THE RELATIONSHIP BETWEEN FUCOIDANS STRUCTURE AND THEIR ACTIVITIES OF INHIBITING HYDROXYL RADICAL IN VITRO / 营养学报

ABSTRACT

Objective To study the relationship between fucoidans structure and their antioxidant activities. Method Fucoidans (HF) were extracted from Laminaria japonica and was separated by anion exchange chromatography on DEAE-Cellulose 52 column (2.5?40 cm), and two fractions HF1 and HF2 were obtained. Fucoidans of low molecular weight (LF) was made after hydrolysis of HF by hydrochloric acid and purification by ultrafiltration. Chemical methods and gas chromatography were used to analyse the sugar composition of these polysaccharides; and infrared spectrum was utilized to determine their structure. The activity of inhibiting hydroxyl radical (?O H ) was evaluated by means of Fenton reaction. Results In HF1, 18.834% uronic acid, 44.197% L-fucose, 31.193% D-galactose and 24.612% D-mannose were detected. As to HF2, 5.878% uronic acid, 81.119% L-fucose and 18.881% D-mannose were found. L-fucose content in LF was 13.033%, equal to 32.084% of that in HF 40.621%. Both in HF1 and LF, sulfate groups were at the C-2 and C-4 positions of L-fucose, while in HF2, sulfate groups only at C-4 position. The concentration of fucoidans inhibiting 50% ?O H (IC50) was 7.6, 5.2 and 8.9 mg/ml for HF, HF1 and HF2 respectively. Nevertheless, LF approximately lost this activity. Conclusion The molecular weight, content and composition of sugar and the combining sites of sulfate groups were found to be related with the activity of inhibiting ?O H radical in fucoidans.