Modelling the solubility of luteolin in liquid solvents with the NRHB equation of state model

Luteolin is a bioactive flavonoid of natural origin with significant anti-microbial and anti-inflammatory properties. The physicochemical properties of luteolin, such as its very high melting point (601 – 614 K) and its very low solubility in water, are mainly affected by the strong specific intermolecular interactions, such as hydrogen bonding [1]. In this study, the solubility of luteolin in several solvents, such as water, alcohols, low and high molecular weight glycols and various other organic solvents, was modelled using the Non-Random Hydrogen-Bonding theory, which is a statistical thermodynamic equation of state model that is based on lattice theory [2]. Due to the severe effect of hydrogen bonding in the crystalline structure and the dissolution behaviour of luteolin, all potential intermolecular hydrogen bonds were explicitly accounted for using literature values for the hydrogen bonding enthalpy and entropy. In this way, and by adjusting one binary interaction parameter to the solubility experimental data, the model successfully correlates the solubility of luteolin in water and the investigated organic solvents, showing an average absolute deviation of 3.3%. Such an approach allows the prediction of the dissolution behaviour both in cases of extremely low solubility (e.g. in water, in which the solubility value is of the order of 1E-06 in mole fraction) and in cases of relatively higher solubility (e.g., in PEG-400, in which the solubility value is of the order of 1E-01 in mole fraction) ([Fig. 1]).

Fig. 1 Solubility of luteolin in low molecular weight glycols and poly(ethylene glycol) with average molecular weight of 400 g mol^-1. Experimental data (symbols) [3] and NRHB calculations (lines).

Funding This research has been co-financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH – CREATE – INNOVATE (project code: T2EDK-01627).

 

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• References

• 1 Peng B, Zi J, Yan W.. Measurement and Correlation of Solubilities of Luteolin in Organic Solvents at Different Temperatures. J Chem Eng Data 2006; 51: 2038-2040
• 2 Panayiotou C. Tsivintzelis l, Economou IG, Nonrandom hydrogen-bonding model of fluids and their mixtures. 2. Multicomponent mixtures, Ind Eng Chem Res 2007; 46: 2628-2636
• 3 Shakeel F, Haq N, Alshehri S, Ibrahim MA, Elzayat EM, Altamimi MA, Mohsin K., Alanazi FK, Alsarra IA. Solubility, thermodynamic properties and solute-solvent molecular interactions of luteolin in various pure solvents. J Molecular Liquids 2018; 255: 43-50

Publication History

Article published online:
16 November 2023