Taming the Oxidative Power of SeO₃ in 1,4-Dioxane, Isolation of Two New Isomers of Mixed-Valence Selenium Oxides, and Two Unprecedented Cyclic Esters of Selenic Acid

The reaction of (SeO₃)₄ with 1,4-dioxane (diox, dioxane) with or without diluting solvent led to the isolation of the unprecedented esters of selenic acid-1,2-ethyl selenate (CH₂O)₂SeO₂ and the glyoxal diselenate O₂Se­[(OCHO)₂]­SeO₂. It was possible to isolate an unknown dimeric form of Se₂O₅ (Se₄O₁₀·(diox)₂) and a geometrical isomer of the mixed-valence oxide <i>trans</i>-Se₃O₇, both stabilized by dioxane. The dioxane adduct of monomeric selenium trioxide SeO₃·diox was obtained from the reaction of (SeO₃)₄ with dioxane in liquid SO₂. The reaction mechanism for the formation of these compounds was elucidated, and the molecular structure of the unstable form of the selenium trioxide was determined, consisting in a trimeric arrangement (SeO₃)₃

Taming the Oxidative Power of SeO₃ in 1,4-Dioxane, Isolation of Two New Isomers of Mixed-Valence Selenium Oxides, and Two Unprecedented Cyclic Esters of Selenic Acid

The reaction of (SeO₃)₄ with 1,4-dioxane (diox, dioxane) with or without diluting solvent led to the isolation of the unprecedented esters of selenic acid-1,2-ethyl selenate (CH₂O)₂SeO₂ and the glyoxal diselenate O₂Se­[(OCHO)₂]­SeO₂. It was possible to isolate an unknown dimeric form of Se₂O₅ (Se₄O₁₀·(diox)₂) and a geometrical isomer of the mixed-valence oxide <i>trans</i>-Se₃O₇, both stabilized by dioxane. The dioxane adduct of monomeric selenium trioxide SeO₃·diox was obtained from the reaction of (SeO₃)₄ with dioxane in liquid SO₂. The reaction mechanism for the formation of these compounds was elucidated, and the molecular structure of the unstable form of the selenium trioxide was determined, consisting in a trimeric arrangement (SeO₃)₃

The free radical contents in <i>E</i>. <i>fetida</i> immediately after the termination of the test.

<p>The error bars indicate standard deviations. The asterisks indicate significant differences (<i>p</i><0.05) compared with the control groups.</p

Determination of GPx activity after exposure to E2 (0–100 μg/kg).

<p>The enzymatic activity was examined in the 1^st; 3^rd; 5^th and 8^th weeks of the experiment. The values are presented as the means of three independent replicates (<i>n</i> = 3). The vertical bars indicate the standard error. The asterisks indicate significant differences (<i>p</i> < .05) compared with the control groups.</p

Influence of E₂ exposure (100 μg/kg) on the expression of mRNA encoding selected antioxidant molecules.

<p>(<b>A</b>) <i>MT</i>, (<b>B</b>) <i>GPx</i> and (<b>C</b>) <i>pcs</i> genes in <i>E</i>. <i>fetida</i>, collected in the 1^st; 3^rd; 5^th and 8^th weeks of the experiment. For evaluation, the corresponding molecular-weight bands of amplicons coinciding with the values shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0145426#pone.0145426.t001" target="_blank">Table 1</a> were obtained using RT-PCR. The fluorescence intensities of the bands, obtained using ethidium bromide staining, were transformed into numerical forms, and expression was normalized to <i>β-actin</i> expression from the same cDNA template. The values are presented as the means of three independent replicates (<i>n</i> = 3). The vertical bars indicate standard error. The asterisks indicate significant differences (<i>p</i> < .05) compared with the control groups.</p

The levels of antioxidant molecules in <i>E</i>. <i>fetida</i> after exposure to E₂ (0–100 μg/L).

<p>(<b>A</b>) The levels of metallothionein, determined using DPV. (<b>B</b>) The ratio between GSH and GSSG, determined using HPLC-ED. The antioxidant molecules were analysed in the 1^st; 3^rd; 5^th and 8^th weeks of the experiment. The values are presented as the means of three independent replicates (<i>n</i> = 3). The vertical bars indicate standard errors. The asterisks indicate significant differences (<i>p</i>.05) compared with the control groups.</p

Schematic depiction of E₂ metabolites.

<p>The E₂ ratios to (<b>A</b>) 4-OHE₂ and (<b>B</b>) the final metabolite (E₂)-3,4-Q represents the conversions over time. In control samples, no E₂, 4-OHE₂ or (E₂)-3,4-Q was found. To evaluate the conversion ratios, the following mass weights were utilized: [E₂ + H]⁺<i>m/z</i> 273.38 Da, [4-OHE₂ + H]⁺<i>m/z</i> 289.38 Da and [(E₂)-3,4-Q + H]⁺ at <i>m/z</i> 287.36 Da. The values are presented as the means of three independent replicates (<i>n</i> = 3). The vertical bars indicate standard error.</p

Examination of <i>E</i>. <i>fetida</i> cross sections after E₂ exposure.

<p>H&E-stained cross sections of <i>E</i>. <i>fetida</i> exposed to E₂ (100 μg/L), collected in the (<b>A</b>) 0^th (control), (<b>B</b>) 1^st, (<b>C</b>) 3^rd, (<b>D</b>) 5^th and (<b>E</b>) 8^th weeks of the experiment. The collected individuals were scanned (<b>a</b>) and employed for the MALDI-IMS analysis of (<b>b</b>) the final metabolites of E₂—[(E₂)-3,4-Q + H]⁺ at <i>m/z</i> 287.36 Da ± 0.05%, (<b>c</b>) [PC₂ and PC₃+ H]⁺ merge at <i>m/z</i> 541.61 Da ± 0.05% (red) and 773.91 Da ± 0.05% (green), respectively, (<b>d</b>) [GSSG + H]⁺ at <i>m/z</i> 613.64 Da ± 0.05% and (<b>e</b>) [MT₁ + H]⁺ at <i>m/z</i> 4798.00 Da ± 0.05% (red) and [MT₂ + H]⁺ at m/z 7412.01 Da (green). Matrix HCCA was used. The following conditions were used to acquire the MALDI spectra: 500 shots per raster spot, 45% laser energy and 50-μm spatial resolution. The length of scale bar is 500 μm.</p

Alternative Synthesis Route of Biocompatible Polyvinylpyrrolidone Nanoparticles and Their Effect on Pathogenic Microorganisms

Herein we describe a novel alternative synthesis route of polyvinylpyrrolidone nanoparticles using salting-out method at a temperature close to polyvinylpyrrolidone decomposition. At elevated temperatures, the stability of polyvinylpyrrolidone decreases and the opening of pyrrolidone ring fractions occurs. This leads to cross-linking process, where separate units of polyvinylpyrrolidone interact among themselves and rearrange to form nanoparticles. The formation/stability of these nanoparticles was confirmed by transmission electron microscopy, X-ray photoelectron spectroscopy, mass spectrometry, infrared spectroscopy, and spectrophotometry. The obtained nanoparticles possess exceptional biocompatibility. No toxicity and genotoxicity was found in normal human prostate epithelium cells (PNT1A) together with their high hemocompatibility. The antimicrobial effects of polyvinylpyrrolidone nanoparticles were tested on bacterial strains isolated from the wounds of patients suffering from hard-to-heal infections. Molecular analysis (qPCR) confirmed that the treatment can induce the regulation of stress-related survival genes. Our results strongly suggest that the polyvinylpyrrolidone nanoparticles have great potential to be developed into a novel antibacterial compound