Hongyan Li

Chemical characteristic and anticoagulant activity of the sulfated polysaccharide isolated from Monostroma latissimum (Chlorophyta).

A polysaccharide was isolated from marine green algae Monostroma latissimum, and its chemical characteristic and anticoagulant activity were investigated. The results demonstrated that the polysaccharide was high rhamnose-containing sulfated polysaccharide, and was mainly composed of 1,2-linked l-rhamnose residues with sulfate groups substituted at positions C-3 and/or C-4. The sulfated polysaccharide exhibited high anticoagulant activities by assays of the activated partial thromboplastin time (APTT) and thrombin time (TT). The anticoagulant property of the sulfated polysaccharide was mainly attributed to powerful potentiation thrombin by heparin cofactor II.

Structural characterization and antioxidant properties of an exopolysaccharide produced by the mangrove endophytic fungus Aspergillus sp. Y16

A homogeneous exopolysaccharide, designated As1-1, was obtained from the culture medium of the mangrove endophytic fungus Aspergillus sp. Y16 and purified by anion-exchange and gel-permeation chromatography. Results of chemical and spectroscopic analyses, including one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopy showed that As1-1 was mainly composed of mannose with small amounts of galactose, and that its molecular weight was about 15 kDa. The backbone of As1-1 mainly consists of (1→2)-linked α-d-mannopyranose units, substituted at C-6 by the (1→6)-linked α-d-mannopyranose, (1→)-linked β-d-galactofuranose and (1→)-linked β-d-mannopyranose units. As1-1 possessed good in vitro antioxidant activity as evaluated by scavenging assays involving 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide radicals. The investigation demonstrated that As1-1 is an exopolysaccharide different from those of other marine microorganisms, and could be a potential antioxidant and food supplement.

Structural characteristics and antioxidant activities of the extracellular polysaccharides produced by marine bacterium Edwardsiella tarda

Two water-soluble extracellular polysaccharides, ETW1 and ETW2, were isolated from the marine bacterium Edwardsiella tarda by ion-exchange and size-exclusion chromatography, and their structures were investigated. ETW1 and ETW2 are mannans, with molecular weights of about 29 and 70kDa, respectively. The main chain of the polysaccharides consists of (1-->3)-linked mannose residues, and branched mannose linkages were also detected. The branch points are located at the C-2 and C-6 positions of the (1-->3)-linked mannose residues. The side chains are composed of (1-->2)-linked mannose residues and (1-->)-linked mannose residues. Antioxidant properties of the two extracellular polysaccharides were evaluated with hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals scavenging activities and lipid peroxidation inhibition in vitro, and results showed that ETW1 and ETW2 had good antioxidant and hydroxyl and DPPH radicals scavenging activities. ETW1 exhibited higher antioxidant activity than ETW2, and could be a potential source of antioxidant and used as possible food supplement or ingredient in the pharmaceutical industry.

Preparation, structure and anticoagulant activity of a low molecular weight fraction produced by mild acid hydrolysis of sulfated rhamnan from Monostroma latissimum.

A low molecular weight fraction, designated LMWP, was prepared by mild acid hydrolysis of sulfated rhamnan from Monostroma latissimum and purified by anion-exchange and gel-permeation chromatography. Chemical and spectroscopic analyses showed that LMWP was mainly composed of rhamnose, and its molecular weight was about 33.6 kDa. The backbone of LMWP consists of 1,3-linked α-L-rhamnose units with partially sulfate groups at the C-2 position. Approximately 25% of 1,3-linked α-L-rhamnose units is substituted at C-2 by sulfated or non-sulfated 1,3-linked α-L-rhamnose and 1,2-linked α-L-rhamnose units. LMWP effectively prolonged clotting time as evaluated by the activated partial thromboplastin time assay and was a potent thrombin inhibitor mediated by heparin cofactor II. The investigation demonstrated that LMWP is a novel sulfated polysaccharide with anticoagulant activity.

Structural Characterization of Extracellular Polysaccharides Produced by the Marine Fungus Epicoccum nigrum JJY-40 and Their Antioxidant Activities

Two extracellular polysaccharides, ENP1 and ENP2, were isolated from the fermentation liquid of the marine fungus Epicoccum nigrum JJY-40 by anion-exchange chromatography and gel-filtration chromatography, and their structures were investigated using chemical and spectroscopic methods including methylation analysis and NMR spectroscopy. The results demonstrated that ENP1 was composed of mannose, glucose, and galactose in the molar ratio of 5.0:2.1:1.0, and the main chain of the polysaccharide consisted of (1u2009→u20092)-linked mannose, (1u2009→u20093)-linked mannose, terminal mannose, (1u2009→u20096)-linked glucose, (1u2009→u20094)-linked glucose, and (1u2009→u20094)-linked galactose. ENP2 was composed of mannose, galactose, glucose, and glucuronic acid in a molar ratio of 12.4:11.2:8.3:1.0, and its glycosidic linkage patterns included terminal mannose, (1u2009→u20096)-linked glucose, (1u2009→u20094)-linked galactose, and (1u2009→u20093)-linked mannose. The two polysaccharides had a partially branched structure with branch point located at C-3 position of (1u2009→u20096)-linked glucose residue. The molecular weights of ENP1 and ENP2 were 19.2xa0kDa and 32.7xa0kDa, respectively. Antioxidant properties of the two polysaccharides were evaluated with hydroxyl, superoxide, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities and lipid peroxidation inhibition in vitro, and results showed that ENP2 and ENP1 had good antioxidant activities, especially ENP2. ENP2 could be effective as a potential antioxidant.

Structure characterization and antitumor activity of the extracellular polysaccharide from the marine fungus Hansfordia sinuosae

A neutral water soluble polysaccharide (HPA) was isolated from the marine fungus Hansfordia sinuosae. Monosaccharide composition analysis indicated that HPA was mainly composed of mannose with minor amounts of galactose and glucose. The molecular weight of HPA was approximately 22.5u202fkDa as analyzed by HPGPC. Structure analysis of HPA with methylation and 1D, 2D NMR indicated that HPA was composed of [α-d-Manp(1→], [→2)-α-d-Manp(1→], [→3)-α-d-Manp(1→] and [→2,6)-α-d-Manp(1→] with [α-d-Manp(1→] linked to C-6 position of [→2,6)-α-d-Manp(1→]. The antitumor effect of HPA was evaluated in vitro. HPA showed remarkable inhibitory effect on human cervical carcinoma HeLa cells and human breast carcinoma MCF-7 cells. When cells were incubated with HPA at 400u202fμg/mL for 48u202fh, the inhibition rate on HeLa and MCF-7 cells was 79.5% and 73.8%, respectively. Furthermore, for HeLa cells, HPA could increase intracellular ROS levels, induce cells apoptosis, decrease mitochondrial membrane potential, and elevate the expression of caspase-3. The results suggested that HPA could be explored as a potential antitumor agent.