br Antioxidant polymers conjugates Natural
Antioxidant-polymers conjugates Natural antioxidants are usually used as a substitute for synthetics but some degradation phenomena could influence their applications. For example, ascorbic ZJ 43 as a natural antioxidant undergoes yellowish coloration as a result of oxidation . Sing and Kaplan reported synthesis of polymeric derivative of ascorbic acid by a lipase catalyzed covalent conjugation of primary hydroxyl group of Vitamin C and an enzymatic reaction catalyzed by horseradish peroxidases (HRP), yielding an ascorbic acid polymerized vinyl polymer . In a study, starch-lignosulfonate graft copolymers were produced by laccase catalysis. In this process, hydroxybenzotriazole hydrate was used as a redox mediator. The obtained polymeric materials indicated strong antioxidant activity that can be employed as food preservatives. This property was attributed to their high phenolic content . Increased bacterial membrane permeability and the dissipation of the membrane potential were observed. The flavonoid-functionalized chitosan is more effective against Gram-positive than Gram-negative bacteria. This is attributed to the composition of the Gram-negative cell membrane which is constituted of lipopolysaccharide, lipoprotein and phospholipids that act as a potential barrier to foreign molecules particularly those with a high molecular weight . Interactions between flavonoids and proteins, may improve antioxidant properties of proteins, and consequently affects human health , . The conjugate indicated stronger inhibitory potential against AAPH-induced LDL oxidation in a catechin moiety concentration-dependent manner, compared to unconjugated catechin. α-amylase is an enzyme that is involved in the carbohydrate digestion by mammals. This enzyme t sugar anomeric center, hydrolyzes R(1,4)-glucosidic linkages with retention of configuration. Finally, the anti-cancer potential of the Gel-GA conjugate was investigated. For this purpose, the effect of Gel-GA conjugate on cancer cell viability with pure gelatin was evaluated . Moreover, the antitumor potential of Gel-GA was proved during the proliferation of DU145 prostate cancer cells.
Introduction The backbone of arabinoxylan molecules is a linear polymer consisting of 1,4-β-linked D-xylopyranose residues and α-L-arabinofuranose moieties attached to D-xylopyranose units O(3) or O(2), or both. Arabinoxylans are either water soluble (water extractable arabinoxylans, WEAX) or insoluble (water unextractable arabinoxylans, WUAX). Cell walls in the cereal aleurone layer contain residues of ferulic acid, which are either covalently linked by an ester bond to C5 of arabinofuranose residues or form dehydrodimers (8-8, 5-5, 8-O-4, 8-5-benzofuran and linear form) and dehydrotrimers (5-5, 8-O-4) (Courtin and Delcour, 2002; Dobberstein and Bunzel, 2010). Ferulic acid is responsible for the antioxidant activity of AX, in particular of those contained in cereal bran (Pekkinen et al., 2014; Ou and Kwok, 2004). Ferulic acid prevents the oxidation of LDL cholesterol and the development of atherosclerosis, inflammation and diabetes, and exhibits anticancer activity (Karunaratne and Zhu, 2016; Kwon et al., 2010). Cereal bran is a rich source of healthy phytochemicals, such as phenolic acids (not only ferulic, but also p-hydroxybenzoic, vanillic, syringic, p-coumaric, caffeic, and sinapic), flavonoids, phytosterols, alkylresorcinols, benzoxazinoids, tocols, lignans, etc. (Andersson et al., 2014). Arabinoxylans form a heteropolysaccharide fraction that beneficially affects human health because it exhibits anti-inflammatory and anti-cancer activities, prevents constipation, lowers blood cholesterol, regulates of blood glucose, and enhances the absorption of minerals. In the large intestine, AX show prebiotic properties as they are fermented to short chain fatty acids (SCFAs), which stimulate the growth of bifidobacteria and lactobacilli (Mendis and Simsek, 2014; Hughes et al., 2007).