Ispitivanje kinetike reakcije natrijum-etilksantogenacetata i alkilamina

In this work kinetics investigation of the reaction between sodium ethyl xantogenacetate (NaEtXAc) and primary as well as secondary alkylamines, for each pair NaEtXAc-amine, was performed. Firstly, in order to determine the wavelength for following the reaction, the influence of the structures of reactants on the absorption was investigated. Absorption of the system was followed at l = 280 nm. The values of rate constants for 16 selected amines, at the different temperatures, were determined. Considering high correlations coefficients, r > 0.988, it was confirmed that investigated reactions are the second-order. On the basis of reaction constants, at the different temperatures, several thermodynamic parameters were calculated such as the energy of activation Ea,, frequency factor A, the entropy of activation DS#2S, Gibbs’s free-energy of activation DG#2S and enthalpy of activation DH#2S. By evaluation of the obtained results some assumptions, that refer to the reaction mechanisms of nucleophilic attack of the amine on the thiocarbonyl carbon, were made. Following the proposed mechanism activated complex, as a critical step, is formed in this reaction.U cilju ispitivanja kinetike reakcije natrijum-etilksantogenacetata (NaEtXAc) sa primarnim i sekundarnim alkilaminima za svaki par NaEtXAc-amin ispitan je prvo uticaj strukture ovih jedinjenja na apsorpciju kako bi se odredila talasna dužina na kojoj će se pratiti reakcija. Praćena je promena apsorpcije sistema na l= 280nm. Određene su konstante brzina reakcija za šesnaest odabranih amina na različitim temperaturama. Na osnovu visokih vrednosti korelacionih koeficijenata r > 0,988, potvrđeno je da ispitivane reakcije slede kinetiku reakcije drugog reda. Na osnovu vrednosti reakcionih konstanti na različitim temperaturama izračunato je nekoliko termodinamičkih parametara ispitivanih reakcija: energija aktivacije Ea, faktor učestanosti A, entropija aktivacije ΔS#25, Gibsova slobodna energija aktivacije ΔG#25 i entalpija aktivacije ΔH#25. Obradom dobijenih rezultata pretpostavljen je reakcioni mehanizam nukleofilnog napada amina na tiokarbonilni ugljenik, pri čemu kao limitirajući korak nastaje aktivirani kompleks

Determination of metal content in some herbal drugs - Empirical and chemometric approach

The concentrations of Cu, Zn, Mn, Fe, K, Ca, Mg, Al, Ba and B in 26 herbal drugs of special importance in phytopharmacywere studied. Flame atomic absorption and emission spectrometry (FAAS, FAES), as well as inductively coupled plasma atomic emission spectrometry (ICP-AES), were applied in this work. The whole procedure, from sample preparation, via dissolution, to measurements, was validated by using CRM (NIST 1573a-tomato leaves), and the obtained recovery values are in the range from 91 to 102%. Drug samples originated from medicinal plants cultivated in Serbia contained Cu (4.47-14.08 mg kg(-1)), Zn (8.4-54.5 mg kg(-1)), Mn (9-155 mg kg(-1)), Fe (47-546 mg kg(-1)), K (0.20-6.24%), Ca (0.18-1.84%), Mg (0.13-1.09%), Al (16-416 mg kg(-1)), Ba (11.70-84.83 mg kg(-1)) and B (5.1-118.7 mg kg(-1)). In order to get a better insight into the elemental patterns, a common chemometric approach to data evaluation was used. Four significant factors identified by principal component analysis (PCA) were attributed partly to the significant influential sources and high mobility of some elements thus referring to potential anthropogenic contamination as well

Evaluation of osteopontin and CA125 in detection of epithelial ovarian carcinoma

The objective of this study was to determine the potential of osteopontin (OPN) and OPN + CA125 (cancer antigen 125) combination in differential diagnosis of the ovarian cancers and non-malignant ovarian disease. Serum and plasma samples were obtained preoperatively from 79 women undergoing surgery for pelvic mass; 48 of them had ovarian carcinoma, and 31 had benign cyst. The samples were analyzed for the levels of OPN and CA 125 (using ELISA and CMIA methods) and then compared with the final pathologic results. The median plasma level of OPN in patients with benign and malignant cysts was 356.33 ng/ml and 865.15 ng/ml, respectively (p lt 0.001). Receiver operating characteristic (ROC) analysis for plasma OPN revealed the area under the curve (AUC) of 0.838. At the predefined specificity of 90%, OPN showed sensitivity of 62.5%, whereas the combination of OPN + CA125 reached 74.9% at the same specificity

Bioactivity of herbal tea of Hungarian thyme based on the composition of volatiles and polyphenolics

Hungarian thyme (Thymus pannonicus All., Lamiaceae) is an aromatic herb used as traditional remedy, a refreshing beverage and a food aromatizer. Herbal teas, i.e., infusions, of Hungarian thyme from eight localities in Serbia were analyzed regarding their polyphenolic and volatile composition, and tested for their antioxidant and antimicrobial activity. The total polyphenolics content, determined by the Folin-Ciocalteu method, ranged from 1122.25 to 1979.93 mg gallic acid/L. HPLC analysis revealed rosmarinic acid (367.42-1199.47 mg/L) and luteolin glucuronides as the main polyphenolics. The volatile fractions of the infusions, analyzed by static headspace extraction coupled with GC and GC-MS analyses, contained citral, 3-octanone, 1-octen-3-ol, linalool and 1,8-cineole as the dominant constituents. The antioxidant activity of the infusions was examined through the ferric reducing antioxidant power (FRAP) (68.09-124.58 mmol Fe2+/L) and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical tests (SC50 1.32-2.96 μL/mL). The antimicrobial activity was tested by the broth microdilution method against standard strains of Gram(+) Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis and Enterococcus faecalis and Gram(-) bacteria Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa, and one strain of yeast Candida albicans. The infusions inhibited microbial growth in the tested concentration range (31.25-500.00 μL/mL) and the strongest activity was exhibited against the strain of C. albicans (MIC 31.25-62.50 μL/mL). The antioxidant and antimicrobial properties of the infusions were, to some extent, in correlation with the composition and content of the polyphenolic compounds, whereas the volatiles noticeably influenced the exhibited antimicrobial activity. © 2016 Elsevier B.V

Procjena unosa bakra umjerenom konzumacijom vina

To estimate Cu exposure level from wine consumption and to assess possible health risk for moderate wine consumers, wine samples were collected from different wine-growing areas of Croatia. Median concentrations were 180 μg L-1, range (76 to 292) μg L-1, in commercial wines and 258 μg L-1, range (115 to 7600) μg L-1, in homemade wines (P>0.05). Maximum permitted level of 1000 μg L-1 was exceeded in three homemade wines. However, daily intake of Cu from wine (in the range from 0.02 mg d-1 to 1.52 mg d-1) estimated from Cu concentration in all wine samples is lower than the tolerable upper intake level of 5 mg d-1 proposed by the EU Scientifi c Committee on Food and does not present a risk to moderate wine consumers.Kako bi se procijenila razina izloženosti bakru prilikom konzumacije vina te utvrdili mogući zdravstveni rizici za umjerene potrošače vina, skupljeni su i ispitani uzorci vina iz različitih vinogradarskih područja Hrvatske. Koncentracije Cu bile su u rasponu od 76 μg L-1 do 292 μg L-1 (medijan 180 μg L-1) u komercijalnim vinima te od 115 μg L-1 do 7.600 μg L-1 (medijan 258 μg L-1) u vinima domaće proizvodnje (P>0,05). U tri ispitana vina domaće proizvodnje koncentracija Cu bila je iznad najviše dopuštene od 1000 μg L-1. Međutim, izračunani dnevni unos Cu u slučaju konzumacije ispitanih vina (u rasponu od 0,02 mg d-1 do 1,52 mg d-1) ne prelazi gornju granicu tolerancije unosa od 5 mg d-1 te nije zdravstveni rizik umjerenim potrošačima vina