Inhibition of Lipid Peroxidation by Enzymatic Hydrolysates from Wheat Bran

Inhibition of Lipid Peroxidation by Enzymatic Hydrolysates from Wheat Bran

Jing Wang^1,2*, Xiaoping Yuan³, Baoguo Sun^1,2 and Yanping Cao^1,2¹College of Chemistry and Environment Engineering, Beijing Technology and Business University, 11 Fucheng Road, CN-100048 Beijing, PR China
²Beijing Higher Institution Engineering Research Center of Food Additives and Ingredients, Beijing Technology and Business University, 11 Fucheng Road, CN-100048 Beijing, PR China
³Department of Science and Technology, China Grain Reserves Corporation, 143A Xizhimenwai Street, CN-100044 Beijing, PR China

Article history:
Received May 14, 2010
Accepted November 4, 2010

Key words:
wheat bran, enzymatic hydrolysates, alloxan, antioxidative enzyme, lipid peroxidation, liver microsome, low-density lipoprotein

Summary:
Wheat bran, an important by-product of the cereal industry, is rich in potentially health-promoting phenolic compounds. The phenolics are mainly esterified to the cell wall polysaccharides. In our previous paper, wheat bran was destarched and deproteinated by α-amylase, protease and amyloglucosidase successively and further hydrolyzed using Bacillus subtilis xylanases, and the enzymatic hydrolysates from wheat bran (EHWB) showed good scavenging activity in vitro. The aim of this study is to further characterize the antioxidant potential of EHWB against various systems, both ex vivo and in vivo, namely, rat liver microsomal lipid peroxidation systems induced by Fe^₂₊/H₂O₂ and Fe³⁺-adenosine diphosphate (ADP)/dihydronicotinamide adenine dinucleotide phosphate (NADPH), copper- and 2,2’-azo-bis(2-amidinopropane) dihydrochloride (AAPH)-induced human low-density lipoprotein (LDL) oxidation systems, and alloxan-induced in vivo lipid peroxidation in mice. EHWB inhibited lipid peroxidation in rat liver microsomes induced by Fe²⁺/H₂O₂ and Fe³⁺-ADP/NADPH in a concentration-dependent manner with 90.3 and 87 % inhibition of lipid peroxidation at 50 mg/L, respectively, which were similar to that of butylated hydroxytoluene (BHT) at 20 mg/L. The antioxidant potential of EHWB at a concentration ranging from 10 to 20 mg/L in the nonenzymatic system was more effective than in the enzymatic system. EHWB strongly inhibited in vitro copper- and AAPH-mediated oxidation of LDL in a concentration- and time-dependent manner with 52.41 and 63.03 % inhibition at 20 mg/L, respectively, which were similar to that of ascorbate at 10 mg/L. EHWB significantly decreased the level of thiobarbituric acid reactive substances (TBARS) and increased the activities of glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) in serum and liver of alloxan-treated mice compared with the control. These results demonstrated that EHWB might be efficient in the protection of food products and humans against free radical-induced oxidative damage.

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