Study On The Interaction Between Tea Polyphenols And Carriers And Biological Macromolecules By Thermodynamic - Spectroscopy

According to World Health Organization survey, cancer patients are rising every year. Cancer is one of the serious illnesses. It has become the second killer to threaten human health, second only to cardiovascular disease. Therefore, anticancer drugs have become a hot research topic among people. Tea polyphenols drugs are the natural antioxidants extracted from tea, they have the effects of anti-aging, inhibition of cardiovascular disease, skin beauty and prevention and anti-cancer. However, the poor solubility and low bioavailability of some antitumor drugs have limited their clinical application. The inclusion technology of cyclodextrin can obviously improve the solubility of drugs. So researches on the interactions between drug molecules and cyclodextrin or biomacromolecule and the thermodynamic properties of drug molecules in simulated body fluid, could reveal the mechanism of drug effect in vivo and provide theoretical basis to study the new drug and improve clinical application.On the basis of literature investigation and the device of laboratory, we measured the interactions of catechins drugs with cyclodextrin or DNA in aqueous solutions by the isothermal titration calorimetry, fluorescence spectroscopy and nuclear magnetic resonance spectroscopy. Based on the calculation and the discussion of the interaction among kinds of solute and solvent molecules, we can explain the pharmacodynamic mechanism of the drug in the human body. Study on the thermodynamic properties of drugs in simulated body fluid using calorimetry, density and conductivity methods can explore the mechanism of the interaction between solute and solvent molecules. As a part of the project supported by National Natural Science Foundation(NO. 21103079, 21473085), the present work mainly composed of four parts:In the first part: The host-guest interactions of(+)-catechin(CA),(-)-epicatechin(EC) with hydroxypropyl-β-cyclodextrin(HP-βCD) in Tris buffer solutions at different pHs were investigated using isothermal titration microcalorimetry and spectroscopic study. The interaction mechanism between drug and β-CD molecules was studied on the basis of the thermodynamic parameters.In the second part: Stydy on the interactions of(+)-catechin(CA),(-)-epicatechin(EC) with DNA in Tris buffer solution at different pHs were investigated with spectroscopy methods. Thermodynamic parameters including number of binding site and binding constants were obtained from the experimental data, which can be used to explore the mechanism of enhancing curative effects of drugs in human body.In the third part: The enthalpic interaction coefficients, dissociation enthalpy, thermodynamic dissociation constant of protocatechuic acid(PCA) in aqueous sodium chloride and potassium chloride solutions at 298.15 K were obtained using calorimetry and conductivity method. The interaction mechanism among solute and solvent molecules in salt solutions were clarified in terms of(solute+solute) and(solute + solvent) interactions.In the fourth part: The enthalpies of dilution, volumetric properties of protocatechuic acid(PCA) in phosphate buffer solution at different pHs were researched at 298.15 K. The interactions among solvated solute molecules were discussed according to the experimental data.