Abstract: The interaction of dihydromyricetin (DMY) with human serum albumin (HSA) was investigated by spectroscopic methodologies and molecular docking.The fluorescence spectral results showed that HSA fluorescence was quenched regularly with the addition of DMY,the quenching mechanism may be a static fluorescence quenching procedue.All the magnitude of binding constants (K_A) were larger than 10⁵ L/mol and the number of binding sites (n) in the binary system were approximate to 1 in different temperature.According to thermodynamic parameters of Van’t Hoff equation,it could be suggested the binding process of DMY with HSA was spontaneous and the main interaction force of DMY with HSA was electrostatic force.The binding distance (r) between the DMY and HSA was calculated to be about 3.32 nm based on the theory of Forster’s nonradiation energy transfer,which indicated that the energy trasfer from HSA to DMY occurs with high possibility.The synchronous and 3D florescence spectroscopy demonstrated that the secondary conformation of HSA has been changed after interaction with DMY.From the result of site marker competitive experiments and the molecular docking,it could be deduced that DMY was inserted into the subdomain IIA (site I) of HSA.

Key words: dihydromyricetin, human serum albumin, fluorescence quenching, binding interaction, molecular docking