Display omitted
•Stable Co(II)-RLMP complexes were synthesized and isolated in the solid state.•Co(II)-RLMP complex formation is confirmed by UV-Vis and ATR-FTIR spectroscopy.•MALDI-TOF/TOF MS ...results confirmed d-Glcp as the RLMP repeating unit.•XRD results show a low crystallinity form of Co(II)-RLMP.•Different model structures of synthesized Co(II)-RLMP complexes are proposed.
Complexes of Co(II) ion with reduced low-molar pullulan (RLMP) (Mw 6000 g/mol) were synthesized in aqueous solutions at boiling temperature in the pH range from 7.5 to 13.5. Obtained Co(II)-RLMP complexes, with cobalt content ∼2–8% (AAS), were characterized by UV-Vis spectrophotometry, FTIR spectroscopy (ATR-FTIR, FT-IRIS), MALDI-TOF/TOF MS, and XRD. Tetragonally distorted Oh coordination of Co(II) ions with O ligand atoms in synthesized complexes is suggested based on the spectrophotometric data. No influence of complexation process on the 4C1 chair conformation of the d-glucopyranose units of pullulan was detected by ATR-FTIR measurements and FT-IRIS showed high homogeneity of synthesized complexes. Some additional depolymerization of pullulan during complex synthesis was indicated by MALDI-TOF/TOF MS but it also revealed good stability of complexes with much weaker binding of Co(II) ion in low molar mass fragments. Even in complexes with highest Co(II) ion content a low degree of crystallinity was detected by XRD analysis.
Synthesis, UV–vis, ATR-FTIR, FT-IRIS, EPR spectroscopic and different physicochemical techniques are described for the direct analysis of bioactive copper(II)–pullulan complexes which permits the ...important anti-hypocupremic and anti-microcitary anemic preparation to be obtained.
Bioactive copper(II) complexes with polysaccharides, like pullulan and dextran, are important in both veterinary and human medicine for the treatment of hypochromic microcitary anemia and hypocupremia. In aqueous alkaline solutions, Cu(II) ion forms complexes with the exopolysaccharide pullulan and its reduced low-molecular derivative. The metal content and the solution composition depend on pH, temperature, and time of the reaction. The complexing process begins in a weak alkali solution (pH >7) and involves OH groups of pullulan monomer (glucopyranose) units. Complexes of Cu(II) ion with reduced low-molecular pullulan (RLMP,
M
w
6000
g
mol
−1) were synthesized in water solutions, at the boiling temperature and at different pH values ranging from 7.5 to 12. The Cu(II) complex formation with RLMP was analyzed by UV–vis spectrophotometry and other physicochemical methods.
Spectroscopic characterizations (ATR-FTIR, FT-IRIS, and EPR) and spectra–structure correlation of Cu(II)–RLMP complexes were also carried out.
Dextran sulphate stabilized silver nanoparticles (AgNPs - DS) were synthesized from aqueous solution of silver nitrate (AgNO3) and dextran sulphate sodium salt (DS). The characterization of AgNPs - ...DS was performed by ultraviolet–visible spectroscopy (UV-VIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and antimicrobial activity. The formation of AgNPs - DS was monitored by colour changes of the reaction mixture from yellowish to brown and by measuring the surface plasmon resonance absorption peak in UV-VIS spectra at 420 nm. The SEM analysis was used for size and shape determination of AgNPs - DS. The presence of elemental silver and its crystalline structure in AgNPs - DS were confirmed by EDX and XRD analyses. The possible functional groups of DS responsible for the reduction and stabilization of AgNPs were determinated by FTIR spectroscopy. The AgNPs - DS showed strong antibacterial activity against Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 11778, Bacillus luteus in haus strain, Bacillus subtilis ATTC 6633, Listeria monocytogenes ATCC 15313, Escherichia coli ATTC 25922, Pseudomonas aeruginosa ATTC 27853, Klebsiella pneumoniae ATTC 700603, Proteus vulgaris ATTC 8427, and antifungal activity against Candida albicans ATTC 2091.
•Dextran sulphate stabilized silver nanoparticles (AgNPs-DS), were synthesized by using a chemical reduction green synthetic method, which involve the application of non-toxic and biodegradable agents such as polysaccharides for the reduction and stabilization of AgNPs.•Nanoparticles, spherical in shape, were characterized by UV-VIS, SEM, XRD, FTIR and EDX methods.•The AgNPs – DS nanoparticles showed strong antibacterial activity against and antifungal activity against.
SMILES notation based optimal descriptors as a universal tool for the QSAR analysis with further application in drug discovery and design is presented. The basis of this QSAR modeling is Monte Carlo ...method which has important advantages over other methods, like the possibility of analysis of a QSAR as a random event, is discussed. The advantages of SMILES notation based optimal descriptors in comparison to commonly used descriptors are defined. The published results of QSAR modeling with SMILES notation based optimal descriptors applied for various pharmacologically important endpoints are listed. The presented QSAR modeling approach obeys OECD principles and has mechanistic interpretation with possibility to identify molecular fragments that contribute in positive and negative way to studied biological activity, what is of big importance in computer aided drug design of new compounds with desired activity.
For the development of atypical antipsychotics, the selective positive allosteric modulation of the ionotropic GABAA receptor (GABAAR) has emerged as a promising approach. In the presented research, ...two unrelated methods were used for the development of QSAR models for selective positive allosteric modulation of 1-containing GABAARs with derivatives of imidazo 1,2-a-pyridine. The development of conformation-independent QSAR models, based on descriptors derived from local molecular graph invariants and SMILES notation, was achieved with the Monte Carlo optimization method. From the vast pool of 0D, 1D, and 2D molecule descriptors, the GA-MLR method developed additional QSAR models. Various statistical methods were utilised for the determination of the developed models’ robustness, predictability, and overall quality, and according to the obtained results, all QSAR models are considered good. The molecular fragments that have a positive or negative impact on the studied activity were obtained from the studied molecules’ SMILES notations, and according to the obtained results, nine novel compounds were designed. The binding affinities to GABAAR of designed compounds were assessed with the application of molecular docking studies and the obtained results showed a high correlation with results obtained from QSAR modeling. To assess all designed molecules’ “drug-likeness”, their physicochemical descriptors were computed and utilised for the prediction of medicinal chemistry friendliness, pharmacokinetic properties, ADME parameters, and druglike nature.
In this article, a sensing element for detection of date rape drugs in drinks is presented. The element consists of a three-dimensional printed holder, in which two embroidered electrodes have been ...fixed, forming a capacitive structure. As the dielectric properties of the liquid between these electrodes’ changes, the capacitance and consequently the impedance are changed. For experimental purposes, diazepam, a model rape drug, sucrose, and sodium chloride, which are used as control ingredients, were dissolved in a 40% V/V alcoholic beverage, serving as solutions for testing and comparison. The selectivity, repeatability, and sensitivity of the proposed sensor were tested. The sensitivity of detection of 1 mg/ml of diazepam in drinks was 0.92628 Ωl/mg, sucrose was 0.94774 Ωl/mg and sodium chloride was 2.46867 Ωl/mg, at 1 MHz. Moreover, with the use of the Cole impedance model, the selectivity of the sensor in the detection of diazepam, through the Nyquist plot and parameter estimation, has been achieved. Sensor repeatability was calculated through the relative standard deviation with the result for 1 mg/ml of diazepam dissolved in alcohol on 1 MHz being 2.48, in terms of impedance modulus. The presented sensor platform can successfully detect drugs in drinks and can protect from many cases of such assaults in a real world.
Display omitted
In this study QSPR models were developed to predict the complexation of structurally diverse compounds with β-cyclodextrin based on SMILES notation optimal descriptors using Monte ...Carlo method. The predictive potential of the applied approach was tested with three random splits into the sub-training, calibration, test and validation sets and with different statistical methods. Obtained results demonstrate that Monte Carlo method based modeling is a very promising computational method in the QSPR studies for predicting the complexation of structurally diverse compounds with β-cyclodextrin. The SMILES attributes (structural features both local and global), defined as molecular fragments, which are promoters of the increase/decrease of molecular binding constants were identified. These structural features were correlated to the complexation process and their identification helped to improve the understanding for the complexation mechanisms of the host molecules.
A large number of studies indicated that caffeic acid represents an important natural phenolic compound with many potential uses in medications and cosmetics, but also with therapeutic implications ...in cardiovascular diseases, various types of cancer, and neurological diseases. In this work we studied kinetics and reaction mechanism of caffeic acid autoxidation in weakly alkaline aqueous solutions (pH 7.4 and 8.4) in the presence of Mg(II) ions by applying high performance liquid chromatography with diode-array detection (HPLC–DAD) and electron spin resonance (ESR) spectroscopy. The results of HPLC–DAD analysis revealed that the presence of Mg(II) ions enhanced the autoxidation rate to a much greater extent than the increase in pH from 7.4 to 8.4. Analysis of DAD UV–Vis and ESR spectra, as well as comparison of the calculated logP values with retention times of chromatographically separated compounds, enabled the identification of the main initial products of caffeic acid autoxidation in the presence of Mg(II) ions as caffeic acid quinone and its dimer and indicated the nature of some minor products (hydroxylated derivatives of caffeic acid and their quinones). ESR spectroscopy disclosed that prolonged autoxidation of caffeic acid leads to the formation of polymeric, humic acid like, products. These findings may be important when considering treatments and/or storage of medications, cosmetics, and foods containing caffeic acid.
Graphical abstract
Abstract The Monte Carlo method was used for QSAR modeling of maleimide derivatives as glycogen synthase kinase-3β inhibitors. The first QSAR model was developed for a series of 74 ...3-anilino-4-arylmaleimide derivatives. The second QSAR model was developed for a series of 177 maleimide derivatives. QSAR models were calculated with the representation of the molecular structure by the simplified molecular input-line entry system. Two splits have been examined: one split into the training and test set for the first QSAR model, and one split into the training, test and validation set for the second. The statistical quality of the developed model is very good. The calculated model for 3-anilino-4-arylmaleimide derivatives had following statistical parameters: r2 =0.8617 for the training set; r2 =0.8659, and rm2 =0.7361 for the test set. The calculated model for maleimide derivatives had following statistical parameters: r2 =0.9435, for the training, r2 =0.9262 and rm2 =0.8199 for the test and r2 =0.8418, r(av)m2 =0.7469 and ∆ rm2 =0.1476 for the validation set. Structural indicators considered as molecular fragments responsible for the increase and decrease in the inhibition activity have been defined. The computer-aided design of new potential glycogen synthase kinase-3β inhibitors has been presented by using defined structural alerts.
