Abstract:

This study aimed to extract polysaccharides from the body wall of Urechis unicinctus by sequential enzymatic
digestion with papain and trypsin and to purify the crude extract by anion exchange column chromatography. The physical
and chemical properties such as monosaccharide composition and molecular weight of the purified polysaccharides were
investigated on the basis of chemical and modern spectroscopic analysis. Then the antioxidant activity in vitro of the
polysaccharides was evaluated. The results showed that the yield of polysaccharides extracted from the body wall of Urechis
unicinctus was 5.3%. Two polysaccharides, namely UP-1 and UP-2, were purified from the crude polysaccharides by anionexchange
chromatography. UP-1 was a neutral polysaccharide composed of mainly glucose with a molecular weight of 340 kD.
UP-2 was a heteropolysaccharide with a molecular weight of about 7.9 kD. UP-2 consisted of mannose, glucosamine,
galactosamine, glucose, galactose and fucose at a molar ratio of 1.0:1.47:0.64:6.49:2.5:3.0. The monosaccharide composition
revealed that UP-2 was a glycosaminoglycan-like polysaccharide. Like most of glycosaminoglycan-like polysaccharides
from marine animals, UP-2 contained 7.4% sulfate ester. The glycosaminoglycan-like polysaccharide had a wide range of
bioactivities and better anti-lipid peroxidation activity than UP-1 as evidenced by its EC50 value at 5.0 mg/mL.

Key words: Urechis unicinctus, polysaccharide, purification, physicochemical property, antioxidant activity