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.
The formation of Co(II) ion complexes with reduced low-molar dextran (RLMD, Mw 5000 g/mol) was studied at the pH range from 7.0 to 13.5. The cobalt content in synthesized Co(II)-RLMD complexes was ...~3–12% (AAS) and it generally increases with pH. Co(II)-RLMD complexes were characterized by UV-Vis spectrophotometry and FTIR spectroscopy. UV-Vis data for synthesized complexes indicate tetragonally distorted Oh coordination of Co(II) ions with O atoms from ligand. The presence of IR bands at 765 cm
and 910 cm
in Co(II)-RLMD complexes indicates the existence of α-(1→6)O-glycosidic bonds. The similarities in the γ(C–H) range of the IR spectra indicate that there is no difference in the conformation of the glucopyranose units in RLMD and Co(II)-RLMD complexes. The occurrence of water molecules in Co(II)-RLMD complexes was confirmed by FTIR spectroscopy of deuterated samples.
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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.
The aims of this research were preparation of Juglans nigra husk extracts by employing an ultrasonic-assisted extraction method and process optimization of minerals extraction using response surface ...methodology. Extracts from J. nigra L. fresh husk were prepared using ethanol (70%, v/v) as a solvent, at different extraction temperatures: 15, 30 and 40 °C, and extraction times: 5, 15, 30, 60 and 80 min. The content of minerals in ethanol extracts was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The response surface methodology (RSM) was developed to evaluate the effect of two extraction factors as well as to optimize the extraction variables for each mineral individually. The RSM models pointed out 40 °C temperature and extraction time in the range 77–80 min as optimal conditions for extraction of macro- and micro-elements. Results of RSM optimization showed the relative order of maximum obtained yield of macro-elements: K>P>S>Ca>Mg and maximum yield of micro-elements was Si>Zn>Sr>Cu.
•Extracts of J. nigra fresh husk were analyzed using ICP-OES.•Optimization of operational variables was performed using RSM models.•RSM determined optimal variables extraction of macro-elements and micro-elements.
The sorption kinetics and thermodynamic parameters of phosphate removal from aqueous solution using quaternary ammonium–modified bottle gourd biomass as a sorbent were studied in a batch reactor. The ...cationic sorbent, containing trimethylammonium and hydroxypropyl groups, was obtained through the chemical reactions of the lignocellulosic Lagenaria vulgaris shell with (3-chloro-2-hydroxypropyl)trimethylammonium chloride. Experimental data of phosphate sorption from aqueous solutions of different initial concentrations (5–140 mg P L−1) have been analysed by reaction kinetics and diffusion models. The characteristic rate constants calculated by linear and non-linear regression analyses of the experimental results are presented. The phosphate sorption reaches equilibrium in 20–30 min, depending on the initial phosphate concentration. The maximum sorption capacity of quaternary ammonium–modified bottle gourd (QABG) sorbent was 18 mg P g−1 at 20 oC. The sorption system is best described by a non-linear equation of the pseudo first-order model (R2 > 0.996). The Weber–Morris model indicated that the sorption process took place in three steps, whereby the intra-particle diffusion is not the only rate-controlling step. In addition, the effect of temperature (20 oC–50 oC) on sorption kinetics was also investigated. The various thermodynamic parameters suggest that phosphate sorption is favoured and is an exothermic process. The activation energy and the sticking probability confirmed that anion exchange is the dominant mechanism. These results provide valuable information for the potential use of agricultural residues in the treatment of wastewaters.
The subject of this paper is the analysis of the Yugoslav-Turkish trade in 1920-1939. The main goal of the research is to point out the qualitative and quantitative indicators of trade between the ...two countries. In addition to the economic scientific approach, which is based on the analysis of statistical indicators derived from data on the exchange between the two countries, a historical approach was applied, which is reflected in the use of historical sources and contextual analysis of processes and events based on them. Despite the modest importance of mutual foreign trade, which could not be significantly affected by the dynamics of strong average annual growth of Yugoslav imports from Turkey, export-import flows between the two countries made a positive contribution to creating a much more important aspect of their relations: political, which was reflected in the signing of the Balkan Pact in 1934.
Practical aspects of Lagenaria vulgaris shell conversion to activated carbon were examined along with its use in ranitidine adsorption. Kinetics and isotherms of adsorption onto Lagenaria vulgaris ...carbon (LVC) were correlated to several theoretical adsorption models. The best fit was found in the case of Langmuir and pseudo-second-order model indicating monolayer adsorption. The influence of pH under kinetic study showed slightly hindered adsorption below pH 4. The optimal adsorbent dosage was set to 1g/L. LVC was characterized by several complementary techniques, including wet chemical techniques such as Boehm’s titrations and determination of pHPZC and pH of LVC, which revealed neutral nature of the adsorbent. N2 sorptometry determined specific surface area of 665m2/g and significant ratio of micropores in the sample with maximum wall’s diameter of 2.2nm. Fourier transform infrared spectroscopy (FTIR) confirmed the role of lignin and cellulose in the formation of the final LVC structure. Porous structure of the material was proved by using scanning electron microscopy. Preparation of LVC material drew attention as an easy and low-cost process for production of a highly efficient adsorbent which exhibited fast kinetics of ranitidine removal in the first minutes of contacting and large adsorption capacity (315.5mg/g) at equilibrium.
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.
A new biosorbent for phosphate uptake based on functionalized bottle gourd
Lagenaria vulgaris
shell (LVS) was synthesized and characterized. The functionalization was achieved through the ...quaternization of the lignocellulosic LVS biomass with trimethylamine. The quaternary ammonium product (QALVS), containing trimethylammonium-hydroxypropyl weak base groups, was tested to remove phosphate from single and multi anion aqueous systems. The elemental and FTIR analyzes clearly indicate the existence of a cationic –N
+
(CH
3
)
3
group on the biosorbent surface, which is responsible for the phosphate biosorption. The biosorption behavior of QALVS towards phosphate was estimated by using different experimental approaches, such as biosorbent dosage (0.5–5.0 g dm
−3
), initial phosphate concentration (5–100 mg dm
−3
), contact time (5–60 min), pH value (2–10), temperature (20–50 °C), and potential interferences of coexisting anions (nitrate, sulfate and chloride). The phosphate biosorption by QALVS was found to be spontaneous and exothermic, ion exchange process, revealing an exchange capacity of 1.12 meq g
−1
at 20 °C and pH 6. The biosorbent displayed potential application for the preconcentration and immobilization of phosphate from aqueous solutions in environmental cleanup.
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