Na+/K+-atpase - activity and inhibition

The aim of the study was to give an overview of the mechanism of inhibition of Na+/K+-ATPase activity. For this purpose, the effect of ouabain like compounds (digoxin, gitoxin), platinum group complexes ([PdCl4]2-, [PdCl(dien)]+ and [PdCl(Me4dien)]+), transition metal ions (Cu2+, Zn2+, Fe2+, Co2+) and heavy metal ions (Hg2+, Pb2+, Cd2+) on the activity of Na+/K+-ATPase isolated from rat synaptic plasma membranes (SPM), cortex of pig and human erythrocytes and was investigated.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Correlation of physico-chemical parameters and phytochemical profile of honeydew honeys with their botanical origin

Predmet istraživanja doktorske disertacije bilo je određivanje fizičko-hemijskih parametara i fitohemijskog profila medljikovaca u cilju definisanja biljnog porekla ove specifične vrste meda. Na osnovu fizičko-hemijskih parametara potvrđena je autentičnost uzoraka u pogledu načina proizvodnje, uzorci potiču od sokova koje luče biljke, ili ekskreta insekata koji se hrane tim sokovima. U cilju određivanja autentičnosti prema biljnom poreklu, pet vrsta medljikovaca (Abies alba Mill., Quercus ilex L., Quercus frainetto Ten., Acer monspessulanum L. i crnogorice) okarakterisano je prema šećernom i fenolnom profilu, δ13C vrednostima medljikovaca i proteina izolovanih iz medljikovaca, sadržaju esencijalnih i toksičnih elemenata, kao i sadržaju isparljivih jedinjenja. Za procenu antioksidativne sposobnosti primenjen je spektroskopski i elektrohemijski pristup. Metode multivarijantne analize korišćene su za dobijanje modela na osnovu kojih su identifikovani markeri biljnog porekla medljikovaca. Rezultati potvrđuju mogućnost procene autentičnosti medljikovaca zasnovane samo na fenolnom profilu i antioksidativnoj sposobnosti, kao i prednost primene ciklične voltametrije za određivanje antioksidativnog potencijala fenolnih jedinjenja u odnosu na spektroskopske metode. Sadržaj elemenata je takođe omogućio klasifikaciju medljikovaca prema biljnom poreklu, dok među šećerima nije pronađen marker koji je specifičan za neku biljnu vrstu. Analiza stabilnih izotopa ugljenika potvrdila je da su uzorci autentični u pogledu proizvodnje meda i da su dobijeni iz C3 biljaka, kao i da vrednosti δ13C proteina izolovanog iz medljikovca mogu takođe biti dobar pokazatelj biljnog porekla. Medljikovci iz roda Quercus spp., Quercus frainetto i Quercus ilex, pokazali su jedinstven hemijski profil.The main aim of this doctoral dissertation was to determine physico-chemical parameters and the phytochemical profile of the honeydew honeys in order to define the botanical origin of this specific type of honey. Physicochemical parameters confirmed that samples were authentic with respect to honey production and originated from secretion produced by certain trees and other plants or from excretions of plant-sucking insects. Authentication according to botanical origin of honeydew honey, for five botanical types (Abies alba Mill., Quercus ilex L., Quercus frainetto Ten., Acer monspessulanum L. and conifers), was performed using sugars and phenolic profiles, δ13C values of the honeydew honey and proteins isolated from the honeydew honey, the content of the essential and toxic elements as well as the content of the volatile compounds. Spectroscopic and electrochemical approaches were applied for evaluation of the antioxidant capacity. Multivariate chemometric analysis was used to obtain models for evaluation of markers of botanical origin. The results confirmed the possibility of assessing the authenticity of honeydew honey based only on the phenolic profile and antioxidant capacity, as well as the advantage of applying cyclic voltammetry to determine the antioxidant potential of phenolic compounds in comparison with spectroscopic methods. Elements content enable the classification of honeydew honey according to botanical origin, while no chemical marker has been found within sugar compounds. Stable isotope carbon analysis confirmed that the samples were authentic with respect to honey production and were obtained from C3 plants, while the values of δ13C of protein isolated from the honeydew honey could be a good indicator of botanical origin. Quercus spp. samples, Quercus frainetto and Quercus ilex, showed specific chemical composition

Inhibition of myeloperoxidase by quercetin

Reaction mechanism of quercetin induced inhibition of myeloperoxidase isolated from human neutrophils was proposed by following peroxidase activity of the enzyme, using the o-dianisidine and H2O2 as substrates. The dependence of initial reaction rate vs. H2O2 concentration in the absence and presence of quercetin revealed the reaction mechanism that involved the enzyme inhibition by the excess of the substrate. The rate and equililbria constants for proposed reaction paths were determinedPhysical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Interaction of some polyoxotunstates with acetylcholinesterase

Polyoxometalates (POMs) are polyanionic oligomeric aggregates of transition metal ions, such as tungsten, molybdenum, vanadium, etc. held together by oxygen bridges, with a high density of negative charge. They are relatively stable, some even highly stable in aqueous solutions at biological pH values. In addition to applications in catalysis, separations, analysis, and as electrondense imaging agents, some of these complexes have been shown to exhibit biological activity in vitro as well as in vivo ranging from anti-cancer, antibiotic, and antiviral to antidiabetic effects. Recent investigations reported some polyoxotungstates as reversible inhibitors of acetylcholinesterase (AChE), making them potential anti-Alzheimer’s drugs. AChE is a serine hydrolase mainly found at neuromuscular junctions and cholinergic brain synapses. Its principal biological role is the termination of impulse transmission at cholinergic synapses. Reversible inhibitors of AChE mostly have therapeutic applications, while toxic effects are associated with irreversible AChE activity modulators. Reversible inhibitors play an important role in the pharmacological manipulation of the enzyme activity, and have been applied in the diagnostic and/or treatment of various diseases such as: myasthenia gravis, AD, postoperative ileus, bladder distention, glaucoma, as well as antidote to anticholinergic overdose. The effect of four new synthesized polyoxotungstates soluble in water on AChE activity was studied. AChE is purified from electric eel and commercially available. The enzyme was treated in vitro with polyoxotungstates in the concentration range from 1 × 10-7 to 1 × 10-3 mol/L at 37ºC for 15 minutes, and the incubation time was 12 min. The obtained dependence remaining enzyme activity vs. the inhibitor concentration fitted the sigmoidal function. IC50values, indicating the enzyme sensitivity toward the inhibitor and the inhibitory capacity of the analyzed compounds, were determined from the inhibition sigmoidal curves. Na10[H2W12O42] × 27H2O did not markedly reduce AChE activity at the highest investigated concentration (1 mmol/L). K7[SiV3W9O40] × 10H2O exhibited a weak inhibitory potential, causing 50% decrease in the enzyme activity at 5 × 10-4 mol/L. However, AChE sensitivity in the presence of K7[Ti2PW10O40] was several hundred times higher, reaching IC50 at 1.15 × 10-6 mol/L. Furthermore, (NH4)14[NaP5W30O110] × 31H2O demonstrated the strongest capacity to inhibit AChE. In the presence of its low concentration of 2 × 10-8 mol/L, the enzyme activity was noticeably reduced related to the control value (obtained without inhibitor), while 50% decrease in AChE activity was achieved at 3.8 × 10-7 mol/L.Fourth International Conferenceon Radiation and Applications in Various Fields of Research, RAD 2016, May 23-27, 2016, Niš, Serbi

Interaction of gold nanoparticles with rat brain synaptosomal plasma membrane Na+/K+-ATPase and Mg2+-ATPase

The aim of the work was to investigate the interaction between borate capped gold nanoparticles (AuNPs) and the rat brain synaptosomal plasma membranes (SPM), as well as the effects of these AuNPs on SPM Na+ /K+ - ATPase and Mg2+-ATPase activity. Influence of AuNPs on Na+ /K+ -ATPase and Mg2+-ATPase activity was investigated as the function of AuNPs and protein concentration and preincubation time. AuNPs induced the stimulation of Na+ /K+ -ATPase activity for more than 100%, while Mg2+-ATPase activity reminded unaffected. We propose that this stimulation of enzyme activity was a consequence of an increase of the active surface of membranes.Physical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

Vasić, V. et al. Na+,K+-ATPase as the Target Enzyme for Organic and Inorganic Compounds. Sensors 2008, 8, 8321-8360

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Estimation of uncertainty of trypsin inhibitor activity measurement in legume crops

Irradiation of legume seeds has emerged as an attractive alternative compared to conventional chemical treatments in seed production. Irradiation is also used for the decontamination of food and feed in order to increase the shelf-life of fresh and dry food materials. The effects of irradiation on nutritive and anti-nutritive factors such as trypsin inhibitors are usually reported together with the measurements obtained by using the quantitative analytical methods. The objective of this study was to measure trypsin inhibitor activity (TIA) of common bean cultivar Oplenac using the microtiter plate method and to identify factors that contribute to the uncertainty of TIA measurement according to the current Guide to the Expression of uncertainty in measurement (GUM). Dominant sources of uncertainty of TIA measurement were: absorbance measurements of sample and positive control reaction mixtures and preparation of the final sample solution using a graduated cylinder (V4). Absorbance measurement of sample reaction mixtures took 37.8% of the overall measurement uncertainty. Preparation of the final sample solution using a graduated cylinder (V4) and absorbance measurement of positive control reaction mixture contributed to the overall uncertainty with 35.1% and 15.8%, respectively. Acquired insight into factors that contribute to the uncertainty of TIA measurement gives directions for the improvement of TIA testing methods and TIA results management

Photochemical degradation of digoxin tested by Na,K-ATPase activity

The photochemical degradation of digoxin aqueous solution was obtained by Xelamp irradiation. The concentrations of digoxin in irradiated solutions were detected by measurements of Na,K-ATPase activity and by HPLC analysis. The excellent agreement using two independent methods for determination of digoxin concentration in the irradiated samples was achieved.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

The influence of diazinon and its metabolites on acetylcholinesterase, NA+/K+-ATPase and antioxidant enzymes in rat brain synaptosomes

The aim of this study was to investigate neurotoxic potential and oxidative stress responses of diazinon and its metabolites, diazoxon and 2-isopropyl-6-methyl-4-pyrimidinol using synaptosomes as a model system. Synaptosomes were isolated from the brain of Wistar albino rats and incubated at 37oC for 1 hour in the presence of selected concentrations of the investigated compounds. Acetylcholinesterase, Na+/K+-ATPase and antioxidant enzymes activities were determined by standard spectrophotometric methods. Diazinon induced concentration-dependent acetylcholinesterase and Na+/K+-ATPase inhibition, while the activity of catalase, superoxide dismutase and glutathione peroxidase was not significantly affected. Increasing concentrations of diazoxon, oxo analog of diazinon, caused almost complete acetylcholinesterase and Na+/K+-ATPase inhibition, and activated antioxidant enzymes: catalase (up to 25%), superoxide dismutase (up to 55%) and glutathione peroxidase (up to 30%). Unlike diazoxon, diazinon hydrolysis product, 2-isopropyl-6-methyl-4-pyrimidinol did not remarkably change the activities of the investigated enzymes, except superoxide dismutase that was stimulated up to 25%. The obtained results suggest that neurotoxic and prooxidative potential of diazinon, thioorganophoshate used as a commercial insecticide preparation, significantly reinforces mostly due to its transformation to diazoxon in the metabolic pathways.Third International Conferenceon Radiation and Applications in Various Fields of Research, RAD 2015, June8-12, 2015, Budva, Montenegr