BioFactors 21 (2004) 325–328 325 IOS Press Antioxidant activity of wheat extracts as affected by in vitro digestion Chandrika Liyanapathirana a and Fereidoon Shahidi a,b,∗ Departments of a Biology and b Biochemistry, Memorial University of Newfoundland, St. John’s, NL, A1B 3X9, Canada Abstract. Phenolic compounds from soft wheat and its milling fractions were extracted and their in vitro antioxidant activity evaluated. Non-hydrolyzed extracts were prepared by extracting phenolics into distilled deionized water. To make hydrolyzed extracts samples were first subjected to pH adjustments in order to simulate gastrointestinal pH conditions. Total phenolic content (TPC) was determined using Folin-Ciocalteu’s procedure. Total antioxidant activity (TAA) was determined using Trolox equivalents antioxidant capacity (TEAC) assay and expressed as Trolox equivalents (TE). Antioxidant activity of wheat extracts was determined using the procedures of inhibition of β-carotene bleaching, scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and inhibition of oxidation of human low density lipoprotein (LDL) cholesterol. The TPC and TAA of wheat extracts tested were significantly increased following hydrolysis. Similarly,the antioxidant activity, as determined by different proced ures, was considerably increased when the samples were subjected to simulated digestion conditions. Keywords: Antioxidant activity, wheat milling fractions, free radical scavenging, LDL oxidation 1. Introduction Whole grains provide a wide range of nutrients and biologically active constituents which may con- tribute to a reduction of the incidence of various chronic diseases [1]. Many constituents in plant foods exert protective properties by acting independently or synergistically as anticancer or cardioprotective agents by a variety of mechanisms [2]. One such protective mechanism attributed to dietary bioactive components is antioxidant activity which is a fundamental property important to life [2]. It has been demonstrated that many of the biological functions including antimutagenicity, anticarcinogenicity and antiaging are related to oxidation/antioxidation balance [3]. In general, food plants such as cereals, fruits, vegetables, nuts and spices form the primary source of naturally occurring antioxidants in the human diet [4]. Antioxidants that scavenge reactive oxygen species (ROS) and free radicals may play a significant role in inhibiting oxidative mechanisms that may otherwise initiate d egenerative diseases such as cancer, cardiovascular disease, cataract, brain dysfunction and arthritis [5]. In the human body endogenous antioxidant systems may not be sufficient to scavenge ROS completely and hence may cause oxidative damage to lipids, proteins and nucleic acids, among others. Therefore, dietary antioxidants may be particularly important in protecting against numerous chronic diseases resulting from oxidative stress [5]. The objective of the study was to determine total phenolic content and total antioxidant activity, to measure total antioxidant activity of wheat extracts using various assays * Corresponding author. Tel.: +1 709 737 8552; Fax: +1 709 737 4000; E-mail: fshahidi@mun.ca. 0951-6433/04/$17.00  2004 – IOS Press and the authors. All rights reserved