Radical Scavenging Capacity and Antioxidant Activity of the E Vitamer Fraction in Rice Bran

Radical scavenging capacity and antioxidant activity of an E vitamer fraction from rice bran were investigated. The E vitamer fraction was prepared by a liquid-liquid extraction method. The free radical scavenging capacity of the E vitamer fraction was measured by the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) method at the concentration range of 2.5 to 640 ppm, whereas the antioxidant activities were measured by both the reducing power and ferric thiocyanate (FTC) methods at different concentrations (0, 2.5, 10, 40, and 160 ppm). Radical scavenging capacity of the fraction was effective up to 160 ppm, then remained stable. Also, at a concentration of 160 ppm, it was highly effective in inhibiting linoleic acid peroxidation. Similarly, superoxide scavenging and antioxidant activities of the E vitamer fraction were compared with those of the synthetic phenol compounds. Results showed that with a concentration of the E vitamer fraction at 160 ppm, the antioxidant activity was comparable to both butylated hydroxytoluene (BHT, 160 ppm) and butylated hydroxyanisole (BHA, 160 ppm). No significant differences (P > 0.05) were found among them. The E vitamer fraction may be a good substitute for the synthetic phenol antioxidants currently used in industry because the former is more natural and comparatively effective in its radical scavenging capacity and antioxidant activity.