Solubility, molecular interactions and mixing thermodynamic properties of piperine in various pure solvents at different temperatures

In this study, the solubility, molecular interactions and mixing thermodynamic properties of a poorly water soluble bioactive compound piperine in twelve different pure solvents namely "water, methanol, ethanol, isopropyl alcohol (IPA), ethylene glycol (EG), propylene glycol (PG), 1-butanol, 2-butanol, ethyl acetate (EA), dimethyl sulfoxide (DMSO), polyethylene glycol-400 (PEG-400) and 2-(2-ethoxyethoxy) ethanol [Transcutol((R))]" were evaluated. The solubility of piperine was determined at temperatures "T = 298.2 K to 318.2 K" and pressure "p = 0.1 MPa". The experimental solubility values of piperine were determined using a static equilibrium method by high-performance liquid chromatography at 254 nm. The solubility data of piperine obtained in this study was regressed using "van't Hoff and Apelblat models" with root mean square deviation values of <5.0%. The solubilities of piperine in mole fraction were obtained maximum in Transcutol (9.17 x 10(-2)) followed by PEG-400 (7.88 x 10(-2)), DMSO (3.59 x 10(-3)), 2-butanol (2.25 x 10(-2)), 1-butanol (2.20 x 10(-2)), IPA (1.82 x 10(-2)), EA (1.54 x 10(-2)), PG (1.47 x 10(-2)), ethanol (1.34 x 10(-2)), methanol (7.91 x 10(-3)), EG (6.70 x 10(-3)) and water (1.52 x 10(-5)) at "T = 318.2 K". Based on the results of activity coefficient, the solute-solvent interaction was seen maximum in piperine-Transcutol and piperine-PEG-400 in comparison with other solute-solvent combination studied. Mixing thermodynamic properties of piperine were determined by activity coefficient model and results indicated spontaneous and entropy-driven dissolution of piperine in most of the pure solvents studied. (C) 2017 Elsevier B.V. All rights reserved .