Establishment of the quantitative structure-activity relationship between the structure of terpenoids and their enhancing drug penetration ability through human skin based on density functional theory / 中国药学杂志

OBJECTIVE: To establish the quantitative structure-activity relationship (QSAR) for predicting the percutaneous permeation enhancing activity of terpenoids, using the indexes of reactivity in molecules as the important descriptors. METHODS: The structural and thermodynamic parameters of 41 terpenoids were optimized using B3/LYP method of DFT at the level of 6-311 + + G (2d, p). The backward method in stepwise multiple regression was used to establish the QSAR model for predicting activities of terpenes that enhanced drug penetration through human skin. RESULTS: The multiple correlation coefficient (r) was determined to be 0.655 and the square cross validated correlation coefficient (RCV2) was determined to be 0. 654. The QSAR model indicated that the electrostatic potentials (VS,ta, VS,max, VS,min), chemical potential (X), thermal capacity (Cp), and dipole moment (D) of individual molecules could be responsible for the in vitro permeation enhancing abilities of terpenoids. CONCLUSION: The indexes of reactivity in molecules based on density functional theory can simulate more exactly the quantitative relationship between the structures of penetration enhancers and their percutaneous permeation enhancing abilities for drugs, which will facilitate reasonable explanation of the model.

Characterization of the interaction between reserpine and bovine serum albumin: Spectroscopic approaches.

The characteristics of the interaction between reserpine and bovine serum albumin (BSA) were studied by fluorescence, UV-vis absorption and Fourier transform infrared (FT-IR) spectroscopy. Spectroscopic analysis revealed that fluorescence quenching of BSA by reserpine was through a static quenching procedure. The binding constant KA of reserpine with BSA at 293, 301 and 309 K was 1.63, 1.78 and 2.35 × 105 moL-1 L respectively, which indicated degree of binding force between reserpine and BSA. There was one binding site between reserpine and BSA. The entropy and enthalpy changes were positive, indicating that interaction of reserpine and BSA was driven mainly by hydrophobic forces. The average binding distance between the donor (BSA) and the acceptor (reserpine) was about 3.84 nm based on the Förster non-radiation energy transfer theory. Results of synchronous fluorescence and FT-IR spectra indicated that the conformation and microenvironment of BSA were changed by the binding of reserpine. The results may provide important insights into the physiological activity of reserpine.

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

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

Inclusion of ginsenoside Rg_3 with hydroxypropyl-?-cyclodextrin / 中草药

Objective To investigate the inclusion of ginsenoside Rg_3 with hydroxylpropyl-?-cyclodextrin (HP-?-CD) in aqueous solutions, inclusion molar ratio of host and guest molecules, and change of thermodynamic parameters during the inclusion process. Methods The measurements of the inclusion mechanism, inclusion molar of the host and guest molecules, and change of thermodynamic parameters were carried out by the following methods: phase solubility, IR, NMR, and TLC methods, respectively. Results The results indicated that the inclusion compound of ginsenoside Rg_3-HP-?-CD was formed. The content analysis of the inclusion compound showed that the inclusion ratio of ginsenoside Rg_3-HP-?-CD was 1∶1. The change in the thermodynamic parameters suggested that the inclusion could proceed (△G