution to improve its water solubility.

Methods

Using the FTIR, 1H-NMR, XRD, DSC and SEM methods, the structural characterization of the prepared complex was analysed.

Key findings

The phase-solubility study has shown that the solubility of BCA was increased twofold in 42% (v/v) ethanol solution after complexation with HP-β-CD. The complex between BCA and HP-β-CD was prepared in the molar ratio of 1 : 1. The antibacterial activity of the inclusion complex was investigated against the various bacteria, fungus and yeast using the microdilution method. The minimal inhibitory concentration values for the analysed strain of bacteria were in the range of 0.84–1.69 mg/cm3, whereby the prepared inclusion complex exhibited less effect on the reduction of the number of Escherichia coli and Klebsiella pneumoniae species compared to pure BCA. The inclusion complex of BCA was significantly more active against Candida albicans than pure BCA. Biochanin A and its inclusion complex has not expressed the activity against Aspergillus niger.

Conclusions

Based on the obtained results, it can be concluded that the antimicrobial activity of BCA was remained unchanged after complexation.

Effect of sulfobutyl ether-β-cyclodextrin and propylene glycol alginate on the solubility of clozapine

Clozapine (CLZ) is an atypical antipsychotic medication used in the treatment of schizophrenia and is poorly soluble in water (0.05 mM). In this study, we have investigated the effect of β-cyclodextrin (CD) and its derivatives on the solubility of CLZ. The solubility of the CLZ was measured to generate a phase solubility diagram, and the interaction between CLZ and sulfobutyl ether-β-cyclodextrin (SBE-β-CD) in aqueous solution was observed by ¹H- and 2D rotating-frame Overhauser enhancement spectroscopy (ROESY)-NMR methods. Moreover, the synergistic effect of SBE-β-CD and water-soluble polymers, including polyvinylpyrrolidone, hydroxypropyl methylcellulose, carboxymethylcellulose sodium salt, polyvinyl alcohol, sodium alginate, and propylene glycol alginate (PGA), on the solubility of CLZ was investigated. The results show that the solubility of CLZ with 1 w/v% PGA was 7.6 mM, which was almost four times greater than that of CLZ without PGA in a 15 mM SBE-β-CD solution. In contrast, the solubility of CLZ with 1 w/v % PGA in an aqueous solution decreased by one-third relative to that of CLZ in a 15 mM SBE-β-CD solution. 2D ROESY-NMR indicated that a CLZ/SBE-β-CD/PGA ternary complex formed. It was found that the combination of PGA and SBE-β-CD enhanced the solubility of CLZ.

Preparation of Amidoxime-Functionalized β-Cyclodextrin-Graft-(Maleic Anhydride-co-Acrylonitrule) Copolymer and Evaluation of the Adsorption and Regeneration Properties of Uranium

The β-cyclodextrin-graft-(maleic anhydride-co-acrylonitrule) copolymer (β-CD-g-(MAH-co-AN)) synthesized through radical polymerization reactions of β-cyclodextrin (β-CD) with maleic anhydride (MAH) and acrylonitrule (AN) in the special monomer proportion, chemically modify with amidoxime groups to obtained the new adsorbent, which was terms as amidoxime-functionalized β-cyclodextrin-graft-(maleic anhydride-co-acrylonitrule) copolymer (β-CD-g-(MAH-co-AO)). Based on the characteristic results of Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), X-ray Diffraction (XRD), and thermalgravity analysis (TGA) techniques, the grafted nitrile groups were successfully converted to amidoxime groups by reaction with hydroxylamine. In this report, the influence of different factors such as pH value and ionic strength, solid-liquid ratio, contact time, initial U(VI) concentration, and temperature on adsorption was investigated by a batch adsorption experiment. The adsorption process fitting results show that the adsorption followed the Langmuir isotherm model and the maximum adsorption capacity was 0.747 g/g at pH 4.0. In addition, the regeneration performance was investigated by varying the concentration of eluent, temperature, and contact time. Under the desorption condition of 0.10 M HNO₃, the adsorbents can be reused 12 times in the case that the adsorption capacity was not significantly reduced. The functionalized copolymer exhibits high selectivity under circumstance of other co-existing ions is present in the solution.

Photostability and antioxidant activity studies on the inclusion complexes of trans-polydatin with β-cyclodextrin and derivatives

The inclusion complexes of trans-polydatin and three cyclodextrins (CDs), namely β-cyclodextrin (β-CD), methyl-β-cyclodextrin (Me-β-CD) and (2-hydroxy) propyl-β-cyclodextrin (HP-β-CD) were prepared.