Selective Synthesis of Azoloyl NH-1,2,3-Triazoles and Azolyl Diazoketones: Experimental and Computational Insights

Here, we report that the reaction of enaminones, from a class of azole series, with sulfonyl azides leads to a difficult-to-separate mixture of two pairs of compounds: (1) 4-azoloyl-NH-1,2,3-triazoles with sulfonamides and (2) azolyl diazoketones with N-sulfonamidines, as a result of the implementation of two competing reactions. On one hand, the electron-donating methyl or methoxy group in the aryl para-position of arylsulfonyl azides favors the production of NH-1,2,3-triazoles together with sulfonamides. On the other hand, the use of highly electrophilic 4-nitrophenylsulfonyl azide promotes the formation of diazoketones and sulfonamidines. It is shown that the direction of each reaction is not only controlled by the nature of the initial enaminones and sulfonyl azides but also depends on the tested solvent. The problem of removing sulfonamides and amidines from the desired products was solved for the first time using new water-soluble enaminones. Based on the experimental and computational studies, the factors contributing to the selective course of alternative reactions were identified, and methods for the synthesis of azoloyl-NH-1,2,3-triazoles and azolyl diazoketones were developed. Density functional theory (DFT) results have shown that the 1,3-dipolar cycloaddition is totally driven toward one single regioisomer with a high asynchronous bond formation, and the introduction of an electron-deficient group in sulfonyl azides induces faster cycloaddition. Additionally, DFT calculations were used to gain further mechanistic insights on the reaction studied here. © 2022 American Chemical Society. All rights reserved.This work was supported by the Russian Science Foundation (grant no. 18-13-00161, prolongation). A.A.H. thanks the computational resources accessed via Iridis4 provided by the University of Southampton

In silico predictive model to determine vector-mediated transport properties for the blood–brain barrier choline transporter

Sergey Shityakov, Carola Förster Department of Anaesthesia and Critical Care, University of Würzburg, Würzburg, Germany Abstract: The blood–brain barrier choline transporter (BBB-ChT) may have utility as a drug delivery vector to the central nervous system (CNS). We therefore initiated molecular docking studies with the AutoDock and AutoDock Vina (ADVina) algorithms to develop predictive models for compound screening and to identify structural features important for binding to this transporter. The binding energy predictions were highly correlated with r2=0.88, F=692.4, standard error of estimate =0.775, and P-value<0.0001 for selected BBB-ChT-active/inactive compounds (n=93). Both programs were able to cluster active (Gibbs free energy of binding <−6.0 kcal*mol-1) and inactive (Gibbs free energy of binding >−6.0 kcal*mol-1) molecules and dock them significantly better than at random with an area under the curve value of 0.86 and 0.84, respectively. In ranking smaller molecules with few torsional bonds, a size-related bias in scoring producing false-negative outcomes was detected. Finally, important blood–brain barrier parameters, such as the logBBpassive and logBBactive values, were assessed to predict compound transport to the CNS accurately. Knowledge gained from this study is useful to better understand the binding requirements in BBB-ChT, and until such time as its crystal structure becomes available, it may have significant utility in developing a highly predictive model for the rational design of drug-like compounds targeted to the brain. Keywords: blood–brain barrier choline transporter, central nervous system, drug delivery vector, molecular docking, virtual screening, Gibbs free energy of binding, diffusio

In silico structure-based screening of versatile P-glycoprotein inhibitors using polynomial empirical scoring functions

Sergey Shityakov, Carola FörsterDepartment of Anesthesia and Critical Care, University of Würzburg, Würzburg, GermanyAbstract: P-glycoprotein (P-gp) is an ATP (adenosine triphosphate)-binding cassette transporter that causes multidrug resistance of various chemotherapeutic substances by active efflux from mammalian cells. P-gp plays a pivotal role in limiting drug absorption and distribution in different organs, including the intestines and brain. Thus, the prediction of P-gp–drug interactions is of vital importance in assessing drug pharmacokinetic and pharmacodynamic properties. To find the strongest P-gp blockers, we performed an in silico structure-based screening of P-gp inhibitor library (1,300 molecules) by the gradient optimization method, using polynomial empirical scoring (POLSCORE) functions. We report a strong correlation (r2=0.80, F=16.27, n=6, P<0.0157) of inhibition constants (Kiexp or pKiexp; experimental Ki or negative decimal logarithm of Kiexp) converted from experimental IC50 (half maximal inhibitory concentration) values with POLSCORE-predicted constants (KiPOLSCORE or pKiPOLSCORE), using a linear regression fitting technique. The hydrophobic interactions between P-gp and selected drug substances were detected as the main forces responsible for the inhibition effect. The results showed that this scoring technique might be useful in the virtual screening and filtering of databases of drug-like compounds at the early stage of drug development processes.Keywords: ATP-binding cassette transporter, P-gp inhibitors, multidrug resistance, molecular docking, POLSCOR

 α-Cyclodextrin dimer complexes of dopamine and levodopa derivatives to assess drug delivery to the central nervous system: ADME and molecular docking studies

Sergey Shityakov, Jens Broscheit, Carola FörsterDepartment of Anesthesiology and Critical Care, University of Würzburg, Würzburg, GermanyAbstract: This paper attempts to predict and emphasize molecular interactions of dopamine, levodopa, and their derivatives (Dopimid compounds) containing 2-phenyl-imidazopyridine moiety with the α-cyclodextrin dimer in order to assess and improve drug delivery to the central nervous system. The molecular docking method is used to determine the energetic profiles, hydrogen bond formation, and hydrophobic effect of 14 host–guest complexes. The results show that the “chemical branching” represented by additional ethyl-acetate residue is energetically unfavorable and promotes a conformational shift due to the high root mean square deviation levels. This phenomenon is characterized by a low number of H-bonds and a significant decrease of the host–guest hydrophobic potential surface. Finally, the overall docking procedure presents a powerful rationale for screening and analyzing various sets of promising drug-like chemical compounds in the fields of supramolecular chemistry, molecular sensing, synthetic receptors, and nanobiotechnology.Keywords: dopamine, levodopa, Dopimid compounds, α-CD dimer, molecular docking, complexatio

Gene expression profiles and protein–protein interaction network analysis in AIDS patients with HIV-associated encephalitis and dementia

Sergey Shityakov,1 Thomas Dandekar,2 Carola Förster1 1Department of Anesthesia and Critical Care, 2Department of Bioinformatics, University of Würzburg, Würzburg, Germany Abstract: Central nervous system dysfunction is an important cause of morbidity and mortality in patients with human immunodeficiency virus type 1 (HIV-1) infection and acquired immunodeficiency virus syndrome (AIDS). Patients with AIDS are usually affected by HIV-associated encephalitis (HIVE) with viral replication limited to cells of monocyte origin. To examine the molecular mechanisms underlying HIVE-induced dementia, the GSE4755 Affymetrix data were obtained from the Gene Expression Omnibus database and the differentially expressed genes (DEGs) between the samples from AIDS patients with and without apparent features of HIVE-induced dementia were identified. In addition, protein–protein interaction networks were constructed by mapping DEGs into protein–protein interaction data to identify the pathways that these DEGs are involved in. The results revealed that the expression of 1,528 DEGs is mainly involved in the immune response, regulation of cell proliferation, cellular response to inflammation, signal transduction, and viral replication cycle. Heat-shock protein alpha, class A member 1 (HSP90AA1), and fibronectin 1 were detected as hub nodes with degree values >130. In conclusion, the results indicate that HSP90A and fibronectin 1 play important roles in HIVE pathogenesis.Keywords: microarray, human immunodeficiency virus, differentially expressed genes, protein–protein interaction network, gene ontology, encephalitis, dementi

Detailed chemical characterization and molecular modeling of serotonin inclusion complex with unmodified β-cyclodextrin

In this study, we analyzed the capability of unmodified β-cyclodextrin (β-CD) to form the stable complex with serotonin hydrochloride (SER), as an important neurotransmitter in the brain. The stable β-CD: SER formulation was prepared and characterized using spectroscopic, thermal, molecular docking, and molecular dynamics techniques, revealing the phenomenon of H-bond formations and the domination of hydrophobic forces between the host molecule and its guest via the amine group of SER and the narrow side of β-CD. The complexation mechanism was mainly enthalpy-driven, representing the improvement in SER photo-stability. Overall, the results highlighted the possibility to use this formulation with improved stability in clinical practice for treatment and prevention of various depressive conditions, such as anxiety disorders

Blood–brain barrier transport studies, aggregation, and molecular dynamics simulation of multiwalled carbon nanotube functionalized with fluorescein isothiocyanate

Sergey Shityakov,1 Ellaine Salvador,1 Giorgia Pastorin,2 Carola Förster1 1Department of Anaesthesia and Critical Care, University of Würzburg, Würzburg, Germany; 2Department of Pharmacy, National University of Singapore, Singapore Abstract: In this study, the ability of a multiwalled carbon nanotube functionalized with fluorescein isothiocyanate (MWCNT–FITC) was assessed as a prospective central nervous system-targeting drug delivery system to permeate the blood–brain barrier. The results indicated that the MWCNT–FITC conjugate is able to penetrate microvascular cerebral endothelial monolayers; its concentrations in the Transwell® system were fully equilibrated after 48 hours. Cell viability test, together with phase-contrast and fluorescence microscopies, did not detect any signs of MWCNT–FITC toxicity on the cerebral endothelial cells. These microscopic techniques also revealed presumably the intracellular localization of fluorescent MWCNT–FITCs apart from their massive nonfluorescent accumulation on the cellular surface due to nanotube lipophilic properties. In addition, the 1,000 ps molecular dynamics simulation in vacuo discovered the phenomenon of carbon nanotube aggregation driven by van der Waals forces via MWCNT–FITC rapid dissociation as an intermediate phase. Keywords: blood–brain barrier, multiwalled carbon nanotube, fluorescein isothiocyanate, Transwell® system, aggregation, fluorescence microscopy, molecular dynamic

Blood-brain barrier transport studies, aggregation, and molecular dynamics simulation of multiwalled carbon nanotube functionalized with fluorescein isothiocyanate

10.2147/IJN.S68429International Journal of Nanomedicine101703-171