Studying Intermolecular Interaction Between Insoluble Active Substances And Serum Albumin By Spectrometry And Molecular Modeling

In recent years,as people pay more attention to the application of natural active substances,the solubilization of insoluble of active molecules has attracted wide attention,further find the green synthesis structure derivative method,and investigate its solubility,storage,transport and mechanism in vivo,become the front fields of natural products chemistry.In this paper,the insoluble active molecules of flavonoids were synthesized by green chemical route.Under physiological conditions,the interaction between eutectic and albumin was investigated by fluorescence spectroscopy and molecular dynamics technology,and the transport mechanism of eutectic in vivo was clarified to investigate the intermolecular interaction between cocrystal and albumin and elucidate the transport mechanism of eutectic in vivo.The results provide important reference value for the absorption,distribution,metabolism and pharmacodynamic information of forest-derived active substances in vivo.The main research contents and results of this work are listed as follows:(1)The intermolecular interaction between Icarrin(ICA)and Human Serum Albumin(HSA)was investigated by spectral method and building molecular model to explore the mechanism of interaction.And the intermolecular interaction model of ICA-HSA was described by using a variety of theoretical equations to compare and discuss their usability.The results showed that the theoretical model was different and the results were different to ICA-HSA.There are two quantitative kinds of trends based on the differences between hypothesis and experimental conditions.In this paper,through constructed the physical model to assist the intermolecular interaction mode of ICA-HSA.The optimal mode of ICA-HSA intermolecular interaction is the double logarithmic equation.Meanwhile,the ICA-HSA intermolecular interaction was analyzed by physical modeling,indicating that the ICA likely occurred in active site Sudlow's sites I and ICA-HSA system mainly has van der Waals force,hydrophobic interaction and hydrogen bonding.(2)The cocrystal of genistein and apigenin were screened and prepared,and their structures were characterized by Fourier transform infrared spectroscopy(FTIR),nuclear magnetic resonance spectroscopy(NMR),differential scanning calorimeter(DSC)and powder diffraction(PXRD).The results showed that the characteristic peaks of genistein-adenine and apigenin-nicotinamide were obviously different from those of the physical mixture of the two raw materials.The screened products were verified by FTIR,NMR and DSC,indicating that genistein-adenine and apigenin-nicotinamide cocrystal were successfully synthesized,meanwhile,the solubility differences between the products and the raw materials were compared and analyzed,showed that the solubility of the eutectic product increased slightly compared with the raw drug.At the same time,the obtained products lay a foundation for the intermolecular interaction between HSA and small molecule group in the further study.(3)The interactions between genistein-adenine/apigenin-nicotinamide cocrystal and HSA were studied by fluorescence spectroscopy,and the difference of interaction between single API raw material and cocrystal system was explained.The results showed that the fluorescence spectras of the interactionbetween cocrystal and HSA were static quenching.The quenching constants,binding constants and thermodynamic parameters were obtained,which showed that the interaction forces between genistein and adenine were mainly van der Waals interaction force and conjugation interaction force,and the hydrogen bond and hydrophobic interaction force between apigenin and nicotinamide.Synchrotron fluorescence spectroscopy showed that the interaction of different systems with HSA resulted in the extrusion of the peptide chain of HSA and the change of the hydrophobicity of the microenvironment around the active site of HSA.(4)The interaction mechanisms between genistein-adenine and apigenin-nicotinamide with HSA were studied by molecular docking and molecular simulation techniques,and the stability of the formed system was also studied at the molecular level.The micro-interaction mechanism,binding site characteristics,intermolecular interaction force types and binding energy of the synthesized cocrystal were further elaborated.The spectroscopic experiments were also confirmed from the other side.The results showed that small molecule groups were embedded in the active cavity of HSA and formed stable complexes through the interaction between small molecule groups and amino acids around HSA.Molecular simulation showed that the RMSD value of the system continued to rise and then tended to balance,indicating that the structure of the complexes was loose at first,and then compact after simulation.