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Abstract

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®]” 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 × 10− 2) followed by PEG-400 (7.88 × 10− 2), DMSO (3.59 × 10− 3), 2-butanol (2.25 × 10− 2), 1-butanol (2.20 × 10− 2), IPA (1.82 × 10− 2), EA (1.54 × 10− 2), PG (1.47 × 10− 2), ethanol (1.34 × 10− 2), methanol (7.91 × 10− 3), EG (6.70 × 10− 3) and water (1.52 × 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.