Spectroscopic Investigation Of Active Component Mangiferin In Anemarrhena Asphoides Bge Interacting With Protein

Investigating the interaction between drugs and proteins has much importance in pharmacokinetics and toxicology. The interaction can exert important effect on the distribution, free concentration, biological activity and metabolism of the drug in blood stream, and provide an important theoretical base on studying human disease, dosage forms and development of new drugs. In this dissertation, mangiferin, an active Component in Chinese Traditional Medicine Anemarrhena asphodeloides Bge, interacting with Bovine Serum Albumin, Insulin and Glucagon was studied. On the basis of the previous research, the following major innovative works were carried out:(1) Mangiferin was chosen to study its interaction to Serum Albumin and Peptides, and the quenching rates, binding constans in different systems were compared.(2) The interaction of mangiferin to insulin and glucagon was investigated in ternary system, the results indicated that the Peptides were competitive with each other to act on mangiferin.(3) The secondary structure compositions of insulin and glucagon were obtained by quantitative analysis using IR self deconvolution with second-derivative resolution enhancement and curve-fitting procedure.This dissertation consists of four chapters.Chapter 1:The structures, functions and natures of proteins were briefly introduced firstly. The studying method, theory, and development of interaction between small ligands and proteins were summarized.Chapter 2:The mechanism of interaction between mangiferin (MA) and bovine serum albumin (BSA) in aqueous solution was investigated by fluorescence spectra, synchronous fluorescence spectra, absorbance spectra and Fourier transform infrared (FT-IR) spectroscopy. The binding constants and binding sites of MA to BSA at different reaction times were calculated. And the distance between MA and BSA was estimated to be 5.20 nm based on Foster's theory. Synchronous fluorescence and FT-IR measurements revealed that the secondary structures of the protein were changed after the interaction of MA with BSAChapter 3:The binding of mangiferin to insulin and glucagon was investigated in ternary system by optical spectroscopy. Fluorescence titration experiments revealed the quenching mechanism. The ratios of binding constants of glucagon-mangiferin to insulin-mangiferin were calculated in "pure" and ternary system, respectively. The results indicated that the Peptides were competitive with each other to act on mangiferin. Values of the thermodynamic parameters and the experiments of pH effect proved that the key interacting forces between mangiferin and the Peptides were hydrophobic interaction. UV-Vis absorption, synchronous fluorescence and Fourier transform infrared measurements showed that the conformation of insulin and glucagon were changed after adding mangiferin.