Search

The molecular structures of six neutral copper(II) complexes with propylenediamine bridges and different terminal groups have been reported and evaluated. Different antioxidant tests were performed on these complexes. Additionally, the antibacterial and antifungal activities of the investigated compounds were assessed. The study was complemented with data on their interaction with human serum albumin (HSA) and evaluated using spectroscopic fluorescence techniques. The copper(II) complexes were found to bind to HSA at multiple sites (n = 0.82–1.72), displaying relatively high binding constants on the order of Ka = (4.8–8.8) × 104 M−1. Furthermore, binding constants calculated from microscale thermophoresis (MST) data were within the range of 1.27 × 104–1.13 × 105 M−1; these results correlated well with the above Ka values obtained by fluorimetry. Molecular docking simulations were employed to study the ability of the complexes to bind to target macromolecules, such as HSA and DNA. As a significant addition to understanding their biological behavior, an MTT assay was performed to investigate the cytotoxicity of the complexes. The antiproliferative activity of the investigated copper(II) complexes with propylenediamine ligands, along with cisplatin as a reference compound, was evaluated in two human cancer cell lines (LS-174 and MCF-7) and one normal cell line (MRC-5). The obtained results are discussed, providing the structure–activity relationship of the copper(II) complexes with Schiff base tetradentate ligands.

Three Schiff base Cu(II) complexes, (N,N’-bis(acetylacetone)­propyl­enediimine)copper(II) complex, [Cu(acac2pn)] (1), (N,N'-bis-(ben­zoyl­acet­one)propylenediimine)copper(II) complex, [Cu(phacac2pn)] (2) and (N,N’-bis-(trifluoroacetylacetone)propylenediimine)­copper(II) complex, [Cu(tfacac2pn)] (3), were used to investigate the interactions with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) using the electronic absorption and spectro­scopic fluorescence methods. UV–Vis absorption studies showed that studied complexes interact with DNA molecule and exhibit moderate binding affinity. Fluorescence studies of complexes 1–3 also showed a possibility for DNA int­ercalation as well as a relatively high binding ability toward BSA. Among the tested complexes, the highest affinity for DNA and BSA molecules was shown by complex 1. Cytotoxic analyses, performed on human colorectal carcinoma HCT-116 and healthy lung fibroblast MRC-5 cell lines, showed that complex 2 exhibited activity on both cell lines, while complexes 1 and 3 did not show any activity.

The knowledge of the structural and chemical properties of biochars is decisive for their application as technical products. For this reason, methods for the characterization of biochars that are generally applicable and allow quality control are highly desired. Several methods that have shown potential in other studies were used to investigate two activated carbons and seven biochars from different processes and feedstock. The chars were chosen to cover a wide range of chemical composition and structural properties as a hardness test for the analytical methods used in this study. Specific problems connected with the pretreatment of samples and drawbacks of some methods for some types of chars could be identified in an integrated consideration of the results from different methods. None of the spectroscopic methods was found to be suitable for the quality control of all types of chars. The most valuable results were obtained by chemical analysis that, however, required the complete determination of the main elements, including that of oxygen, and of inorganic components for adequate results. The combination of X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopy allows a rough characterization of surface functional groups, but cannot discriminate aliphatic and aromatic OH groups. FT-IR might be a suitable method for the quality control of biochars made at lower temperature. The results of Raman spectroscopy did not well correlate with the amount of sp2 hybridized carbon determined by XPS. A better correlation of XPS data was found with the electrical polarization determined by the method of spectral induced polarization that was used for the first time in conjunction with extensive analytical characterization.

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.

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.

Background: Diazepam belongs to the group of 1,4-benzodiapines. It is used for the treatment of anxiety, convulsions and as a muscle relaxant. The presence of 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 preparationsMethods: Electrode modification was done by ex-situ deposition of antimony on 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 unmodified electrode. Under optimal conditions, linear sweep voltammetry was used for the determination of 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.

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.

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%.

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.

Measurement of antithyroglobulin antibodies (TgAb) is an inevitable laboratory tool in the management of thyroid gland diseases. Currently available immunoassays still have limitations underlying the necessity of the introduction of fast, sensitive, and label-free technologies. Our aim was to develop a method for TgAb measurement in human serum based on the quartz crystal microbalance (QCM) technology. We immobilized thyroglobulin on the surface of Attana LNB Carboxyl sensor chip®, prepared standard curve covering the range of 1–50000 kIU/L, and established optimal measurement conditions. The validation included determination of the detection limit (LOD), functional sensitivity, linearity, precision, as well as the comparison with the results of the radioimmunoassay (RIA). The LOD and functional sensitivity were 4.2 kIU/L and 4.7 kIU/L, respectively. The method was linear in the range of 20–10000 kIU/L. The regression equation for comparison with RIA was CQCM = 1.0056 • CRIA – 24.2778, whereby no significant proportional or systematic difference was present. There was a good agreement with RIA in the classification of patients according to the clinical significance of the results. The developed method has advantages over currently available assays in terms of better LOQ, a higher upper limit of linearity, and precision. The characteristics of the developed method unambiguously show that the application of the QCM biosensors offers a highly reliable novel approach for the measurement of TgAb in human serum.

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.

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.

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.