INVESTIGATION ON ELECTROCHEMICAL BEHAVIOR OF EMODIN AND ITS APPLICATION

Emodin showed a second order derivative reduction wave with peak potential of -0.75 V(SCE) by single sweep oscillopolarography using H₃BO₃-Na₂B₄O₇ (pH 8.50) as base solution. The peak height of emodin is proportional to the concentration in the range of 1.42×10^-7～5.7×10^-6 mol·L^-1 and 7.1×10^-6～7.1×10^-5 mol·L^-1, respectively. The detection limit is 0.7×10^-7 mol·L^-1. It can be employed for the determination of emodin in Rheum officinale Baill with satisfaction. The electrochemical behavior of emodin was studied and the electrode reaction mechanism was proposed. In addition, it was found that emodin, aloe emodin, chrysophanol, rhein and physcion can scavenge superoxide anion radical produced by the autoxidation of pyrogallol. The scavenging activity is in the order: emodin>aloe-emodin>chrysophanol>rhein>physcion.