Investigation of Physiological Properties of Transglycosylated Stevia with Cationic Surfactant and Its Application To Enhance the Solubility of Rebamipide.

The poor water solubility of rebamipide was enhanced by the mixed micelles of transglycosylated stevia (Stevia-G) and trimethylammonium chloride with varying carbon chain length (C nTAC, n = 14, 16, and 18). Fluorometry, isothermal titration calorimetry (ITC) and dynamic light scattering techniques examined the aggregation properties of Stevia-G and C nTAC. Synergism was found between Stevia-G and C nTAC using the approaches of Clint and Rubingh. The negative interaction parameter (average βm = -4.17, -5.47, and -7.07) and excess free energy (average ΔG°ex = -2.47, -3.06, and -3.88 kJ mol-1) increased with increasing chain length of C nTAC. The negative B1 values by the Maeda approach suggested that chain-chain interactions contribute to the formation of a mixed micelle. The solubilization of rebamipide in the mixed micelle was evaluated in the term of the molar solubilization ratio (MSR) and partition coefficient ( Km). The Km from the Stevia-G/C16TAC system was highest at a low mole fraction of C nTAC (0.2-0.6). In conclusion, the solubilization of rebamipide was more favorable between Stevia-G and C16TAC, although the stability of the mixed micelle was enhanced by an increase in hydrophobicity of the longer chain lengths used in C nTAC.