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1947 M20 М23 Ispitivani su uticaji primene mono- i dvokomponentnih organskih modifikatora na određivanje lipofilnosti 12 tetradentatnih Šifovih baza metodom reverzno-fazne tankoslojne hromatografije. Osnovni cilj je da se proceni tip interakcije između posmatranih jedinjenja i komponenti primenjenih hromatografskih sistema i uspostavi neki obrazac ponašanja kako bi se lakše izabrala kombinacija organskih modifikatora koji će simulirati interakciju u biološkim sistemima na osnovu činjenica da iste osnovne intermolekularne interakcije su odgovorne za ponašanje supstanci i u biološkom i u hromatografskom sistemu. Primenjeni organski modifikator pokazuje sposobnost modifikacije površine primenjenog sorbenta, što utiče na ispoljavanje lipofilnosti posmatranih jedinjenja. Korišćeni su jednokomponentni organski modifikatori iz različitih grupa Snajderovog trougla, kao i njihove dvokomponentne smeše. Pored toga, uporedili smo eksperimentalno određene izračunate parametre lipofilnosti. The influences of the application of mono- and two-component organic modifiers on lipophilicity determination of 12 tetradentate Schiff bases by reversed-phase thin layer chromatography were investigated. The main goal is to estimate types of interaction between observed compounds and components of the applied chromatographic systems and establish some behaviour pattern in order to easier choose a combination of organic modifiers which will simulate interaction in biological systems based on the facts that the same basic intermolecular interactions are responsible for the behaviour of substances in both the biological and chromatographic system. The applied organic modifier shows the ability to modify the surface of the applied sorbent, which affects the manifestation of lipophilicity of the observed compounds. Mono-component organic modifiers from different groups of the Snyder triangle were used, as well as their two-component mixtures. In addition, we compared experimentally determined calculated parameters of lipophilicity. more...

Background: Diazepam belongs to the group of 1,4-benzodiapines. It is used for the treatment of anxiety, convulsions and as muscle relaxants. The presence of a 4,5-azomethine group enables its electrochemical detection. Introduction: A screen-printed electrode modified with antimony film was used for the determination of diazepam in pharmaceutical preparations Methods: Electrode modification was done by ex-situ deposition of antimony on a commercially available screen-printed electrode. Parameters affecting the electroanalytical response of the sensor, such as deposition potential, deposition time, and antimony concentration, were examined and optimized. The modified electrode showed enhanced electroactivity for diazepam reduction compared to the unmodified electrode. Under optimal conditions, linear sweep voltammetry was used for the determination of the analyte. Results: The sensor showed linear dependence in the range from 0.5 to 10 μmol/L, the correlation coefficient was 0.9992. The limit of detection was 0.33 μmol/L, corresponding limit of quantification was 1.08 μmol/L. Modification enabled determination of diazepam in the presence of oxygen. Conclusion: The modified electrode was used for the determination of diazepam in tablets. Results confirmed the applicability of the electrochemical sensor. more...

Papain is a proteolytic enzyme of great commercial value. It is a cysteine protease highly expressed in Carica papaya fruit latex, but also present in papaya leaves. Purification procedures mostly deal with the latex and include a combination of precipitation and/or chromatographic techniques. Due to its solubility, structure and activity characteristics, the pH and salt content play significant roles in handling papain extracts. Here we report a simple, rapid and easily scalable procedure for papain purification from papaya leaves, which contain different contaminants as compared to papaya latex. Sodium chloride precipitation of contaminants at pH 5 followed by ammonium sulphate precipitation resulted in the removal of other leaf proteins and protein fragments from papain solution and about a 3-fold purification. The procedure also benefits from the suppression of autoproteolysis and preservation of the native structure, as confirmed by FTIR analysis, and the high recovery of activity of over 80%. more...

In this study carbon cryogel, cryogel doped with nitrogen, and both nitrogen and sulfur co-doped carbon cryogels (nominal concentration of nitrogen was in the range 2–10 wt%) were synthesized and used as an adsorbent for the removal of carbamazepine, naproxen, diazepam and diclofenac from water. A batch adsorption kinetics study was performed by determination of contact time influence, the effect of pH, and adsorption isotherms. Structural and morphological analysis showed that there are no changes in turbostratic carbon structure induced by doping/co-doping, but noticeable morphology changes were observed. The presence of both nitrogen and nitrogen/sulfur were confirmed and results showed low content on the surface, especially for sulfur. Obtained high values of the specific surface area for co-doped samples (up to 1530 m2/g) can be caused by sulfur atoms burning or leaving the material during carbonization. The results of the adsorption kinetics study showed that the adsorption of all pharmaceuticals on all tested samples followed the pseudo-second-order kinetic model. The maximum adsorption capacity obtained from the Langmuir isotherm model is higher for doped (91.28–168.92 mg/g) and co-doped (152.97–488.06 mg/g) samples than for pristine sample (59.75–266.28 mg/g). Calculated adsorption energy values from the Dubinin-Radushkevich model indicate that the possible mechanism was physisorption. Desorption tests that were carried out showed satisfactory reusability for all samples. The favorable adsorption characteristics for the co-doped sample with a higher nominal concentration of nitrogen and sulfur qualifies as a potentially good adsorbent for the removal of pharmaceuticals from water. more...

Graphite furnace atomic absorption spectroscopy (GFAAS) was applied to identification of historical pigments. The method is adapted to determine different metals, usually found in pigments. Operating conditions were optimized, such as sample drying step, pyrolysis and atomization temperatures, modifiers, and volume of sample introduced into the atomizer, to reduce interferences due to a complex sample matrix. Using the optimized method pigments in samples from the painting Coronation of the Virgin from the Church of the Shroud of the Holy Virgin in Barič were identified. The samples were analyzed also by Raman microscopy to verify the identification achieved by GFAAS. Raman microscopy confirmed the assumptionsmade based on GFAAS results. Using the two techniques a variety of pigments have been identified, such as calcite, leadwhite, goethite, hematite, ultramarine, vermilion, minium, carbon black. Based on GFAAS results the presence of azuritewas observed in the blue paint sample, although this finding was not confirmed by Raman microscopy. Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/4949] more...

Gallic acid (GA) is one of the most important and present natural phenolic compounds due to its well-known biological properties, and its detection and monitoring is of great importance. Silver nanoparticles (AgNPs) are one of the most studied metallic nanomaterials used in various fields, from biomedical applications to electrochemical sensing devices. In this work, we used the pulsed laser ablation technique in liquid for the one-step preparation of nanoparticles of silver from a pure silver plate base in N,N-dimethylformamide. Obtained nanomaterial was characterized using morphological and electrochemical methods and used for modification of screen-printed carbon electrodes (SPCE). Successful immobilization at the surface is confirmed using the surface profiling method. A newly obtained sensor was used for the detection of GA. After parameters optimization, a differential pulse voltammetric protocol was developed, using two approaches - concentration vs. current (GA determination) and peak area vs. current (estimation of the antioxidant capacity). For the first approach sensor linearity was found to be in the range from 0.50 µM to 10 µM, with the limit of detection (LOD) of 0.16 µM and limit of quantification (LOQ) of 0.50 µM. In the second system operating linear range was the same, while LOD and LOQ were 0.11 µM and 0.34 µM, respectively. Practical application of the method was tested using two approaches: direct measurement of gallic acid in biological fluids and estimation of the antioxidant capacity and food quality purpose. Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/5717] more...

The aggregation of proteins into fibrillar, amyloid-like aggregates generally results in an improved, positive effect on various techno-functional properties within food products, such as gelation, emulsification, and foam stabilization. These highly stable structures, characterized by their repetitive, β-sheet rich motifs, may develop as the result of the thermal treatment of protein-rich food products. Heavy metal ions can influence amyloid-like aggregation of food proteins. Lead(II) and cadmium(II) represent some of the most abundant and common environmental water and food pollutants. In this work, the influence of heavy metal ions, lead and cadmium on amyloid-like aggregation of ovalbumin at high temperatures (90 °C) and under acidic conditions (pH 2.0) was investigated. Ovalbumin is used as a general model for how heavy metals can affect amyloid-like aggregation of a food protein. Structural changes were monitored via Thioflavin T and 8-Anilino-1-naphthalenesulfonic acid fluorescence, Fourier-Transform infrared spectroscopy, atomic force microscopy, dynamic light scattering, as well as computational analyses. The obtained results indicate that the added heavy metal ions bind to different sites within ovalbumin prior to thermal treatment. Lead binding sites are closer to the hydrophobic regions of an protein, while cadmium ion binding sites are more exposed. This specific binding of metal ions affects the morphologies of amyloid-like aggregates, resulting in lead-induced branching of amyloid-like fibrils, or cadmium-induced tangling of fibrils into dense amyloid clusters. This additive effect of heavy metal ions is most evident in ovalbumin samples which contain a mixture of both heavy metal ions. more...

164 161 М60 М63 In this work, biochar originating from paper fibres was examined. Biochar was prepared via pyrolysis method at 550°C. Oxygen-containing functional groups on biochar surface were determined. The surface functional groups of biochar were analysed by Fourier transform infrared spectroscopy. The amount of oxygen-containing functional groups was performed with Boehm titration. The total acidity of biochar was mostly attributed to carboxylic and lactonic groups. more...

М60 М64 Kompleksi metala sa tetradentatnim Šifovim bazama ispoljavaju različitu biološku aktivnost, što omogućava ciljne sinteze novih biološki aktivnih jedinjenja. Proučavane su interakcije H[Rh(acac2en)Cl2] (1) i H[Rh(phacac2en)Cl2] (2) sa humanim serum albuminom (HSA) i sa DNK, primenom fluorescentne i UV-Vis spektroskopije (298 K, pH 7,4). Dobijene su relativno visoke vrednost dinamičke konstante vezivanja (Ksv) i to 3,88·104 M-1 za (1), 7,02·104 M-1 za (2), što ukazuje na značajno vezivanje za HSA. Izračunate konstante unutrašnjeg vezivanja (Kb) su: 2,87·105 M-1 za (1), 4,22·105 M-1 za (2). Vrednosti navednih konstanti ukazuju na dobru interakciju između kompleksa Rh(III) i DNK. Ponašanje ispitivanih kompleksa je u saglasnosti sa razlikama u njihovim strukturama. Moleksulski doking potvrđuje dobijene eksperimentalne podatke različitih interakcija u kojima se kompleks vezuje za molekul proteina. Tetradentate Schiff base metal complexes exhibit different biological activity, which enables targeted syntheses of new biologically active compounds1. The interaction of H[Rh(acac2en)Cl2] (1) and H[Rh(phacac2en)Cl2] (2) with human serum albumine (HSA) and with DNA by fluorescence and UV-Vis spectroscopy (at 298 K, pH 7.4) were investigated. Relatively high values of the dynamic quenching constant (Ksv) are obtained: 3.88·104 M-1 for (1), 7.02·104 M-1 for (2), which indicates binding to HSA. Calculated intrinsic binding constants (Kb) which are 2.87·105 M-1 for (1), 4.22·105 M-1 for (2) suggest a good interaction between the Rh(III) complexes and DNA. The behavior is in accordance with differences in structures of investigated compounds. Molecular docking studies confirm experimental findings of different interactions through which complexes are bound to the protein molecule. more...

This paper describes the determination of Pb and Cu with a Nafion-modified glassy carbon electrode and MnCo2O4 nanoparticles as working electrode for anodic stripping voltammetry. Pb and Cu were accumulated in HCl/KCl (0.1 mol dm-3) at a potential of -1.4 V (vs. Ag/AgCl electrode) for 480 s, followed by a linear sweep anodic stripping voltammetry (ASV) scan from -1.0 to +0.5 V. Under optimum conditions, the calibration curves were linear in the range of 0.01 - 8 and 0.01 - 5 mg dm-3 for Pb and Cu, respectively. Effect of sample dilution, accumulation time and potential were optimized. A study of interfering substances was performed. A significant increase in current was obtained at the modified electrode in comparison with the bare glassy carbon electrode. The modified electrode was successfully applied for determination of Pb and Cu in wine samples after a simple preparation procedure. Pb and Cu content in wine was used for estimation of the target hazard quotient (THQ) values for minimal and maximal levels of the metals. more...

Uvod: Kofein je prirodni alkaloid, izolovan iz više od 60 biljnih vrsta. Preko 80 % svetske populacije svakodnevno unosi kofein u organizam kroz konzumaciju kafe, čajeva, čokolade i, u poslednje vreme, energetskih pića. Ne treba zanemariti činjenicu da kofein, kao farmakološki aktivna supstanca, ulazi u sastav mnogih lekova koji se na tržištu Republike Srbije izdaju bez lekarskog recepta. Sem toga, kofein je psihoaktivni stimulans, blag je diuretik i pokazuje interakciju sa nekim lekovima usled indukcije CYP1 i CYP2 izoenzima, zbog čega je potrebno voditi računa o količini koja se unese u organizam. U skladu s tim, važno je i da sadržaj kofeina u energetskim pićima odgovara podacima koje proizvođači navode na deklaraciji. Cilj: Cilj ovog rada bio je spektrofotometrijsko određivanje sadržaja kofeina u uzorcima energetskih pića i čajeva proizvođača dostupnih na tržištu R. Srbije. Materijal i metode: Kofein je određivan metodom ultraljubičaste i vidljive (UV/VIS) spektrofotometrije u devet vrsta energetskih pića i po četiri uzorka crnog i zelenog čaja. Rezultati: U uzorcima energetskih pića određeni sadržaj kofeina je u opsegu od 26,81 do 35,44 mg/100 mL i u skladu je s deklarisanim sadržajem. Sadržaj kofeina u uzorcima čajeva varira u odnosu na vrstu (11,27-22,61 mg/100 mL zeleni i 13,85-22,73 mg/100 mL crni), ali je vezan i za poreklo, uslove gajenja i proces prerade čajeva. Zaključak: Ultraljubičasta i vidljiva spektrofotometrija se pokazala kao brza, precizna i jednostavna metoda za određivanje kofeina u energetskim pićima i čajevima. Imajući u vidu dobijene rezultate, važno je istaći da unos kofeina kroz uobičajenu dnevnu konzumaciju čajeva i energetskih pića ne bi trebalo da utiče negativno na zdravlje ljudi. Svakako treba imati u vidu da se ovaj alkaloid dodatno može uneti i putem drugih izvora, što je posebno važno za određene grupe pacijenata. Introduction: Caffeine is a natural alkaloid, isolated from more than 60 plant species. Over 80% of the world’s population consumes caffeine on daily basis through the consumption of coffee, tea, chocolates and, more recently, energy drinks. As a pharmacologically potent substance caffeine is an ingredient of many medicaments available on the pharmaceutical market of Republic of Serbia without a doctor’s prescription. Besides that, caffeine acts as a psychoactive stimulant, mild diuretic, and displays an interaction with some medicaments due to the induction of CYP1 and CYP2 isoenzymes. Keeping in mind all of the above, it is necessary to take into account the daily caffeine intake, as well as to control its content in energy drinks.Aim: The aim of this study was spectrophotometric determination of caffeine content in energy drinks and tea, available in markets of the Republic of Serbia. Material and Methods: Caffeine was determinated by UV/VIS spectrophotometry in nine types of energy drinks and eight samples of black and green tea. Results: The results showed that caffeine content in energy drink samples ranged from 26.81 to 35.44 mg/100mL and corresponds to declaration. The caffeine content in tea samples varies with the species (11.27-22.61 mg/100mL for green and 13.85-22.73 mg/100mL for black tea), but also with origin, growth conditions and tea processing.Conclusion: The obtained data suggest that UV/VIS spectrophotometry can be used for ro-utine determination and control of caffeine content in energy drinks and tea. It is important to note that caffeine intake through the usual daily consumption of tea and energy drinks should not have a negative impact on human health, but this alkaloid could be additionally consumed through other sources, which is especially important for certain groups of patients. more...

A chemical characterization and biological activity of 7 honey types (multifloral, linden, rapeseed, sunflower,phacelia, acacia and honeydew honey) from different regions of Serbia were presented. The physicochemicalcharacteristics, mineral content, antioxidant and antimicrobial activity were estimated and discussed. All honeysshowed good nutritional characteristics, according to the adopted criteria of the standard codex for honey. Theconcentrations of 15 elements in honey samples were determined using inductively coupled plasma opticalemission spectroscopy (ICP-OES). Limits of quantification were in the range from 0.003 mg/kg (Cd, Cr, Cu, Mn,and Pb) to 1.50 mg/kg for sodium. Precision was expressed as relative standard deviation and its values werelower than 1.50%. Accuracy was evaluated with certified reference material (fish protein, DORM 4, NRC andcooking chocolate, SRM 2384, NIST) and obtained recovery percentages were 71-127%. The content of the mostabundant elements (K, Mg, and Na) and microelements (Al, Cu, Fe, Mn, Ni, Se, Si, and Zn) showed a significantvariability in accordance of their botanical and geographical origin, but also the influence of harvest conditions.The levels of toxic metals (As, Cd, Cr, and Pb) are much lower than the maximal allowed for these metalsaccording to European Commission Regulation. The antioxidant activity was evaluated by DPPH(Diphenylpicrylhydrazyl) assay while antimicrobial activity against Gram positive and Gram negative bacteria(E. coli and S. aureus) and fungi Candidi albicans was estimated by microdilution assay. The free radicalscavenging assay (%RSA) varies significantly among the honey samples. The highest antioxidant activity wasobserved with honeydew honeys (over 75% RSA) and the lowest was observed in the acacia, ranging from 22.96to 24.57% RSA. All honeys tested in this study exhibited antibacterial activity, with inhibition of bacterialgrowth, generally the higher against E. coli (80% for linden honeys) than against S. aureus (mostly much lowerthan 50%). Activity against Candidi albicans was almost negligible. The dataset composed of all experimentalresults was subjected to a chemometric evaluation and cluster analysis as hierarchical nonsupervised methodwas applied. According to the obtained outcome of applied algorithms, both botanical and geographical originhave important role in the elemental composition, antioxidant and antimicrobial activities. This is the peer-reviewed version of the following article: Đogo Mračević, S.; Krstić, M.; Lolić, A.; Ražić, S. Comparative Study of the Cheical Composition and Biological Potential of Honey from Different Regions of Serbia. Microchemical Journal 2020, 152, 104420. [https://doi.org/10.1016/j.microc.2019.104420]. Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/4996] more...

М30 М34 Šifove baze i njihovi Cu(II) kompleksi su poznati po svojoj biološkoj aktivnosti. U ovom radu proučavana je antibakterijska aktivnost protiv gram-negativnih sojeva Escherichia coli, Pseudomonas aeruginosa i Staphilococcus piogenes, kao i Gram-pozitivnih Staphilococcus piogenes i Pseudomonas aeruginosa, zajedno sa antifungalnim dejstvom protiv Musperg strainilusa, A. Takođe, tehnički jednostavni i brzi testovi kao što su ABTS, HORAC i ORAC korišćeni su za ispitivanje antioksidativne aktivnosti kako bi se uporedili dobijeni rezultati sa različitim tipovima testova. Uprkos tome što je princip svake grupe antioksidativnih esejnih metoda sličan, osetljivost primenjenih metoda za ispitivanje antioksidansa zavisi od različitih faktora, kao što su pH medijuma, prisustvo lipofilnog i/ili hidrofilnog dela i supstituenata ispitivanih jedinjenja. Proučavani Cu(II) kompleksi su pokazali bolju antimikrobnu aktivnost u poređenju sa odgovarajućim Šifovim bazama. Jedinjenja su pokazala antioksidativna svojstva uklanjanja slobodnih radikala. Rezultati različitih metoda otkrili su da jedinjenja mogu donirati elektron ili vodonik i nakon toga reagovati sa slobodnim radikalima ili prekinuti lančane reakcije u obrascu koji zavisi od doze. Schiff bases, and their Cu(II) complexes, are known for their biological activity. In this work, antibacterial activity against Gram-negative strains of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus pyogenes, as well as Gram-positive Staphylococcus pyogenes and Pseudomonas aeruginosa was studied, together with antifungal activity against Candida, Aspergillus, and Mucor strains. Also, technically simple, and rapid tests like ABTS, HORAC, and ORAC were used to investigate the antioxidant activity in order to compare obtained results with different type of tests. Despite that principle of each group of the antioxidant assay methods is similar, The sensitivity of the antioxidant assay methods applied depends on various factors, such as media pH, the presence of lipophilic and/or hydrophilic part and substituents of the investigated compounds. The studied Cu(II) complexes showed better antimicrobial activity compared to corresponding Schiff bases. The compounds exhibited antioxidant properties of scavenging free radicals. The results from different methods revealed that compounds can donate an electron or hydrogen and subsequently react with free radicals or terminate chain reactions in a dose-dependent pattern. more...

A new glucose biosensor for selective and sensitive determination of glucose in beverage samples was developed. A copper complex with a Schiff base, N,N’-bis(acetylacetonato) propylenediimine, was used as a mediator. It was mixed with glucose oxidase (GOx) and prepared as carbon paste electrode (CPE). Cyclic voltammetry was used for electrochemical measurements. The biosensor showed improved sensitivity when enzyme mediator ratio was 1 : 5, and working pH was 6.6 in 0.1 M phosphate buffer. The linear response of the biosensor for glucose concentration was in the range from 0.5 to 10 mM, with low detection limit of 0.36 mM (calculated as 3 s/n) and sensitivity of 0.16 μA/mM. The reproducibility of the biosensor, calculated as relative standard deviation, was 1.9% for 6 intra-day measurements. Biosensor was stored at +4 °C between experiments, and it was stable during 14 days after the preparation. The developed biosensor was applied on determination of glucose in commercial beverages (apple and cherry juice) and obtained results showed good agreement with the reference method. more...

A method using modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) without clean-up step based on the sample dilution approach followed by the liquid chromatography coupled with the tandem mass spectrometry (LC-MS/MS) has been established for determination of 179 pesticide residues in cabbage and rice samples. Two different LC columns were used and their sensitivity was investigated regarding the sample volume. Evaluation of the matrix effect in context of sample dilution and applied extraction solvents was investigated. The method was validated according to Document SANTE/12682/2019. For cabbage samples, recoveries were 70–120% for concentration level of 5 μg/kg; and 70–115% for concentration level of 50 μg/kg; precision RSDr more...

The improvement of living standards has a significant impact on food and food production. Meat and meat products, due to their high nutritional value, are an important segment of human nutrition and a rich source of elements such as Fe, Zn, Mn, Ca, K, Mg. On the other hand, meat can accumulate heavy metals such as Cd and Pb. Toxic metal concentrations in the muscles are rare, but the liver and kidneys have an ability of accumulation. Nitrites are very important in the meat industry as additives and preservatives, but downside effects of nitrite addition are the development of toxic and carcinogenic nitrosoamine. In monitoring the quality of meat and meat products, it is important to keep track of metal content, but also the residual concentration of nitrite. The aim of this study was to determine the content of Cd, Cu, Fe, and Zn in samples of pork and beef meat and pig liver and the content of nitrites in samples of pork and beef meat and meat products - patches and sausages. Metals were determined using the ICP-AES method and nitrate by the standard method SRPS ISO 2918/1999. The content of iron in the liver, pork and beef meat is 189.2 μg / kg, 89.78 μg / kg and 87.79 μg / kg respectively. The content of Cu and Zn in all tested samples is below MAC values, and Cd in pork meat sample is 1.2 times more than MAC values. The content of nitrite is below the MAC values and represents the residual concentration of these compounds. more...

The influence of additives (alkyl polyglucoside, Glucopon 600 CS UP and alcohol ethoxylate C18E100) on the behavior of the water/toluene/Lutensol ON 50 (technical oxoalcohol, i-C10E5) microemulsion system as a function of temperature and composition has been investigated. The phase behavior of the microemulsions was determined by vertical sections through the Gibbs phase prism (fish-like phase diagrams). Alkyl polyglucoside shifts the one phase region to lower temperatures compared with water/toluene/Lutensol ON 50 mixtures. This is contrary to the expectation, considering the extreme hydrophilic nature of the sugar headgroup. The addition of hydrophilic alcohol ethoxylate (C18E100) to the water/toluene/Lutensol ON 50 system increases the solubilization capacity of the surfactant, even if the co-surfactant is used in small quantities, and shifts the one-phase region to higher temperature by a few degrees Celsius. [Projekat Ministarstva nauke Republike Srbije, br. 172051] more...

Cobalt(III) complexes derived from thio- and selenosemicarbazone ligands have been studied to elucidate the nature and consequences of S to Se substitution on their possible biological activity. Solid state structures of cobalt(III) complexes with bis-tridentate coordinated 2-quinolinecarboxaldehyde thio- and selenosemicarbazone were determined by single crystal X-ray diffraction analysis. The complexes were also characterized by spectroscopic methods and cyclic voltammetry. Electronic properties of the complexes were studied using DFT and TD–DFT methods. Finally, evident in vitro antioxidant activity of the complexes was demonstrated. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172035 and Grant no. 172055] more...

This study describes the effects of the substituents on electrochemical behavior and antioxidant activity of the six tetradentate Schiff bases, containing ethane-1,2-diamine or propane-1,2-diamine as the amine part and pentane-2,4-dione and/or 1-phenylbutane-1,3-dione as beta-diketone, and corresponding copper(II) complexes. Cyclic voltammograms of these compounds were recorded in dimethylsulfoxide and 0.1 M sodium perchlorate as supporting electrolyte with glassy carbon as working electrode at different scan rates. The voltammograms of Schiff bases alone showed only one irreversible peak. Voltammograms recorded for complexes showed the presence of quasi-reversible processes taking place at the metal center and reversible process at the ligand part. Both steric and inductive effects of substituents and structure of imine bridge of Schiff base ligands as well as complexes were discussed. These effects appear relevant for the antioxidant activity. Antioxidant activity of the investigated compounds expressed as Trolox equivalent antioxidant capacity is also discussed. The electrochemical behavior showed a high correlation with the antioxidant activity for investigated compounds. more...

A gas-diffusion flow injection method with amperometric detection for indirect copper determination on a silver electrode is developed. The flow through system is equipped with two injection valves and a gas-diffusion unit. In the first step, a signal of cyanide solution was recorded. In the following step a signal of cyanide in the presence of copper was measured. Interferences (Cd(II), Co(II), Ag(I), Ni(II), Fe(III), Hg(II) and Zn(II)) were investigated and successfully removed. The calibration graph is linear in the range 1-90 μmol dm-3 of copper, correlation coefficient is 0.993, the regression equation is I = (0.0455±0.0015)c + (0.4611±0.0671), I is relative signal decrease in μA and c is concentration in μmol dm-3. Relative standard deviation for six consecutive injections of 30 μmol dm-3 copper(II) was 1.47 % and for 1 μmol dm-3 copper(II) was 3.40 %. The detection limit, calculated as 3 s/m (where s is a standard deviation of nine measurement of a reagent blank and m is the slope of the calibration curve), was 0.32 μmol dm-3, which corresponds to 2.44 ng of copper(II) (loop volume was 0.12 cm3). The method enables 60 analyses per hour and it was successfully applied on determination of copper in drinking water samples. [Acknowledgements. The authors acknowledge the grant from the Ministry of Education and Science of the Republic of Serbia, Project number 172051] more...

A rapid, selective, and sensitive kinetic flow-injection method for iodide content determination with amperometric detection on a platinum electrode was developed. The method is based on the catalytic effect of iodide on the Mn3+ reaction with As3+ in the presence of sulfuric acid. The calibration curve was linear in the concentration range from 5.0 x 10(-7) to 1.0 x 10(-4) mol/L iodide. The limit of detection (LOD) was found to be 5.0 x 10(-9) mol/L iodide. The relative standard deviations (RSD) were 1.68% and 3.03% for 1.0 x 10(-3) mol/L standard and 1.0 x 10(-6) mol/L iodide solution (n = 6), respectively. The method has been successfully applied for determination of iodide in waters, table salts, fodder, organic substances and human blood sera. The results were compared with those obtained by a standard AOAC (Association of Official Analytical Chemists) method, as well as with those obtained by a kinetic spectrophotometric procedure for determination of iodide. Free full text: [https://doi.org/10.2116/analsci.21.525] more...

An analytical methodology for the simultaneous determination of seven pharmaceuticals and two metabolites belonging to the non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics therapeutic groups was developed based on off-line solid-phase extraction and ultra-high performance liquid chromatography coupled to tandem mass spectrometry (SPE-UHPLC-MS/MS). Extraction conditions were optimized taking into account parameters like sorbent material, sample volume and sample pH. Method detection limits (MDLs) ranging from 0.02 to 8.18 ng/L were obtained. This methodology was successfully applied to the determination of the selected pharmaceuticals in seawater samples of Atlantic Ocean in the Northern Portuguese coast. All the pharmaceuticals have been detected in the seawater samples, with pharmaceuticals like ibuprofen, acetaminophen, ketoprofen and the metabolite hydroxyibuprofen being the most frequently detected at concentrations that can reach some hundreds of ng/L. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3362] more...

The occurrence of seven pharmaceuticals and two metabolites belonging to non-steroidal anti-inflammatory drugs and analgesics therapeutic classes was studied in seawaters. A total of 101 samples covering fourteen beaches and five cities were evaluated in order to assess the spatial distribution of pharmaceuticals among north Portuguese coast. Seawaters were selected in order to embrace different bathing water quality (excellent, good and sufficient). Acetaminophen, ketoprofen and the metabolite hydroxyibuprofen were detected in all the seawater samples at maximum concentrations of 584, 89.7 and 287 ng L-1, respectively. Carboxyibuprofen had the highest seawater concentration (1227 ng L-1). The temporal distribution of the selected pharmaceuticals during the bathing season showed that, in general, higher concentrations were detected in August and September. The environmental risk posed by the pharmaceuticals detected in seawaters towards different trophic levels (fish, daphnids and algae) was also assessed. Only diclofenac showed hazard quotients above one for fish, representing a potential risk for aquatic organisms. These results were observed in seawaters classified as excellent bathing water. Additional data is needed in order to support the identification and prioritization of risks posed by pharmaceuticals in marine environment. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3340] more...

The lipophilic character of polydentate Schiff bases was investigated by reversed-phase thin-layer chromatography. In order to determine retention parameter as a measure of the lipophilicity of the tested compounds, three different binary solvent systems, composed of water and organic modifier (methanol, acetonitrile, and tetrahydrofuran), were used. Lipophilicity parameters together with 2D molecular descriptors were subjected to the multivariate statistical analysis. Principal component analysis was employed to reveal the most influential factors governing the lipophilicity of the investigated compounds. Finally, the influence of organic modifier on determination of lipophilicity parameters was discussed. more...

Proteomic approach in combination with mass spectrometry demonstrates a great potential for identification of proteinaceous materials in works of art. In this study we used a linear trap quadrupole Orbitrap (LTQ-Orbitrap), a state-of-the-art mass spectrometer for parts per million accuracy analyses of peptides behind tryptic hydrolysis. After the efficiency of the proteomic method was confirmed for reference and model samples, micro-samples from historical paintings were for the first time analysed using this technique. Superior performances of the liquid chromatography–mass spectrometry approach using a LTQ-Orbitrap mass spectrometer allowed identification of egg yolk peptides in two samples from nineteenth-century Orthodox icons, indicating egg tempera as the painting technique. Accurate precursor ion masses, in the range of ±2 ppm, and retention times of tryptic peptides strengthen protein identification. Additionally, in all historical samples the presence of animal glues suggested that the ground layer was likely bound using bovine collagen. Comparing to results acquired using matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry in our previous study, here we achieved higher ion scores and protein scores, better sequence coverage and more identified proteins. In fact, a combination of the two mass spectrometric techniques provided overlapping and complementary data, related to the detection of peptides with different physicochemical properties. more...

Schistosomiasis is a serious disease currently estimated to affect more that 207 million people worldwide. Due to the intensive use of praziquantel, there is increasing concern about the development of drug-resistant strains. Therefore, it is necessary to search for and investigate new potential schistosomicidal compounds. This work reports the in vivo effect of the alkaloid epiisopiloturine (EPI) against adults and juvenile worms of Schistosoma mansoni. EPI was first purified its thermal behavior and theoretical solubility parameters charaterised. In the experiment, mice were treated with EPI over the 21 days post-infection with the doses of 40 and 200 mg/kg, and 45 days post-infection with single doses of 40, 100 and 300 mg/kg. The treatment with EPI at 40 mg/kg was more effective in adult worms when compared with doses of 100 and 300 mg/kg. The treatment with 40 mg/kg in adult worms reduced parasite burden significantly, lead to reduction in hepatosplenomegaly, reduced the egg burden in faeces, and decreased granuloma diameter. Scanning electron microscopy revealed morphological changes to the parasite tegument after treatment, including the loss of important features. Additionally, the in vivo treatment against juvenile with 40 mg/kg showed a reduction of the total worm burden of 50.2%. Histopathological studies were performed on liver, spleen, lung, kidney and brain and EPI was shown to have a DL50 of 8000 mg/kg. Therefore EPI shows potential to be used in schistosomiasis treatment. This is the first time that schistosomicidal in vivo activity of EPI has been reported., Author Summary Schistosomiasis, a disease caused by worms from the genus Schistosoma, is one of the most widespread neglected tropical diseases in the world. Due to the intensive use of praziquantel, some reports of drug resistance have emerged. Thus it is important to search for new chemotherapeutic agents for the treatment disease. This research showed that epiisopiloturine, an imidazole alkaloid extracted from the leaves of Pilocarpus microphylus, has activity against S. mansoni in vivo. This material is produced as a by-product of an existing commercial process, and thus can be produced in large quantities at relatively low cost. The low toxicity and high drug tolerance in mammals shows the potential of epiisopiloturine as a new candidate schistosomicidal compound. more...

A selective and sensitive procedure for the fast and indirect determination of chloride by the gas-diffusion FIA method has been optimized and applied for the determination of chloride in water samples which contained different amounts of the analyte. The examined samples were: seawater, tap water and very pure water from the water- steam system of the power plant ?Nikola Tesla B? in Obrenovac. Application of an amperometric detector (model LC-17A; BAS, West Lafayette, USA) enables the detection limit to be decreased down to 0.05 ?mol/dm3 of chloride, which corresponds to 35.5 pg, and adjustment of the acceptor flow rate and direction inside the gas-diffusion unit. In this way the optimized FIA system has excellent repeatability. For 5 ?mol/dm3 it was found to be 1.11 % (n=5). The throughput of this method is 60 samples per hour. more...

The retention behavior and lipophilicity parameters of some antiphychotics were determined using reversed-phase thin layer chromatography. Quantitative structure-activity relationships studies have been performed to correlate the molecular characteristics of observed compounds with their retention as well as with their chromatographically determinated lipophilicity parameters. The effect of different organic modifiers (acetone, tetrahydrofuran, and methanol) has been studied. The retention of investigated compounds decreases linearly with increasing concentration of organic modifier. The chemical structures of the antipsychotics have been characterized by molecular descriptors which are calculated from the structure and related to chromatographically determinated lipophilicity parameters by multiple linear regression analysis. This approach gives us the possibility to gain insight into factors responsible for the retention as well as lipophilicity of the investigated set of the compounds. The most prominent factors affecting lipophilicity of the investigated substances are Solubility, Energy of the highest occupied molecular orbital, and Energy of the lowest unoccupied molecular orbital. The obtained models were used for interpretation of the lipophilicity of the investigated compounds. The prediction results are in good agreement with the experimental value. This study provides good information about pharmacologically important physico-chemical parameters of observed antipsychotics relevant to variations in molecular lipophilicity and chromatographic behavior. Established QSAR models could be helpful in design of novel multitarget antipsychotic compounds. more...

The objectives of this study were to gain insights into structure-retention relationships and to propose the model to estimating their retention. Chromatographic investigation of series of 36 Schiff bases and their copper(II) and nickel(II) complexes was performed under both normal- and reverse-phase conditions. Chemical structures of the compounds were characterized by molecular descriptors which are calculated from the structure and related to the chromatographic retention parameters by multiple linear regression analysis. Effects of chelation on retention parameters of investigated compounds, under normal- and reverse-phase chromatographic conditions, were analyzed by principal component analysis, quantitative structure-retention relationship and quantitative structure-activity relationship models were developed on the basis of theoretical molecular descriptors, calculated exclusively from molecular structure, and parameters of retention and lipophilicity. more...

Aim of this work is to propose an analytical protocol for proteinaceous binder identification in paintings using tryptic peptide analysis and MALDI-TOF mass spectrometry strengthened with MALDI-TOF/TOF tandem mass spectrometry (LIFT method). Proteinaceous binders are enzymatically digested with trypsin. From each individual protein frequently occurring in binders, a specific set of peptides is releasing during enzymatic digestion giving a peptide mass fingerprint (PMF) of that particular protein. The most intensive peptide peaks in PMF were determined and annotated with their corresponding amino acid sequence by MALDI-TOF/TOF analysis and subsequent database search. Before analyzing historical painting samples, procedure was tested and optimized on several painting model samples for a reliable and efficient identification of proteinaceous materials. The method is avoiding sample manipulation as much as possible in order to reduce sample loss. Since the applied procedures led to protein identification of binding media in model samples, MALDI-TOF/TOF was for the first time applied for analysis of proteinaceous binders in old painting samples. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3500] more...

A selective and sensitive analytical procedure for rapid arsenic determination by gas-diffusion flow injection analysis with amperometric detection was developed. The method is based on the arsenite reduction by NaBH4. Derived arsine diffuses through a PTF membrane into the acceptor flow stream and is amperometrically determined on a platinum working electrode. The limit of detection (3 a) at room temperature was 5 gg/dm(3) of As(III). The relative standard deviation for a 1 mg/dm(3) As(III) standard was 1.96% for six repetitive injections. Arsenic(V) was determined after its prereduction with potassium iodide. Arsenic determination was not interferred with by 1 mg/dm(3) Sb(III), 5 mg/dm(3) Sn(II), 10 mg/dm(3) Se(IV), 1 mg/dm(3) As(V), 1 mg/dm(3) hydrasine, 1 mg/dm(3) Fe(II) or 0.5 mg/dm(3) Fe(III) solution. The throughput of this method was 60 analyses per hour. This method was successfully applied to arsenic determination in some power plant waste water samples. Free full text: [https://doi.org/10.2116/analsci.24.877] more...

Different Schiff base complexes have biological activities that make them suitable for drug design. The biological properties of tetradentate Schiff base copper(II) complexed with N,N′-bis(acetylacetone)propylenediimine have been studied. The cytotoxic activity towards Caco-2 cells were determined by MTT, Anexin V and PI apoptosis assays. N,N′-bis(acetylacetone)propylenediimine-copper(II) showed the anti-cancer and anti-proliferative properties by inducing apoptosis in Caco-2 cells. A comparison of the cytotoxic activity of this compound with cisplatin shows that it is more effective on the colorectal cancer cell line Caco-2. The binding capacity and interaction of N,N′-bis(acetylacetone)propylenediimine-copper(II) with HSA were systemically investigated by in vitro fluorescence spectroscopy, CD spectroscopy, and in silico molecular docking study. Furthermore, in vitro and in silico interaction studies indicated that the complex binds to HSA through a static quenching mechanism without changes in protein conformation. The calculated number of binding sites was in line with molecular docking studies. The obtained Ka value suggests that the compound can be released from the protein in target cells. The tetradentate Schiff base copper(II) complex exhibited in vitro biological activities against cancer epithelial cells, which depend on the molecular structure of the complex, causing apoptosis, and the complex can bind to the protein drug carrier in circulation to the target tissue. Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/4400] This is peer-reviewed version of the following article: (1) Stevanović, N. R.; Apostolović, D.; Milčić, M. K.; Lolić, A.; Hage, M. van; Ćirković-Veličković, T.; Baošić, R. Interaction, Binding Capacity and Anticancer Properties of N,N′-Bis(Acetylacetone)-Propylenediimine-Copper(II) on Colorectal Cancer Cell Line Caco-2. New Journal of Chemistry 2021, 45 (14), 6231–6237. [https://doi.org/10.1039/D1NJ00040C]. more...

This paper describes a direct method for arsenic determination and speciation in wine samples by hydride atomic emission spectrometry with inductively coupled plasma (ICP-AES). Optimization of the method included investigation of several parameters that impact the intensity of spectral lines: concentration of reaction media (hydrochloric acid), reduction reagent concentration (sodium borhydride), power generator and the carrier flow rate. The effect of ethanol on spectral lines was especially investigated because it enabled arsenic determination without prior preparation. Optimal conditions for As(III) were 8 mol/L HCl and 0.1% NaBH(4), for dimethylarsinite (DMA) determination 0.005mol/L HCl and 0.02% NaBH(4), and for As(V) 4 mol/L HCl and 2% NaBH(4). Total arsenic was determined in samples after their treatment in a microwave digestion unit. Results were compared to the FIA method, arsenic was determined with the standard addition method, and the results showed agreement. Detection limits (mu g/L) for determination of As(V), DMA, and As(III) were found to be 0.4, 0.6, and 0.10, respectively. Good recoveries (89.9-102.0%) of added spikes were obtained for all samples. The proposed method has been validated by means of reference materials and the results obtained were in agreement with certified values. more...

The objectives of this study were to gain insights into the structure-retention and structure-lipophilicity relationships of series of twenty antidepressants and to propose model for estimating their retention and lipophilicity. The lipophilicity of antidepressants has been determined by reversed-phase thin-layer chromatography using binary methanol-water mobile phases. The chemical structures of the antidepressants have been characterized by molecular descriptors which are calculated from the structure and related to the chromatographic retention parameters as well as chromatographically determinated lipophilicity parameters by multiple linear regression analysis. The obtained models were used for interpretation of the lipophilicity and retention behavior of the investigated compounds. more...