ABSTRACT
Chitin, (1 → 4)-linked 2-acetamido-2-deoxy-β-d-glucan, is found in invertebrates and crustaceans as a structural material in their exoskeletons (Jeon and Kim 2000a,b; Muzzareli 2002). Chitosan, a polymer of glucosamine (GlcN), is prepared by alkaline deacetylation of chitin. Chitin and chitosan have exhibited several biological functions to serve as safe bioactive substances useful in various applications. Chitin and chitosan, naturally occurring biopolymers, have attracted much attention during the past decades owing to their unique properties as safe biomaterials ensuring human health. These outstanding properties of biocompatibility, biodegradability, polyelectrolyte properties, presence of reactive functional groups, and ability to modify the structure via chemical modications has attracted their applicability in biomedical and pharmaceutical industries (Kim and Park 2001; Huang et al. 2003; Sashiwa and Aiba 2004). Currently, the trend among scientists across the world is to research on naturally occurring bioactive compounds to modify them to make novel compound that enhance their properties. Among them is chitin, a polysaccharide, abundantly found in nature, and chitosan formed by deacetylation of chitin. In addition, chitin oligosaccharides (NA-COSs) and chitooligosaccharides (COSs), partially hydrolyzed products of chitin and chitosan, are of great interest in various areas because of their noncytotoxic and high water-soluble properties (Kim et al. 2006); they and their derivatives have numerous biological properties such as immunoenhancing activity, antitumor activity, antihypertensive effects, anticoagulant (Kim et al. 2006), antibacterial activity, antifungal activity (Yang et al. 2005; Vong and Ngo 2010), and antioxidant activity (Ngo et al. 2008a). In this chapter, the antioxidant activity and antimicrobial effects of chitin, chitosan, and their derivatives have been summarized. Moreover, the chapter also discusses some synthetic and productive methods of certain derivatives of chitin and chitosan, and the potential applications of their antimicrobial and antioxidant properties.
