Rutin/Sulfobutylether-ß-Cyclodextrin as a Promising Therapeutic Formulation for Ocular Infection.

Ocular pathologies present significant challenges to achieving effective therapeutic results due to various anatomical and physiological barriers. Natural products such as flavonoids, alone or in association with allopathic drugs, present many therapeutic actions including anticancer, anti-inflammatory, and antibacterial action. However, their clinical employment is challenging for scientists due to their low water solubility. In this study, we designed a liquid formulation based on rutin/sulfobutylether-ß-cyclodextrin (RTN/SBE-ß-CD) inclusion complex for treating ocular infections. The correct stoichiometry and the accurate binding constant were determined by employing SupraFit software (2.5.120) in the UV-vis titration experiment. A deep physical-chemical characterization of the RTN/SBE-ß-CD inclusion complex was also performed; it confirmed the predominant formation of a stable complex (Kc, 9660 M-1) in a 1:1 molar ratio, with high water solubility that was 20 times (2.5 mg/mL) higher than the free molecule (0.125 mg/mL), permitting the dissolution of the solid complex within 30 min. NMR studies revealed the involvement of the bicyclic flavonoid moiety in the complexation, which was also confirmed by molecular modeling studies. In vitro, the antibacterial and antibiofilm activity of the formulation was assayed against Staphylococcus aureus and Pseudomonas aeruginosa strains. The results demonstrated a significant activity of the formulation than that of the free molecules.

Characterization and In Vivo Antiangiogenic Activity Evaluation of Morin-Based Cyclodextrin Inclusion Complexes.

Morin (MRN) is a natural compound with antiangiogenic, antioxidant, anti-inflammatory, and anticancer activity. However, it shows a very low water solubility (28 µg/mL) that reduces its oral absorption, making bioavailability low and unpredictable. To improve MRN solubility and positively affect its biological activity, particularly its antiangiogenic activity, in this work, we prepared the inclusion complexes of MNR with sulfobutylether-ß-cyclodextrin (SBE-ß-CD) and hydroxypropyl-ß-cyclodextrin (HP-ß-CD). The inclusion complexes obtained by the freeze-drying method were extensively characterized in solution (phase-solubility studies, UV-Vis titration, and NMR spectroscopy) and in the solid state (TGA, DSC, and WAXD analysis). The complexation significantly increased the water solubility by about 100 times for MRN/HP-ß-CD and 115 times for MRN/SBE-ß-CD. Furthermore, quantitative dissolution of the complexes was observed within 60 min, whilst 1% of the free drug dissolved in the same experimental time. 1H NMR and UV-Vis titration studies demonstrated both CDs well include the benzoyl moiety of the drug. Additionally, SBE-ß-CD could interact with the cinnamoyl moiety of MRN too. The complexes are stable in solution, showing a high value of association constant, that is, 3380 M-1 for MRN/HP-ß-CD and 2870 M-1 for MRN/SBE-ß-CD. In vivo biological studies on chick embryo chorioallantoic membrane (CAM) and zebrafish embryo models demonstrated the high biocompatibility of the inclusion complexes and the effective increase in antiangiogenic activity of complexed MRN with respect to the free drug.

1,2-Dibenzoylhydrazine as a Multi-Inhibitor Compound: A Morphological and Docking Study.

In the framework of the multitarget inhibitor study, we report an in silico analysis of 1,2-dibenzoylhydrazine (DBH) with respect to three essential receptors such as the ecdysone receptor (EcR), urease, and HIV-integrase. Starting from a crystallographic structural study of accidentally harvested crystals of this compound, we performed docking studies to evaluate the inhibitory capacity of DBH toward three selected targets. A crystal morphology prediction was then performed. The results of our molecular modeling calculations indicate that DBH is an excellent candidate as a ligand to inhibit the activity of EcR receptors and urease. Docking studies also revealed the activity of DBH on the HIV integrase receptor, providing an excellent starting point for developing novel inhibitors using this molecule as a starting lead compound.

Bicalutamide Anticancer Activity Enhancement by Formulation of Soluble Inclusion Complexes with Cyclodextrins.

Bicalutamide (BCL) is a nonsteroidal antiandrogen drug that represents an alternative to castration in the treatment of prostate cancer, due to its relatively long half-life and tolerable side effects. However, it possesses a very low water solubility that can affect its oral bioavailability. In this work, we developed inclusion complexes of BCL with the highly soluble hydroxypropyl-ß-cyclodextrin (HP-ß-CyD) and sulfobutylether-ß-cyclodextrin (SBE-ß-CyD) to increase the water solubility and anticancer activity of BCL. The inclusion complexes were prepared using the freeze-drying method and were then characterized in a solid state via differential scanning calorimetry and X-ray analysis and in solution via phase-solubility studies and UV-vis and NMR spectroscopy. The BCL/HP-ß-CyD and BCL/SBE-ß-CyD inclusion complexes were amorphous and rapidly dissolved in water. Both the 1H-NMR spectra and molecular modeling studies confirmed the penetration of the 2-(trifluoromethyl)benzonitrile ring of BCL within the cavity of both cyclodextrins (CyDs). Due to the consistent improvement of the water solubility of BCL, the inclusion complexes showed higher antiproliferative activity toward the human prostate androgen-independent cell lines, DU-145 and PC-3, with respect to free BCL. These results demonstrate the ability of HP-ß-CyD and SBE-ß-CyD to complex BCL, permitting the realization of liquid formulations with potentially high oral bioavailability and/or possible parenteral administration.

Development of Chitosan/Cyclodextrin Nanospheres for Levofloxacin Ocular Delivery.

Levofloxacin (LVF) is an antibacterial drug approved for the treatment of ocular infections. However, due to the low ocular bioavailability, high doses are needed, causing bacterial resistance. Polymeric nanospheres (NPs) loading antibiotic drugs represent the most promising approach to eradicate ocular infections and to treat pathogen resistance. In this study, we have developed chitosan NPs based on sulfobutyl-ether-ß-cyclodextrin (CH/SBE-ß-CD NPs) for ocular delivery of LVF. CH/SBE-ß-CD NPs loading LVF were characterized in terms of encapsulation parameters, morphology, and sizes, in comparison to NPs produced without the macrocycle. Nuclear magnetic resonance and UV-vis spectroscopy studies demonstrated that SBE-ß-CD is able to complex LVF and to influence encapsulation parameters of NPs, producing high encapsulation efficiency and LVF loading. The NPs were homogenous in size, with a hydrodynamic radius between 80 and 170 nm and positive zeta potential (ζ) values. This surface property could promote the interaction of NPs with the negatively charged ocular tissue, increasing their residence time and, consequently, LVF efficacy. In vitro, antibacterial activity against Gram-positive and Gram-negative bacteria showed a double higher activity of CH/SBE-ß-CD NPs loading LVF compared to the free drug, suggesting that chitosan NPs based on SBE-ß-CD could be a useful system for the treatment of ocular infections.

Green Efficient One-Pot Synthesis and Separation of Nitrones in Water Assisted by a Self-Assembled Nanoreactor.

This article reports an alternative method for preparing nitrones using a tetrahedral capsule as a nanoreactor in water. Using the hydrophobic cavity of the capsule allowed us to reduce the reaction times and easily separate the nitrones from the reaction mixture, obtaining reaction yields equal or comparable to those obtained with the methods already reported. Furthermore, at the basis of this methodology, there is an eco-friendly approach carried out that can certainly be extended to other synthesis methods for the preparation of other substrates by exploiting various types of macrocyclic hosts, suitably designed and widely used in supramolecular chemistry.

Physicochemical Characterization and Antioxidant Activity Evaluation of Idebenone/Hydroxypropyl-ß-Cyclodextrin Inclusion Complex †.

Idebenone (IDE) is an antioxidant drug active at the level of the central nervous system (CNS), whose poor water solubility limits its clinical application. An IDE/2-hydroxypropyl-ß-cyclodextrin (IDE/HP-ß-CD) inclusion complex was investigated by combining experimental methods and theoretical approaches. Furthermore, biological in vitro/ex vivo assays were performed. Phase solubility studies showed an AL type diagram, suggesting the presence of a 1:1 complex with high solubility. Scanning electron microscopy (SEM) allowed us to detect the morphological changes upon complexation. The intermolecular interactions stabilizing the inclusion complex were experimentally characterized by exploring the complementarity of Fourier-transform infrared spectroscopy in attenuated total reflectance geometry (FTIR-ATR) with mid-infrared light, Fourier-transform near-infrared (FT-NIR) spectroscopy, and Raman spectroscopy. From the temperature evolution of the O-H stretching band of the complex, the average enthalpy ΔHHB of the hydrogen bond scheme upon inclusion was obtained. Two-dimensional (2D) rotating frame Overhauser effect spectroscopy (ROESY) analysis and computational studies involving molecular modeling and molecular dynamics (MD) simulation demonstrated the inclusion of the quinone ring of IDE inside the CD ring. In vitro/ex vivo studies evidenced that complexation produces a protective effect of IDE against the H2O2-induced damage on human glioblastoma astrocytoma (U373) cells and increases IDE permeation through the excised bovine nasal mucosa.

Gemcitabine anticancer activity enhancement by water soluble celecoxib/sulfobutyl ether-ß-cyclodextrin inclusion complex.

We investigated the complexation of celecoxib (CCB) into sulfobuthyl-ether-ß-cyclodextrin (SBE-ß-CD) for the realization of an inhalable dry-powder formulation containing gemcitabine (GEM) for lung anticancer therapy. Complexation increased the water solubility of CCB (0.003 mg/mL and 0.834 mg/mL for CCB free and complexed, respectively) and produced a quantitative dissolution of the drug within 15 min. The CCB/SBE-ß-CD inclusion complex showed a high stability constant (8131 M-1) not influenced by the presence of GEM in solution. Two-dimensional NMR experiments and computational studies demonstrated that the pyrazole ring of CCB penetrates deeper into SBE-ß-CD from the secondary rim. The aromatic rings are positioned at the edge of the cavity, establishing hydrogen bonds with the SBE-ß-CD that stabilized the complex. CCB showed limited cytotoxic activity on A549 cell lines. Complexation significantly increased activity passing from 30% to 45% cell mortality. Moreover, CCB/SBE-ß-CD strongly improved the cytotoxicity of GEM, observing about 60% of cell mortality for the combined formulation.

A Pseudouridine Isoxazolidinyl Nucleoside Analogue Structural Analysis: A Morphological Approach.

An in silico study has been conducted upon (3'RS,5'SR)-5-[2'-benzyl-5'-hydroxymethyl-1',2'-isoxazolidin-3'-yl]uracil through a molecular dynamics/docking approach that highlights its potential inhibitory activity upon the wild-type pseudouridine 5'-monophosphate glycosidase. The crystal structure of this compound has been solved by means of X-ray single crystal diffraction and the data inferred were used to predict its crystal morphology. These data were compared with optical microscopy images and confirmed the validity of the computed models. This robust approach, already used for several other different compounds, provides a fast and reliable tool to standardize a crystallization method in order to get similar and good quality crystals. As different crystal shapes could be associated with different polymorphic forms, this method could be considered a fast and cheap screening to choose among different and coexistent polymorphic forms. Furthermore, a match with the original crystal structure of pseudouridine 5'-monophosphate is provided.

Molecular modeling studies of pseudouridine isoxazolidinyl nucleoside analogues as potential inhibitors of the pseudouridine 5'-monophosphate glycosidase.

In this paper, we investigated the hypothesis that pseudouridine isoxazolidinyl nucleoside analogues could act as potential inhibitors of the pseudouridine 5'-monophosphate glycosidase. This purpose was pursued using molecular modeling and in silico ADME-Tox profiling. From these studies emerged that the isoxazolidinyl derivative 1 5'-monophosphate can be effectively accommodated within the active site of the enzyme with a ligand efficiency higher than that of the natural substrate. In this context, the poor nucleofugality of the N-protonated isoxazolidine prevents or slows down, the first mechanistic step proposed for the degradation of the pseudouridine 5'-monophosphate glycosidase, leading to the enzyme inhibition. Finally, the results of the physicochemical and ADME-Tox informative analysis pointed out that compound 1 is weakly bounded to plasma protein, only moderately permeate the blood-brain barrier, and is non-carcinogen in rat and mouse. To the best of our knowledge, this is the first paper that introduces the possibility of inhibition of pseudouridine 5'-monophosphate glycosidase by a molecule that competing with the natural substrate hinders the glycosidic C-C bond cleavage.

DNA intercalators based on (1,10-phenanthrolin-2-yl)isoxazolidin-5-yl core with better growth inhibition and selectivity than cisplatin upon head and neck squamous cells carcinoma.

((3RS,5SR)- and ((3RS,5RS)-2-(2-methoxybenzyl)-3-(1,10-phenanthrolin-2-yl)isoxazolidin-5-yl)methanol have been synthesized, according to 1,3-dipolar cycloaddition methodology, as DNA intercalating agents and evaluated for their anticancer activity against human cervical carcinoma HeLa and head and neck squamous cells carcinoma cell lines. The synthesized compounds exhibited good cytotoxic activity with IC50 better than cisplatin, used as the main and effective treatment for HNSCC, and a 24.3-72.0-fold selectivity respect to the 184B5 non-cancerous immortalized breast epithelial cell lines. Unwinding assay, circular dichroism data, and Uv-vis melting experiments confirmed that these compounds act as DNA intercalators with a binding constant in the order of 104 M-1. Docking studies showed that both compounds can interact as intercalating agent with both poly-d(AT)2 and poly-d(GC)2, preferring an entrance by the minor groove of the poly-d(AT)2.

Novel Sigma Receptor Ligand-Nitric Oxide Photodonors: Molecular Hybrids for Double-Targeted Antiproliferative Effect.

This contribution reports the synthesis and evaluation of novel hybrid compounds that conjugate a sigma (σ) receptor pharmacophore and a nitric oxide (NO) photodonor. All compounds preserve their capability to generate NO under visible light and possess overall σ receptor nanomolar affinity, with one of them (8b) exhibiting remarkable σ2 receptor selectivity. Compounds 8b, 11a, and 11b were tested on tumorigenic MCF-7 and A2058 cells expressing high levels of σ2 and σ1 receptor, respectively. Considerable loss of cell viability was detected under light excitation, while negligible effects in the dark were detected. Moreover, they did not show any significant cytotoxicity in the dark or under irradiation on nontumorigenic NCTC-2544 keratinocytes. NO-induced reduction of cellular viability was demonstrated by in-cell NO detection and total nitrite estimation. For the first time, a combination of σ receptor moieties and a NO photodonor is reported, providing distinctive ligands potentially useful for cancer management.

Serendipitous discovery of potent human head and neck squamous cell carcinoma anti-cancer molecules: A fortunate failure of a rational molecular design.

Histone deacetylase inhibitors (HDACis) play an important role as valuable drugs targeted to cancer therapy: several HDACis are currently being tested in clinical trials. Two new potential HDACis 1a and 1d, characterized by the presence of a biphenyl-4-sulfonamide group as a connection unit between the N-{4-[(E)-(2-formylhydrazinylidene)methyl]-3-hydroxyphenyl} and the 2-hydroxy-N-(trifluoroacetyl)benzamide moiety, respectively, as two zinc-binding group (ZBG), have been designed, synthesized and tested for their biological activity. Surprisingly, compounds 1a and 12, this last exclusively obtained in place of 1d, exhibited a very low HDAC inhibitory activity. A serendipitous assay of these two compounds, conducted on three chemoresistant cell lines of head and neck squamous cell carcinoma (HNSCC), showed their antiproliferative activity at low nanomolar concentrations, better than cisplatin. In vitro, biological assays indicated that compounds 1a and 12 are able to increase acetylation of histone H3 and to interfere with the PI3K/Akt/mTOR pathway by inducing the accumulation of PTEN protein.

Hyphenated 3D-QSAR statistical model-scaffold hopping analysis for the identification of potentially potent and selective sigma-2 receptor ligands.

A 3D quantitative structure-activity relationship (3D-QSAR) model for predicting the σ2 receptor affinity has been constructed with the aim of providing a useful tool for the identification, design, and optimization of novel σ2 receptor ligands. The model has been built using a set of 500 selective σ2 receptor ligands recovered from the sigma-2 receptor selective ligand database (S2RSLDB) and developed with the software Forge. The present model showed high statistical quality as confirmed by its robust predictive potential and satisfactory descriptive capability. The drawn up 3D map allows for a prompt visual comprehension of the electrostatic, hydrophobic, and shaping features underlying σ2 receptor ligands interaction. A theoretic approach for the generation of new lead compounds with optimized σ2 receptor affinity has been performed by means of scaffold hopping analysis. Obtained results further confirmed the validity of our model being some of the identified moieties have already been successfully employed in the development of potent σ2 receptor ligands. For the first time is herein reported a 3D-QSAR model which includes a number of chemically diverse σ2 receptor ligands and well accounts for the individual ligands affinities. These features will ensure prospectively advantageous applications to speed up the identification of new potent and selective σ2 receptor ligands.

Design, Synthesis, and Antibacterial Activity of a Multivalent Polycationic Calix[4]arene-NO Photodonor Conjugate.

The role of nitric oxide (NO) as an antimicrobial and anticancer agent continues to stimulate the search of compounds generating NO in a controlled fashion. Photochemical generators of NO are particularly appealing due to the accurate spatiotemporal control that light-triggering offers. This contribution reports a novel molecular construct in which multiple units of 3-(trifluoromethyl)-4-nitrobenzenamine NO photodonor are clustered and spatially organized by covalent linkage to a calix[4]arene scaffold bearing two quaternary ammonium groups at the lower rim. This multivalent calix[4]arene-NO donor conjugate is soluble in hydro-alcoholic solvent where it forms nanoaggregates able to release NO under the exclusive control of visible light inputs. The light-stimulated antibacterial activity of the nanoconstruct is demonstrated by the effective bacterial load reduction of Gram-positive Staphylococcus aureus ATCC 6538 and Gram-negative Escherichia coli ATCC 10536.

Adipocyte fatty acid binding protein 4 (FABP4) inhibitors. A comprehensive systematic review.

Small molecule inhibitors of adipocyte fatty acid binding protein 4 (FABP4) have attracted interest following the recent publications of beneficial pharmacological effects of these compounds. FABP4 is predominantly expressed in macrophages and adipose tissue where it regulates fatty acids (FAs) storage and lipolysis and is an important mediator of inflammation. In the past years, hundreds FABP4 inhibitors have been synthesized for effective atherosclerosis and diabetes treatments, including derivatives of niacin, quinoxaline, aryl-quinoline, bicyclic pyridine, urea, aromatic compounds and other novel heterocyclic compounds. This review provides an overview of the synthesized and discovered molecules as adipocyte fatty acid binding protein 4 inhibitors (FABP4is) since the synthesis of the putative FABP4i, BMS309403, highlighting the interactions of the different classes of inhibitors with the targets.

5'-Spiro-cyclopropanated lactose derivatives as suitable intermediates for the chain elongation: synthesis of a new 6-deoxy-6-methyl δ-eptulose.

A δ-dicarbonyl heptose has been prepared through an electrophilic ring opening procedure of a 5'-spirocyclopropanated lactose derivative. The reported synthetic procedure outlines a new route for the transformation of this renewable disaccharide into new and interesting δ-dicarbonyl sugars, synthetic precursors of cyclitols, carba- and azasugars. The experimental results of the cyclopropanation process have been successfully rationalized by in silico studies.

Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route.

The intramolecular aldol condensation of aldohexos-5-ulose derivatives of the D-xylo and L-ribo stereoseries has been studied. Only one of the four possible inososes was isolated from both stereoseries in reasonable yields (30-38%). The results obtained, together with the previous findings for the L-arabino and L-lyxo stereoseries, allowed for the rationalisation of a mechanism of the reaction based on open-transition-state models and electron-withdrawing inductive effects. Complementary reductions of the intermediate inososes were possible by changing the reaction conditions, and two isomeric inositol derivatives were obtained with complete stereoselection from each inosose. The presented approach permits us to control the configuration of three out of the six stereocentres of the inositol frame and gives access to seven of the nine inositols. Noteworthy, for the D-xylo derivative, the two-step sequence (condensation followed by reduction with NaBH(OAc)3) represents the biomimetic synthesis of myo-inositol. Furthermore, the sugar-based pathway leads directly to enantiomerically pure selectively protected inositols and does not require any desymmetrisation procedure which is needed when myo-inositol and other achiral precursors are employed as starting materials. As an example of application of the method, the indirect selective protection of secondary inositols' hydroxy functions, by placing specific protecting groups on the aldohexos-5-ulose precursor has been presented.

Synthesis and physico-chemical characterization of a ß-cyclodextrin conjugate for sustained release of Acyclovir.

We report the synthesis of an oligomeric prodrug of the antiviral agent Acyclovir (Acy) conjugated to ß-cyclodextrin (ß-CyD). The drug was selectively linked through a succinic spacer to one of the primary hydroxyl groups of ß-CyD by ester linkage in a 1:1 molar ratio. The conjugate was purified by semipreparative reverse-phase chromatography and characterized by FAB mass spectrometry and NMR experiments. The release of Acy from the conjugate was evaluated both in acidic and in neutral conditions and in the presence of porcine liver esterase. In all cases we observed the release of both free Acy and Acy succinate (AcySucc) at differing rates as a function of the hydrolysis conditions. In the presence of esterase the release of free Acy was favoured over AcySucc, showing a release rate of 100% of Acy within 7 days.

New amphiphilic derivatives of poly(ethylene glycol) (PEG) as surface modifiers of colloidal drug carriers. III. Lipoamino acid conjugates with carboxy- and amino-PEG(5000) polymers.

Within a research directed to developing new polymeric materials, suitable for decorating the surface of colloidal drug carriers, PEG5000 polymers containing a free carboxyl or amine group at one end were conjugated to an α-lipoamino moiety (LAA). The conjugates were characterized by FT-IR, (1)H-NMR, and MALDI-TOF mass spectrometry. They showed the same profile of solubility as the parent PEGs in water and in some polar and apolar solvents of pharmaceutical use. Representative terms showed to be well tolerated when incubated with Caco-2 or L929 cell cultures. Dedicated differential scanning calorimetry (DSC) studies were performed to prove the interaction of increasing molar fractions of the PEG5000-LAA conjugates with dipalmitoylphosphatidylcholine (DPPC) bilayers, to gain information about their possible incorporation in drug nanocarriers. While the parent PEGs affected only the superficial structure of bilayers, the amphiphilic PEG-LAA conjugates induced a perturbing effect on the thermotropic behavior of DPPC liposomes, according to the structure of the linked LAA residue. A molar concentration of these PEG-LAA between 5 and 10% was individuated as the most suitable to produce stable vesicles.