Abstract: The interaction between gardenoside and bovine serum albumin (BSA) was studied by fluorescence and UV-Vis absorption spectrometry under simulated physiological conditions. The quenching mechanism of the intrinsic fluorescence of BSA by gardenoside was investigated by Stern-Volmer and Lineweaver-Burk equations.It was proved that the quenching mechanism of BSA by gardenoside was a static quenching procedure with quenching constants of 4.632×10⁴, 3.515×10⁴ and 3.575×10⁴ mol/L at 298, 310 and 322K, respectively. Binding constants and number of binding sites at corresponding temperature were 1.805×10⁴, 2.546×10⁴ and 4.165×10⁴ as well as 1.334, 1.112 and 0.944, respectively. The thermodynamic parameters were ΔG＜0，ΔH＜0，ΔS＞0, which proved the electrostatic force played a major role between BSA and gardenoside.The distance was calculated to be 1.78 nm using Fosters resonance energy transfer.

Key words: Bovine serum albumin, gardenoside, fluorescence spectrometry