The Study On Synthesis And Bioactivities Of Alkoxylate Derivatives Of Low-molecular-weight κ-carrageenan

Low-molecular-weightκ-carrageenan (LMW-KC) was achieved by degradingκ-carrageenan (KC) with hydrochloric acid, and then react with bromoalkane which has long carbon chain under the condition of which the NaH was base in the DMSO, and the alkoxylate derivatives of low-molecular-weightκ-carrageenan was gained. The process and the structure of outcome was characterized by IR,GPC,13C NMR,1H NMR and so on, and the antioxidant activities of LMW-KC and its alkoxylate derivatives was evaluated. The results were showed as follows:Theκ-carrageenan was degraded in the 0.1M sulfuric acid for 1h, Low-molecular-weightκ-carrageenan (LMW-KC) with the number-average molecular weight of 10060 was achieved. Compared with theκ-carrageenan which was not degraded, disaccharide repeating units of LMW-KC were not destroyed, and the content of S was not changed.Three alkoxylate derivatives with long carbon chain of LMW-KC was synthesized. The LMW-KC reacted with bromoalkane which has long carbon chain by SN2 nucleophillic substitute reaction, the alkoxylate derivatives of low-molecular-weightκ-carrageenan was gained. The structure of disaccharide repeating units were not destroyed after alkoxylate. The result revealed that hydroxyl groups at C-2 of G4S residues ofκ-carrageenan were completely substituted, while those at C-6 of G4S residues and C-2 of DA residues were partly substituted. Meanwhile, hydroxyl groups at C-2 and C-6 of G4S residues ofκ-carrageenan were partly substituted.The activities of LMW-KC and its alkoxylate derivatives for scavenging DPPH·, superoxide radial anion was measured to evaluate the antioxidant. The result of antioxidant shows that: comparedκ-carrageenan, the antioxidant activities of the derivatives increased apparently.