Barbara Matuszczak

Synthesis, induced-fit docking investigations, and in vitro aldose reductase inhibitory activity of non-carboxylic acid containing 2,4-thiazolidinedione derivatives.

In continuation of our studies, we here report a series of non-carboxylic acid containing 2,4-thiazolidinedione derivatives, analogues of previously synthesized carboxylic acids which we had found to be very active in vitro aldose reductase (ALR2) inhibitors. Although the replacement of the carboxylic group with the carboxamide or N-hydroxycarboxamide one decreased the in vitro ALR2 inhibitory effect, this led to the identification of mainly non-ionized derivatives with micromolar ALR2 affinity. The 5-arylidene moiety deeply influenced the activity of these 2,4-thiazolidinediones. Our induced-fit docking studies suggested that 5-(4-hydroxybenzylidene)-substituted derivatives may bind the polar recognition region of the ALR2 active site by means of the deprotonated phenol group, while their acetic chain and carbonyl group at position 2 of the thiazolidinedione ring form a tight net of hydrogen bonds with amino acid residues of the lipophilic specificity pocket of the enzyme.

Design and in vitro evaluation of a novel polymeric P-glycoprotein (P-gp) inhibitor.

The aim of the present study was to improve the inhibitory properties of poly(ethylene glycol) (PEG) as excipient in drug delivery systems by covalent attachment of thiol moieties. This was achieved by grafting PEG to polyethylenimine (PEI) and finally thiolation with γ-thiobutyrolatone. Furthermore, the potential of this novel thiolated PEG-g-PEI co-polymer on the transport of rhodamine-123 (Rho-123) as P-gp substrate across freshly excised rat intestinal mucosa was evaluated in Ussing-type chambers. Apparent permeability coefficients (P(app)) were calculated and compared with values gained from experiments with the well-established P-gp inhibitors verapamil, reduced GSH, 6-mercatopurine and vitamin E-TPGS and the structurally similar compounds, myrj 52 and brij 35. The thiolated co-polymer displayed 145.07 ± 1.64 μmol/g of remaining primary amino groups, 84.30 ± 5.43 μmol/g of immobilized thiol groups and 12.74 ± 1.57 μmol/g of disulfide bonds. The approximate molecular mass of the thiolated co-polymer was 16,000 Da. The (1)H-NMR spectrum of PEG-g-PEI co-polymer was characterized by the presence of signal groups of PEG, hexamethylene diisocyanate (HMDI) and PEI substructures. Studies with Caco-2 cells revealed that the thiolated co-polymer shows 6.69 ± 0.27% of cytotoxicity by LDH assay and 93.33 ± 0.07% of cell viability by MTT assay. The thiolated co-polymer in a concentration of 0.5% (w/v) displayed a more pronounced effect on the absorptive transport of Rho-123 (P(app)=15.2 ± 1.0 × 10(-)(6)cm/s) in comparison to reduced GSH, 6-mercatopurine, vitamin E-TPGS, myrj 52 and brij 35. The thiolated co-polymer increased the transport of Rho-123 up to 3.3-fold in comparison to Rho-123 without any inhibitor used as control (P(app)=4.7 ± 0.1 × 10(-)(6)cm/s). The thiolated co-polymer applied in a concentration of 0.1%, 0.25% and 0. 5% (w/v) did not only enhance the absorption but also decreased the secretory transport of Rho-123 resulting in efflux ratios (secretory P(app)/absorptive P(app)) of 1.0, 1.4 and 2.0, respectively. Because of these features the novel thiolated PEG-g-PEI co-polymer seems to exhibit promising properties as novel P-gp inhibitor.

Experimentally validated HERG pharmacophore models as cardiotoxicity prediction tools.

The goal of this study was to design, experimentally validate, and apply a virtual screening workflow to identify novel hERG channel blockers. The hERG channel is an important antitarget in drug development since cardiotoxic risks remain as a major cause of attrition. A ligand-based pharmacophore model collection was developed and theoretically validated. The seven most complementary and suitable models were used for virtual screening of in-house and commercially available compound libraries. From the hit lists, 50 compounds were selected for experimental validation through bioactivity assessment using patch clamp techniques. Twenty compounds inhibited hERG channels expressed in HEK 293 cells with IC50 values ranging from 0.13 to 2.77 μM, attesting to the suitability of the models as cardiotoxicity prediction tools in a preclinical stage.

The Inhibitory Activity of Diazinyl-Substituted Thiourea Derivatives on Human Immunodeficiency Virus Type 1 Reverse Transcriptase

Starting from 2-(2-aminoethyl)pyridine, a series of N-diazinyl-N′-[2-(2-pyridyl)ethyl]thioureas was prepared via the (2-pyridyl)ethylisothiocyanate and was screened as non-nucleoside human immunodeficiency virus type 1 reverse transcriptase inhibitors. Derivatives bearing a 3-pyridazinyl or a 4-pyrimidinyl moiety turned out to be the most potent compounds. However, they exhibited less activity than nevirapine or trovirdine.

Pyridazines, 71. A Novel Type of 1,2-Diazine Æ 1,2-Diazole Ring Contraction

Reaction of the 3,6-dichloro-4-pyridazinecarboxamide derivative (2) with sodium hydride in dimethylformamide does not afford a pyridazino[3,4-b]-[1,5]benzodiazepine system (3) but results in a ring transformation to give the quinoxalinyl-substituted pyrazole derivative (4). The structure of this unexpected reaction product could be elucidated by means of a crystal structure determination; a mechanistic interpretation of this novel type of a pyridazine → pyrazole ring contraction is proposed

Synthesis and characterization of thiolated β-cyclodextrin as a novel mucoadhesive excipient for intra-oral drug delivery

The objective of the present study was to synthesize and characterize cysteamine conjugated β-cyclodextrin (β-CD-Cys) as a novel mucoadhesive oligomeric excipient for intra-oral drug delivery. β-CD-Cys conjugates were obtained in a two-step synthetic pathway, whereby, vicinal diol groups of the oligomer were oxidized using increasing concentrations of sodium-per-iodate (NaIO4), prior to the covalent coupling of cysteamine via reductive amination. Quantification of immobilized thiol groups through Ellmans test revealed 561.56 ± 81 μmol/g, 1054.26 ± 131 μmol/g and 1783.92 ± 201 μmol/g of free thiol groups attached to the oligomer backbone depending on the extent of oxidation. β-CD-Cys conjugates at concentrations of 0.5% (m/v) showed no toxic effects on Caco-2 cells within 72 h. Furthermore, β-CD-Cys conjugates displayed a 4-fold improved water solubility compared to the parent oligomer. β-CD-Cys conjugates (β-CD-Cys561, β-CD-Cys1054 and β-CD-Cys1783) showed 2.86-, 15.09- and 49.08-fold improved retention time on porcine intestinal mucosa and 9.66-, 16.43- and 34.51-fold improved on the porcine buccal mucosa, respectively. Formation of inclusion complexes of miconazole nitrate and β-CD-Cys1054 resulted in 150-fold increased solubility of miconazole nitrate. According to these results, it seems that β-CD-Cys conjugates might provide a new promising tool for delivery of poorly water soluble therapeutic agents, such as miconazole nitrate for intra-oral delivery.

Mucus permeating thiolated self-emulsifying drug delivery systems.

CONTEXT Mucus represents a critical obstacle for self-emulsifying drug delivery systems (SEDDS) targeting the epithelial membrane site. OBJECTIVE The aim of the study was the development of a novel SEDDS to overcome the mucus barrier. MATERIALS AND METHODS Two novel conjugates N-dodecyl-4-mercaptobutanimidamide (thiobutylamidine-dodecylamine, TBA-D) and 2-mercapto-N-octylacetamide (thioglycolicacid-octylamine, TGA-O) were synthesized, incorporated into SEDDS and analyzed for stability, cytotoxicity and physico-chemical characteristics using dynamic light scattering. Mucus interaction studies were performed using in vitro assays based on multiple particle tracking, rotational silicone tubes and rheology. RESULTS AND DISCUSSION TBA-D was synthesized using dodecylamine and iminothiolane as thiol precursor (yield=55 ± 5%). TGA-O was obtained via crosslinking of octylamine with SATA ((2,5-dioxopyrrolidin-1-yl) 2-acetylsulfanylacetate) (yield=70 ± 6%). The chemical structure of target compounds was confirmed via NMR analysis. The thiol-conjugates were incorporated in an amount of 3% (m/m) into SEDDS (Cremophor EL 30%, Capmul MCM 30%, Captex 355 30% and propylene glycol 10%), namely thiolated SEDDS leading to a droplet size around 50 nm and zeta potential close to 0 mV. Thiolated SEDDS with an effective diffusion coefficient 〈Deff〉 of up to 0.871 ± 0.122 cm(2) s(-1) × 10(-9) were obtained. Rotational silicone studies show increased permeation of the thiolated SEDDS A in comparison with unthiolated control. Rheological studies confirmed the mucolytic activity of the thiol-conjugates which differed only by 3% from DTT (dithiothreitol) serving as positive control. CONCLUSION Low molecular weight thiol-conjugates were identified to improve the mucus permeation, leading to highly efficient mucus permeating SEDDS, which were superior to conventional SEDDS and might thus be a new carrier for lipophilic drug delivery.

Pyridazino[3,4-b][1,5]benzoxazepin-5(6H)-ones : synthesis and biological evaluation

Starting from 3,6-dichloro-4-pyridazinecarboxylic acid chloride a series of novel pyridazino[3,4-b][1,5]benzoxazepin-5(6H)-ones as 1,2-diazine isosters of nonnucleoside reverse transcriptase inhibitors was prepared via N-(2-hydroxyphenyl)-3,6-dichloro-4-pyridazinecarboxamides. The inhibition of HIV-1 reverse transcriptase was evaluated.

1-substituted 4-[chloropyrazolyl][1,2,4]triazolo[4,3-a]quinoxalines : Synthesis and structure-activity relationships of a new class of benzodiazepine and adenosine receptor ligands

Starting from 3‐(3‐chloro‐1H‐pyrazol‐5‐yl)‐1H‐quinoxalin‐2‐one (2) a series of substituted [1,2,4]triazolo[4,3‐a]quinoxalines (3a‐f) was prepared via a multistep reaction sequence. Affinities of the novel derivatives 3a‐f for benzodiazepine as well as for adenosine A1‐ and A2A‐receptors of rat brain were determined by radioligand binding assays. 1‐Methyl‐4‐(3‐chloro‐1H‐pyrazol‐5‐yl) derivative 3a exhibited submicromolar affinity for the benzodiazepine binding site of GABAA receptors (Ki = 340 nM) and was less potent at A1‐ (Ki = 7.85 μM) and A2A‐ (Ki = 1.43 μM) adenosine receptors (AR). Derivatives with larger substituents in the 1‐position showed reduced binding to benzodiazepine and A2A‐AR, but increased A1‐AR affinity, the 2‐thienylmethyl derivative 3f being the most potent and selective A1‐AR ligand of the present series (Ki = 200 nM).

Thiolated graphene oxide as promising mucoadhesive carrier for hydrophobic drugs

The aim of this study was to improve the mucoadhesive properties of graphene by conjugating thiol ligands, in order to formulate an oral delivery system for hydrophobic drugs showing long mucus residence time. Graphene oxide was obtained by oxidation of graphite and then was thiolated following two synthetic paths. On the one hand, the hydroxyl groups were conjugated with thiourea passing through the formation of a brominated intermediate. On the other hand, the carboxylic acid groups were conjugated with cysteamine via carbodiimide chemistry. The mucoadhesive properties of thiolated graphene were evaluated by rheological measurements and by residence time assay. Then, valsartan was loaded on thiolated graphene and the release profile was evaluated in simulated intestinal fluid. Following both synthetic paths it was possible to obtain thiolated graphene bearing 215-302μmol SH/g product. Both products induced after 1h incubation an increase of mucus viscosity of about 22-33-fold compared to unmodified graphite. The residence time assay confirmed that 60% of thiolated graphene could be retained on intestinal mucosa after 4h incubation, whereas just 20% of unmodified graphite could be retained. Valsartan could be loaded with a drug loading of about 31±0.3% and a sustained release profile was observed for both formulations. According to the presented data, the thiolation of graphene could improve its mucoadhesive properties. Therefore, thiolated graphene represents a promising platform for oral delivery of hydrophobic drugs, possessing a long residence time on intestinal mucosa which allows the release of the loaded drug close to the adsorptive epithelium.