Morteza Jabbari

The solid–liquid equilibria of a poorly water-soluble antioxidant agent namely naringoside were assayed to determine solubility in binary liquid mixtures of water + isopropanol (iso-PrOH) between 298.15 K and 320.15 K under atmospheric pressure. The mole fraction solubilities of naringoside in the saturated solution were determined using a combination of static shake-flask and ultraviolet spectrophotometry techniques. The dissolution behavior of naringoside was correlated with three solution models consisting of the van’t Hoff equation, the modified Apelblat equation and the Buchowski-Ksiazczak λH equation. The modified Apelblat equation was more consistent than the two other correlation models. Apparent thermodynamic analysis of naringoside dissolution was also performed at the mean harmonic temperature using the model parameters of the modified Apelblat equation. Furthermore, the Kamlet, Abboud and Taft Linear Solvation Energy Relationship (KAT-LSER) model was applied to analyze the effect of the solute–solvent intermolecular interactions on the solubility of this natural bioactive product. © 2018, Iranian Chemical Society.

The radical scavenging performance and antioxidant activity of γ-alumina nanoparticles towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical were investigated by spectroscopic and computational methods. The radical scavenging ability of γ-alumina nanoparticles in the media with different polarity (i.e. i-propanol and n-hexane) was evaluated by measuring the DPPH absorbance in UV–Vis absorption spectra. The structure and morphology of γ-alumina nanoparticles before and after adsorption of DPPH were studied using XRD, FT-IR and UV–Vis spectroscopic techniques. The adsorption of DPPH free radical on the clean and hydrated γ-alumina (1 1 0) surface was examined by dispersion corrected density functional theory (DFT-D) and natural bond orbital (NBO) calculations. Also, time-dependent density functional theory (TD-DFT) was used to predict the absorption spectra. The adsorption was occurred through the interaction of radical nitrogen N[rad] and NO2 groups of DPPH with the acidic and basic sites of γ-alumina surface. The high potential for the adsorption of DPPH radical on γ-alumina nanoparticles was investigated. Interaction of DPPH with Brønsted and Lewis acidic sites of γ-alumina was more favored than Brønsted basic sites. The following order for the adsorption of DPPH over the different active sites of γ-alumina was predicted: Brønsted base < Lewis acid < Brønsted acid. These results are of great significance for the environmental application of γ-alumina nanoparticles in order to remove free radicals. © 2018[/accordion]
AUTHOR KEYWORDS: Adsorption; Antioxidant; DFT; DPPH; Radical scavenger; γ-Alumina
INDEX KEYWORDS: Adsorption; Alumina; Aluminum oxide; Antioxidants; Chemical bonds; Computation theory; Density functional theory; Electromagnetic wave absorption; Hexane; Nanoparticles; Scavenging, 2 ,2-diphenyl-1-picrylhydrazyl; Dispersion-corrected density functional; DPPH; Environmental applications; Radical scavengers; Spectroscopic technique; Structure and morphology; Time dependent density functional theory, Free radicals
PUBLISHER: Elsevier B.V.

Jabbari, M., Teymoori, F. An insight into effect of micelle-forming surfactants on aqueous solubilization and octanol/water partition coefficient of the drugs gemfibrozil and ibuprofen (2018) 262, pp. 1-7.

DOI: 10.1016/j.molliq.2018.04.054

Aqueous micellar solubilization of ibuprofen and gemfibrozil drugs was investigated at constant temperature (25.0 ± 0.1) °C and atmospheric pressure using shake-flask and UV–vis spectrophotometric techniques. The solubility measurement was done in presence of three surfactants possessing different head groups, namely sodium dodecylsulfate (anionic SDS), cethyltrimethylammonium bromide (cationic CTAB) and polyethylene glycol dodecyl ether (non-ionic Brij 35) as well as their binary mixtures. The micellar solubility descriptors of χ (molar solubilization capacity), K (micelle–water partition coefficient), and ΔGs ∘ (standard free energy of solubilization) were obtained to estimate quantitatively the solubilization efficiency of the surfactant systems. Moreover, the octanol-water partition coefficient of these drugs was also evaluated in the micellar solutions. The results obtained in the aqueous micellar system demonstrate that, irrespective of the surfactant type, the solubility of drugs increases with increasing the concentration of micelles. It was found that the solubility of ibuprofen and gemfibrozil in Brij 35 and CTAB solutions, respectively is higher compared to that in the other surfactants. However, the partition coefficients of these drugs show an inverse trend with solubility data. Finally, the effect of the surfactant type on solubility enhancement of the drugs is explained in terms of possible interactions between the drug and the micelle. © 2018 Elsevier B.V.

The autoprotolysis process in aqueous co-solvent mixtures containing 0–60% (v/v) acetonitrile (ACN) was investigated at constant temperature 25.0 ± 0.1°C by using a high-precision and rapid potentiometric technique. During all measurements, the ionic strength was adjusted to 0.25 mol dm−3 with one of the supporting electrolytes KNO3, NaNO3 or KNO3/NaNO3 mixture (1:1) and the autoprotolysis constants (pKap) were calculated from potentiometric data. In the present study, the variation of the pKap values with co-solvent composition was analysed based on non-specific and specific solute–solvent interactions using the Kamlet, Abboud and Taft (KAT) approach. The experimental results obtained show that the general trend of autoprotolysis constants in different ionic media is as follows: KNO3 > NaNO3/NaNO3 > NaNO3, and these variations increase with increasing the amount of co-solvent ACN. The effect of ionic media used on the pKap values is discussed in terms of the weak interactions between the solvent system and the anionic and cationic components of the background electrolytes. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.