ANTIOXIDANT MECHANISM OF STEVIA-REBAUDIAN A EXTRACT AND ANTIOXIDANT ACTIVITY OF INORGANIC SALTS

Stevia rebaudiana hot water extracts were shown to have highly antioxi dant activity against sardine oil and linoleic acid. The most active f raction which was reported in the previous paper contained large amoun ts of potassium. The activity was decreased by the removal of cations from the fraction by ion exchange chromatography. The activity was rec overed by the addition of potassium carbonate to the fraction from whi ch cations were removed. It was suggested that the potassium ion parti cipated in the antioxidant activity of S. rebaudiana. When antioxidant activities of inorganic salts were investigated, it was ascertained t hat potassium carbonate (K2CO3), potassium bicarbonate (KHCO3), sodium phosphate (Na3PO4), potassium chloride (KCl) and sodium carbonate (Na 2CO3) functioned as antioxidant compounds against linoleic acid. The m ost active inorganic salt was potassium carbonate. It was suggested th at the function of the antioxidant activities of S. rebaudiana was mai nly due to the scavenging of free radicals and next to the scavenging of superoxides. The activity of potassium carbonate was also mainly du e to the scavenging activity of free radicals.