Antioxidant Activity of β-Glucan

β-Glucans extracted from barley, which mainly contains β-(1,3-1,4)-D-glucan, are used extensively as supplements and food additives due to their wide biologic activities, including a reduction in blood lipid level. In this study, the antioxidant activity of β-glucan was examined to assess potential new benefits associated with β-glucan, because oxidative stress is considered one of the primary causal factors for various diseases and aging. β-Glucan extracted from barley was found to possess significant antioxidant activity. The amount of antioxidant activity was influenced by different physiologic properties (e.g., structure and molecular size) of β-glucan, which varied depending on the source and extraction method used. The antioxidant activity of β-glucan was significantly higher than that of various polymers that are used as food additives. These results indicate that β-glucan has promise as a polymeric excipient for supplement and food additive with antioxidant and other benefits, which may contribute to enhancing health and beauty. 1. Introduction β-Glucan is a polysaccharide comprised of β-linked D-glucose molecules. Various β-glucans have been extracted from various sources such as fungi, baker’s yeast, barley, oats, and seaweed. The physicochemical properties of β-glucans differ depending on characteristics of their primary structure, including linkage type, degree of branching, molecular weight, and conformation (e.g., triple helix, single helix, and random coil structures) [1, 2]. β-Glucans extracted from barley, which mainly contains β-(1,3-1,4)-D-glucan, have been demonstrated to reduce blood lipid levels, including cholesterol and triglyceride levels [3–5]. The mechanisms by which β-glucans reduce blood lipid levels have been shown to include prevention of cholesterol reabsorption by adsorption, elimination of bile acid by adsorption, an increase in bile acid synthesis, and suppression of hepatic cholesterol biosynthesis by short-chain fatty acids produced by fermentation with intestinal bacteria [6–8]. Claims that barley products reduce the danger of coronary heart disease have been endorsed by the Food and Drug Administration of the United States [9]. In addition, β-glucans extracted from barley have also been reported to possess various other biologic activities, for example, reducing blood glucose level, enhancing insulin response [10], protecting against stress ulcers [11], and restraining allergic reactions [12]. Furthermore, β-glucans extracted from barley have been used in health products as a diet food, because glucan is a dietary