Determination of Plasma Protein Binding Rate of Hydroxytyrosol in Normoxic and Hypoxic Rat by HPLC-Ultrafiltration Method

OBJECTIVE To establish a method for determination of plasma protein binding rate of hydroxytyrosol, and compare the difference of plasma protein binding rate in normoxic and hypoxic rats. METHODS The protein binding rate of hydroxytyrosol in normoxic and hypoxic rats plasma was determined by HPLC-ultrafiltration. RESULTS When the concentration of hydroxytyrosol in rat plasma was 3, 6 and 12 mg·mL^-1, the plasma protein binding rates of hydroxytyrosol with normoxic rats were (17.23±1.11)%, (16.88±1.37)% and (16.70±0.98)%, and the plasma protein binding rates with hypoxic rats were (12.31±1.79)%, (12.75±1.20)% and (13.42±1.98)%. The difference of the plasma protein binding rate was significant between the normoxic and hypoxic rats(P<0.01). CONCLUSION The binding strength of hydroxytyrosol to plasma protein of normoxic rats is low and does not show concentration dependence within the concentration range of 3-12 mg·mL^-1. The binding strength of hydroxytyrosol to plasma protein of hypoxic rats is significantly lower than that of hydroxytyrosol to plasma protein of normoxic rats.