Objective: To establish the structural modified technology of gentiopicroside

and investigate the physicochemical properties of its acetylated product. Method: Orthogonal test was adopted to optimize the structural modified technology of gentiopicroside with reaction time

reaction temperature and molar ratio of acetic anhydride-gentiopicroside as factors

then single factor test was designed for optimizing the most significant factor.The apparent oil/water partition coefficient

stability test and powder properties were studied for investigating the physicochemical properties of the acetylated product. Result: Optimum acetylation process was established with pyridine as catalyst

acetic anhydride as acetylation agent

molar ratio of acetic anhydride-gentiopicroside(10:1)

reaction at 20℃ for 12 hours.Yield of the acetylated product was 94.02%.The reaction product

purified by silica gel column chromatography

was determined to be tetra-acetylated gentiopicroside by ultraviolet spectrum and mass spectrum;lgP of the apparent oil/water partition coefficient(P) was 1.40

P reduced with increasing pH value.Tetra-acetyl gentiopicroside was sensitive to high temperature and acid

not sensitive to high humidity and strong light.Tetra-acetyl gentiopicroside had poor liquidity. Conclusion: The optimized technology for structural modification of gentiopicroside is stable and controllable.Absorption characteristics of the acetylated productin vivo is better than that of gentiopicroside

which can improve its bioavailability.