Studies on dimerisation of tocopherols under the influence of methyl linoleate peroxides

The stability of plant oils is related to the level of polyunsaturated fatty acids and the presence of native antioxidants--especially tocopherols. During storage, lipids or the fat products undergo oxidation and tocopherol dimers and trimers are formed. These compounds possess reducing and antioxidant properties and participate in oxidation clearly inhibiting this process. In the present study, the correlation between levels of peroxides formed during autoxidation of methyl linoleate and simultaneous decomposition of tocopherols was examined. The peroxide value was investigated. Quantities of decomposed tocopherols and formation of their dimers were determined by high-performance liquid chromatography (HPLC). Mass spectrum analysis confirmed thatthe analysed compounds were dimes. Dimerisation of gamma-T begins at the smaller quantity of the methyl linoleate peroxides than dimerisation of delta-T. At the beginning of methyl linoleate autoxidation dimerisation of gamma-T in relation to its loss was smaller. The quantity of gamma-T dimers with ether bonds in total dimers pointed to faster binding of phenoxy radicals than transformation into the phenyl ones. delta-T dimers with phenyl bonds constitute about 65% of the total. The quantity of peroxides in methyl linoleate, necessary for quantitative and qualitative changes of homologous tocopherols, decreased from delta-T to alpha-T.     

Integrated three-dimensional shape and reflection properties measurement system

Creating accurate three-dimensional (3D) digitalized models of cultural heritage objects requires that information about surface geometry be integrated with measurements of other material properties like color and reflectance. Up until now, these measurements have been performed in laboratories using manually integrated (subjective) data analyses. We describe an out-of-laboratory bidirectional reflectance distribution function (BRDF) and 3D shape measurement system that implements shape and BRDF measurement in a single setup with BRDF uncertainty evaluation. The setup aligns spatial data with the angular reflectance distribution, yielding a better estimation of the surface's reflective properties by integrating these two modality measurements into one setup using a single detector. This approach provides a better picture of an object's intrinsic material features, which in turn produces a higher-quality digitalized model reconstruction. Furthermore, this system simplifies the data processing by combining structured light projection and photometric stereo. The results of our method of data analysis describe the diffusive and specular attributes corresponding to every measured geometric point and can be used to render intricate 3D models in an arbitrarily illuminated scene.     

Magnetic-aligned,magnetite-filled epoxy composites with enhanced thermal conductivity

This paper investigates the influence of magnetic field-assisted filler alignment technology on the morphology and the thermal conductivity of magnetite-filled epoxy composites. A magnetic field was applied during the solidification of the composite in order to change the position of the filler and its distribution in the polymer matrix. It is shown that the applied procedure leads to the filler being oriented along the direction of the magnetic field, and as a result, the thermal conductivity is improved by up to 120 % compared to a composite with randomly oriented filler obtained without the assistance of a magnetic field. This positive effect is caused by the appearance of conductive paths at a much lower content of the filler when the composite solidification is assisted by a magnetic field, relative to an equivalent isotropic sample. These morphological changes were confirmed by microscopic and X-ray microtomography imaging. The temperature dependences of thermal conductivity were also investigated over a broad temperature range for a magnetite-filled epoxy composite sample and compared to the bulk magnetite reference, showing that thermal behaviour of the magnetite-filled composite is stable, which is a promising result when considering the future application of the technology.     

The Composites of PCL and Tetranuclear Titanium(IV)-oxo Complexes as Materials Exhibiting the Photocatalytic and the Antimicrobial Activity

Excessive misuse of antibiotics and antimicrobials has led to a spread of microorganisms resistant to most currently used agents. The resulting global threats has driven the search for new materials with optimal antimicrobial activity and their application in various areas of our lives. In our research, we focused on the formation of composite materials produced by the dispersion of titanium(IV)-oxo complexes (TOCs) in poly(ε-caprolactone) (PCL) matrix, which exhibit optimal antimicrobial activity. TOCs, of the general formula [Ti₄O₂(OⁱBu)₁₀(O₂CR’)₂] (R’ = PhNH₂ (1), C₁₃H₉ (2)) were synthesized as a result of the direct reaction of titanium(IV) isobutoxide and 4-aminobenzoic acid or 9-fluorenecarboxylic acid. The microcrystalline powders of (1) and (2), whose structures were confirmed by infrared (IR) and Raman spectroscopy, were dispersed in PCL matrixes. In this way, the composites PCL + nTOCs (n = 5 and 20 wt.%) were produced. The structure and physicochemical properties were determined on the basis of Raman microscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), electron paramagnetic resonance spectroscopy (EPR), and UV–Vis diffuse reflectance spectroscopy (DRS). The degree of TOCs distribution in the polymer matrix was monitored by scanning electron microscopy (SEM). The addition of TOCs micro grains into the PCL matrix only slightly changed the thermal and mechanical properties of the composite compared to the pure PCL. Among the investigated PCL + TOCs systems, promising antibacterial properties were confirmed for samples of PCL + n(2) (n = 5, 20 wt.%) composites, which simultaneously revealed the best photocatalytic activity in the visible range.     

Effect of randomly methylated beta-cyclodextrin on physical properties of soils

The application of cyclodextrins in several soil remediation technologies has been increasingly studied, but little is known about their effects on soil physical properties. One of the popular soil remediation additives, randomly methylated beta-cyclodextrin (RAMEB), was found to significantly alter surface and pore properties of soil clay minerals. Therefore, in this paper we studied the effect of various RAMEB doses on physical properties of selected soils, representing a wide range of clay content (3-49%). The results showed that soil physical properties were greatly modified by RAMEB treatment. Analysis of water vapor adsorption isotherms revealed that RAMEB increased water adsorption and surface area in sandy soils and decreased them in clayey soils. An increase in adsorption energy of water in RAMEB-treated soils indicated that desorption of nonpolar pollutants can be enhanced. Water vapor desorption isotherms showed that the volumes and radii of micropores (nanometers range) increased above 1% RAMEB concentration. The micropores became more rough and complex after RAMEB treatment as deduced from an increase in fractal dimensions. The volume of soil mesopores measured by mercury intrusion porosimetry (micrometers range) gradually decreased in most soils with an increase in RAMEB concentration whereas the average mesopore radius increased, indicating that finer mesopores were blocked by RAMEB. Measurements of the granulometric composition of soils by sedimentation analysis showed that the amount of coarse-size soil fractions increased on the expense of finer fractions due to aggregation of smaller particles. Behavior of the studied soils after RAMEB treatment depended on their clay content and the dose of cyclodextrin. In clay-rich soils, strong interactions of cyclodextrins with the soil solid phase governed the resulting soil properties. In clay-poor soils, the cyclodextrin excess (not interacted with clays) played a dominant role. Modification of surface, pore, and aggregation properties of soils by RAMEB can have a significant effect in soil remediation technologies.     

The stability of the casein–gluconate matrix in reduced‐lactose kefir with soluble fraction polysaccharides containing β‐glucan from Pleurotus ostreatus

In this experimental study, the soluble fraction of polysaccharides (SFP) was isolated from the fruiting bodies of Pleurotus ostreatus mushrooms, to stabilise the casein–gluconate kefir matrix. Soluble fraction of polysaccharides dissolved in water or in milk was added to the lactose‐reduced milk (0.5% w/v). Fermentation was carried out at 22 °C (to pH 4.4, 31°SH). Kefirs with SFP dissolved in the milk showed higher firmness, cohesiveness and consistency than the control kefir. The dissolving of SFP in the milk reduced spontaneous whey syneresis and prevented changes in water holding capacity. Soluble fraction of polysaccharides decreased the feeling of prickling in the kefirs and their mouth‐coating properties.     

Sorption of copper,zinc and cobalt by oat and oat products

We determined copper, zinc and cobalt sorption by oat and its products under variable pH conditions as well as the content of neutral dietary fiber (NDF) and its fractional composition. Adsorbents in a model sorption system were: oat, dehulled oat, oats bran and oats flakes. Three various buffers (pH 1.8, 6.6 and 8.7) were used as dispersing solutions. Results collected during this study indicate that copper, zinc and cobalt sorption is significantly affected by the type of cereal raw material. Zinc and copper ions are subjected to higher sorption than cobalt ions. Examined metal ions were subjected to high sorption under conditions corresponding to the duodenum environment (pH 8.7( regardless of the kind of adsorbent. A little lower sorption capacity is observed under conditions close to the neutral environment, while the lowest one is found in environment reflecting conditions of stomach juice (pH 1.8). Zinc ions are bound intensively by dehulled oat, while oats flakes bound mostly copper and cobalt, independently on environmental conditions. Contents of dietary fiber in oat, dehulled oat, oat bran and oat flakes were: 40.1, 19.3, 20.3 and 14.3%, respectively. The dominating fraction in all oat products was the fraction of hemicelluloses. The content of remaining fractions varies in dependence on the product.     

The Phenoxyalkyltriazine Antagonists for 5-HT6 Receptor with Promising Procognitive and Pharmacokinetic Properties In Vivo in Search for a Novel Therapeutic Approach to Dementia Diseases

Among the serotonin receptors, one of the most recently discovered 5-HT₆ subtype is an important protein target and its ligands may play a key role in the innovative treatment of cognitive disorders. However, none of its selective ligands have reached the pharmaceutical market yet. Recently, a new chemical class of potent 5-HT₆ receptor agents, the 1,3,5-triazine-piperazine derivatives, has been synthesized. Three members, the ortho and meta dichloro- (1,2) and the unsubstituted phenyl (3) derivatives, proved to be of special interest due to their high affinities (1,2) and selectivity (3) toward 5-HT₆ receptor. Thus, a broader pharmacological profile for 1–3, including comprehensive screening of the receptor selectivity and drug-like parameters in vitro as well as both, pharmacokinetic and pharmacodynamic properties in vivo, have been investigated within this study. A comprehensive analysis of the obtained results indicated significant procognitive-like activity together with beneficial drug-likeness in vitro and pharmacokinetics in vivo profiles for both, (RS)-4-[1-(2,3-dichlorophenoxy)propyl]-6-(4-methylpiperazin-1-yl)-1,3,5-triazin-2-amine (2) and (RS)-4-(4-methylpiperazin-1-yl)-6-(1-phenoxypropyl)-1,3,5-triazin-2-amine (3), but insensibly predominant for compound 2. Nevertheless, both compounds (2 and 3) seem to be good Central Nervous System drug candidates in search for novel therapeutic approach to dementia diseases, based on the 5-HT₆ receptor target.     

Nitric Oxide-Dependent Mechanisms Underlying MK-801- or Scopolamine-Induced Memory Dysfunction in Animals: Mechanistic Studies

MK-801, an NMDA receptor antagonist, and scopolamine, a cholinergic receptor blocker, are widely used as tool compounds to induce learning and memory deficits in animal models to study schizophrenia or Alzheimer-type dementia (AD), respectively. Memory impairments are observed after either acute or chronic administration of either compound. The present experiments were performed to study the nitric oxide (NO)-related mechanisms underlying memory dysfunction induced by acute or chronic (14 days) administration of MK-801 (0.3 mg/kg, i.p.) or scopolamine (1 mg/kg, i.p.). The levels of L-arginine and its derivatives, L-citrulline, L-glutamate, L-glutamine and L-ornithine, were measured. The expression of constitutive nitric oxide synthases (cNOS), dimethylaminohydrolase (DDAH1) and protein arginine N-methyltransferases (PMRTs) 1 and 5 was evaluated, and the impact of the studied tool compounds on cGMP production and NMDA receptors was measured. The studies were performed in both the cortex and hippocampus of mice. S-nitrosylation of selected proteins, such as GLT-1, APP and tau, was also investigated. Our results indicate that the availability of L-arginine decreased after chronic administration of MK-801 or scopolamine, as both the amino acid itself as well as its level in proportion to its derivatives (SDMA and NMMA) were decreased. Additionally, among all three methylamines, SDMA was the most abundant in the brain (~70%). Administration of either compound impaired eNOS-derived NO production, increasing the monomer levels, and had no significant impact on nNOS. Both compounds elevated DDAH1 expression, and slight decreases in PMRT1 and PMRT5 in the cortex after scopolamine (acute) and MK-801 (chronic) administration were observed in the PFC, respectively. Administration of MK-801 induced a decrease in the cGMP level in the hippocampus, accompanied by decreased NMDA expression, while increased cGMP production and decreased NMDA receptor expression were observed after scopolamine administration. Chronic MK-801 and scopolamine administration affected S-nitrosylation of GLT-1 transport protein. Our results indicate that the analyzed tool compounds used in pharmacological models of schizophrenia or AD induce changes in NO-related pathways in the brain structures involved in cognition. To some extent, the changes resemble those observed in human samples.     

Glutamate and GABA in Microglia-Neuron Cross-Talk in Alzheimer’s Disease

The physiological balance between excitation and inhibition in the brain is significantly affected in Alzheimer’s disease (AD). Several neuroactive compounds and their signaling pathways through various types of receptors are crucial in brain homeostasis, among them glutamate and γ-aminobutyric acid (GABA). Activation of microglial receptors regulates the immunological response of these cells, which in AD could be neuroprotective or neurotoxic. The novel research approaches revealed the complexity of microglial function, including the interplay with other cells during neuroinflammation and in the AD brain. The purpose of this review is to describe the role of several proteins and multiple receptors on microglia and neurons, and their involvement in a communication network between cells that could lead to different metabolic loops and cell death/survival. Our review is focused on the role of glutamatergic, GABAergic signaling in microglia–neuronal cross-talk in AD and neuroinflammation. Moreover, the significance of AD-related neurotoxic proteins in glutamate/GABA-mediated dialogue between microglia and neurons was analyzed in search of novel targets in neuroprotection, and advanced pharmacological approaches.