abstract
In this work, the solubility of curcumin, gallic acid, and caffeine was measured in aqueous solutions of deep eutectic solvents (DES) and its constituents individually (HBA: cholinium chloride, and HBD: ethylene glycol and 1,2-propanediol) at 298.2 K. The solubility behavior was evaluated by experimental and in silico (by COSMO-RS model) approaches. Additionally, the solubilization kinetics of the curcumin was also evaluated. The finds of this work showed that the use of proper additives can favor the solubility of hydrophobic biomolecules, such as curcumin, in aqueous media. When the gallic acid solubility curves were determined, the hydrotropic effect was observed. This fact allows manipulating the solubilization or precipitation of this biomolecule according to the target application. For the caffeine, in its turn, all additives reduced the solubility of caffeine in relation to pure water. To support the understanding of the experimental data, the biomolecules and additives polarity were calculated by COSMO-RS, through their sigma-profile. The in silico approach reinforces the postulate that there is a set of factors involved in solubilization processes, being some of them: the non-polar charges, size, and linearity of the chemical chain, of both solvent and solute. Finally, the dissolution kinetics of curcumin was determined demonstrating the DES' viscosity effect on the mass transfer processes which are the basis of the solubility mechanism. The results here explored reinforces the importance of understanding the role of the polarity, size, and linearity of the chemical chain of all compounds involved in the solubility assay. The comprehension of these facts is of great importance to process development for the food and pharmacist industry, allowing to tune the solubility of the target biomolecule. (C) 2021 Elsevier B.V. All rights reserved.
keywords
DEEP EUTECTIC SOLVENTS; CURCUMIN; FOOD; DRUG
subject category
Chemistry, Physical; Physics, Atomic, Molecular & Chemical
authors
Oliveira, G; Farias, FO; Sosa, FHB; Igarashi-Mafra, L; Mafra, MR
our authors
Filipe Hobi Bordon Sosa
Junior Researcheracknowledgements
This study was financed by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Brasil (CAPES) - Finance Code 001. M. R. Mafra and L. Igarashi-Mafra are grateful to the Brazilian National Council for Scientific and Technological Development (CNPq Grant 310182/2018-2 and 308517/2018-0, respectively).