Dissolution enhancement of Gefitinib by solid dispersion and complexation with β-cyclodextrins: In vitro testing, cytotoxic activity, and tablet formulation

Cancer is the leading cause of mortality worldwide. In patients with metastatic non-small cell lung cancer, epidermal growth factor receptor (EGFR) is often overexpressed. Gefitinib (GEF), an inhibitor of EGFR, is approved for the treatment of patients with metastatic non-small cell lung cancer (NSCLC). However, the low solubility and dissolution of GEF limits its bioavailability. Numerous methods, including solid dispersion (SD) and complexation, have been reported to enhance the dissolution of poorly soluble drugs. In this study, GEF complexes were prepared using methyl-β-cyclodextrin (MβCD) and hydroxypropyl-β-cyclodextrin (HPβCD) in two molar ratios (1:1 and 1:2), furthermore, GEF SDs were prepared using polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and poloxamer-188(PXM) in three different ratios (1:2, 1:4 and 1:6 w/w). Dissolution studies were conducted on the prepared formulations. Dissolution results showed a 1.22-2.17-fold enhancement in drug dissolution after one hour compared to untreated GEF. Two formulations that showed higher dissolution enhancement were subsequently evaluated for in-vitro cytotoxicity and were formulated into tablets. The selected PVP-GEF (1:4 w/w) and MβCD-GEF (1:1M) formulas displayed improved cytotoxicity compared to untreated GEF. The IC50 values of the PVP-GEF and MβCD-GEF were 4.33 ± 0.66 and 4.84 ± 0.38 µM, respectively which are significantly lower (p < 0.05) than free GEF. In addition, the formulated tablets exhibited enhanced dissolution compared to pure GEF tablets. PVP-GEF SD tablets released (35.1 %±0.4) of GEF after one hour, while GEF-MβCD tablets released (42.2 % ± 0.7) after one hour. In the meantime, tablets containing pure GEF showed only 15 % ± 0.5 release at the same time. The findings of this study offer valuable insights for optimizing the dissolution and hence therapeutic capabilities of GEF while mitigating its limitations.

Mucoadhesive polymers: Design of S-protected thiolated cyclodextrin-based hydrogels

AIM

This study aims to design chemically crosslinked thiolated cyclodextrin-based hydrogels and to evaluate their mucoadhesive properties via mucosal residence time studies on porcine small intestinal mucosa and on porcine buccal mucosa.

METHODS

Free thiol groups of heptakis(6-deoxy-6-thio)-β-cyclodextrin (β-CD-SH) were S-protected with 2-mercaptoethanesulfonic acid (MESNA) followed by crosslinking with citric acid. Cytotoxicity was assessed by hemolysis as well as resazurin assay. Hydrogels were characterized by their rheological and mucoadhesive properties. Ritonavir was employed as model drug for in vitro release studies from these hydrogels.

RESULTS

The structure of S-protected β-CD-SH was confirmed by IR and 1H NMR spectroscopy. Degree of thiolation was 390 ± 7 µmol/g. Hydrogels based on native β-CD showed hemolysis of 12.5 ± 2.5 % and 13.6 ± 2.7 % within 1 and 3 h, whereas hemolysis of just 3.5 ± 2.8 % and 3.9 ± 3.0 % was observed for the S-protected thiolated CD hydrogels, respectively. Both native and S-protected thiolated hydrogels showed minor cytotoxicity on Caco-2 cells. Rheological investigations of S-protected thiolated β-CD-based hydrogel (16.2 % m/v) showed an up to 13-fold increase in viscosity in contrast to the corresponding native β-CD-based hydrogel. Mucosal residence time studies showed that thiolated β-CD-based hydrogel is removed to a 16.6- and 2.4-fold lower extent from porcine small intestinal mucosa and porcine buccal mucosa in comparision to the native β-CD-based hydrogel, respectively. Furthermore, a sustained release of ritonavir from S-protected thiolated β-CD-based hydrogels was observed.

CONCLUSION

Because of their comparatively high mucoadhesive and release-controlling properties, S-protected thiolated β-CD-based hydrogels might be promising systems for mucosal drug delivery.

Cyclodextrin microneedles for the delivery of a nanoparticle-based peptide antigen vaccine

In recent years, microneedles (MNs) have gained considerable interest in drug formulation due to their non-invasive and patient-friendly nature. Dissolving MNs have emerged as a promising approach to enhance drug delivery across the skin in a painless manner without generating sharp waste and providing the possibility for self-administration. Cyclodextrins, a group of cyclic oligosaccharides, are well-established in pharmaceutical products due to their safety and unique ability to form inclusion complexes with various drug molecules. In this manuscript, we report the development and characterization of dissolving MNs composed of cyclodextrins for intradermal delivery of a cyclodextrin-based nanoparticulate vaccine. Different cyclodextrins were tested and the most promising candidates were fabricated into MNs by micromolding. The MNs' piercing effectiveness and drug permeation across the skin were tested ex vivo. Furthermore, in vivo studies were carried out to assess the skin's tolerance to cyclodextrin-based MNs, and to evaluate the immune response using a model peptide antigen in a mouse model. The data revealed that the MNs were well-tolerated and effective, even leading to dose-sparing effects. This study highlights the potential of cyclodextrin-based dissolving MNs as a versatile platform for intradermal vaccine delivery, providing a compatible matrix for nanoparticulate formulations to enhance immune responses.

Progress in cyclodextrins as important molecules regulating catalytic processes of glycoside hydrolases

Cyclodextrins (CDs) are important starch derivatives and commonly comprise α-, β-, and γ-CDs. Their hydrophilic surface and hydrophobic inner cavity enable regulation of enzyme catalysis through direct or indirect interactions. Clarifying interactions between CDs and enzyme is of great value for enzyme screening, mechanism exploration, regulation of catalysis, and applications. We summarize the interactions between CDs and glycoside hydrolases (GHs) according to two aspects: 1) CD as products, substrates, inhibitors and activators of enzymes, directly affecting the reaction process; 2) CDs indirectly affecting the enzymatic reaction by solubilizing substrates, relieving substrate/product inhibition, increasing recombinant enzyme production and storage stability, isolating and purifying enzymes, and serving as ligands in crystal structure to identify functional amino acid residues. Additionally, CD enzyme mimetics are developed and used as catalysts in traditional artificial enzymes as well as nanozymes, making the application of CDs no longer limited to GHs. This review concerns the regulation of GHs catalysis by CDs, and gives insights into research on interactions between enzymes and ligands.

Synthesis and characterization of fluorescent poly(α-cyclodextrin)/carbon quantum dots composite for efficient removal and detection of toluene and xylene from aqueous media

This study reports the synthesis and characterization of a supramolecular composite comprised of carbon dots (CDots) embedded within net-poly[(α-cyclodextrin)-ν-(citric acid)] (α-CD/CA/CDots) for the removal and detection of toluene and xylene from aqueous media. The remarkable stability of CDots within the composite enables the preservation of photoluminescence properties for prolonged storage and extended UV-light irradiation. As demonstrated, following the adsorption of both organic compounds, the composite detected them in the aqueous medium due to a fluorescence quenching mechanism. Spectroscopic analyses reveal that the accessible Stern-Volmer quenching constants for toluene and xylene are KSVa = 15.4 M-1 and KSVa = 10.3 M-1, respectively. As a result, the α-CD/CA/CDots composite were sensitive to the tested volatile organic compounds (LODtoluene = 3.7 mg/L and LODxylene = 4.9 mg/L). Optimal conditions for toluene and xylene adsorption were found, allowing to achieve noticeable adsorption capabilities (qe(toluene) = 68.9 and qe(xylene) = 48.2 mg/g) and removal efficiencies exceeding 70%. Different characterization techniques confirmed the successful synthesis of the composite and elucidated the interaction mechanisms between the adsorbent and the tested compounds. In summary, the multifunctionality demonstrated by the α-CD/CA/CDots composite ranks it as an efficient and promising adsorbent and detection probe for this class of water contaminants.

Quorum quenching effect of cyclodextrins on the pyocyanin and pyoverdine production of Pseudomonas aeruginosa

Various virulence determinants in Pseudomonas aeruginosa are regulated by the quorum sensing (QS) network producing and releasing signalling molecules. Two of these virulence determinants are the pyocyanin and pyoverdine, which interfere with multiple cellular functions during infection. The application of QS-inhibiting agents, such as cyclodextrins (CDs), appears to be a promising approach. Further to method development, this research tested in large-volume test systems the effect of α- and β-CD (ACD, BCD) at 1, 5, and 10 mM concentrations on the production of pyocyanin in the P. aeruginosa model system. The concentration and time-dependent quorum quenching effect of native CDs and their derivatives on pyoverdine production was tested in a small-volume high-throughput system. In the large-volume system, both ACD and BCD significantly inhibited pyocyanin production, but ACD to a greater extent. 10 mM ACD resulted in 58% inhibition, while BCD only ~40%. Similarly, ACD was more effective in the inhibition of pyoverdine production; nevertheless, the results of RMANOVA demonstrated the significant efficiency of both ACD and BCD, as well as their derivatives. Both the contact time and the cyclodextrin treatments significantly influenced pyoverdine production. In this case, the inhibitory effect of ACD after 48 h at 12.5 mM was 57%, while the inhibitory effect of BCD and its derivatives was lower than 40%. The high-level significant inhibition of both pyocyanin and pyoverdine production by ACD was detectable. Consequently, the potential value of CDs as QS inhibitors and the antivirulence strategy should be considered. KEYPOINTS: • Applicability of a simplified method for quantification of pyocyanin production was demonstrated. • The cyclodextrins significantly affected the pyocyanin and pyoverdine production. • The native ACD exhibited the highest attenuation in pyoverdine production.

Designing and preparing supramolecular encapsulation systems based on fraxetin and cyclodextrins for highly selective detection of nicotine

Herein, a series of water-soluble supramolecular inclusion complexes (ICs) probes were prepared using cyclodextrins (CDs) and fraxetin (FRA) to detect nicotine (NT) with high selectivity in vitro and in vivo. The FRA/CD ICs prepared through the saturated solution method exhibited excellent water solubility, stability, and biocompatibility. A clear host-guest inclusion model was provided by the theoretical calculations. The investigation revealed that NT was able to enter into the cavities of FRA/β-CD IC and FRA/γ-CD IC, and further formed charge transfer complexes with FRA in the CD cavities, resulting in a rapid and highly selective fluorescence-enhanced response with the lowest detection limits of 1.9 × 10-6 M and 9.7 × 10-7 M, and the linear response ranged from 0.02 to 0.3 mM and 0.01-0.05 mM, respectively. The IC probes showed good anti-interference performance to common interferents or different pH environments, with satisfactory reproducibility and repeatability of response to NT. Furthermore, the potentiality of the probes was confirmed through fluorescence imaging experiments using human lung cancer cells and the lung tissue of mice. This study offers a fresh perspective for detecting NT in environmental and biomedical analysis.

Redox-Regulated Synthetic Channels: Enabling Reversible Ion Transport by Modulating the Ion-Permeation Pathway

Natural redox-regulated channel proteins often utilize disulfide bonds as redox sensors for adaptive regulation of channel conformations in response to diverse physiological environments. In this study, we developed novel synthetic ion channels capable of reversibly switching their ion-transport capabilities by incorporating multiple disulfide bonds into artificial systems. X-ray structural analysis and electrophysiological experiments demonstrated that these disulfide-bridged molecules possess well-defined tubular cavities and can be efficiently inserted into lipid bilayers to form artificial ion channels. More importantly, the disulfide bonds in these molecules serve as redox-tunable switches to regulate the formation and disruption of ion-permeation pathways, thereby achieving a transition in the transmembrane transport process between the ON and OFF states.

β-cyclodextrin polymer composites for the removal of pharmaceutical substances, endocrine disruptor chemicals, and dyes from aqueous solution- A review of recent trends

Cyclodextrin (CD) and its derivatives are receiving attention as a new-generation adsorbent for water pollution treatment due to their external hydrophilic and internal hydrophobic properties. Among types of CD, β-Cyclodextrin (βCD) has been a material of choice with a proven track record for a range of utilities in distinct domains, owing to its unique cage-like structural conformations and inclusion complex-forming ability, especially to mitigate emerging contaminants (ECs). This article outlines βCD composites in developing approaches of their melds and composites for purposes such as membranes for removal of the ECs in aqueous setups have been explored with emphasis on recent trends. Electrospinning has bestowed an entirely different viewpoint on polymeric materials, comprising βCD, in the framework of diverse functions across a multitude of niches. Besides, this article especially discusses βCD polymer composite membrane-based removal of contaminants such as pharmaceutical substances, endocrine disruptors chemicals, and dyes. Finally, in this article, the challenges and future directions of βCD-based adsorbents are discussed, which may shed light on pragmatic commercial applications of βCD polymer composite membranes.

Cyclodextrins and derivatives in drug delivery: New developments, relevant clinical trials, and advanced products

Cyclodextrins (CD) and derivatives are functional excipients that can improve the bioavailability of numerous drugs. Because of their drug solubility improving properties they are used in many pharmaceutical products. Furthermore, the stability of small molecular drugs can be improved by the incorporation in CDs and an unpleasant taste and smell can be masked. In addition to well-established CD derivatives including hydroxypropyl-β-CD, hydroxypropyl-γ-CD, methylated- β-CD and sulfobutylated- β-CD, there are promising new derivatives in development. In particular, CD-based polyrotaxanes exhibiting cellular uptake enhancing properties, CD-polymer conjugates providing sustained drug release, enhanced cellular uptake, and mucoadhesive properties, and thiolated CDs showing mucoadhesive, in situ gelling, as well as permeation and cellular uptake enhancing properties will likely result in innovative new drug delivery systems. Relevant clinical trials showed various new applications of CDs such as the formation of CD-based nanoparticles, stabilizing properties for protein drugs or the development of ready-to-use injection systems. Advanced products are making use of various benefical properties of CDs at the same time. Within this review we provide an overview on these recent developments and take an outlook on how this class of excipients will further shape the landscape of drug delivery.

Citric acid cross-linked β-cyclodextrins: A review of preparation and environmental/biomedical application

The β-cyclodextrins (β-CD) are biocompatible macrocyclic candidates for the preparation of various composites with enhanced functions. While nontoxic and biodegradable citric acid (CA) is the favorite crosslinking agent for fabricating hierarchical advanced structures. The carboxyl and hydroxyl groups on CA can serve as "structural bridges" and enhance the solubility of β-CD. Leading to the construction of CA cross-linked β-CD with marvelous complicated structures and targeted functions. Here, we directly categorized the grafted composite materials into two main types such as organic and inorganic materials. Particularly, some representative composite materials are listed and analyzed in detail according to their preparation, advantages of unique characteristics, as well as the possible applications in environmental and biomedical fields such as adsorption of pollutants, sensors, and biomedical applications.

Interactions of Cyclodextrins and their Hydroxyl Derivatives with Etodolac: Solubility and Dissolution Enhancement

BACKGROUND

Poor solubility and dissolution rate of drugs are largely responsible for erratic drug absorption and limited oral bioavailability. Etodolac (ETO) is a non-steroidal anti-inflammatory drug (NSAID) that is classified as BCS class II (dissolution rate-dependent absorption). ETO has high safety and efficacy in pain relief and control of inflammation. ETO is commercially available as (400- 600 mg) tablets; poor solubility and dissolution rate of ETO could result in variable oral absorption and inconsistent analgesic responses. The aim of this study was to improve solubility and dissolution rates of ETO by complexation with cyclodextrins (CDs).

METHODS

Four different CDs namely β-, γ-, HP β-CDs, and HP γ-CDs were prepared using three different methods; solvent evaporation (CO), freeze-drying (FD), and physical mixing (PM). The prepared drug: excipient mixtures were investigated for aqueous solubility, as well as via DSC, XRD, FTIR, SEM, dissolution, and docking.

RESULTS

The results revealed a solubility phase diagram of the AL type, indicating a 1:1 complexation of ETO: CD. These results agreed with our molecular docking calculations. DSC, FTIR, XRD, and SEM results confirmed the formation of an inclusion complex. The complexation efficiency, solubility, and dissolution enhancement were in the order of HPγ-CD > γ -CD > HPβ-CD > β-CD. FD method was superior to both CO and PM.

CONCLUSION

Superior dissolution enhancements of ETO were recorded for the FD mixture (up to 90% dissolved in less than 10 min). In conclusion, γ- and hydroxypropyl γ-derivative of cyclodextrins can be considered a promising excipient for enhancement of dissolution rates concerned for ETO.

Molecular insights to the anti-COVID-19 potential of α-, β- and γ-cyclodextrins

SARS-CoV-2 viral infection is regulated by the host cell receptors ACE2 and TMPRSS2, and therefore the effect of various natural and synthetic compounds on these receptors has recently been the subject of investigations. Cyclodextrins, naturally occurring polysaccharides derived from starch, are soluble in water and have a hydrophobic cavity at their center enabling them to accommodate small molecules and utilize them as carriers in the food, supplements, and pharmaceutical industries to improve the solubility, stability, and bioavailability of target compounds. In the current study, computational molecular simulations were used to investigate the ability of α-, β- and γ-Cyclodextrins on human cell surface receptors. Cell-based experimental approaches, including expression analyses at mRNA and protein levels and virus replication, were used to assess the effect on receptor expression and virus infection, respectively. We found that none of the three CDs could dock effectively to human cell surface receptor ACE2 and viral protease Mpro (essential for virus replication). On the other hand, α- and β-CD showed strong and stable interactions with TMPRSS2, and the expression of both ACE2 and TMPRSS2 was downregulated at the mRNA and protein levels in cyclodextrin (CD)-treated cells. A cell-based virus replication assay showed ∼20% inhibition by β- and γ-CD. Taken together, the study suggested that (i) downregulation of expression of host cell receptors may not be sufficient to inhibit virus infection (ii) activity of the receptors and virus protein Mpro may play a critical and clinically relevant role, and hence (iii) newly emerging anti-Covid-19 compounds warrant multimodal functional analyses.Communicated by Ramaswamy H. Sarma.

Assessing the greenification potential of cyclodextrin-based molecularly imprinted polymers for pesticides detection

Cyclodextrins, with their unparalleled attributes of eco-friendliness, natural abundance, versatile utility, and facile functionalization, make a paramount contribution to the field of molecular imprinting. Leveraging the unique properties of cyclodextrins in molecularly imprinted polymers synthesis has revolutionized the performance of molecularly imprinted polymers, resulting in enhanced adsorption selectivity, capacity, and rapid extraction of pesticides, while also circumventing conventional limitations. As the concern for food quality and safety continues to grow, the need for standard analytical methods to detect pesticides in food and environmental samples has become paramount. Cyclodextrins, being non-toxic and biodegradable, present an attractive option for greener reagents in imprinting polymers that can also ensure environmental safety post-application. This review provides a comprehensive summary of the significance of cyclodextrins in molecular imprinting for pesticide detection in food and environmental samples. The recent advancements in the synthesis and application of molecularly imprinted polymers using cyclodextrins have been critically analyzed. Furthermore, the current limitations have been meticulously examined, and potential opportunities for greenification with cyclodextrin applications in this field have been discussed. By harnessing the advantages of cyclodextrins in molecular imprinting, it is possible to develop highly selective and efficient methods for detecting pesticides in food and environmental samples while also addressing the challenges of sustainability and environmental impact.

Spectrophotometric thermodynamic analysis of methylene blue aggregation in water by chemometrics; what comes in the presence of different cyclodextrins?

Spectrophotometry has been utilized to characterize the thermodynamic/dynamic properties of self-aggregation of methylene blue (MB) in water, particularly while interacting with a modulator like different cyclodextrins (α-, β-, hydroxypropyl-β- (HP-β-), and γ-CDs). These systems comprise many interactions that make such chemical systems sophisticated. We developed a mathematical modeling-fitting analysis for the simultaneous quantitative analysis of thermodynamic parameters of chemical reactions, relying on the fitting algorithm. Through analyzing simulated photometric titration data, we demonstrate the simultaneous determination of thermodynamic parameters of the different guest/host interactions. This first has brought the need for the calculation of the visible-light absorption spectrum and the thermodynamic parameters for the pure dimerization system. Therefore, the multiwavelength spectral-mole ratio data of aqueous solutions of MB over a concentration range of 2.5 × 10-5 to 4.5 × 10-5 M while temperature is changing; or being titrated with CDs solutions at various temperatures were collected, augmented, and then have been fed to solid mathematical routines to determine the potential existence of dimeric aggregates. The results of thermodynamics indicated that the positions of the monomer/dimer equilibria do not alter by the presence of α-CD. The apparent dimerization was suppressed upon addition of β- or HP-β-CDs, while the addition of γ-CD enhanced the dimerization.

Cyclodextrin-based supramolecular deep eutectic solvent (CycloDES): A vehicle for the delivery of poorly soluble drugs

The aim of this work was to develop a new class of deep eutectic solvent (DES) composed of a complexation agent, namely hydroxy-propyl-β-cyclodextrin (HPβCD), to exploit a synergic solubilization-enhancing approach. For this purpose, cyclodextrin-based supramolecular DES (CycloDES) were physical-chemical characterized and loaded with three different BCS class II model drugs, specifically Cannabidiol, Indomethacin, and Dexamethasone, evaluating the influence of different factors on the observed solubility and permeation compared with the only HPβCD/drug complexation. Hence, CycloDESs were presented as a possible vehicle for drugs and represent a novel potential approach for solving BCS class II and IV solubility issues, demonstrating at least a 100-fold improvement in the investigated drug solubilities. Furthermore, CycloDESs demonstrated a significantly improved resistance to dilution preserving a high percentage of drug in solution (i.e. 93% for Indomethacin) when water is added to the DES if compared with a glucose-choline chloride DES, used as a standard. This evidence guarantees the solubility-enhancing effect useful for the delivery of BCS class II and IV drugs converting solid raw material to advantageous liquid vehicles bypassing the rate-determining dissolution step.

Ion mobility mass spectrometry enables the discrimination of positional isomers and the detection of conformers from cyclic oligosaccharides-metals supramolecular complexes

Cyclic oligosaccharides are well known to interact with various metals, able to form supramolecular complexes with distinct sizes and shapes. However, the presence of various isomers in a sample, including positional isomers and conformers, can significantly impact molecular recognition, encapsulation ability and chemical reactivity. Therefore, it is crucial to have tools for deep samples probing and correlation establishments. The emerging ion mobility mass spectrometry (IM-MS) has the advantages to be rapid and sensitive, but is still in its infancy for the investigation of supramolecular assemblies. In the herein study, it was demonstrated that IM-MS is suitable to discriminate several isomers of cyclodextrins (CD)-metals complexes, used as cyclic oligosaccharide models. In this sense, we investigated branched 6-O-α-glucosyl- or 6-O-α-maltosyl-β-cyclodextrins (G1-β-CD and G2-β-CD) and their purely cyclic isomers: CD8 (γ-CD) and CD9 (δ-CD). The corresponding collision cross section (CCS) values were deducted for the main positive singly and doubly charged species. Experimental CCS values were matched with models obtained from molecular modelling. The high mobility resolving power and resolution enabled discrimination of positional isomers, identification of various conformers and accurate relative content estimation. These results represent a milestone in the identification of carbohydrate conformers that cannot be easily reached by other approaches.

Study on the formation and anti-biofilm properties of cinnamon essential oil inclusion complexes by the structure of modified β-cyclodextrins

Essential oils (EOs), which are plant-oriented anti-biofilm agents, are extensively encapsulated by cyclodextrins to overcome their aqueous solubility and chemical instability, and achieve slow release during long-term storage. However, the biological activities of EOs decreased after initial encapsulation in CDs. In this study, modified-β-cyclodextrins (β-CDs) were screened as wall materials to maintained the initial anti-biofilm effect of pure CEO. The inhibitory and bactericidal activities of CEO encapsulated in five types of β-CDs with different substituents (primary hydroxyl, maltosyl, hydroxypropyl, methyl, and carboxymethyl) against Staphylococcus aureus biofilm were evaluated. Crystal violet assay and 3D-View observations suggested that CEO and its inclusion complexes (CEO-ICs) inhibited Staphylococcus aureus biofilm formation through the inhibition of colonising spreading, exopolysaccharide synthesis, and cell surface properties. Molecular docking revealed the causes of the decrease in the anti-biofilm effect after encapsulation, and quantitative structure-activity relationship assays provided MIC and MBIC prediction equation for modified-β-cyclodextrins inclusion complexes. Maltosyl-β-CD was screened as the best wall material to retained the anti-biofilm activities as pure cinnamon essential oil in initial stage, and its inclusion complexes can effectively inhibited biofilm formation in milk. This study provides a theoretical guidance for the selection β-CDs to encapsulate CEO as plant-oriented anti-biofilm agents to inhibit bacterial biofilm formation.

Screening of Cyclodextrins in the Processing of Buserelin Dry Powders for Inhalation Prepared by Spray Freeze-Drying

Purpose

In this study, we prepared inhalable buserelin microparticles using the spray freeze-drying (SFD) method for pulmonary drug delivery. Raffinose as a cryoprotectant carrier was combined with two levels of five different cyclodextrins (CDs) and then processed by SFD.

Methods

Dry powder diameters were evaluated by laser light scattering and morphology was determined by scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis were utilized for the determination of crystalline structures. The aerodynamic properties of the spray freeze-dried powders were evaluated by twin stage impinger (TSI) and the stability of prepared samples was assessed under normal and accelerated conditions.

Results

The prepared powders were mostly porous spheres and the size of microparticles ranged from 9.08 to 13.53 μm, which are suitable as spray-freeze dried particles. All formulations showed amorphous structure confirmed by DSC and XRD. The aerosolization performance of the formulation containing buserelin, raffinose and 5% beta-cyclodextrin (β-CD), was the highest and its fine particle fraction (FPF) was 69.38%. The more circular and separated structures were observed in higher concentrations of CDs, which were compatible with FPFs. The highest stability was obtained in the formulation containing hydroxypropyl beta-cyclodextrin (HP-β-16. CD) 5%. On the contrary, sulfobutylether beta-cyclodextrin (SBE-β-CD) 5% bearing particles showed the least stability.

Conclusion

By adjusting the type and ratio of CDs in the presence of raffinose, the prepared formulations could effectively enhance the aerosolization and stability of buserelin. Therefore, they can be proposed as a suitable career for lung drug delivery.

Bioresponsive and multifunctional cyclodextrin-based non-viral nanocomplexes in cancer therapy: Building foundations for gene and drug delivery, immunotherapy and bioimaging

The interest towards application of nanomaterials in field of cancer therapy is that the drawbacks of conventional therapies including chemoresistance, radio-resistance and lack of specific targeting of tumor cells can be solved by nanotechnology. Cyclodextrins (CDs) are amphiphilic cyclic oligosaccharides that can be present in three forms of α-, β- and γ-CDs, and they can be synthesized from natural sources. The application of CDs in cancer shows an increasing trend due to benefits of these nanocomplexes in improving solubility and bioavailability of current bioactives and therapeutics for cancer. CDs are widely utilized in delivery of drugs and genes in cancer therapy, and by targeted delivery of these therapeutics into target site, they improve anti-proliferative and anti-cancer potential. The blood circulation time and tumor site accumulation of therapeutics can be improved using CD-based nanostructures. More importantly, the stimuli-responsive types of CDs including pH-, redox- and light-sensitive types can accelerate release of bioactive compound at tumor site. Interestingly, the CDs are able to mediate photothermal and photodynamic impact in impairing tumorigenesis in cancer, enhancing cell death and improving response to chemotherapy. In improving the targeting ability of CDs, their surface functionalization with ligands has been conducted. Moreover, CDs can be modified with green products such as chitosan and fucoidan, and they can be embedded in green-based nanostructures to suppress tumorigenesis. The internalization of CDs into tumor cells can occur through endocytosis and this can be clethrin-, caveolae- or receptor-mediated endocytosis. Furthermore, CDs are promising candidates in bioimaging, cancer cell and organelle imaging as well as isolating tumor cells. The main benefits of using CDs in cancer therapy including sustained and low release of drugs and genes, targeted delivery, bioresponsive release of cargo, ease of surface functionalization and complexation with other nanostructures. The application of CDs in overcoming drug resistance requires more investigation.

Cyclodextrin glucanotransferase: fundamentals and biotechnological implications

Cyclodextrin glucanotransferase (CGTase) is an extracellular enzyme of the GH13 α-amylase family that catalyzes a unique intramolecular reaction known as cyclization to transform α-1, 4-glucans and similar starches into cyclodextrins. They also catalyze intermolecular transglycosylation reactions namely coupling, disproportionation, and some hydrolyzing effects on starch. The monomeric structures of the CGTase exhibit five domains (A, B, C, D, and E domains) with different molecular weights and amino acid sequences depending on the source. Among bacteria, Bacillus genus covers approximately 90% of the CGTase producers, while other genera like Klebsiella, Paenibacillus, and Thermoanaerobacter also shown decent contributions in recent studies. CGTase production is highly supported by alkaliphilic bacteria under submerged fermentation rather than solid-state fermentation. The bacterial sources, biochemical properties, production conditions, and structure of CGTases are compiled in this review. Cyclodextrins have the unique property of making inclusion complexes with various compounds, hence widely used in the food, pharmaceutical, cosmetics, laundry, and chemical sectors. This review presents a comprehensive view of CGTase produced by Bacillus spp., and other bacterial genera like Klebsiella, Paenibacillus, and Microbacterium. It also gives insight of the properties and recent biotechnological applications of cyclodextrins. KEY POINTS: • Transglycosylation reactions catalyzed by CGTase and their structural properties. • Comparative data of CGTase production by various genera and Bacillus spp. • Structures, properties, and applications of different cyclodextrins.

Leveraging the use of in vitro and computational methods to support the development of enabling oral drug products: An InPharma commentary

Due to the strong tendency towards poorly soluble drugs in modern development pipelines, enabling drug formulations such as amorphous solid dispersions, cyclodextrins, co-crystals and lipid-based formulations are frequently applied to solubilize or generate supersaturation in gastrointestinal fluids, thus enhancing oral drug absorption. Although many innovative in vitro and in silico tools have been introduced in recent years to aid development of enabling formulations, significant knowledge gaps still exist with respect to how best to implement them. As a result, the development strategy for enabling formulations varies considerably within the industry and many elements of empiricism remain. The InPharma network aims to advance a mechanistic, animal-free approach to the assessment of drug developability. This commentary focuses current status and next steps that will be taken in InPharma to identify and fully utilize 'best practice' in vitro and in silico tools for use in physiologically based biopharmaceutic models.

Modification of conducting arylidene copolymers by formation of inclusion complexes: synthesis, characterization, and applications as highly corrosion inhibitors for mild steel

Modifying the metal surface is one solution to the industry's growing corrosion problem. Thus, via threading approach and insertion of copolymers (CoP5-7) containing polyarylidenes through the internal cavity beta-cyclodextrin β-CD, novel pseudopolyrotaxanes copolymers (PC5-7) are developed, resulting in mild steel corrosion inhibition. Inhibitors of corrosion based on β-CD molecules adsorb strongly to metal surfaces because of their many polar groups, adsorption centers, many linkages of side chains, and benzene rings. The corrosion inhibition efficiencies IE % statistics have been revised via the Tafel polarization method and Spectroscopy based on the electrochemical impedance (EIS), with PC7 achieving the highest 99.93% in 1.0 M H₂SO₄; they are mixed-type inhibitors. The chemical composition of the resulting PCs is determined with Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) is utilized to examine the morphological structure of the produced polymers, and X-ray diffraction is employed to identify crystallinity. Encapsulating CoP5-7 with β-CD changes the morphological structures and increases the generated PCs' crystallinity. The thermal stability of PCs is studied, indicating the presence of these CoPs within the β-CD cavities enhances their thermal stability. This research will be a stepping stone for developing high-efficiency anti-corrosion coatings and various industrial applications.

Competitive formation of molecular inclusion complexes of chlordecone and β-hexachlorocyclohexane with natural cyclodextrins: DFT and molecular dynamics study

CONTEXT

Chlordecone (CLD) and β-hexachlorocyclohexane (β-HCH) are chlorinated pesticides that coexist as persistent organic pollutants in the groundwater of several countries in the Caribbean, being an environmental issue. This work evaluates theoretically the competitive formation of host-guest complexes pesticides@cyclodextrines (CDs) as an alternative for water purification and selective separation of pesticides.

METHODS

Quantum mechanical calculations based on density functional theory (DFT) and classical molecular dynamics (MD) simulations were used to achieve information on geometries, energies, structure, and dynamics of guest-host complexes in the gas phase, implicit solvent medium, and in aqueous solutions.

RESULTS

DFT studies showed that interactions of both pesticides with CDs are mediated by steric factors and guided by maximization of the hydrophobic interactions either with the other pesticide or with the CD cavity's inner atoms. MD results corroborate the formation of stable complexes of both pesticides with the studied CDs. α-CD exhibited a preference for the smaller β-HCH molecule over the CLD that could not perturb the formed complex.

CONCLUSIONS

The simulation of competitive formation with γ-CD illustrated that this molecule could accommodate both pesticides inside its cavity. These results suggest that CDs with smaller cavity sizes such as α-CD could be used for selective separation of β-HCH from CLD in water bodies, while γ-CD could be used for methods that aim to remove both pesticides at the same time.

Three generations of thiolated cyclodextrins: A direct comparison of their mucus permeating and mucoadhesive properties

AIM

This study aims to compare the mucus permeating and mucoadhesive properties of three generations of thiolated cyclodextrins (CDs).

METHODS

Free thiol groups of thiolated γ-CDs (CD-SH) were S-protected with 2-mercaptonicotinic acid (MNA), leading to a second generation of thiolated CDs (CD-SS-MNA) and with 2 kDa polyethylene glycol (PEG) bearing a terminal thiol group leading to a third generation of thiolated CDs (CD-SS-PEG). The structure of these thiolated CDs was confirmed and characterized by FT-IR, ¹H NMR and colorimetric assays. Thiolated CDs were evaluated regarding viscosity, mucus diffusion, and mucoadhesion.

RESULTS

The viscosity of the mixture of CD-SH, CD-SS-MNA, or CD-SS-PEG with mucus increased up to 11-, 16-, and 14.1-fold compared to unmodified CD within 3 hours, respectively. Mucus diffusion increased in the following rank order: unprotected CD-SH < CD-SS-MNA < CD-SS-PEG. The residence time of CD-SH, CD-SS-MNA, and CD-SS-PEG on porcine intestine was up to 9.6-, 12.55-, and 11.2-fold prolonged compared to native CD, respectively.

CONCLUSION

According to these results, S-protection of thiolated CDs can be a promising approach to improve their mucus permeating and mucoadhesive properties.

STATEMENT OF SIGNIFICANCE

Three generations of thiolated cyclodextrins (CDs) with different types of thiol ligands have been synthesized to improve mucus interaction. 1^st generation of thiolated CDs was synthesized by converting hydroxyl groups into thiols by reaction with Thiourea. For 2^nd generation, free thiol groups were S-protected by reaction with 2-mercaptonicotinic acid (MNA), resulting in high reactive disulfide bonds. For 3^rd generation, terminally thiolated short PEG chains (2 kDa) were used for S-protection of thiolated CDs. Mucus penetrating properties were found to be increased as follows: 1^st generation < 2^nd generation < 3^rd generation. Furthermore, mucoadhesive properties were improved in the following rank order: 1^st generation < 3^rd generation < 2^nd generation. This study suggests that the S-protection of thiolated CDs can enhance mucus penetrating and mucoadhesive properties.

A novel multiwalled carbon nanotube-cyclodextrin nanocomposite for solid-phase microextraction-gas chromatography-mass spectrometry determination of polycyclic aromatic hydrocarbons in snow samples

Novel solid-phase microextraction coatings based on the use of multiwalled carbon nanotube-cyclodextrin (MWCNT-CD) nanocomposites were developed for the determination of 16-priority polycyclic aromatic hydrocarbons at ultratrace levels in snow samples. The performance of both β- and γ-CD was tested to increase the detection capabilities towards the heaviest and most lipophilic compounds, i.e., five- and six-ring PAHs. To facilitate the interactions of MWCNTs with CDs, an oxidation procedure using both HNO₃ and H₂O₂ was applied, obtaining superior results using MWCNTs-H₂O₂-γ-CD fiber. Detection and quantitation limits below 0.7 and 2.3 ng/L, RSD lower than 21%, and recoveries of 88(± 2)-119.8(± 0.4)% proved the reliability of the developed method for the determination of PAHs at ultratrace levels. The complexation capability of the γ-CD was also demonstrated in solution by NMR and fluorescence spectroscopy studies and at solid state by XRD analysis. Finally, snow samples collected in the ski area of Dolomiti di Brenta were analyzed, showing a different distribution of the 16 priority PAHs, being naphthalene, phenanthrene, fluoranthene, and pyrene the only compounds detected in all the analyzed samples.

OKL-1111, A modified cyclodextrin as a potential universal reversal agent for anticoagulants

BACKGROUND

Antithrombotic therapy is inevitably associated with a risk for bleeding and these bleeding complications can be life-threatening. Recently, specific reversal agents were developed for the direct factor Xa and thrombin inhibitors (DOACs). However, next to the fact that these agents are relatively expensive, the use of selective reversal agents complicates treatment of bleeding patients in practice. In a series of screening experiments, we discovered a class of cyclodextrins with procoagulant properties. In this study we characterize a lead compound, OKL-1111, and demonstrate its potential use as a universal reversal agent.

OBJECTIVES

To assess the anticoagulant reversal properties of OKL-1111, in vitro and in vivo.

METHODS

The effect of OKL-1111 on coagulation in the absence and presence of DOACs was investigated in a thrombin generation assay. Its reversal effect on a variety of anticoagulants in vivo was investigated in a rat tail cut bleeding model. A possible prothrombotic action of OKL-1111 was assessed in a Wessler model in rabbits.

RESULTS

OKL-1111 concentration-dependently reversed the in vitro anticoagulant effects of dabigatran, rivaroxaban, apixaban and edoxaban in the thrombin generation assay. Also in the absence of a DOAC, OKL-1111 concentration-dependently accelerated coagulation in this assay, but did not initiate coagulation. The reversal effect was also seen for all DOACs in the rat tail cut bleeding model. In addition, when tested with other anticoagulants, OKL-1111 also reversed the anticoagulant effect of the vitamin K antagonist warfarin, the low molecular weight heparin enoxaparin, the pentasaccharide fondaparinux and the platelet inhibitor clopidogrel in vivo. OKL-1111 did not have prothrombotic effects in the Wessler model.

CONCLUSION

OKL-1111 is a procoagulant cyclodextrin with a currently unknown working mechanism that has potential to become a universal reversal agent for anticoagulants and platelet inhibitors.

The challenge of improving pterostilbene (PTS) solubility for solid and semi-solid dosage forms: The obtention of binary and ternary systems

Pterostilbene (PTS) is a drug candidate with low water solubility and poor bioavailability. On the other hand, drug:cyclodextrins complexes frequently provide bulk powders with low drug concentrations, which is crucial for obtention solid or semi-solid pharmaceutical dosage forms. In order to determine the optimal conditions for enhancing the solubility of PTS:BCD (β-cyclodextrin) complex, a Box-Behnken design was performed. Although the optimal conditions have been applied, low complexation efficiency (0.127) and the bulk powder remained. A PTS:BCD:HPMC (HPMC, hydroxypropyl methylcellulose) ternary system was developed to overcome this limitation, comparing two media, water and a mixture of ethanol-water. When ethanol was used as a co-solvent, the PTS:BCD:HPMC ternary system (freeze-dried) contained 116.65 ± 1.40 mg/g of PTS. This value was 3.4-fold higher than the PTS content observed when the same ternary system was obtained in aqueous media (34.8 mg/g) and 2.8-fold higher than the PTS content observed for PTS:BCD complex (freeze-dried) obtained using ethanol as a co-solvent. Dissolution tests revealed that after 120 min, in a buffer with a pH value of 1.2, only 43% of PTS dissolved. In contrast, 80% and 90% of PTS were dissolved from the PTS:BCD complex and PTS:BCD:HPMC ternary system, respectively. Moreover, the dissolution was fast in a buffer with a pH value of 6.8. PTS:BCD complex reached the maximum PTS dissolution at 75 min and PTS:BCD:HPMC at 45 min. In summary, the results of this study demonstrated, for the first time, that low-bulk powders with a high content of PTS can be obtained from PTS:BCD:HPMC ternary systems using ethanol as a co-solvent. This new finding offers a valuable alternative for producing solid or semi-solid formulations containing highly soluble PTS.

Thiolated cyclodextrins: A comparative study of their mucoadhesive properties

AIM

The aim of this study was the comparison of the mucoadhesive properties of nonionic, negatively, and positively charged thiolated cyclodextrins (CDs), including α-, β-, and γ-CDs of low and high degree of thiolation.

METHODS

Native α-, β-, and γ-CDs were thiolated with phosphorous pentasulfide in sulfolane (CD-SH) (i), via reductive amination with cysteamine after oxidative ring opening (CD-Cya) (ii), and via esterification with mercaptosuccinic acid (CD-MSA) (iii). These thiolated CDs were characterized via ¹H NMR and Ellman's test. Cytotoxicity was determined via resazurin and hemolysis assay. Mucoadhesive properties were evaluated via rheological studies with freshly isolated porcine mucus, as well as residence time studies on porcine small intestinal mucosa.

RESULTS

The structure of thiolated CDs was confirmed via ¹H NMR. The degree of thiolation was in the range of 594-1034 µmol/g for low and 1360-3379 µmol/g for high CD-SH, whereas thiolated CD-Cya and thiolated CD-MSA exhibited a degree of thiolation of 1142-3242 µmol/g and 243-1227 µmol/g, respectively. Just cationic CDs showed cytotoxicity. Nonionic highly thiolated α-CD-SH, α-CD-Cya, and α-CD-MSA exhibited with mucus 5.6-, 15.7- and 2.8-fold improved dynamic viscosity, while improvement was 7.7-, 6.1-, and 5.4-fold for the corresponding thiolated β-CDs and 12.3-, 15.4- and 17.8-fold for the corresponding thiolated γ-CDs compared with native CDs, respectively. A prolonged mucosal residence time following the rank order γ > β > α was observed for all thiolated CDs, whereby γ-CD-Cya, nonionic highly thiolated β-CD-SH and α-CD-Cya showed the highest mucoadhesive properties.

CONCLUSION

A high degree of thiolation and the introduction of cationic charges are mainly responsible for high mucoadhesive properties of CDs.

Evaluation of β-lapachone-methyl-β-cyclodextrin inclusion complex prepared by spray drying and its application against different developmental stages of Schistosoma mansoni in murine model

BACKGROUND

β-lapachone (β-lap) is a naphthoquinone widely found in species of vegetables. However, its poor aqueous solubility limits its systemic administration and clinical applications in vivo. To overcome this limitation, several studies have been carried out in order to investigate techniques that can enhance the solubility and dissolution rate of β-lap, such as the use of inclusion complexes with cyclodextrin.

PURPOSE

To evaluate the in vivo effect of β-lap complexed in methyl-β-cyclodextrin (MβCD) on the evolutionary stages of Schistosoma mansoni in a murine model.

METHODS

The development and characterization of the physicochemical properties of the inclusion complex of β-lap in β-lap:MβCD was prepared by solubility and dissolution tests, FTIR, DSC, X-RD and SEM. The mice were infected and subsequently treated with β-lap:MβCD orally with 50 mg/kg/day and 100 mg/kg/day for 5 consecutive days, starting therapy on the 1^st (skin schistosomula), 14^th (pulmonary schistosomula), 28^th (young worms) and 45^th (adult worms) days after infection. Control groups were also formed; one infected untreated, treated with MβCD, and the other treated with PZQ.

RESULTS

The loss of the crystalline form of β-lap in the β-lap:MβCD complex obtained by spray drying was proven through physical-chemical characterization analyses. β-lap:MβCD caused reduction in the number of worms of the 33.56%, 35.7%, 35.45% and 36.45%, when the dose was at 50 mg/kg, and 65.00%, 60.34%, 52.72% and 65.01%, in the dose 100 mg/kg; when treatment was started in the 1^st, 14^th, 28^th and 45^th days after infection, respectively. It was also possible to observe a significant reduction in the number of immature eggs and an increase in the number of ripe and dead eggs and, consequently, a reduction in the damage caused by the egg antigens to the host tissue, where we attributed the reduction in the average diameter of the granulomas to the β-lap.

CONCLUSION

The dissolved content of β-lap:MβCD by spray drying reached almost 100%, serving for future formulations and delineation of the mechanisms of action of β-lap against S. mansoni.

Interactions between plant-derived antioxidants and cyclodextrins and their application for improving separation, detection, and food quality issues

Plant-derived antioxidants (PD-AOs) are important for food preservation, as well as for human health and nutrition. However, the poor chemical stability and water solubility of many PD-AOs currently limit their application as functional ingredients in foods and pharmaceuticals. Moreover, it is often difficult to isolate and detect specific antioxidants in multi-component systems, which again limits their potential in the food and medical industries. In this review, we highlight recent advances in the use of cyclodextrins (CDs) to overcome these limitations by forming simple, modified and competitive host-guest interactions with PD-AO. The host-guest properties of CDs can be used to enhance the separation efficiency of PD-AOs, as well as to improve their dispersion and stability in food systems. Moreover, the competitive complexation properties of CDs with target molecules can be used to selectively isolate PD-AOs from multi-component systems and develop detection technologies for PD-AOs. Overall, CD-antioxidant interactions have great potential for addressing isolation, detection, and food quality issues.

Synthetic K+ Channels Constructed by Rebuilding the Core Modules of Natural K+ Channels in an Artificial System

Different types of natural K⁺ channels share similar core modules and cation permeability characteristics. In this study, we have developed novel artificial K⁺ channels by rebuilding the core modules of natural K⁺ channels in artificial systems. All the channels displayed high selectivity for K⁺ over Na⁺ and exhibited a selectivity sequence of K⁺ ≈Rb⁺ during the transport process, which is highly consistent with the cation permeability characteristics of natural K⁺ channels. More importantly, these artificial channels could be efficiently inserted into cell membranes and mediate the transmembrane transport of K⁺ , disrupting the cellular K⁺ homeostasis and eventually triggering the apoptosis of cells. These findings demonstrate that, by rebuilding the core modules of natural K⁺ channels in artificial systems, the structures, transport behaviors, and physiological functions of natural K⁺ channels can be mimicked in synthetic channels.

Stable Luminescent [Cu(NN)(PP)]+ Complexes Incorporating a β-Cyclodextrin-Based Diphosphane Ligand with Metal-Confining Properties

A β-cyclodextrin-based diphosphane with metal-confining properties was efficiently synthesized thanks to an unprecedented Smiles-like rearrangement of diphenyl-(2-phosphanylphenyl)phosphane in the presence of excess n-BuLi. The cis-chelating bidentate ligand is capable of forming very stable heteroleptic [Cu(NN)(PP)]⁺ complexes in which a metal-bound diimine ligand (bpy, phen, or mmp) is located within the cyclodextrin cavity. As a result of ligand encapsulation, flattening of the metal tetrahedral geometry in the excited state is disfavored, thereby resulting in enhanced luminescent properties.

Computational Modeling on Binding Interactions of Cyclodextrin s with the Human Multidrug Resistance P-glycoprotein Toward Efficient Drug-delivery System Applications

BACKGROUND

Herein, molecular docking approaches and DFT ab initio simulations were combined for the first time, to study the key interactions of cyclodextrins (CDs: α-CD, β-CD, and γ-CD) family with potential pharmacological relevance and the multidrug resistance P-gp protein toward efficient drug-delivery applications. The treatment of neurological disorders and cancer therapy where the multiple drug-resistance phenomenon mediated by the P-gp protein constitutes the fundamental cause of unsuccessful therapies.

OBJECTIVES

To understand more about the CD docking mechanism and the P-gp.

METHODS

In order to achieve the main goal, the computational docking process was used. The observed docking-mechanism of the CDs on the P-gp was fundamentally based on hybrid backbone/side-chain hydrophobic interactions,and also hybrid electrostatic/side-chain interactions of the CD-ligands' OHmotifs with acceptor and donor characteristics, which might theoretically cause local perturbations in the TMD/P-gp inter-residues network, influencing ligand extrusion through the blood-brain barrier. P-gp residues were conformationally favored. Despite the structural differences, all the cyclodextrins exhibit very close Gibbs free binding energy values (or affinity) by the P-gp binding site (transmembrane domains - TMDs).

RESULT

The obtained theoretical docking-mechanism of the CDs on the P-gp was fundamentally based on hybrid backbone/side-chain hydrophobic interactions, and also hybrid electrostatic/side-chain interactions of the OH-motifs of the CD-ligands with acceptor and donor properties which theoretically could induce allosteric local-perturbations in the TMDs-inter-residues network of P-gp modulating to the CD-ligand extrusion from the blood-brain-barrier (or cancer cells).

CONCLUSION

Finally, these theoretical results open new horizons for evaluating new nanotherapeutic drugs with potential pharmacological relevance for efficient drug-delivery applications and precision nanomedicine.

Novel nonylphenol-degrading bacterial strains isolated from sewage sludge: Application in bioremediation of sludge

Nonylphenol (NP) is an anthropogenic pollutant frequently found in sewage sludge due to the insufficient degrading effectiveness of conventional WWTPs and has attracted attention as an endocrine disruptor. The aim of this study was to isolate specific NP-degrading bacteria from sewage sludge to be used in the degradation of this contaminant through bioaugmentation processes in aqueous solution and sewage sludge. Up to eight different bacterial strains were isolated, six of them not previously described as NP degraders. Bacillus safensis CN12 presented the best NP degradation in solution, and glucose used as an external carbon source increased its effect, reaching DT₅₀ degradation values (time to decline to half the initial concentration of the pollutant) of only 0.9 days and a complete degradation in <7 days. Four NP metabolites were identified throughout the biodegradation process, showing higher toxicity than the parent contaminant. In sewage sludge suspensions, the endogenous microbiota was capable of partially degrading NP, but a part remained adsorbed as bound residue. Bioaugmentation was used for the first time to remove NP from sewage sludge to obtain more environmentally friendly biosolids. However, B. safensis CN12 was not able to degrade NP due to its high adsorption on sludge, but the use of a cyclodextrin (HPBCD) as availability enhancer allowed us to extract NP and degrade it in solution. The addition of glucose as an external carbon source gave the best results since the metabolism of the sludge microbiota was activated, and HPBCD was able to remove NP from sewage sludge to the solution to be degraded by B. safensis CN12. These results indicate that B. safensis CN12 can be used to degrade NP in water and sewage sludge, but the method must be improved using consortia of B. safensis CN12 with other bacterial strains able to degrade the toxic metabolites produced.

Quercitrin loaded cyclodextrin based nanosponge as a promising approach for management of lung cancer and COVID-19

Lung cancer and pandemic acute respiratory disease, COVID-19, are examples of the most worldwide widespread diseases. The aim of the current study is to develop cyclodextrin based nanosponge (CD-NS) for loading the flavonoid drug, quercitrin (QCT). This is to improve its solubility in an attempt to enhance its activity against lung cancer as well as SARS-CoV-2 virus responsible for COVID-19. Preparation of CD-NS was performed by ultrasound-assisted synthesis method. Two CDs were employed, namely, β cyclodextrin (βCD) and 2-hydroxy propyl-β-cyclodextrin (2-HPβCD) that were crosslinked with diphenyl carbonate, one at a time. QCT loaded CD-NS revealed entrapment efficiency and particle size ranged between 94.17 and 99.03% and 97.10–325.90 nm, respectively. QCT loaded 2-HPβCD-NS revealed smaller particle size compared with that of QCT loaded βCD-NS. Zeta potential absolute values of the prepared formulations were >20 mV, indicating physically stable nanosystems. The selected formulations were investigated by Fourier transform infrared spectroscopy, X-ray powder diffraction and scanning electron microscopy which proved the formation of QCT loaded CD-NS exhibiting porous structure. QCT exhibited partial and complete amorphization in βCD-NS and 2-HPβCD-NS, respectively. In vitro release revealed an improved release of QCT from CD-NS formulations. The biological activity of free QCT and QCT loaded CD-NS was investigated against lung cancer cell line A549 as well as SARS-CoV-2 virus. The results revealed that IC₅₀ values of free QCT against lung cancer cell line A549 and SARS-CoV-2 were higher than those exhibited by QCT loaded CD-NS by 1.57–5.35 and 5.95–26.95 folds, respectively. QCT loaded 2-HPβCD-NS revealed enhanced in vitro release and superior biological activity compared with QCT loaded βCD-NS.

alternariol-induced acute toxicity in HeLa cells and in zebrafish embryos

Alternariol (AOH) is a mycotoxin produced by Alternaria fungi, it appears as a contaminant in tomatoes, grains, and grapes. The chronic exposure to AOH may cause carcinogenic and xenoestrogenic effects. Cyclodextrins (CDs) are cyclic oligosaccharides, they form host-guest complexes with apolar molecules. In this study, the interactions of AOH with CD monomers and polymers were examined employing fluorescence spectroscopy. Thereafter, the protective effects of certain CDs vs. AOH-induced toxicity were investigated on HeLa cells and on zebrafish embryos. Our major observations are the following: (1) Sugammadex forms highly stable complex with AOH (K = 4.8 ×10⁴ L/mol). (2) Sugammadex abolished the AOH-induced toxicity in HeLa cells, while native β-CD did not show relevant protective effect. (3) Each CD tested decreased the AOH-induced mortality and sublethal adverse effects in zebrafish embryos: Interestingly, native β-CD showed the strongest protective impact in this model. (4) CD technology may be suitable to relieve AOH-induced toxicity.

Dissipation of a mix of priority PAHs in soils by using availability enhancers. Effect of aging and pollutant interactions

A remediation strategy using three non-toxic availability enhancers (two cyclodextrins and a rhamnolipid biosurfactant) was applied to various soils artificially contaminated with a mix of Polycyclic Aromatic Hydrocarbons (PAHs) considered priority pollutants at two levels of contamination: only with 7 low molecular weight PAHs (LMW PAHs, 5 with 3-ring and 2 with 4-ring - fluoranthene and pyrene) or with 14 PAHs (from 3 to 6 rings). Natural attenuation of PAHs in all soils showed degradation capacity for the LMW PAHs, with a final content of LMW PAHs <5% of their initial concentration. Conversely, the rest of PAHs (high molecular weight PAHs, HMW) remained in the soils (61% - 83.5%), indicating abiotic dissipation of HMW PAHs due to formation of non-extractable residues in soils. The influence of the presence of HMW PAHs on the degradation of the 7 LMW PAHs was also tested, showing a general decrease in the time to obtain 50% dissipation (DT₅₀), statistically significant for acenaphthene, acenaphthylene and fluorene. Availability enhancers showed different effects on PAHs dissipation. 2-hydroxypropyl-β-cyclodextrin (HP) decreased DT₅₀ of some of the lighter PAHs, whereas the rhamnolipid (RL) caused a slight DT₅₀ increase due to its initial toxicity on native soil microorganisms, but showing later high degradation rate for LMW PAHs. On the contrary, randomly methylated-β-cyclodextrin (RAMEB) slowed down PAHs degradation due to its high adsorption onto soil surface, blocking the desorption of PAHs from the soils. The high number of experimental factors not studied simultaneously before (soil type, co-contamination, availability enhancers and incubation time) allowed to conduct a statistical analysis which supported the conclusions reached. Principal Component Analysis separated the studied PAHs in 3 groups, in relation with their molecular weight and Kow. The first principal component was related with LMW PAHs, and separate the inefficient RAMEB from the other availability enhancers.

Modelling drug diffusion through unstirred water layers allows real-time quantification of free/loaded drug fractions and release kinetics from colloidal-based formulations

The correlation between in vivo and in vitro data is yet not sufficiently optimized to allow a significant reduction and replacement of animal testing in pharmaceutical development. One of the main reasons for this lies in the poor mechanistic understanding and interpretation of the physical mechanisms enabling formulation rely on for deploying the drug. One mechanism that still lacks a proper interpretation is the kinetics of drug release from nanocarriers. In this work, we investigate two different types of classical enabling formulations - i) cyclodextrin solutions and ii) liposomal dispersions - by a combination of an experimental method (i.e. UV-Vis localized spectroscopy) and mathematical modelling/numerical data fitting. With this approach, we are able to discriminate precisely between the amount of drug bound to nanocarriers or freely dissolved at any time point; in addition, we can precisely estimate the binding and diffusivity constants of all chemical species (free drug/bound drug). The results obtained should serve as the first milestone for the further development of reliable in vitro/in silico models for the prediction of in vivo drug bioavailability when enabling formulations are used.

Improved ocular delivery of quercetin and resveratrol: A comparative study between binary and ternary cyclodextrin complexes

The number of patients affected by Dry Eye Disease (DED) had notably increased worldwide, addressing the need of novel therapeutic approaches. Polyphenols, quercetin (QUE) and resveratrol (RSV) show necessary antioxidant and anti-inflammatory properties to manage DED, but their application as topical eyedrops is restricted by low aqueous solubility and low chemical stability. Cyclodextrins (CD) are widely used to improve physicochemical characteristics of drugs. Consequently, the aim of this study was to make a comparison between binary complexes with quercetin, resveratrol and cyclodextrins and tertiary complexes adding hyaluronic acid (HA). Both complexes were able to enhance solubility and stability of QUE and RSV. AFM imaging and DLS measurements disclose the formation of spherical nanoaggregates within tertiary complexes of both QUE and RSV with mean diameters of 103 and 82 nm. Neither complex demonstrated cytotoxic effect in in vitro studies in corneal (HCE) and conjunctival (IM-ConjEpi) cell lines. In HCE cells, complexes containing QUE or RSV at their highest concentrations were able to scavenge more than 95 % of the ROS that were produced intracellularly (p < 0.005). Similar response was observed with IM-ConjEpi cells. The antioxidant effect was maintained in the complexes with HA. This confirmed their potential as viable topical treatment for DED.

Chitosan/sulfobutylether-β-cyclodextrin based nanoparticles coated with thiolated hyaluronic acid for indomethacin ophthalmic delivery

Indomethacin (IND) is topically administered for the treatment of the anterior segment diseases such as conjunctivitis, uveitis, and inflammation prevention for post-cataract surgery, as well as posterior segment diseases as macular edema. Currently IND is available as 0.1% w/v hydroxypropyl-β-cyclodextrin-based eye drop formulation and its bioavailability is limited by several drawbacks such as the nasolacrimal duct draining, the reflex blinking and the low volume of the conjunctival sac. In this study, chitosan (CS)/sulfobutylether-β-cyclodextrin (SBE-β-CD) based nanoparticles (NPs) with a mean diameter of 340 (±7) nm, a ζ-potential value of +18.3 (±0.5) mV and coated with thiolated low molecular weight hyaluronic acid were formulated to improve both the solubility and the residential time in the conjunctival sac of the loaded drug IND. The NPs were prepared through the ionotropic gelation technique, exploiting the interaction between the positively charged amino group of CS and the negatively charged sulfonic group of SBE-β-CD. The mucoadhesive properties of the NPs were evaluated on chicken trachea and esophagus tissues using a texture analyser. The irritability effects of NPs were disclaimed with Hecam test. The developed coated NPs showed increased residential time in the conjunctival sac, displayed no irritancy or toxicity for local administration, making them an optimal and innovative drug delivery system for the treatment of anterior segment inflammation diseases. On the other hand, the uncoated NPs displayed better permeating properties since they are smaller and could be further exploited for the treatment of posterior segment diseases.

Macrocyclic Cavitand β-Cyclodextrin Inhibits the Alcohol-induced Trypsin Aggregation

Trypsin, the most abundant pancreatic protein, aids in protein digestion by hydrolysis and exhibits aggregation propensity in presence of alcohol which can further lead to pancreatitis and eventually pancreatic cancer. Herein, by several experimental and theoretical approaches, we unearth the inhibition of alcohol-induced aggregation of Trypsin by macrocyclic cavitand, β-cyclodextrin (β-CD). β-CD interacts with the native protein and shows inhibitory effect in a dose dependent manner. Moreover, the secondary structures and morphologies of Trypsin in presence of β-CD also clearly emphasize the inhibition of fibril formation. From Fluorescence Correlation Spectroscopy, we observed an enhancement in diffusion time of Nile Red with ~ 2.5 times increase in hydrodynamic radius, substantiating the presence of fibrillar structure. Trypsin also shows reduction in its functional activity due to alcohol-induced aggregation. Our simulation data reports the probable residues responsible for fibril formation which was validated by molecular docking studies.

Formulation and characterization of eprosartan mesylate and β-cyclodextrin inclusion complex prepared by microwave technology

The goal of this work was to improve the aqueous solubility and dissolution rate of eprosartan mesylate by preparing inclusion complex of drug with β-cyclodextrin (β-CD) by microwave technique. In order to determine the solubility of eprosartan, phase solubility was determined and dissolution study was also conducted. Further, analytical techniques for instance, particle size distribution, differential scanning calorimetry, powder X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy were used for the characterization of inclusion complex. In addition, the binding pattern of eprosartan with the β-CD was investigated by molecular modeling study. Phase solubility study revealed that approximately 4.48 folds improvement in the solubility of drug was noted with β-CD (10 mM). The estimated stability constant (K_c) values for eprosartan:β-CD binary mixture was found to be 280.78 M^–1. The prepared inclusion complex of drug with β-CD presented better drug release profile (62.96 ± 2.01% in 1 h) as compared to their physical mixture (41.41 ± 1.77% in 1 h) or drug per se (29.97 ± 3.13%). The inclusion complex demonstrated different features and properties from pure drug, and we inferred that this could be due to the inclusion of drug into cyclodextrin cavity that confirmed by different analytical method. Molecular modeling study demonstrated a good affinity of eprosartan to entangle to β-CD. The outcomes have shown that guest molecule has many significant interactions with the host molecule. These observations are very interesting and may be a valuable approach to improve the solubility and in turn the bioavailability of eprosartan.

Recent Updates on Supramolecular-Based Drug Delivery - Macrocycles and Supramolecular Gels

Supramolecules-based drug delivery has attracted significant recent research attention as it could enhance drug solubility, retention time, targeting, and stimuli responsiveness. Among the different supramolecules and assemblies, the macrocycles and the supramolecular hydrogels are the two important categories investigated to a greater extent. Here, we provide the most recent advancements in these categories. Under macrocycles, reports on drug delivery by cyclodextrins, cucurbiturils, calixarenes/pillararenes, crown ethers and porphyrins are detailed. The second category discusses the supramolecular hydrogels of macrocycles/polymers and low molecular weight gelators. The updated information provided could be helpful to advance R & D in this vital area.

The chirality determination of amino acids by forming complexes with cyclodextrins and metal ions using ion mobility spectrometry, and a DFT calculation

Chiral recognition is of highly interest in the areas of chemistry, pharmaceuticals, and bioscience. An effective strategy of enantiomeric determination of amino acids (AAs) was developed in this work. All 19 natural AAs enantiomers can be easily distinguished by ion mobility-mass spectrometry of the non-covalent complexes of AAs with cyclodextrins (α-CD, β-CD and γ-CD) and Mg²⁺ without any chemical derivatization. Differences of the mobilities between the enantiomers' complexes is from 0.006 to 0.058 V s/cm². In addition, the complex of [β-CD + Phe + Mg]²⁺ was selected as an example to study the relative quantification by measuring L/D-Phe at different molar ratio of 10:1 to 1:10 in the μM range, resulting in a good linearity (R² > 0.99) and high sensitivity at 2 μM. A DFT calculation was also performed to illustrate the detailed molecular structure of the complexes of CDs, Mg²⁺ and D- or L-Phe. Both experiment and theoretical calculation showed that Mg²⁺ plays an important role in host/guest interactions, which changed the molecular conformations by non-covalent interaction between Mg²⁺ and CDs, and resulted in the different collision cross-sections of the complex ions of CDs, Mg²⁺ and D- or L-AAs in the gas phase. This effective and convenient strategy could potentially be utilized in scientific research and industry for routine enantiomeric determination of natural AAs, peptides and some other small chiral biomolecules such as non-natural AAs and carboxylic acid-containing drugs.

Cyclodextrins inclusion complex: Preparation methods, analytical techniques and food industry applications

This review offers a vision of the chemical behaviour of natural ingredients, synthetic drugs and other related compounds complexed using cyclodextrins. The review takes care of different sections related to i) the inclusion complexes formation with cyclodextrins, ii) the determination of the inclusion formation constant, iii) the most used methods to prepare host inclusion in the non-polar cavity of cyclodextrins and iv) the analytical techniques to evidence host inclusion. The review provides different literature that shows the application of cyclodextrins to improve physical, chemical, and biological characteristics of food compounds including solubility, stability and their elimination/masking. Moreover, the review also offers examples of commercial food/supplement products of cyclodextrins to indicate that cyclodextrins can be used to generate biotechnological substances with innovative properties and improve the development of food products.

Formation and Nanoscale Characterization of Asymmetric Supported Lipid Bilayers Containing Raft-Like Domains

The development of new strategies for achieving stable asymmetric membrane models has turned interleaflet lipid asymmetry into a topic of major interest. Cyclodextrin-mediated lipid exchange constitutes a simple and versatile method for preparing asymmetric membrane models without the need for sophisticated equipment. Here we describe a protocol for preparing asymmetric supported lipid bilayers mimicking membrane rafts by cyclodextrin-mediated lipid exchange and the main guidelines for obtaining structural information and quantitative measures of their mechanical properties using Atomic force microscopy and Force spectroscopy; two powerful techniques that allow membrane characterization at the nanoscale.

Sustainable mechanochemical synthesis of β-cyclodextrin polymers by twin screw extrusion

Cyclodextrin nanosponges (CD-NS) are cross-linked cyclodextrin polymers characterized by a nanostructured three-dimensional network. CD-NSs in the last years found many different applications in the pharmaceutical field for the controlled release of drugs and for the absorption of undesired substances from physiological media, food, and wastewater. Most of CD-NS syntheses involve the solubilization of the chosen CD in closed batch, using a suitable organic polar aprotic liquid, which may affect potential environmental or biomedical applications. Since the research is now moving towards more sustainable approaches, new and greener syntheses of CD-NS are now being developed. Here, it is reported a new eco-friendly and efficient synthesis of nanosponges through mechanochemistry. Mechanochemistry involves the application of mechanical forces to drive and control chemical reactions by transferring energy to chemical bonds. The mechanochemical approach involves the use of a twin-screw extruder (TSE) as a chemical reactor: TSE are capable of fine temperature control and, furthermore, TS Extrusion is a continuous process and not a batch process. Among the many available CD-NS syntheses, we tested our solvent-free approach on a β-CD/citric acid (CA) system. Moreover, using TSE, the same polymer was obtained in a considerably shorter time. The so obtained NSs were used for the adsorption and removal of probe molecules, in comparison with NSs prepared by cross-linking β-CD with CA in batch.

A supramolecular thermosensitive gel of ketoconazole for ocular applications: In silico, in vitro, and ex vivo studies

The incidence of corneal fungal infections continues to be a growing concern worldwide. Ocular delivery of anti-fungal drugs is challenging due to the anatomical and physiological barriers of the eye. The ocular bioavailability of ketoconazole (KTZ), a widely prescribed antifungal agent, is hampered by its limited aqueous solubility and permeation. In the study, the physicochemical properties of KTZ were improved by complexation with sulfobutylether-β-cyclodextrin (SBE-β-CD).KTZ-SBE-β-CD complex was studied in silico with docking and dynamics simulations, followed by wet-lab experiments.The optimized KTZ-SBE-β-CD complex was loaded into a thermosensitivein situ gel to increase corneal bioavailability. The supramolecular complex increased the solubility of KTZ by 5-folds and exhibited a 10-fold increment in drug release compared to the pure KTZ. Owing to the diffusion, thein situ gel exhibited a more sustained drug release profile. Theex vivocorneal permeation studies showed higher permeation from KTZ-SBE-β-CD in situ gel (flux of ∼19.11 µg/cm²/h) than KTZin situ gel (flux of ∼1.17 µg/cm²/h). The cytotoxicity assays and the hen's egg chorioallantoic membrane assay (HET-CAM) confirmed the formulations' safety and non-irritancy. In silico guided design of KTZ-SBE-β-CD inclusion complexes successfully modified the physicochemical properties of KTZ. In addition, the loading of the KTZ-SBE-β-CD complex into an in situ gel significantly increased the precorneal retention and permeation of KTZ, indicating that the developed formulation is a viable modality to treat fungal keratitis.

Effect of Soluplus® on γ-cyclodextrin solubilization of irbesartan and candesartan and their nanoaggregates formation

The poor aqueous solubility of irbesartan (IRB) and candesartan cilexetil (CAC) may hamper their bioavailability when orally or topically administered. Among several attempts, the promising nanoaggregate formation by γ-cyclodextrin (γCD) complexation of drugs in aqueous solution with or without water-soluble polymers was investigated. According to phase solubility studies, Soluplus® showed the highest complexation efficiency (CE) of drug/γCD complexes among the polymers tested. The aqueous solubility of IRB and CAC was markedly increased as a function of Soluplus^® concentrations. The binary drug/γCD and ternary drug/γCD/Soluplus^® complex formations were supported and confirmed by solid-state characterizations, including differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier transform infrared (FT-IR) spectroscopy. The true inclusion mode was also proved by proton nuclear magnetic resonance (¹H-NMR) spectroscopy. The nanoaggregate size and morphology of binary and ternary systems were observed using dynamic light scattering (DLS), and transmission electron microscopy (TEM) techniques. The size of these nanocarriers depends on the concentration of Soluplus^®. The use of Soluplus^® could significantly enhance drug solubility and stabilize complex nanoaggregates, which could be a prospective platform for drug delivery systems.