Determination of the Binding Rate of Rat Plasma Protein with Five Anthraquinones in Rhubarb

OBJECTIVE To develop a method for the simultaneous determination of the binding rate of plasma protein with aloe-emodin, rhein, emodin, chrysophanol and physcion. METHODS The equilibrium dialysis method was carried out to imitate the binding process between five anthraquinones and plasma protein. Plasma samples were treated with solid-phase extraction and the binding rate was determined by HPLC. RESULTS The extract recoveries of aloe-emodin, rhein, emodin, chrysophanol and physcion were 68.6%, 91.5%, 78.6%, 88.2% and 71.4%, the binding rates of plasma protein were 93.1%, 91.3%, 95.2%, 87.5% and 89.7%. CONCLUSION This method shows the high binding rate of five anthraquinones to plasma protein. The binding rates of five anthraquinones are not proportionally dependent on plasma concentration.