Role of electrolytes in the solubility of l -proline and its transfer free energetics

Silybin Cocrystals with Improved Solubility and Bioavailability

Backgroud/Objectives: Silymarin, an extract from milk thistle, is widely recognized for its therapeutic potential in treating liver disorders. However, its clinical utility is limited by the poor solubility and low bioavailability of its key active ingredient, Silybin. In this study, we sought to address this issue through the development of a novel cocrystal of Silyin. Methods: Silybin-L-proline cocrystal was synthesized and the physicochemical properties of the cocrystal were characterized by PXRD, TGA, DSC, and FTIR. Dissolution tests were conducted in various pH solutions, and the impact of precipitation inhibitors was evaluated. Furthermore, pharmacokinetic study in rats were performed to assess the bioavailability. Results: The dissolution studies demonstrated that the cocrystal has a significant improvement in dissolution performance, particularly in acidic environments. Furthermore, the use of precipitation inhibitors, such as PVP, prolonged the supersaturation period for adequate absorption. Pharmacokinetic studies in rats revealed that the cocrystal exhibited a 16-fold increase in bioavailability compared to the raw Silybin extract, outperforming the commercial Silybin-phosphatidylcholine complex. Conclusions: The Silybin-L-proline cocrystal significantly enhances dissolution and bioavailability, indicating its potential to improve the therapeutic efficacy of Silybin in clinical applications.

Molecular interaction studies of L-proline in water and ethanol at different temperatures using dielectric relaxation, refractive index and DFT methods

The complex dielectric permittivity of L-Proline in water and ethanol solutions with molar concentrations ranging from 0.025 M to 0.15 M was measured by open-ended coaxial probe technique. The measurements were carried out across a frequency span of 0.02 < ν/GHz < 20 and temperatures varying from 298.15 K to 323.15 K. The densities (ρ) and refractive index (nD) of the L-proline in aqueous and ethanol solutions were also determined to provide insights into the solute-solvent interactions in the system. The Havriliak-Negami equation was employed to compute the dielectric relaxation time of the mixtures. The relaxation time of L-Proline in an ethanol medium was found to be higher than that of L-Proline in an aqueous medium due to the greater degree of self-association of ethanol molecules. Additionally, the relaxation time of the mixtures lengthened with rising molar concentration, which is attributed to the presence of hydrogen bonds among L-Proline and aqueous/ethanol molecules. The strength of the hydrogen bond interaction of L-Proline in both mediums was calculated using single-point energy calculations employing IEFPCM/PCM solvation models through DFT/B3LYP and MP2 approaches with a 6-311 G ++ (d, p) basis set. The results were correlated with the hydrogen bond strength, Gibbs' free energy of activation parameter, and dipole-dipole interactions.

Solubility analysis of homologous series of amino acids and solvation energetics in aqueous potassium sulfate solution

In this study we estimated the solubilities of glycine, D,L-alanine, D,L-nor-valine and D,L-serine in aqueous mixtures of potassium sulfate (K₂SO₄) at 298.15 K using analytical 'gravimetric method'. The experimental solubilities of homologous series of amino acids in aqueous K₂SO₄ mixture were discussed in terms of relative solubility, salting-in and salting-out effect by evaluating the influential constants. The effect of physicochemical and chemical factors on solubility were discussed briefly and correlated with the thermodynamics. Initially, the study of solvation energetics such as transfer Gibbs energies were evaluated based on the calculations from solubility data and relative stability of the experimental molecules was discussed under the experimental condition.