Purification, partial characterization and bioactivity of sulfated polysaccharides from Grateloupia livida

Purification, preliminary characterization and bioactivity of polysaccharides from Grateloupia livida (GL) were investigated. Three water-soluble sulfated polysaccharide fractions (GLP-1, GLP-2 and GLP-3) were isolated and purified from the edible and medicinal red seaweed, Grateloupia livida (Harv.) Yamada by DEAE Sepharose CL-6B and Sephadex G-100 column chromatography, and chemical characterization was performed by HPGPC, GC-MS, FT-IR and SEM. In addition, anticoagulant activities were determined by activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT) using normal human plasma in vitro. The antioxidant activities against DPPH and ABTS⁺ radicals were evaluated and compared. The molecular weights of GLP-1, GLP-2 and GLP-3 were 39.5, 60.4 and 3.36kDa, respectively. Monosaccharide analysis revealed that three polysaccharide fractions were homopolysaccharides and comprised of galactose only. Anticoagulant assays indicated that crude GLP, and purified GLP-1 and GLP-2 effectively prolonged APTT and TT, but not PT. All polysaccharide fractions exhibited significant in vitro antioxidant activities in a dose-dependent manner. GLP-2 showed consistently better anticoagulant and antioxidant activities compared with GLP, GLP-1 and GLP-3. These results demonstrate that sulfated polysaccharides isolated from Grateloupia livida can serve as readily available alternative natural sources of anticoagulant and antioxidant agents.