A potential source of free radicals in iodine-based chemical oscillators

The iodide-peroxide system in an acidic medium was investigated as a potential source of free radicals in iodine-based chemical oscillators. The radicals were detected by EPR spin-trapping using spin-trap 5-(tert-butoxycarbonyl)-5-methyl-1-pyrroline N-oxide (BMPO), which forms stable spin-adducts with oxygen-centered radicals. The iodide-peroxide system is introduced as an easily available laboratory source of free radicals.     

Interactions between CdTe quantum dots and DNA revealed by capillary electrophoresis with laser‐induced fluorescence detection

Quantum dots (QDs) are one of the most promising nanomaterials, due to their size‐dependent characteristics as well as easily controllable size during the synthesis process. They are promising label material and their interaction with biomolecules is of great interest for science. In this study, CdTe QDs were synthesized under optimal conditions for 2 nm size. Characterization and verification of QDs synthesis procedure were done by fluorimetric method and with CE. Afterwards, QDs interaction with chicken genomic DNA and 500 bpDNA fragment was observed employing CE‐LIF and gel electrophoresis. Performed interaction relies on possible matching between size of QDs and major groove of the DNA, which is approximately 2.1 nm.     

Smart poly(2-hydroxyethyl methacrylate/itaconic acid) hydrogels for biomedical application

pH- and temperature-sensitive hydrogels, based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA) copolymers, were prepared by γ-irradiation and characterized in order to examine their potential use in biomedical applications. The influence of comonomer ratio in these smart copolymers on their morphology, mechanical and thermal properties, biocompatibility and microbe penetration capability was investigated. The mechanical properties of copolymers were investigated using the dynamic mechanical analysis (DMA), while their thermal properties and morphology were examined by thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The morphology, mechanical and thermal properties of these hydrogels were found to be suitable for most requirements of biomedical applications. The in vitro study of P(HEMA/IA) biocompatibility showed no evidence of cell toxicity nor any considerable hemolytic activity. Furthermore, the microbe penetration test showed that neither Staphylococcus aureus nor Escherichia coli passed through the hydogel dressing; thus the P(HEMA/IA) dressing could be considered a good barrier against microbes. All results indicate that stimuli-responsive P(HEMA/IA) hydrogels have great potential for biomedical applications, especially for skin treatment and wound dressings.     

Stereoelectronic effects on 1H nuclear magnetic resonance chemical shifts in methoxybenzenes

Investigation of all O-methyl ethers of 1,2,3-benzenetriol and 4-methyl-1,2,3-benzenetriol (3-16) by 1H NMR spectroscopy and density-functional calculations disclosed practically useful conformational effects on 1H NMR chemical shifts in the aromatic ring. While the conversion of phenol (2) to anisole (1) causes only small positive changes of 1H NMR chemical shifts (Delta delta < 0.08 ppm) that decrease in the order Hortho > Hmeta > Hpara, the experimental O-methylation induced shifts in ortho-disubstituted phenols are largest for Hpara, Delta delta equals; 0.19 +/- 0.02 ppm (n = 11). The differences are due to different conformational behavior of the OH and OCH3 groups; while the ortho-disubstituted OH group remains planar in polyphenols due to hydrogen bonding and conjugative stabilization, the steric congestion in ortho-disubstituted anisoles outweighs the conjugative effects and forces the Ar-OCH3 torsion out of the ring plane, resulting in large stereoelectronic effects on the chemical shift of Hpara. Conformational searches and geometry optimizations for 3-16 at the B3LYP/6-31G** level, followed by B3LYP/6-311++G(2d,2p) calculations for all low-energy conformers, gave excellent correlation between computed and observed 1H NMR chemical shifts, including agreement between computed and observed chemical shift changes caused by O-methylation. The observed regularities can aid structure elucidation of partly O-methylated polyphenols, including many natural products and drugs, and are useful in connection with chemical shift predictions by desktop computer programs.     

Interplay of thermochemistry and structural chemistry, the journal (volume 24, 2013, issues 1–2) and the discipline

The contents of issues 1 and 2 for the calendar year 2013 are summarized in the current review of the journal Structural Chemistry. In addition, a brief thermochemical commentary is added to the summary of each paper.     

Quantification of microporosity in fruit by MRI at various magnetic fields: comparison with X-ray microtomography

Microstructure determines the mechanical and transport properties of fruit tissues. One important characteristic of the microstructure is the relative volume fraction of gas-filled intercellular spaces, i.e., the tissue microporosity. Quantification of this microporosity is fundamental for investigating the relationship between gas transfer and various disorders in fruit.     

Characterization of Food Packaging Films with Blackcurrant Fruit Waste as a Source of Antioxidant and Color Sensing Intelligent Material

Chitosan and pectin films were enriched with blackcurrant pomace powder (10 and 20% (w/w)), as bio-based material, to minimize food production losses and to increase the functional properties of produced films aimed at food coatings and wrappers. Water vapor permeability of active films increased up to 25%, moisture content for 27% in pectin-based ones, but water solubility was not significantly modified. Mechanical properties (tensile strength, elongation at break and Young’s modulus) were mainly decreased due to the residual insoluble particles present in blackcurrant waste. FTIR analysis showed no significant changes between the film samples. The degradation temperatures, determined by DSC, were reduced by 18 °C for chitosan-based samples and of 32 °C lower for the pectin-based samples with blackcurrant powder, indicating a disturbance in polymer stability. The antioxidant activity of active films was increased up to 30-fold. Lightness and redness of dry films significantly changed depending on the polymer type. Significant color changes, especially in chitosan film formulations, were observed after exposure to different pH buffers. This effect is further explored in formulations that were used as color change indicators for intelligent biopackaging.     

The Effect of Olive Fruit Fly Bactrocera oleae (Rossi) Infestation on Certain Chemical Parameters of Produced Olive Oils

Olives affected by active and damaging infestation (olive fruit fly Bactrocera oleae (Rossi)) were assayed for their chemical composition. Biophenols were determined by HPLC, sterols, triterpenic dialcohols, and fatty acids by gas chromatography analysis. The acquired data were statistically analyzed. Oils produced from “Istrska belica” fruit affected by active infestation compared to the oils made from fruit affected by damaging infestation showed higher amounts of total oleuropein biofenols (377.3 versus (vs.) 106.6 mg/kg), total biophenols (755 vs. 377 mg/kg), lignans (85.3 vs. 32.9 mg/kg), the dialdehydic form of decarboxymethyl oleuropein aglycone (DMO-Agl-dA) (148.3 vs. 49.0 mg/kg), its oxidized form (DMO-Agl-dA)ox (35.2 vs. 8.5 mg/kg), the dialdehydic form of oleuropein aglycone (O-Agl-dA) (61.1 vs. 8.0 mg/kg), the dialdehydic form of ligstroside aglycone (L-Agl-dA) (63.5 vs. 28.0 mg/kg), the aldehydic form of oleuropein aglycone (O-Agl-A) (40.6 vs. 8.4 mg/kg), and lower amounts of tyrosol (Tyr) (6.0 vs. 13. 9 mg/kg) and the aldehydic form of ligstroside aglycone (L-Agl-A) (13.8 vs. 40.3 mg/kg). Higher values of stigmasterol (2.99%) and lower values of campesterol (2.25%) were determined in oils affected by damaging infestation; an increase in triterpenic dialcohols was also observed (3.04% for damaging and 1.62% for active infestation). Oils affected by damaging infestation, compared to active infestation, showed lower amounts of oleic acid (73.89 vs. 75.15%) and higher amounts of myristic (0.013 vs. 0.011%), linoleic (7.27 vs. 6.48%), and linolenic (0.74 vs. 0.61%) acids.     

Enzymatically Extracted Apple Pectin Possesses Antioxidant and Antitumor Activity

The biological activity of apple pectin extracted conventionally or enzymatically using endo-xylanase and endo-cellulase, was tested in vitro. The analyses were performerd in tetraplicates and the statistical significance of the differences were assessed using ANOVA, Tukey post hoc and LSD (the least significant difference) tests. Multivariate regression analysis was applied to determine the structural components that have a crucial importance for antioxidant and antitumor properties of pectins. The pectins extracted by enzymes contained up to four times more ferulic acid and showed twice as great ability to neutralize free radicals and Fe(III) reduction. The antiradical potential positively correlated with phenols, fucose and rhamnose content. In the assays performed on HT-29 human adenocarcinoma and B16F10 melanoma cell cultures, the “green” pectins, contrary to acid isolated ones, exhibited remarkable anti-neoplastic potential while being nontoxic to nontransformed L929 cell line. The pectins in the dose of 1 mg/mL were capable of inhibiting adhesion (max 23.1%), proliferation (max 40.4%), invasion (max 76.9%) and anchorage-independent growth (max 90%) of HT-29 cells (significance level p < 0.001). These pectin preparations were slightly less active towards B16F10 cells. The enzyme-isolated apple pectins may be useful as a functional food additive and an ingredient of the ointment formulas for post-surgical melanoma treatment.