Internalization of Ineffective Platinum Complex in Nanocapsules Renders It Cytotoxic

Anticancer therapy by platinum complexes, based on nanocarrier‐based delivery, may offer a new approach to improve the efficacy and tolerability of the platinum family of anticancer drugs. The original rules for the design of new anticancer platinum drugs were affected by the fact that, although cisplatin (cis‐[PtCl₂(NH₃)₂) was an anticancer drug, its isomer transplatin was not cytotoxic. For the first time, it is demonstrated that simple encapsulation of an inactive platinum compound in phospholipid bilayers transforms it into an efficient cytotoxic agent. Notably, the encapsulation of transplatin makes it possible to overcome the resistance mechanisms operating in cancer cells treated with cisplatin and prevents inactivation of transplatin in the extracellular environment. It is also shown that transplatin delivered to the cells in nanocapsules, in contrast to free (nonencapsulated) complex, forms cytotoxic cross‐links on DNA.     

Determination of ultratrace dissolved arsenite in water – selective coprecipitation in the field combined with HGAFS and ICP–MS measurement in the laboratory

Because stabilization of arsenite in water samples during transit and storage is troublesome, this work deals with a method to prevent this by on-site selective coprecipitation of arsenite with dibenzyldithiocarbamate and recovery of the coprecipitate by filtration through a 0.45-μm membrane filter. In the laboratory arsenic on the filter is quantitatively released by oxidation of arsenite to arsenate with H₂O₂ (6%) in alkaline medium (8 mmol L^–1 NaOH) at elevated temperature (85?°C) for 30 min followed by ultratrace determination by routine HGAFS and ICP–MS. It is shown that arsenate contamination of the coprecipitate is so low that arsenate concentrations three orders of magnitude higher than the arsenite concentration do not interfere; this is essential, because arsenate is usually the dominant arsenic species in water. Because significant preconcentration can be achieved in the solution obtained from the leached filter (normally a factor 20 but easily increased to 100) very low detection limits can be obtained (only limited by the purity of the materials and the cleanliness of working); a realistic limit of determination is 0.01 μg L^–1 arsenite. The procedure was used for the determination of arsenite in two ground waters from an ash depository site in the ?alek valley (Slovenia). The matrix contained some elements at very high levels but this did not impair the efficiency of arsenite coprecipitation. The results obtained by use of HGAFS and ICP–MS were not significantly different at the 5% level for sub-μg L^–1 arsenite concentrations.     

UVA-activated 8-methoxypsoralen (PUVA) causes G2/M cell cycle arrest in Karpas 299 T-lymphoma cells

We investigated the effect of UVA-activated 8-methoxypsoralen (PUVA) on the cell line Karpas 299 derived from anaplastic large-cell lymphoma (ALCL) expressing chimeric fusion protein nucleophosmin-anaplastic lymphoma kinase (NPM/ALK). NPM/ALK activates phosphatidylinositol 3 kinase (PI3K)/Akt pathway responsible for the cell protection from apoptosis. We found that PUVA treatment first induced G2/M cell cycle arrest resulting in a decrease in the cell proliferation rate. The mitochondrial apoptosis was triggered immediately following PUVA treatment, as we judged from the unmasking of mitochondrial membrane antigen 7A6. However, the mitochondrial membrane depolarization was not observed and caspase-3 was only slightly activated. The late apoptotic events were lacking: neither translocation of phosphatidylserine to the outer side of plasma membrane nor DNA fragmentation occurred. We revealed that PUVA enhanced the expression of peroxiredoxin, stress protein endoplasmin and galectin-3. Galectin-3 has been shown to protect mitochondrial membrane integrity and prevent cytochrome c release thereby blocking the effector stage of apoptosis. We suggest that the elevated level of this protein following PUVA treatment acts in synergy with the constitutively expressed chimeric kinase NPM/ALK to block the apoptosis.     

Enzyme-linked immunosorbent assay in analysis of deoxynivalenol: investigation of the impact of sample matrix on results accuracy

Enzyme-linked immunosorbent assay (ELISA) represents a bioanalytical strategy frequently used for rapid screening of mycotoxin deoxynivalenol (DON) in cereals and derived products. Due to a considerable affinity of some anti-DON antibodies to structurally similar DON metabolites, such as DON-3-glucoside (DON-3-Glc) and 3-acetyl-DON (3-ADON), a significant overestimation of DON concentrations may occur. A validation study of six commercial DON-dedicated ELISA kits, namely Ridascreen DON, Ridascreen FAST, DON, DON EIA, AgraQuant DON Assay, Veratox 5/5, and Veratox HS was carried out on wheat, barley, and malt matrices. Performance characteristics of all tested ELISAs were determined using aqueous solutions of DON, DON-3-Glc, and 3-ADON analytical standards, further with extracts of artificially spiked blank cereals, and finally with matrix-matched standards of all three compounds. In the final phase, the accuracy of data was assessed through a comparison of DON concentrations determined by particular ELISAs and reference ultra-high-performance liquid chromatography–tandem mass spectrometry method. For this purpose, both quality control materials and a comprehensive set of naturally and artificially contaminated samples of wheat, barley, and malt were analyzed. High cross-reactivities were proved for both DON-3-Glc and 3-ADON in the majority of examined assays, and moreover, a considerable contribution of some matrix components to overestimation of DON results was confirmed.     

A New Solvated Phosphoric Triamide, [(C6H4(3-CH3)NH)3P(O)] · (C2H5OH): A Database Analysis of N Atom Geometry in Compounds with an [N]3P(O) Fragment

Abstract

In the crystal structure of the title compound C₂₁H₂₄N₃OP · C₂H₅OH, there are three crystallographically independent phosphoric triamide molecules and three ethanol molecules. The environments of the nitrogen atoms are practically planar. The phosphorus atoms display a distorted tetrahedral environment; the maximum and minimum values of angles are observed for one O?P?N and one N?P?N angles, respectively. In this structure, the phosphoramide and ethanol molecules are linked by some different intermolecular O?H···O and N?H···O hydrogen bonds to form chains. The title solvated compound has been further characterized by IR and ³¹P{¹H}, ¹H and ¹³C NMR spectroscopy. The geometry of the nitrogen atoms in this compound is analyzed and compared with those of analogous structures deposited in the Cambridge Structural Database (CSD; Allen, Acta Cryst. 2002, B58, 380-388).     

PEG‐Modified Macroporous Poly(Glycidyl Methacrylate) and Poly(2‐Hydroxyethyl Methacrylate) Microspheres to Reduce Non‐Specific Protein Adsorption

To minimize non‐specific protein adsorption on macroporous poly(glycidyl methacrylate) and poly(2‐hydroxyethyl methacrylate) microspheres containing amino and/or carboxyl groups, the microspheres are coated with α,ω‐bis‐carboxy poly(ethylene glycol) and amino‐terminated poly(ethylene glycol‐co‐propylene glycol) or α‐methoxy‐ω‐amino poly(ethylene glycol). Adsorption of bovine serum albumin (BSA), γ‐globulin, ¹²⁵I‐BSA, pepsin, and chymotrypsin on neat and PEGylated microspheres is determined by UV–VIS spectroscopy of supernatants and eluates or by measurement of radioactivity in an ionization chamber. Neat and PEGylated microspheres adsorb 0.8–70% and 0.02–44% of protein, respectively.

     

Antibacterial properties of polyaniline-silver films

In situ polymerised thin polyaniline (PANI) films produced on polystyrene dishes were tested for their antibacterial activity with respect to Escherichia coli and Staphylococcus aureus, representing both gram-positive and gram-negative bacteria. PANI films were subsequently used for the reduction of silver ions to metallic Ag. PANI salt and base in original forms and after the deposition of Ag were studied. PANI salt showed a significant antibacterial effect against both bacteria strains while the efficacy of neat PANI base was only marginal. After the Ag deposition, the PANI base exhibited different levels of antibacterial effect depending on the type of the bacterial strain; the growth of gram-positive Staphylococcus aureus was inhibited depending on the Ag concentration on the film, while Escherichia coli remained uninfluenced. Efficacy of the PANI salt with deposited Ag against both bacteria strains was comparable with that of PANI alone and was not affected by the Ag concentration. The results show that Ag deposition can be a suitable method for the preparation of PANI base films with improved antibacterial properties.     

1,3-substituted imidazolidine-2,4,5-triones: synthesis and inhibition of cholinergic enzymes

A series of novel and highly active acetylcholinesterase and butyrylcholinesterase inhibitors derived from substituted benzothiazoles containing an imidazolidine-2,4,5-trione moiety were synthesized and characterized. The molecular structure of 1-(2,6-diisopropyl-phenyl)-3-[(1R)-1-(6-fluoro-1,3-benzothiazol-2-yl)ethyl]-imidazolidine-2,4,5-trione (3g) was determined by single-crystal X-ray diffraction. Both optical isomers are present as two independent molecules in the triclinic crystal system. The lipophilicity of the compounds was determined as the partition coefficient log K(ow) using the traditional shake-flask method. The in vitro inhibitory activity on acetylcholinesterase from electric eel and butyrylcholinesterase isolated from equine serum was determined. The inhibitory activity on acetylcholinesterase was significantly higher than that of the standard drug rivastigmine. The discussed compounds are also promising inhibitors of butyrylcholinesterase, as some of the prepared compounds inhibit butyrylcholinesterase better than the internal standards rivastigmine and galanthamine. The highest inhibitory activity (IC?? = 1.66 μmol/L) corresponds to the compound 1-(4-isopropylphenyl)-3-[(R)-1-(6-fluorobenzo[d]thiazol-2-yl)ethyl]imidazolidine-2,4,5-trione (3d). For all the studied compounds, the relationships between the lipophilicity and the chemical structure as well as their structure-activity relationships are discussed.     

High-performance liquid chromatographic method with amperometric detection employing boron-doped diamond electrode for the determination of sildenafil, vardenafil and their main metabolites in plasma

A simple, fast and sensitive HPLC method with electrochemical detection employing boron-doped diamond electrode (BDD) for the determination of sildenafil (Viagra™), vardenafil (Levitra™) and their main metabolites, N-desmethyl sildenafil and N-desethyl vardenafil in human plasma is presented. The assay involved drug extraction by tert-butyl methyl ether and isocratic reversed-phase liquid chromatography with amperometric detection. Complete separation of all analytes was achieved within 12 min. The mobile phase consisted of 20 mM sodium dihydrogen phosphate with 40 mM sodium perchlorate/acetonitrile (70:30, v/v), pH 3.5. The electrode working potential was +1520 mV (vs. Pd/H₂). Calibration curves were linear over the concentration range of 10–400 ng mL⁻¹. Phloretin was used as an internal standard. The limits of detection (LOD) and quantification (LOQ) for the studied analytes were within the range of 2–4 ng mL⁻¹ and 7.0–13.4 ng mL⁻¹, respectively. The developed method was applied to human plasma samples spiked with analytes at therapeutic concentrations. The study confirms the method's suitability for both pharmacokinetic studies and therapeutic monitoring.