Pavel Valášek

Cell Proliferation of HaCaT Keratinocytes on Collagen Films Modified by Argon Plasma Treatment

Argon plasma treatment was used to modify the surface of atelocollagen films using a plasmochemical reactor. To evaluate the effects of the treatment, the untreated and treated samples were characterized by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM) imaging, and X-ray Photoelectron Spectroscopy (XPS) techniques. Cell growth was carried out by culturing human immortalized keratinocyte (HaCaT) cells and proliferation was measured via MTT assay. It was observed that argon plasma treatment significantly enhanced the extent of cell proliferation, which was ascribed to the favourable role of plasma treatment in inducing surface oxygen-containing entities together with increasing surface roughness. This can be considered as a potentially promising approach for tissue regeneration purposes.

Phenolic compounds from Allium schoenoprasum, Tragopogon pratensis and Rumex acetosa and their antiproliferative effects.

Experimental studies have shown that phenolic compounds have antiproliferative and tumour arresting effects. The aim of this original study was to investigate the content of phenolic compounds (PhC) in flowers of Allium schoenoprasum (chive), Tragopogon pratensis (meadow salsify) and Rumex acetosa (common sorrel) and their effect on proliferation of HaCaT cells. Antiproliferative effects were evaluated in vitro using the following concentrations of phenolic compounds in cultivation medium: 100, 75, 50 and 25 µg/mL. Phenolic composition was also determined by HPLC. The results indicate that even low concentrations of these flowers’ phenolic compounds inhibited cell proliferation significantly and the possible use of the studied herb’s flowers as sources of active phenolic compounds for human nutrition.

Contribution of individual phenolics to antioxidant activity and in vitro digestibility of wild rices (Zizania aquatica L.)

Zizania aquatica L. was analysed for total flavonoids, phenolics and HPLC profile in both free and bound phenolic fractions. The highest content of flavonoids (378-455mgRE/kg) was detected in bound fractions, while the highest polyphenols content (1061-2988mgGAE/kg) was determined in free fractions. Additionally, predominant phenolics were identified. To understand the contribution of individual phenolics to an antioxidant activity their mutual correlations were evaluated. Regarding free flavonoids, the main contributors to an antioxidant activity (r>0.7111) were epigallocatechin, epicatechin and rutin; while epicatechin, quercetin and rutin were the main contributors in bound fractions (r>0.6868). Concerning free phenolic acids, the main contributors to an antioxidant activity (r>0.7585) were ferulic, vanillic, ellagic, sinapic and syringic acids; while caffeic, sinapic, syringic, o-coumaric, p-hydroxy benzoic, vanillic, protocatechuic, gallic and cinnamic acids were the main contributors in bound fractions of wild rice (r>0.6538). Finally, in vitro organic matter and dry matter digestibility were assessed.

Total polyphenolic compounds contents (TPC), total antioxidant activities (TAA) and HPLC determination of individual polyphenolic compounds in selected Moravian and Austrian wines

AbstractWine samples (Grüner Veltliner (GV) and Zweigelt (ZW) from four different geographical regions of Austria and Czech Republic) were analyzed to determine their total phenolic content (TPC) by applying the Folin-Ciocalteau method, total antioxidant activity (TAA) by FRAP (ferric reducing antioxidant power) and DPPH (1,1-diphenyl-2-picryl-hydrazyl) assays, and to identify and quantify eleven phenolic compounds using a HPLC/UV-VIS method.

The Effect of Hydrolysis Degree on the Properties of Antibacterial Polymeric Films Based on Poly(vinyl alcohol) and Zinc Sulphate for Biomedical Applications

Fully and partially hydrolyzed poly(vinyl alcohol) (PVA) was modified with zinc sulphate in the concentration range from 0 to 9 wt% of recalculated zinc content using the solvent cast technique. The resulting polymeric films were characterized by optical microscopy, stress–strain analysis, differential scanning calorimetry and Fourier transform infrared spectroscopy (FT-IR–ATR). In addition, agar diffusion test and dilution and spread plate technique were used for determination of antibacterial properties of the films against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) bacterial strains. A mathematical model was applied on the measured data and parameters characterizing the antibacterial efficiency of the material were calculated and discussed. The results revealed that the PVA hydrolysis degree can play an important role in all studied properties, including antibacterial activity of the all PVA-based materials.

Flexible polyvinyl alcohol/2-hydroxypropanoic acid films: effect of residual acetyl moieties on mechanical, thermal and antibacterial properties

Abstract This work ascertains the effect of the degree of hydrolysis of polyvinyl alcohol under extended interaction with 2-hydroxypropanoic acid (lactic acid). Systems based on three different types of polyvinyl alcohol matrices (of hydrolysis degree 80, 88 and 98 mol%) and lactic acid were characterized according to their physicochemical, mechanical and thermal properties. An agar diffusion test and the dilution and spread plate technique were conducted to facilitate antibacterial activity to counteract Staphylococcus aureus and Escherichia coli. A mathematical model was applied to the experimental data to estimate the antibacterial efficacy of the resultant flexible films.

The importance of higher alcohols and esters for sensory evaluation of rheinriesling and chardonnay wine varieties

For a consumer, one of the first characters for evaluation of wine is its scent. A pleasant aroma of wine associated with the subsequent taste experience can be remembered by the consumer for a long time and appreciated appropriately. For this reason, the aromatic properties of wine are very important to both consumers and producers. The question, however, is to assess the evaluation of wine sensory evaluation based on a rapidly developing chemical analysis without the use of a panel of evaluators. This study has dealt with the problem of the correlation of sensory evaluation of wine with the total content of higher alcohols and esters in wine prepared from the same wine varieties (Rheinriesling and Chardonnay) on the same vineyard under the same climatic conditions and processed using the same production technology in the years 2008 - 2012. The total content of higher alcohols and esters was determined by gas chromatography with a mass spectrometer (GC/MS). The correlation between the sensory evaluation and the total content of higher alcohols has not been established. However, the direct effect of the total content of the esters on the level of the sensory analysis of the two varieties studied was demonstrated. This can be an important economic indicator for a manufacturer who can estimate the sensory quality of the wine only on the basis of chemical analysis and thus estimate the success of the wine on the consumer market. Normal 0 21 false false false EN-GB X-NONE X-NONE

Influence of composition of feed and lactation period on mineral composition of Mare's

Effects of lactation period and feed on essential minerals composition of mares milk were studied. Average Ca, P, Na and Mg concentrations in feed DM were 0.66, 4.30, 0.13 and 2.21 g.kg-1 of DM (dry matter), respectively. In regard to milk all elements concentrations were not similar to each other due to the changes of the lactation day differences. Average Ca, P, Na and Mg concentrations (in DM) caused by breed differences and lactation days were 1.95, 1.08, 0.53 and 0.22 g.kg-1, respectively. During the milk period, a high-quality feed were maintaining the major mineral composition of mares milk in 1.5 - 2 times higher amount than milk of mare fed with pasture and a low-quality feed. The colostrum stage of mare was much shorter than other animals, the mares milk on the 2nd day of lactation showed properties of initial milk in which its composition, particularly in minerals, were two times higher when compare to that on milk periods that was started from 5th day after parturition. It seemed that some factors, except well physiological conditions, such as mares age, number of foaling, sex of foal etc. did not affect milk nutrient composition.

LIQUID CHROMATOGRAPHIC DETERMINATION OF POLYPHENENOLS IN CZECH BEERS DURING BREWING PROCES

High performance liquid chromatographic (HPLC/UV) method was adapted for simultaneous determination of seven polyphenols, including derivatives of benzoic (gallic and vanillic acids) and cinnamic acids (p-coumaric, ferulic and sinapic acids), flavan-3-ols (catechin) and flavonols (rutin) in worts and beers at the various stages of the brewing process. Based on the semi-quantitative HPLC analysis, total polyphenols chromatographic index (TPCI) was in the ranges of 5.18 - 19.4 mg/L and 7.37 - 20.7 mg/L for all worts and beers, respectively. The HPLC analyses showed that relatively high levels of (+)-catechin and gallic acid were in all the worts and the beers, while the values were much lower for ferulic acid, rutin, vanillic acid, sinapic acid and p-coumaric acid. Polyphenols with relatively high concentrations, that were detected in all tested worts and beers, were gallic acid (1.29 - 4.75 mg/L resp. 2.59 - 4.97 mg/L), (+)-catechin (1.66 - 7.95 mg/L resp. 4.70 - 10.0 mg/L) and ferulic acid (0.41 - 4.53 mg/L resp. 1.05 - 2.87 mg/L). On the other side, the sinapic acid (0.72 - 1.59 mg/L resp. 0.72 - 2.5 mg/L), rutin (1.17 - 2.03 mg/L resp. 1.16 - 2.85 mg/L), p-coumaric acid (ND - 4.73 mg/L resp. ND - 1.44 mg/L) and vanillic acid (ND - 1.52 mg/L resp. 0.75 - 1.81 mg/L) were detected in lowest concentrations. In both, worts and beers investigated in this study, the changes in the contents of individual polyphenols were not uniform. In the case of some polyphenols, a decrease in the content was observed after boiling the worts with hops or after the main fermentation until maturation and filtration, but with some polyphenols, the concentrations were constant until the end of the process or even increased.

Content of 4(5)-methylimidazole, caffeine and chlorogenic acid in commercial coffee brands

Content of 4(5)-methylimidazole (4-MeI), caffeine and chlorogenic acid in commercial coffee brands were determined using high-performance liquid chromatography (HPLC) with UV DAD and MS detectors. Positive ion ESI mass spectra of the 4-MeI standard yielded intense signals corresponding to [M+H] + (83.0604) and [2M+H] + ions (165.1115). Also, adducts of 4-MeI with acetonitrile from mobile were detected – [M+ACN] + ions (124.0849). The LOD of 2.5 ng mL -1 and LOQ of 8.4 ng.mL -1 were calculated according to the following formulas: LOD = 3.SD/S, and LOQ = 10.SD/S, where S is the slope of the calibration curve and SD is the standard deviation of the noise. The caffeine content was compared to the results of the standard addition, 1 st derivative and liquid-liquid extraction spectrophotometry. 4-MeI was in tens µg g -1 in the Vietnamese coffees while in units µg.g -1 in all Czech and Brazilian coffees (<2.4 µg.g -1 and <4.9 µg.g -1 , respectively). The results for caffeine were within the documented range (0.31 – 2.20%) in all coffee samples. The lower content of caffeine and chlorogenic acid was observed in Vietnamese coffees. All the methods used for determination of caffeine in the Czech and Brazilian coffees gave acceptable precision and accuracy. However, there were significant differences in the results in Vietnamese coffees. The caffeine extractability (100 °C, 3 min brewing) almost reached 100% in Czech and Brazilian coffees, while it was less than 90% in Vietnamese coffees. The Czech and Brazilian coffees tend to produce more caffeine in brews than the Vietnamese coffee because of the different composition of blends and the particle size degree.