Determination of antioxidant component and activity of rice bran extract

Abstract

Rice bran is one of the most important co-products in the rice milling. In this research, antioxidant activity of two Iranian rice bran varieties, Fajr and Tarem, extracted by three different solvents (methanol, ethanol and ethyl acetate) was evaluated. The order of antioxidant activity was evaluated by measurement of total phenolic content, antioxidant activity in linoleic acid system, reducing power and scavenging capacity by DPPH radical. The methanolic extract of Fajr rice bran showed a total phenolic content of 3.31 mg Gallic acid/gr rice bran and a DPPH free radical-scavenging activity of 93.91%, achieved at 50 mg/ml concentration, and a percent inhibition of linoleic acid peroxidation of 68.01% with reducing power. These results indicated that the methanolic components of the rice bran extracts might potentially be natural antioxidants. Rice bran is a rich source of natural antioxidants which can be used as free radical scavengers. It is widely recognized that many of the today's diseases are due to the oxidative stress that results from an imbalance between formation and neutralization of free radicals. The rice bran oil antioxidants are very efficient in reducing low density lipoprotein and total serum cholesterol. Vitamin E is a generic term for a group of four tocopherols (α, β, γ and δ) and four tocotrienols (α, β, γ and δ), of which α-tocopherol has the highest biological activity (1). Rice bran oil contains about 0.1-0.14 vitamin E components and 0.9%-2.9% oryzanol; the concentrations can vary substantially, according to the origin of the rice. Oryzanol is