Identification and thermodynamic parameter of ginsenoside Rh_2 with HP-?-CD in aqueous solution / 中草药

ABSTRACT

Objective To identify the inclusion compound of ginsenoside Rh2 with hydroxylpropyl-?-cyclodextrin (HP-?-CD) in aqueous solution, and to investigate the change of thermodynamic parameters during the inclusion process. Methods The measurements of the inclusion mechanism, inclusion molar ratio of the host and guest molecules, and change of thermodynamic parameters were carried out by the following methods separately; thin layer chromatography (TLC), differential scanning calorimetry (OSC), infrared (IR) spectrometry, phase solubility method, and thermodynamic method, respectively. Results That all the phase solubility diagrams showed a typical AL-type in various temperatures and suggested the formation of a soluble complex of 1∶1 molar ratio. TLC and IR Spectroscopy confirmed that the significant interaction between the host and guest molecules was probably due to the inclusion of aglycone of Rh2 molecule into the hydrophobic cavity of HP-?-CD molecule. The change in the thermodynamic parameters suggested that the inclusion could proceed spontaneously (?G