rss_2.0Acta Chimica Slovaca FeedSciendo RSS Feed for Acta Chimica Slovaca Chimica Slovaca Feed retention capacity as a useful tool for quality evaluation of flours produced from Slovak bred wheat varieties<abstract> <title style='display:none'>Abstract</title> <p>Wheat varieties (IS Danubius and MS Luneta) bred in Slovakia were assessed for their bakery potential. It was found that flour produced from IS Danubius was characterised by significantly higher level of wet and dry gluten content (30.91 and 20.53 %, respectively) and exhibited higher gluten swelling capacity (29.3 %) in comparison to commercial wheat flour that is usually available in Slovak markets. Solvent retention capacity (solvation in specific solvents) of the tested flours was also determined. The measurements showed that these parameters significantly differ from those determined for commercially available flour, whereas the flour produced from IS Danubius wheat variety had the highest lactic acid retention capacity (124.15 %). Correlation analysis indicated strong positive correlations between solvent retention capacity values and gluten characteristics. Furthermore, it was found that baked rolls prepared from IS Danubius flour showed significantly higher loaf volume compared to commercial wheat flour. This study proves lactic acid retention capacity and sucrose retention capacity as parameters enabling the prediction of gluten network quality in dough and of qualitative parameters of baked goods. From the sensory evaluation resulted that the highest score for overall acceptance was observed in IS Danubius baked rolls, which significantly differs from both MS Luneta and commercial wheat flour.</p> </abstract>ARTICLEtrue effect of phenol derivatives on electrochemical oxidation potentials: Correlation of theoretical reaction Gibbs free energies<abstract> <title style='display:none'>Abstract</title> <p>Reaction Gibbs free energies for electron abstraction from phenol and its 74 derivatives were calculated using the composite <italic>ab-initio</italic> approach (G4) in combination with the implicit solvation model. Resulting values were correlated with 38 oxidation potentials obtained from cyclic voltammetry measurements. Substitution effect and the role of substituents in <italic>ortho</italic>-, <italic>meta</italic>-, and <italic>para</italic>-position were also quantified by Hammett constants. The evaluated linear dependences can be used to reliably estimate electrochemical potentials of substituted phenols solvated in water.</p> </abstract>ARTICLEtrue partial charge model in chemistry: chemical accuracy of theoretical approaches for diatomic molecules<abstract> <title style='display:none'>Abstract</title> <p>Atomic partial charges cannot be physically measured but they play a significant role in many chemical theories and theoretical models. Therefore, they are, evaluated from experimentally acquired properties or calculated by quantum chemistry computational methods. This study is focused on determining chemical accuracy of various theoretical methods of computing atomic partial charges based on quantum chemistry. Values of gas-phase atomic partial charges were acquired by Mulliken (MUL) population analysis, natural bond analysis (NBO), Merz-Singh-Kollman (MSK) scheme, and atomic polar tensor (APT) charges computed considering Density Functional Theory and <italic>ab initio</italic> Møller-Plesset up to the second order levels. Correlations between the calculated values were determined by principal component analysis (PCA) and further confirmed by linear regression. The best agreement between experimentally evaluated atomic partial charges and theoretical values was obtained with the MSK scheme.</p> </abstract>ARTICLEtrue and validation of HPLC-FLD method for aflatoxin M determination in milk and dairy products<abstract> <title style='display:none'>Abstract</title> <p>Milk and dairy products are the most consumed foods in human diet and their safety is in the attention centre of control authorities. Aflatoxin M<sub>1</sub> (AFM<sub>1</sub>) is a dangerous toxin that can occur in milk and dairy products as a metabolite formed from aflatoxin B<sub>1</sub> contained in contaminated animal feed. Therefore, the aim of this study was to develop and validate a reliable method for the determination of AFM<sub>1</sub> content in milk and dairy products based on HPLC with fluorescence detection employing immunoaffinity columns (IAC) pre-treatment. Optimal chromatographic separation of AFM<sub>1</sub> was achieved using a water/acetonitrile mixture (80/20, v/v) as a mobile phase, column with C<sub>18</sub> stationary phase maintained at 25 °C, and fluorescence detection at excitation wavelengths of 360 nm and emission of 440 nm. Efficacy of AFM<sub>1</sub> extraction from the samples was found to be influenced by the elution agent composition. The best results were obtained using 1.25 mL of acetonitrile/methanol (3/2, v/v) and 1.25 mL of water. Validation parameters of the proposed method met the criteria set by the European legislation with the limits of detection and quantification at 0.002 and 0.007 µg/kg, respectively. Also, suitability of the method was confirmed by its application for AFM<sub>1</sub> determination in certified reference material. Finally, the method was applied for AFM<sub>1</sub> determination in 25 milk and dairy products collected in Slovakia; the AFM<sub>1</sub> content was below the limit of quantification. It was concluded that the method is suitable for AFM<sub>1</sub> content monitoring in milk and dairy products.</p> </abstract>ARTICLEtrue novel potent perfluorophenylhydrazone derivatives, 1-((4-bromothiophen-2-yl)methylene)-2-(perfluorophenyl) hydrazine, and 1-((4-bromo-5-methylthiophen-2-yl)methylene)-2-(perfluorophenyl)hydrazine as multi-target compounds to combat Alzheimer disease and their crystal, molecular, and electronic properties<abstract> <title style='display:none'>Abstract</title> <p>Two potent novel perfluorophenylhydrazone derivatives are presented as multi-target compounds to combat Alzheimer disease C<sub>11</sub>H<sub>4</sub>BrF<sub>5</sub>N<sub>2</sub>S, 1-((4-bromothiophen-2-yl)methylene)-2-(perfluorophenyl) hydrazine, (I) and C<sub>12</sub>H<sub>6</sub>BrF<sub>5</sub>N<sub>2</sub>S, 1-((4-bromo-5-methylthiophen-2-yl)methylene)-2-(perfluorophenyl) hydrazine, (II), which can potentially be improved by further design. Their multi-target structures and features have been combined as potential AD therapeutics. Crystals (I), and (II), are molecules with two rings and a hydrazone part as a centre of the molecule. The compounds have been synthesised and characterised by elemental spectroscopic (<sup>1</sup>H-NMR) analysis. Crystal structures of the solid phase were determined by single crystal X-ray diffraction method. Both compounds crystallise in the monoclinic space group with <italic>Z</italic> = 4 and <italic>Z</italic> = 2 molecules per unit-cell. Compound (I) crystallises as a racemate in the centrosymmetric space group and compound (II) crystallises as a non-racemate in the non-centrosymmetric space group. Their “absolute configuration and conformation for bond values” were derived from the anomalous dispersion (rmad) for (II). Crystal structures revealed diverse non-covalent interactions such as intra- and inter-hydrogen bonding, π-ring…<italic>π</italic>-ring, C—H…<italic>π</italic>-ring. The expected stereochemistry of hydrazones atoms C7, N2 and N1 were confirmed for (I) and (II). Both molecules show “boat conformation” like a 6-membered ring. Results of single crystal studies were reproduced with the help of Hirshfeld surface study and Gaussian software.</p> </abstract>ARTICLEtrue of biologically active compounds from : Comparison of techniques and multiple response optimization<abstract> <title style='display:none'>Abstract</title> <p>The presented paper deals with the selection of most efficient extraction method for obtaining biologically active compounds (mainly antioxidants) from the black chokeberry (<italic>Aronia melanocarpa</italic>) fruits. Two conventional methods (maceration and Soxhlet extraction) as well as a more recent accelerated solvent extraction (ASE) were employed. The extracts were evaluated by means of their overall yield, antioxidant activity (TEAC assay), total phenolic content (TPC), ascorbic acid (AA), and malic acid (MA) content. Both Soxhlet extraction and ASE led to the highest overall yields (42 %) of the extract; however, in terms of TEAC and TPC, the extracts obtained by ASE were usually superior. The highest TEAC value (227.7 mg TE/g) as well as the highest TPC (67.9 mg GAE/g) were obtained by ASE using 40 % (v/v) ethanol at 140 °C after 30 min. The ASE method was further analyzed using a 2<sup>3</sup>-factorial design where the effect of temperature (40—140 °C), extraction time (5—30 min), and solvent composition (40—96 % ethanol) was investigated. While temperature and solvent composition significantly affected the extract properties, the effect of extraction time was small or even insignificant. The regression model obtained from ANOVA was further used for multiresponse optimization of ASE conditions using the global desirability function as a criterion for overall extract quality.</p> </abstract>ARTICLEtrue of gut resistomes in healthy individuals and patients with severe alcoholic hepatitis<abstract> <title style='display:none'>Abstract</title> <p>Human gut microbiota has been in the centre of scientific interest for a long period of time. Overall health status of an individual has a great impact on the composition of gut microbiota; however, gut microbiota can affect human health. Antibiotic resistance genes (ARGs) are often a part of human gut microbiome. In this paper, total genomic DNA was extracted from stool samples of 147 healthy individuals and of 45 patients with severe alcoholic hepatitis. The presence of six common ARGs (<italic>bla</italic><sub>TEM</sub>, <italic>bla</italic><sub>SHV</sub>, <italic>bla</italic><sub>OXA</sub>, <italic>vanA, tet</italic>(A), <italic>tet</italic>(E)) was analysed in the genomic DNA by end-point PCR. The results show significantly higher occurrence of ARGs in the DNA samples from patients (<italic>p</italic> = 0.0001) showing multiple ARGs significantly more often than in healthy individuals (<italic>p</italic> = 0.00003). Antibiotic treatment in patients strongly correlated with the occurrence of ARGs (<italic>p</italic> = 0.0038). Nutrition and sex of healthy individuals did not have significant effect on the occurrence of ARGs (<italic>p</italic> = 0.156; <italic>p</italic> = 0.456). ARGs’ occurrence in healthy individuals was the highest in the oldest age group, but the age of individuals and ARGs’ occurrence were not related (<italic>p</italic> = 0.617). In conclusion, the results underline the importance of health for normal functioning of gut microbiota. Antibiotic resistance represents a challenge in the treatment of patients with liver diseases.</p> </abstract>ARTICLEtrue of bioactive coumarins from lime peel as sample pretreatment before chromatographic analysis<abstract> <title style='display:none'>Abstract</title> <p>Analysis of lime peel was applied to assess their suitability for various intended purposes, e.g., application in perfumery, cosmetics, and cleaning products, or as a source of bioactive or other value-added compounds. Targeted analysis allows wider usability of the waste part of these natural materials. In the present study, a novel, efficient, lab-simple, time-saving analytical method for coumarins determination in lime peel, including sample pretreatment by extraction and quantification by HPLC with fluorescence detection (FLD), is introduced. Optimal conditions of ultrasound assisted extraction included water as extraction solvent, temperature of 40 °C, and extraction time of 10 min. A magnetic molecularly imprinted polymer was employed as solid phase extraction adsorbent for primary extract cleaning, isolation, and enrichment of coumarins before chromatographic analysis. Recovery of herniarin and umbelliferone was more than 86 % ((RSD ≤ 4.8 %). Linear range of 50—1000  ng/mL with correlation coefficient above 0.998 was obtained for the proposed HPLC-FLD method. The limit of quantification was 8.2 and 44 ng/mL for herniarin and umbelliferone, respectively. These results show that the proposed sample pretreatment procedure is suitable for analytical purposes and is perspective also for the analysis of other citrus samples, as well as for future scale-up preparative isolation of bioactive coumarins from citrus peel.</p> </abstract>ARTICLEtrue of as an alternative ingredient in value added bread and pasta products<abstract><title style='display:none'>Abstract</title> <p>Natural sources and healthy cereal-based food have recently received a lot of attention by both professionals and the common population for improving overall well-being. In this case, <italic>Opuntia</italic> cactus and <italic>Opuntia</italic> derivates show high potential in the production of health-promoting cereal-based products.</p> <p>This study comprehensively reviews nutritional composition, health benefits of <italic>Opuntia</italic> spp. and its utilisation in the production of bread and pasta products. Moreover, the effect of this ingredient on the rheological properties of wheat dough and physical parameters as well as sensory properties of incorporated products is also discussed.</p> </abstract>ARTICLEtrue masterbatches and their use in polylactic acid fibres dyeing<abstract><title style='display:none'>Abstract</title> <p>This article is focused on the preparation of colour masterbatches from renewable sources based on polylactic acid, which were modified with inorganic pigments. Titanium dioxide, carbon black, and iron oxides were used as inorganic pigments. Due to the composition of the prepared colour PLA masterbatches, the influence of the inorganic pigment on the rheological and thermal properties was monitored. Rheological properties were determined using a capillary viscosimeter and a rotary rheoviscosimeter with a geometry plate/plate. The colour PLA masterbatches prepared in this way were subsequently used to dye polylactic acid fibres in the mass. The prepared fibres were drawn to the maximum drawn ratio <italic>λ</italic><italic><sub>max</sub></italic>. In case of fibres, the influence of composition and drawn ratio on thermal and mechanical properties was monitored.</p> </abstract>ARTICLEtrue of ferrate during long-term storage<abstract> <title style='display:none'>Abstract</title> <p>Surface water and groundwater are polluted with pharmaceuticals, detergents, pesticides, and many other substances. Application of ferrates seems to be a perspective option for wastewater treatment as ferrates are not only powerful oxidizing agents but also an excellent disinfecting and coagulating agents decomposing many stable inorganic, organic, and biological compounds. Final products of their decomposition do not include carcinogenic or toxic products. In this paper, stability of electrochemically prepared potassium ferrate encapsulated in packaging materials printed on a 3D printer was monitored. In the experiment, electrochemically prepared potassium ferrate with different purity (21.4 %, 63.5 % and 67.3 %) was used. Stability of potassium ferrate was monitored for one month and that of other ferrates for three months. Different storage conditions of ferrate samples were also compared. Storage conditions had a significant influence on the ferrate stability.</p> </abstract>ARTICLEtrue on secondary metabolites of F742 and their role in antibiosis<abstract> <title style='display:none'>Abstract</title> <p>Soil-borne pathogenic fungi responsible for serious damage in agriculture are widely distributed. Traditional approach to control these pathogens leads to the use of chemical fungicides, many of which have proven harmful side effects on the environment. Mycoparasitic fungi of the genus <italic>Trichoderma</italic> have been used for pathogens biocontrol as well as for their ability to promote plant growth. As increased mycoparasitic activity of mutant strain <italic>Trichoderma atroviride</italic> F742 has been observed, its use as a biocontrol agent might be considered. In this work, we focused on mycoparasitic activity of the strain <italic>T. atroviride</italic> F742 prepared by UV mutagenesis (from parental strain <italic>T. atroviride</italic> F534) and the physiological role of <italic>T. atroviride</italic> metabolites in antibiosis.</p> <p><italic>T. atroviride</italic> F742 shows remarkable mycoparasitic activity attacking and colonizing phytopathogens <italic>(Alternaria alternata</italic>, <italic>Botrytis cinerea</italic>, <italic>Fusarium culmorum</italic>). Its isolated metabolites inhibit the growth of bacteria, yeasts, and fungi <italic>Candida albicans, A. alternata</italic> and <italic>F. culmorum.</italic> As different expression patterns in the secondary metabolites production of ABC transporters have been observed, we suggest their role in transport of secondary metabolites produced by <italic>T. atroviride</italic> F742.</p> </abstract>ARTICLEtrue and light-induced SCO effect in Fe(II) complexes and coordination polymers<abstract> <title style='display:none'>Abstract</title> <p>The review presents several families of spin crossover (SCO) active Fe(II) coordination compounds with photoactive N-donor heterocyclic ligands, in which the photoinduced structural changes can activate reversible change of spin state and thus control magnetic properties under isothermal conditions. Detailed description of structural, spectral, and magnetic behavior for selected examples of photoisomerizable coordination compounds are provided. From the application point of view, light is an excellent tool to control SCO properties. The first and best known approach called Light Induced Excited Spin State Trapping (LIESST) has a significant technological limitation due to low temperatures (&lt; 120 K) required for the trapping and existence of photoexcited metastable states. The second and more elegant approach known as Ligand-Driven Light-Induced Spin Crossover (LD-LISC) seems to be a very suitable strategy utilizing light-induced structural changes to control the spin. Isomerization of photoswitchable groups, such as azobenzenes or stilbenes, can cause reversible transformation between two isomeric forms after exposition to selective wavelengths at ambient temperature. A very recent third approach, the Guest-Driven Light-Induced Spin Crossover (GD-LISC) effect employing the photoisomerizable guest molecules to control the spin state has also been introduced.</p> </abstract>ARTICLEtrue of white grape preparation on sensory quality of cookies<abstract><title style='display:none'>Abstract</title><p>Grape skin pomace is rich in proteins, ash, lipids, carbohydrates, vitamins, and compounds with important biological properties such as phenolic compounds. Because of its complex composition, grape skin pomace can be used for nutritional enrichment of various cereals products. The aim of study was to investigate the effects of grape skin pomace on the sensory properties of cookies. Results indicated that grape skin pomace can be incorporated in cookies as a partial replacement up to 15 % of composite flour without negatively affecting the sensory quality of cookies.</p></abstract>ARTICLEtrue properties of curcuminoids isolated from L.<abstract><title style='display:none'>Abstract</title><p>The evaluation of antioxidant potential of food has received much attention in recent years. Antioxidant compounds can scavenge free radicals and thereby can protect the human body from free radicals. This study was focused on the isolation of curcuminoids from the dried turmeric rhizome, and studying their antioxidant activity. The presence of curcuminoids was identified in turmeric sample by Nuclear Magnetic Resonance (NMR) analysis. Since neutral curcumin is known to be poorly soluble, the synthesis of curcumin-cyclodextrin and curcumin-phospholipid complexes was also performed. The antioxidant activity of isolated curcuminoids was assessed by two methods (ABTS and FRAP assay) and their scavenging activities were compared with those of prepared complexes. The ability to reduce ABTS radical cation decreased as follows: quercetin &gt; trolox &gt; curcuminoids &gt; curcumin-cyclodextrin complex &gt; curcumin-phospholipid complex. The reducing potential of tested samples in descending order was quercetin &gt; trolox &gt; curcumin-cyclodextrin complex &gt; curcuminoids &gt; curcumin-phospholipid complex.</p></abstract>ARTICLEtrue cultivars — phenolic compounds profiles and antioxidant properties<abstract><title style='display:none'>Abstract</title><p>Common buckwheat (<italic>Fagopyrum esculentum</italic>) and tartary buckwheat (<italic>Fagopyrum tataricum</italic>) cultivars originating in different world countries were investigated and compared for their quantitative and qualitative abundance of phenolics and flavonoids. Moreover, the antioxidant properties were tested using two different methods. The total phenolic and total flavonoid content ranged from 0.897 to 4.226 mg GAE g<sup>−1</sup> dw and from 0.238 to 4.626 mg rutin g<sup>−1</sup> dw, respectively. Flavonoids — rutin, quercetin, and hydroxybenzoic acids — gallic, protocatechuic, vanillic and syringic were identified and quantified. Rutin was the most abundant flavonoid and protocatechuic acid was the most abundant phenolic acid in evaluated cultivars. All cultivars showed significant antiradical properties, but their chelating activity was weak. The German cultivar of tartary buckwheat Lifago had significantly higher phenolic content and better antioxidant properties than other cultivars. The content of rutin was 24 times higher and free radicals scavenging activity about 70 % higher than the average value of other cultivars.</p></abstract>ARTICLEtrue effects of nitrate-containing phase change materials used with copper<abstract><title style='display:none'>Abstract</title><p>The paper presents the results of a study on the corrosion behaviour of copper (EN CW004A) in five possible phase change materials (PCMs): magnesium nitrate hexahydrate pure and with an addition of Mg(OH)<sub>2</sub> (0.5 wt. %) or Sr(OH)<sub>2</sub> (0.5 wt. %) at 90 °C, calcium nitrate tetrahydrate at 50 °C and a mixture of magnesium nitrate hexahydrate and calcium nitrate tetrahydrate (1:1 mass ratio) at 72 °C. The corrosion rate of copper samples is low except for the use of Mg(NO<sub>3</sub>)<sub>2</sub> · 6H<sub>2</sub>O with/without an addition of Mg(OH)<sub>2</sub>. The lowest corrosion rate was observed for the mixture Mg(NO<sub>3</sub>)<sub>2</sub> · 6H<sub>2</sub>O—Ca(NO<sub>3</sub>)<sub>2</sub> · 4H<sub>2</sub>O (1:1), and it was ca six times lower than that of pure magnesium nitrate hexahydrate.</p></abstract>ARTICLEtrue of GABA shunt affects response to nutritional and environmental stimuli<abstract><title style='display:none'>Abstract</title><p>The fungus <italic>Trichoderma atroviride</italic> is a member of the genus <italic>Trichoderma</italic> to which belong many species known for high cellulase production, formation of various antibiotics, plant biocontrol and antagonistic activities against other fungi. Deletion of <italic>T. atroviride</italic> glutamate decarboxylase gene <italic>gad</italic> caused minor defects in germination, hyphal branching, slower growth and disruption of conidiation pattern. GABA can be used by fungi as a secondary carbon source and as a primary nitrogen source. We analyzed the effect of different nutrient compositions and environmental conditions (light and temperature) on growth and development of <italic>T. atroviride</italic> in strains defective in the functional GAD. The <italic>gad</italic> mutants grown on NH<sub>4</sub>NO<sub>3</sub> as a sole carbon source grew slower and formed conidiation bands closer to each other which was clearly demonstrated during their cultivation in race tubes. The <italic>gad</italic> mutants exhibited slightly lower apical extension growth rate at the room temperature but their apical extension rate dropped significantly at 30 °C. Higher temperature had also inhibitory effect on <italic>gad</italic> mutant conidiation, whereas 30 °C seems optimal temperature for the parental strain. The optimal temperature for <italic>gad</italic> mutant conidiation was lower than in F534, about 25 °C.</p></abstract>ARTICLEtrue of enantiomeric composition of fluoxetine by synchronous fluorescence spectrometry coupled with multivariate calibration in biological samples<abstract><title style='display:none'>Abstract</title><p>This paper presents rapid and low cost analytical method for the determination of the fluoxetine enantiomeric composition in biological samples (urine). The combination of synchronous fluorescence spectrometry and inverse multivariate calibration methods was used. The chiral recognition of the fluoxetine was based on the creating of the diastereomeric complexes with <italic>β</italic>-cyclodextrin. A net analytical signal of diastereomeric complexes was obtained by the addition of aliquot part of urine into calibration and validation sets. This step ensures the elimination of the urine matrix effect. The synchronous fluorescence spectra at the constant wavelength differences (Δλ) of 30 and 50 nm, based on RMS %RE values, were chosen for chemometric analysis. Principal component regression (PCR) and partial least square method (PLS) were compared to determine the enantiomeric composition. The most suitable results were provided by the PLS model constructed from the synchronous data at Δλ = 50 nm. The calculated figure of merit was used for validation of proposed method.</p></abstract>ARTICLEtrue of the growth of in milk in dependence on temperature<abstract><title style='display:none'>Abstract</title><p>The effect of temperature on the growth dynamics of <italic>Lactobacillus plantarum</italic> in the model environment of UHT milk was investigated. Based on the experiments between temperatures ranged from 8 to 40 °C, growth dynamics of the studied isolate was positively determined by the cultivation temperature that led to increasing intensity of growth in the exponential phase (except for temperatures 38 and 40 °C). Final counts in stationary phase have reached concentrations about 10<sup>7</sup> CFU · ml<sup>−1</sup> from initial 10<sup>3</sup> CFU · ml<sup>−1</sup>, except for marginal 8 and 40 °C. Experimentally, it was found, that optimal temperature was close to 37 °C, where the fastest specific growth rate in an exponential phase was recorded (μ = 0.7683 h<sup>−1</sup>, t<sub>d</sub> = 54 min) and the stationary phase was reached after 24 h of incubation. During the growth and multiplication of <italic>Lb. plantarum</italic>, no significant decrease of pH values in comparison to initial ones in dependence on temperature were determined (0.00—0.24 units).</p></abstract>ARTICLEtrue