Wyniki wyszukiwania - Biblioteka Nauki

1

Rate and Equilibrium in Aqueous 1:2 Chelation of Copper(II) by 2-Pyridinecarboxylic Acid Hydrazide. Antituberculosis Activity

100%

Hernando J. , Blanco C. A. , Caballero I. , Prieto T.

Polish Journal of Chemistry

|

2002

|

tom Vol. 76 / nr 12

1673-1680

EN

Chelation reactions of 2-pyridinecarboxylic acid hydrazide, widely used drug in antituberculous regimens, with copper(II) have been investigated in aqueous solution at a temperature of 25_C. The ionization equilibria of the ligand and the stability of the metal-ligand complexes have also been characterized. Kinetic results show that the rate constant for monochelated complex formation is several times larger than the rate constant for dichelated complex formation. Adetailed mechanism is proposed to account for the kinetic data.

2

Heavy Metals Chelating Ability and Antioxidant Activity of Phragmites australis Stems Extracts

100%

Sellal A. , Belattar R. , Bouzidi A.

Journal of Ecological Engineering

|

2019

|

tom Vol. 20, nr 2

116--123

EN

In this study, the ability of hexane (HSE), chloroform (CSE), ethyl acetate (EASE) and methanolic (MSE) stems extracts from Phragmites australis or EDTA (as standard) to chelate iron using ferrozine method or zinc and copper using the murexide method is carried out in vitro. When the increased volumes of the HSE studied were taken from a stock solution of a fixed concentration 1 mg/ml at 25–175 μl for the iron and zinc chelating assay, 1–7 mg/ml for the copper chelating assay gave a significant (p≤ 0.01) activity. The obtained results showed that the HSE have the highest capacity to chelate ferrous ions below the EDTA (standard chelator) with absorbance arrive to the lesser extent 0.24±0.005, 0.04±0.013 which expresses 86% and 97% (compared to the control) of inhibition, respectively. For the murexide chelation, the results obtained also showed that the HSE and EDTA have a good (p≤ 0.01) chelating dose dependent effect towards zinc and copper ions with increased absorbance 0.45±0.02 and 0.42±0.02 with 54% and 56% of inhibition, respectively, for the zinc chelation and 0.66±0.03, 0.13±0.005 represent 44% and 88% for copper chelation. In contrast to the antioxidant capacity, the extract of hexane, ethyl acetate, chloroform and methanol from leaves, stems and roots of the Phragmites australis plant have a very low scavenger effect to the radical DPPH where the maximum inhibition is approximately 13.79%, obtained with the maximum volume. Finally, the HPLC analysis of effective extract (HSE) confirmed the presence of oxalic, citric, malic, succinic, fumaric, formic, acetic, propionic and butyric or iso butyric acid.

3

Modification of the deoxyribose test to detect strong iron binding

72%

Sadowska-Bartosz I. , Galiniak S. , Bartosz G.

Acta Biochimica Polonica

|

2017

|

tom 64

|

nr 1

195-198

EN

Deoxyribose test has been widely used for determination of reactivities of various compounds for the hydroxyl radical. The test is based on the formation of hydroxyl radical by Fe2+ complex in the Fenton reaction. We propose a modification of the deoxyribose test to detect strong iron binding, inhibiting participation of Fe2+ in the Fenton reaction, on the basis of examination of concentration dependence of deoxyribose degradation on Fe2+ concentration, at a constant concentration of a chelating agent.

4

Fe[II], Cu[II] and Zn[II] chelating activity of buckwheat and buckwheat groats tannin fractions

72%

Karamac M.

Polish Journal of Food and Nutrition Sciences

|

2007

|

tom 57

|

nr 3

357-362

EN

Phenolic compounds were extracted from buckwheat and buckwheat groats into 80% acetone (v/v). The crude extracts were separated with Sephadex LH-20 column chromatography into low molecular weight phenolic compounds and tannin fractions. The tannin fractions were characterised by colour reaction with vanillin/HCl reagent, ability for protein precipitation as well as SE-HPLC method. Chelation of Cu(II) and Zn(II) by tannin fractions was determined by reaction with tetramethylmurexide (TMM) whereas Fe(II) chelation was investigated by forming complexes with ferrozine. The tannin fractions obtained from buckwheat and buckwheat groats gave similar results in vanillin test; A500/mg was 1.04. Also results obtained using precipitation method were comparable. SE-HPLC chromatograms showed that in tannin fraction of buckwheat groats polymers with molecular weight ≥ tannic acid were present. On the chromatogram of buckwheat tannins peaks were shifted to lower molecular weight compounds. Tannins of buckwheat were stronger chelators of all metal ions tested (Fe(II), Cu(II) and Zn(II)) than tannins of buckwheat groats. Ions of copper were chelated the most effectively; 1 mg of buckwheat and buckwheat groats tannin fractions added per assay bound 86.0% and 72.9% of Cu(II), respectively. Buckwheat tannins used in the test at a level of 2.5 mg/assay bound approximately twice more Fe(II) than the same addition of buckwheat groats tannins. Zn(II) was chelated to the lowest extent, 17.2% was bound by buckwheat tannins and 13.5% by buckwheat groats tannins (5 mg of tannin/assay).

PL

Ekstrakty acetonowe z gryki i kaszy gryczanej rozdzielano na kolumnie wypełnionej żelem Sephadex LH-20 na frakcję niskocząsteczkowych związków fenolowych i taninową. Frakcje taninowe scharakteryzowano za pomocą reakcji z waniliną, zdolności do strącania białka oraz metodą SE-HPLC z zastosowaniem kolumny TSK Gel G2000SWXL (TosoHaas). Kompleksowanie jonów Cu(II) i Zn(II) przez taniny oznaczano w reakcji z tetrametylomureksydem (TMM). Chelatowanie Fe(II) badano wykorzystując reakcję barwną kompleksowania ferrozyny. Wyniki testu z waniliną przeprowadzonego z frakcjami taninowymi z gryki i kaszy gryczanej były podobne; wartość A500/mg wynosiła 1,04. Również w metodzie strąceniowej obie próby wykazały zbliżone do siebie rezultaty. Rozdział SE-HPLC tanin z kaszy gryczanej charakteryzował się obecnością polimerów o masach cząsteczkowych większych lub równych masie cząsteczkowej kwasu taninowego. Na chromatogramie frakcji taninowej z gryki piki były przesunięte w stronę mniejszych mas cząsteczkowych. Frakcja tanin z gryki wiązała więcej wszystkich testowanych jonów metali w porównaniu z frakcją tanin z kaszy gryczanej. Obie frakcje tanin najefektywniej chelatowały jony Cu(II). Frakcja tanin gryki dodana do próby w ilości 1 mg związała 86,0% jonów miedzi, natomiast frakcja z kaszy gryczanej – 72,9%. Dodatek 2,5 mg/próbę tanin gryki wiązał ponad dwa razy więcej jonów Fe(II), niż taka sama ilość tanin z kaszy gryczanej. Jony cynku były najsłabiej chelatowane. Frakcja tanin gryki (5 mg) kompleksowała 17,2% a tanin kaszy gryczanej – 13,5% jonów Zn(II).

5

Stress-induced behaviour in adult and old rats: effects of neonatal asphyxia, body temperature and chelation of iron

58%

Rogalska J. , Caputa M. , Wentowska K. , Nowakowska A.

Journal of Physiology and Pharmacology. Supplement

|

2006

|

tom 57

|

nr 8

17-34

EN

Perinatal asphyxia in mammals leads to iron accumulation in the brain, which results in delayed neurobehavioural disturbances, including impaired learning and abnormal alertness over their entire life span. The aim of this investigation was to verify our hypothesis that newborn rats, showing reduced normal body temperature, are protected against neurotoxicity of the asphyxia up to senescence. Alertness was studied in adult and old male Wistar rats after exposure to critical neonatal anoxia: (i) at physiological neonatal body temperature of 33°C, (ii) at body temperature elevated to 37°C, or (iii) at body temperature elevated to 39°C (the thermal conditions remained unchanged both during anoxia and for 2 h postanoxia). To elucidate the effect of iron-dependent postanoxic oxidative damage to the brain, half of the group (iii) was injected with deferoxamine, a chelator of iron. Postanoxic behavioural disturbances were recorded in open-field, elevated plus-maze, and sudden silence tests when the rats reached the age of 12 and 24 months. Open-field stress-induced motor activity was reduced in rats subjected to neonatal anoxia under hyperthermic conditions. In contrast, these rats were hyperactive in the plus-maze test. Both the plus-maze and sudden silence tests show reduced alertness of these rats to external stimuli signalling potential dangers. The behavioural disturbances were prevented by body temperature of 33°C and by administration of deferoxamine.

6

Aktywnosc przeciwutleniajaca wysokotaninowych ekstraktow z surowcow roslinnych

36%

Amarowicz R. , Troszynska A. , Karamac M.

Bromatologia i Chemia Toksykologiczna

|

2005

|

tom 38

|

nr Supl.

193-195

PL

Z nasion fasoli adzuki, gryki, kaszy gryczanej orzechów włoskich i laskowych oraz migdałów otrzymano ekstrakty związków fenolowych stosując 80% aceton. Zawartość fenoli ogółem i tanin w ekstraktach oznaczono metodami kolorymetrycznymi. Ekstrakty wykazywały zróżnicowaną aktywność przeciwutleniającą i antyrodnikową oraz różną zdolność do chelatowania Fe(II).

EN

The extracts of adzuki bean, buckwheat, buckwheat grits, walnuts, hazelnut, and almond were prepared using 80% acetone. The extracts were characterised for the content of total phenolics and tannins, antiradical activity, Total Antioxidant Activity, antioxidant activity in ß-carotene-linolcate model system, and Fe (II) chelating activity. The highest TAA value was noted for walnut extract (5,25 µmol Trolox/mg). This extract was also the best DPPH radical scavenger. The extracts of buckwheat and buckwheat acted as the best antioxidants in emulsion system. The best Fe (II) chelating properties were noted for walnut and buckwheat extracts.