Zhongshan Zhang

Potential antioxidant and anticoagulant capacity of low molecular weight fucoidan fractions extracted from Laminaria japonica.

A low molecular weight fucoidan (DFPS), obtained from the brown seaweed Laminaria japonica, was separated into three fractions by anion-exchange column chromatography. All three fractions (DF1, DF2, DF3) predominantly contained variety fucose, galactose and sulfate group. The antioxidant and anticoagulant activities of these fractions were investigated. The results showed that all fractions possessed considerable antioxidant activities, DF1 was most active. All samples inhibited coagulant in APTT, TT and PT assays obviously. Available data presented the content of sulfate group, the molar ratio of sulfate/fucose and sulfate/total sugar, and the molecular weight played an important role on antioxidant and anticoagulant activity.

Structural studies on a novel fucogalactan sulfate extracted from the brown seaweed Laminaria japonica.

A low molecular weight fucogalactan, obtained from the brown seaweed Laminaria japonica, was separated into three fractions (LF1, LF2 and LF3) by DEAE-Sepharose FF column chromatography. All three fractions contained predominantly fucose, sulfate group and galactose. The results showed that the main fraction LF2 consisted of l-fucose, d-galactose and sulfate at a molar ratio 6:1:9. Structural study on the LF2 was carried out by NMR spectroscopy. The backbone of LF2 was primarily (1-->3)-linked alpha-l-fucopyranose residues (75%) and a few (1-->4)-alpha-l-fucopyranose linkages (25%). The branch points were at C-4 of 3-linked alpha-l-fucopyranose residues by beta-d-galactopyranose unites (35%, molar ratio) or at C-2 of 3-linked alpha-l-fucopyranose residues by non-reducing terminal fucose unites (65%, molar ratio). Sulfate groups occupied at position C-4 or C-2, sometimes C-2, 4 to fucose residues, and C-3 and/or C-4 to galactose residues. The structure of LF2 was supposed as following: .

Synthesized phosphorylated and aminated derivatives of fucoidan and their potential antioxidant activity in vitro.

Three sulfated polysaccharide derivatives (phosphorylated and aminated fucoidan) were synthesized, and their potential antioxidant activities were investigated employing various established in vitro systems. Two methods were used in phosphorylation fucoidan: polyphosphoric acid and POCl(3) method. Aminated fucoidan was prepared using the epichlorohydrin and ammonia water. All fucoidan derivatives possessed considerable antioxidant activity, and exhibited stronger antioxidant ability than fucoidan in certain tests. The phosphorylated fucoidan showed stronger hydroxyl radical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power. The mechanism on influence the antioxidant activity of samples of phosphate and amino group was indicated.

Degradation and the antioxidant activity of polysaccharide from Enteromorpha linza

Polysaccharide extracted from Enteromorpha linza possesses excellent antioxidant activities, but its molecular weight was greatly high which influences the activity. In this study, the combination of ascorbic acid and H(2)O(2) was used as degradation reagents in order to obtain the lower molecular weight product. The results suggested that the most effective molar ratio of the two reagents was 1. Three degraded polysaccharides were selected to evaluate their antioxidant activities in vitro and characterized the relationship between antioxidant activity and chemical characteristics. It was found that the degraded sample with lower molecular weight possessed the higher antioxidant activities.

Sulfation, anticoagulant and antioxidant activities of polysaccharide from green algae Enteromorpha linza.

Sulfated polysaccharides exerted potent biological property which was relative to degree of sulfation, molecular weight, substitution position and chain conformation. In present study, the polysaccharide with low molecular weight (LEP) from Enteromorpha linza was sulfated with chlorosulfuric acid in formamide. The obtained polysaccharide sulfate was selected to evaluate their antioxidant activities and the anticoagulant activity in the coagulation assays, activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT). The data obtained in vitro models indicated that high DS and moderate Mw showed the best anticoagulant and antioxidant activities.

Preparation of the different derivatives of the low-molecular-weight porphyran from Porphyra haitanensis and their antioxidant activities in vitro

Porphyran extracted from Porphyra haitanensis is a sulfated polysaccharide, which possesses excellent antioxidant activities. In this study, we prepared one low-molecular-weight porphyran and its sulfated, acetylated, phosphorylated and benzoylated derivatives. Their antioxidant activities were investigated including scavenging effect of superoxide, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl radicals. The results of chemical analysis and FT-IR spectrums showed the modification was successful. And in addition, we found that certain derivative exhibited stronger antioxidant activity than low-molecular-weight porphyran. The benzoylated derivative showed the most excellent antioxidant activity in three assays, so this derivative needs to be attended to.

Synthesized different derivatives of low molecular fucoidan extracted from Laminaria japonica and their potential antioxidant activity in vitro

Six low molecular fucoidan (DFPS) derivatives were synthesized successfully, and their potential antioxidant activities were investigated employing various established in vitro systems. All DFPS derivatives possessed considerable antioxidant activity, and had stronger antioxidant ability than DFPS in certain tests. The benzoylated DFPS (PHDF) showed strongest scavenging activity on superoxide, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, however, DFPS exhibited greatest reducing power. Available data suggested that substituted groups of DFPS played an important role on antioxidant activity, and the mechanism on influence the antioxidant activity of samples of substituted group was indicated.

Phosphorylation of low-molecular-weight polysaccharide from Enteromorpha linza with antioxidant activity.

In this study, the phosphorylated derivative of low-molecular-weight polysaccharide from Enteromorpha linza was prepared. And then the antioxidant activities of all the samples were investigated including scavenging effects of superoxide and hydroxyl radicals and reducing power. The results of chemical composition, FT-IR spectrum and DSC analysis showed the modifications of polysaccharide were successful. And moreover, the phosphorylated derivative showed excellent antioxidant activity in these three assays, so this derivative needs to be attention in further.

Carboxymethylation of polysaccharides from Tremella fuciformis for antioxidant and moisture-preserving activities.

The carboxymethylated polysaccharide (CATP), which derived from water-insoluble crude Tremella fuciformis polysaccharide (ATP), was prepared. And then the antioxidant and moisture-preserving activities of the samples were investigated. The results of chemical composition and FT-IR analysis showed the carboxymethylated modifications of polysaccharide were successful. The degree of substitution (DS) of four carboxymethylated derivatives were different with the molar of monochloroacetic acid. Their water solubility and biological activities were improved with the increase of DS. And moreover, a high antioxidant and moisture-preserving activities of CATPs was observed, so this derivative needs to be attention and studied in further. Results proved that the carboxymethylation could effectively enhance their potential biological properties of the polysaccharide.

Free-radical degradation by Fe2+/Vc/H2O2 and antioxidant activity of polysaccharide from Tremella fuciformis

The free-radical degradation and antioxidant activity of polysaccharide from Tremella fuciformis was investigated. In present study, the combination of Fe(2+), ascorbic acid and H2O2 was used as degradation regents in order to obtain the lower molecular weight product. The result ascertained oxidative-reduce degradation did not change the main structure of polysaccharides in the test conditions. Five degraded polysaccharides were selected to evaluate their antioxidant activities in vitro. It was found that the degraded sample with lower molecular weight possessed the higher antioxidant activities. It was possible that free-radical degradation is an effective way for enhancing antioxidant activity to decrease molecular weight of polysaccharides.