67B-14 |
|
J.-S. KIM1, J. M. Woo1, H. S. Kim1, and H. Y. Chung2. (1) Pulmuone R&D Center, Pulmuone Co. Ltd., Seodaemun PO Box 146, Seodaemun-Ku, Seoul, 120-600, South Korea, (2) Biology Dept., Food and Nutritional Sciences Programme, and Food Sci. Lab., The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, HKG, China Tocotrienols are minor plant constituents found abundantly in rice bran and in palm oil which can provide a significant source of vitamin E animal feeds. Tocotrienols were reported to have an intrinsic hypocholesterolemic effect by inhibiting HMG-Co A reductase activity. They may have similar antioxidative property as tocopherols in food and biological system due to their similar chemical structures. However, the antioxidant activity and mechanism of tocotrienols to scavenge the free radicals and to inhibit the peroxidation of linoleic acid are less understood. The purpose of the study was to investigate the scavenging effect on free radical and the inhibiting effect on peroxide formation by tocotrienols. Free radical scavenging activity of tocotrienols at different concentrations (0, 2.5, 10, 40, and 160 ppm) was monitored by the DPPH (1,1-diphenyl-2-picrylhydrazyl) method whereas inhibition of linoleic acid peroxidation was evaluated using the thiocyanate method with the linoleic acid emulsion (0.02 M, pH 7.0) incubated for 5 d at 37 C . Thiobarbutric acid (TBA) test to determine malonaldehyde formation from linoleic acid peroxidation was measured on the final incubation day. Free radical scavenging activity increased with increasing concentration levels of tocotrienols. Tocotrienols exhibited 38.4, 77.6, 91.7 and 95.2 % radical scavenging activity at the concentration of 2.5, 10, 40 and 160 ppm, respectively. In the initial four days, oxidation of linoleic acid without tocotrienol was accompanied by a rapid increase in the peroxide value. The activity of tocotrienols evaluated by the thiocyanate method showed low absorbance values indicating a high level of antioxidant activity. All treatments showed similar trends in antioxidant activity when evaluated by both thiocyanate method and TBA test. This study illustrated that tocotrienols might be able to inhibit the formation of free radicals and peroxides produced during linoleic acid oxidation in food and biological system.
Session 67B, Food Chemistry: Antioxidants and bioactive agents
|