Hypolipidemic and Antioxidative Effects of Aqueous Enzymatic Extract from Rice Bran in Rats Fed a High-Fat and -Cholesterol Diet

PURPOSE: The aqueous enzymatic extract from rice bran (AEERB) was rich in protein, γ-oryzanol and tocols. The aim of this study was to investigate the effects of AEERB on the regulation of lipid metabolism and the inhibition of oxidative damage. METHODS: The antioxidant activity of AEERB in vitro was measured in terms of radical scavenging capacity, ferric reducing ability power (FRAP) and linoleic acid emulsion system-ferric thiocyanate method (FTC). Male Wistar rats were fed with a normal diet and a high-fat and high-cholesterol diet with or without AEERB. After treatment, biochemical assays of serum, liver and feces lipid levels, the antioxidant enzyme activity, malondialdehyde (MDA) and protein carbonyl were determined. RESULT: AEERB is completely soluble in water and rich in hydrophilic and lipophilic functional ingredients. AEERB scavenged DPPH• and ABTS•+ and exhibited antioxidant activity slightly lower than that of ascorbic acid in the linoleic acid system. The administration of AEERB reduced serum lipid levels and the atherogenic index compared with those of the hyperlipidemic diet group (HD). The administration of AEERB significantly lowered liver lipid levels, inhibited hepatic 3-hydroxyl-3-methylglutaryl CoA reductase activity, and efficiently promoted the fecal excretion of total lipids and total cholesterol (TC) (p < 0.05). Dietary AEERB enhanced antioxidant status in the serum, liver and brain by increasing the antioxidant enzyme activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) and decreasing the content of MDA and protein carbonyl. CONCLUSIONS: The results indicated that AEERB might act as a potent hypolipidemic and antioxidant functional food.