Search

A simple, rapid, and robust hydrophilic interaction liquid chromatography–tandem mass spectrometry method has been applied for the determination of acrylamide in bread, potato-based heat-processed products, and cereal-based infant food. The QuEChERS methodology was used for sample extraction and clean-up. Enzyme asparaginase was used to prepare an acrylamide-free bread-like matrix, thereby eliminating the lack of acrylamide-free food matrices as one of the limitations for method development and validation. The obtained linear range was 10–2500 µg/kg, and the limit of detection and the limit of quantification were 2.71 and 10.0 μg/kg (S/N = 3 and 10, respectively). The developed method demonstrated good recoveries (98.9–102.8%), intra-day (2.1–3.8%), and inter-day precision (2.9–4.0%). The acrylamide was found in all samples; the concentrations were lower than benchmark levels set by the European Union. In the baby food sample, the AA concentrations were below the limit of quantification (10 µg/kg), and the benchmark level set by the European Union is 40 µg/kg. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, a simple, sensitive, and precise flow injection system was optimized and applied to ascorbic acid determination with a carbon paste electrode modified with the Schiff base copper complex. The modified sensor showed increased sensitivity toward ascorbic acid oxidation with a decrease of oxidation potential by 200 mV. Under optimized flow parameters, working potential, gasket thickness, sample and reaction coil volumes, and flow rate, the developed flow system gave a linear response from 5 to 75 μmol/L of ascorbic acid. The calculated limit of detection was 4.5 μmol/L, calculated as 3σ/s which corresponds to the absolute value of 40 ng for the 50 μL sample coil. The precision for six consecutive injections of 5 and 75 μmol/L ascorbic acid solutions was determined as a relative standard deviation of 5.8 % and 1.5 %, respectively. The flow injection system enabled up to 120 analyses per hour. An optimized flow system was applied to the determination of ascorbic acid in dietary supplements, after simple preparation. [ABSTRACT FROM AUTHOR]

Cancer remains one of the most common diseases worldwide in terms of deaths and claims many lives every day. Transition metal complexes are candidates in the development of anticancer drugs, with cisplatin being used in chemotherapy worldwide. Copper, an endogenous metal, is known for its pronounced redox potential and nucleophilicity, especially when bound to biological molecules. Cu (II) complexes were synthesized containing ethane‐1,2‐diamine as amine moiety and pentane‐2,4‐dione and/or 1‐phenylbutane‐1,3‐dione, pentane‐2,4‐dione and/or 1,1,1‐trifluoropentane‐2,4‐dione or 1,1,1‐trifluoropentane‐2,4‐dione and/or 1‐phenylbutane‐1,3‐dione as β‐diketone moiety. Standard methods were used to confirm the structure of complexes 1–6. X‐ray crystal structure analysis characterized complex 1 containing the ligand ethane‐1,2‐diamine and pentane‐2,4‐dione. The interactions of complexes 1–6 with calf thymus DNA (ct‐DNA) were followed by electronic absorption and fluorescence spectroscopy methods and by viscosity measurements. In contrast, interaction with Salmon Sperm DNA was investigated using the electrophoretic mobility shift assay. The results indicate a moderate affinity of complexes 1–6 for binding to DNA. Gel electrophoresis also shows that the studied complexes have a concentration‐dependent interaction with DNA. Spectroscopic fluorescence techniques were used to monitor the affinity of the complexes for bovine serum albumin (BSA). Complexes 1–6 showed satisfactory binding ability for BSA. Cytotoxicity analyses were performed on the human colorectal carcinoma HCT‐116 and healthy lung fibroblast MRC‐5 cell lines, showing that complex 5 exhibited selectivity between cancer and normal cells, which is critical for drug development. [ABSTRACT FROM AUTHOR]

The aim of this research was to determine the content of arsenic (As), cadmium (Cd), lead (Pb), and nickel (Ni) in selected lipsticks and face foundations of different price categories and the health risk assessment associated with these toxic elements via dermal and oral exposure. The samples (10 lipstick and 10 face foundations) were purchased from local markets in Belgrade, Serbia. The samples were prepared by acid digestion and analyzed by atomic absorption spectrometry (flame atomization for Cd, Pb, and Ni and electrothermal atomization for As). Arsenic was found in 50% of lipstick samples and in only two face foundation samples with the highest concentration of 0.28 mg/kg in the lipstick sample. Lead concentration was in the range of 1.15 to 5.12 mg/kg in ten samples. Nickel was found in five samples out of 20, with the highest concentration of 4.20 mg/kg. Cadmium was found in only one face foundation sample in the cheaper price range (1.11 mg/kg). The obtained results indicate that concentrations of As, Pb, Cd, and Ni were within the permissible limits according to Serbian legislation. Health risk associated with these elements was assessed as non-carcinogenic and carcinogenic risk. Obtained hazard quotients (HQs) and hazard indexes (HIs) were below 1, indicating the absence of significant non-carcinogenic health risk due to exposure to these toxic elements (TEs). The carcinogenic risk results show that investigated cosmetic products can be considered low-risky due to the possibility of causing malignant disease. [ABSTRACT FROM AUTHOR]

A simple modification of bare glassy carbon electrode by electropolymerization of glycine by cyclic voltammetry was applied to the detection of ibuprofen. The polyglycine modified glassy carbon electrode was characterized by cyclic voltammetry and the electroactive surface area was determined. The study of ibuprofen in acetic acid buffer (0.25 M, pH 4.0) presented an electrocatalytic effect toward ibuprofen oxidation, increasing the current response and decrease of oxidation potential, at the modified electrode compared to the bare. Under the optimal conditions, the modified electrode gave a linear response in the ibuprofen concentration range of 10 to 200 μM, obtained correlation coefficient was 0.9993. the calculated limit of detection (3Sb/m) was 1.0 μM and the limit of quantification (10Sb/m) was 3.5 μM. the sensor was successfully used for the determination of ibuprofen in pharmaceutical preparations with satisfactory recoveries, 93–107 %. The new sensor showed good selectivity, repeatability, and reproducibility with satisfactory stability. [ABSTRACT FROM AUTHOR]

This study assesses heavy metal content in soil, water, and plant material from sites located around the lignite mine and the power plant "Gacko", Bosnia and Herzegovina. The samples were collected, prepared, and analyzed for heavy metals content using the flame atomic absorption spectrophotometer. Samples were analyzed for cadmium, lead, copper, zinc, manganese, and iron. To identify the relationship among the metals in samples and their possible sources, Pearson's correlation and principal component analysis were performed. Health risk assessment was applied to establish potential health risks posed to humans caused by contaminants in different environmental compartments. The results of our analyses show that most soil samples contain copper, and one of those samples had a copper concentration of more than 70 µg/g, which is a critical upper value for agricultural use. In the soil samples that were analyzed, cadmium was also detected, and its concentration was greater than 2 µg/g. Lead, on the other hand, had a concentration that was higher than the maximum permissible for unpolluted soils in 40% of the soil samples that were analyzed. Lead and cadmium concentrations in surface waters mostly contribute to a non-carcinogenic risk in the scenario of recreational swimming exposure. The presence of Cd, a highly toxic element in water, may be explained by the leaching of artificial fertilizers used in the study area, whereas Pb's origin may be geological. The results of this study recommend routine heavy metal monitoring in samples of soil, water, and plants from the examined area so that, if metal concentrations continue increasing, remedial action should be advised to prevent accumulation in the food chain. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 assumptions made based on GFAAS results. Using the two techniques a variety of pigments have been identified, such as calcite, lead white, goethite, hematite, ultramarine, vermilion, minium, carbon black. Based on GFAAS results the presence of azurite was observed in the blue paint sample, although this finding was not confirmed by Raman microscopy. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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%. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The porous spinel oxide nanoparticles, MnCo2O4, were synthesized by citrate gel combustion technique. Morphology, crystallinity and Co/Mn content of modified electrode was characterized and determined by Fourier transform infra-red spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction pattern analysis (XRD), simultaneous thermogravimetry and differential thermal analysis (TG/DTA). Nanoparticles were used for modification of glassy carbon electrode (GCE) and new sensor was applied for simultaneous determination of Pb(II) and Cd(II) ions in water samples with the linear sweep anodic stripping voltammetry (LSASV).The factors such as pH, deposition potential and deposition time are optimized. Under optimal conditions the wide linear concentration range from 0.05 to 40 μmol/dm3was obtained for Pb(II), with limit of detection (LOD) of 8.06 nmol/dm3 and two linear concentration ranges were obtained for Cd(II), from 0.05 to 1.6 μmol/dm3 and from 1.6 to 40 μmol/dm3, with calculated LOD of 7.02 nmol/dm3. The selectivity of the new sensor was investigated in the presence of interfering ions. The sensor is stable and it gave reproducible results. The new sensor was succesfully applied on determination of heavy metals in natural waters. [ABSTRACT FROM AUTHOR]

This work presents the development of a flow injection system for differential pulse amperometry (DPA) for diazepam determination in the presence of oxygen. The thin flow cell consisted of the bare glassy carbon electrode, reference silver/silver chloride, and stainless steel as the auxiliary electrode. Electrochemical reduction of diazepam (DZP) was characterised by cyclic voltammetry. Azomethine reduction peak was used for DZP quantification. The detector response was linear in the range 20–250 µmol/dm3 of diazepam, with a calculated detection limit of 3.83 µg/cm3. Intraday and interday precision were 1.53 and 10.8%, respectively. The method was applied on three beverage samples, energetic drink, and two different beer samples, and obtained recoveries were from 93.65 up to 104.96%. The throughoutput of the method was up to 90 analyses per hour. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]