The rice bran, a by-product of rice milling process, is well known for various functional components, such as tocopherol, tocotrienol, γ-oryzanol, carrying antioxidant activities. This study was conducted to investigate the antioxidant components and antioxidant activities in rice bran of different Korean rice cultivars. The 8 isomers of vitamin E, γ-oryzanol, flavonoids, and polyphenolics in rice bran from 16 Korean premium and high quality rice cultivars were quantified. DPPH and ABTS radical scavenging activities and reducing power of the ethanol extracts of rice bran were measured. ‘Hopum’ showed the highest total vitamin E content, 221.47 μg/g among the cultivars, and ‘Hanseol’ showed the lowest content. The rice bran showed different compositions of α-, β-, γ-, δ- tocopherol and tocotrienol among rice cultivars. The antioxidant contents were also different by cultivar; the γ-oryzanol contents ranged from 1.99 mg/g (Unkwang) to 4.30 mg/g (Chilbo), the polyphenol contents ranged from 427.22 mg gallic acid eq./100 g (Odaebyeo) to 775.80 mg gallic acid eq./100 g (Hopum). ‘Hopum’ also had the highest DPPH and ABTS free radical scavenging activities, 9.82% and 187.5 AEAC mg/100 g, respectively. In vitro, the rice bran extracts from ‘Hopum’ had significantly higher antioxidant activities than that of other cultivars.

Vitamin E is a fat-soluble vitamin that exists in eight different forms, which are α , β , ~gamma , and δ tocopherol, and α , β , ~gamma , and δ tocotrienol. Tocopherols and tocotrienols are important antioxidant in foods, feeds and their raw materials, where they scavenge lipid radicals. Each form has its own biological activity, the measure of potency or functional use in the body. Antioxidants such as vitamin E act to protect cells against the effects of free radicals, which are potentially damaging by-products of the body's metabolism. Free radicals can cause cell dam-age that may contribute to the development of cardiovascular disease and cancer, The content of tocopherols and tocotrienols vary depending on the environmental condition such as growing regions, temperature, crops and varieties. This report deals with chemical and physical properties and extends to their nutritional and health effect on the tocopherols and tocotrienols in cereal grains.