Studies of polysaccharides from three edible species of Nostoc (cyanobacteria) with different colony morphologies: Structural characterization and effect on the complement system of polysaccharides from Nostoc commune

The cyanobacterium Nostoc commune Vaucher produces quite complex extracellular polysaccharides. The cyanobacterium is nitrogen fixing, and on growing the cyanobacterium in media with and without nitrogen, different types of extracellular polysaccharides were obtained. These were also different from the polysaccharides present in N. commune collected in the field. High pH anion exchange chromatography (HPAEC) of weak acid hydrolysates of the culture-grown material demonstrated that, in this case, HPAEC was useful for comparison of the different polymers. The main differences between the polymers from the field group and the culture-grown samples were the presence of substantial amounts of arabinose, 2-O-methylglucose, and glucuronic acid in the latter. Methylation studies also revealed a difference in the branching points on the glucose units between the field and cultured samples, being 1,4,6 for the first and 1,3,6 for the latter. The field acidic fraction gave, on weak acid hydrolysis and separation on BioGel P2 and HPAEC, 12 oligosaccharide fractions that were isolated and studied by different mass spectroscopy techniques. The structures of the oligosaccharides were determined, and two different series that can originate from two repeating pentamers were identified: GlcAl-4/6GlcM1-4Ga11-4Glc1-4Xyl and GlcAl-4/6Glc1-4Ga11-4Glc1-4Xyl. The difference between these oligosaccharides lies in the methyl substituent on carbon 2 of the glucose unit next to the nonreducing glucuronic acid unit. The polysaccharides from field material were shown to have a strong effect on the complement system.

Studies on polysaccharides from three edible species of Nostoc (Cyanobacteria) with different colony morphologies: Comparison of monosaccharide compositions and viscosities of polysaccharides from field colonies and suspension cultures

Hot water-soluble polysaccharides woe extracted from field colonies and suspension cultures of Nostoc commune Vaucher, Nostoc flagelliforme Berkeley et Curtis, and Nostoc sphaeroides Kutzing. Excreted extracellular polymeric substances (EPS) were isolated from the media in which the suspension cultures were grown. The main monosaccharides of the field colony polysaccharides from the three species were glucose, xylose, and galactose, with an approximate ratio of 2:1:1. Mannose was also present, but the levels varied among the species, and arabinose appeared only in N. flagelliforme. The compositions of the cellular polysaccharides and EPS from suspension cultures were more complicated than those of the field samples and varied among the different species. The polysaccharides from the cultures of N. flagelliforme had a relatively simple composition consisting of mannose, galactose, glucose, and glucuronic acid, but no xylose, as was found in the field colony polysaccharides. The polysaccharides from cultures of N. sphaeroides contained glucose (the major component), rhamnose, fucose, xylose, mannose, and galactose. These same sugars were present in the polysaccharides from cultures of N. commune, with xylose as the major component. Combined nitrogen in the media had no qualitative influence on the compositions of the cellular polysaccharides but affected those of the EPS of N. commune and N. flagelliforme. The EPS of N. sphaeroides had a very low fetal carbohydrate content and thus was not considered to be polysaccharide in nature. The field colony polysaccharides could be separated by anion exchange chromatography into neutral and acidic fractions having similar sugar compositions. Preliminary linkage analysis showed that 1) xylose, glucose, and galactose were 1-->4 linked, 2) mannose, galactose, and xylose occurred as terminal residues, and 3) branch points occurred in glucose as 1-->3,4 and 1-->3,6 linkages and in xylose as a 1-->3,4 linkage. The polymer preparations from field colonies had higher kinematic viscosities than those from corresponding suspension cultures. The high viscosities of the polymers suggested that they might DE suitable for industrial uses.

Chemical characteristic of bioactive polysaccharides isolated from Ornithogalum caudatum Ait.

A water-soluble crude extract prepared from Ornithogalum caudatum Ait. (OCA) showing a high immunomodulating activitiy was isolated and characterized by virtue of get filtration and column chromatography. The presence of the monosaccharides has been established by the chemical analysis. The quantitative analysis of the alditol acetate derivatives of them showed the ratios of the monosaccharides analyzed by means of GC respectively. The concentrations of protein(280 nm) and carbohydrate (496 nm) were detected respectively. The information of the molecular weight from the pure polysaccharide was obtained by several standard Dextrans from the Sephadex chromatography.

Antioxidant activity of different molecular weight sulfated polysaccharides from Ulva pertusa Kjellm (Chlorophyta)

Polysaccharides extracted from Ulva pertusa Kjellm ( Chlorophyta) are a group of sulfated heteropolysaccharides, the ulvans. In this study, different molecular weight ulvans were prepared by H2O2 degradation and their antioxidant activities investigated including superoxide and hydroxyl radical scavenging activity, reducing power and metal chelating ability. The molecular weights of natural and degraded ulvans were 151.7, 64.5, 58.0, and 28.2 kDa, respectively, as determined by high performance gel permeation chromatography. Among the four samples, U-3 ( the lowest molecular weight sample) showed significant inhibitory effects on superoxide and hydroxyl radicals with IC50 values of 22.1 mu g mL(-1) and 2.8 mg mL(-1); its reducing power and metal chelating ability were also the strongest among the four samples. All the other samples also demonstrated strong activity against superoxide radicals. The results indicated that molecular weight had a significant effect on the antioxidant activity of ulvan with low molecular weight ulvan having stronger antioxidant activity.

Antihyperlipidemic effects of different molecular weight sulfated polysaccharides from Ulva pertusa (Chlorophyta)

Ulvan, a sulfated polysaccharide from Ulva pertusa, was degraded to yield two low molecular weight fractions U1 and U2. The molecular weights of ulvan and its fractions were determined and varied from 151.6 to 28.2 kDa. They were fed to rats on a hypercholesterolemic diet for 21 days to evaluate and compare the antihyperlipidemic actions. Ulvan-based diet significantly lowered the levels of serum total cholesterol (-45.2%, P < 0.05) and low density lipoprotein cholesterol (LDL-cholesterol, -54.1%, P < 0.05). While U1- and U2-based diets significantly elevated the levels of serum high density lipoprotein cholesterol (HDL-cholesterol, +22.0% for U1, not significant; +61.0% for U2; P < 0.05) and reduced triglyceride (TG, -82.4% for U1, -77.7% for U2; P < 0.05) in rats as compared to control diet. In addition, consumptions of various ulvans significantly increased fecal bile acid excrement. The results indicated that ulvans with different molecular weights exhibited diverse effects on lipid metabolism. The high molecular weight ulvan was effective in serum total and LDL-cholesterol, whereas low molecular weight fractions were in TG and HDL-cholesterol. The fractions were considered to be more beneficial to hyperlipidemia associated with diabetes over ulvan. (C) 2003 Elsevier Ltd. All rights reserved.

Polysaccharides from Ulva pertusa (Chlorophyta) and preliminary studies on their antihyperlipidemia activity

Polysaccharides from Ulva pertusa were isolated and prepared by extraction in hot water and precipitation by ethanol. The water-soluble polysaccharides were chemically well defined, containing 47.0% total carbohydrate, 23.2% uronic acids, 17.1% sulfate groups, 1.0% N and 29.9% ash. Gas chromatography analysis demonstrated that the neutral sugars were mainly composed of rhamnose, xylose and glucose and smaller amounts of mannose, galactose and arabinose. The FTIR and C-13-NMR spectra indicated that basic repeating units of the polysaccharides were (beta-D-GlcpA-(1->4)-alpha-L-Rhap 3S) and (alpha-L-IdopA-(1->4)-alpha-L-Rhap 3S). Fifty ICR mice were used to study the effect of water-soluble polysaccharides from Ulva pertusa on the level of plasma lipids, with inositol niacinate as positive control. The results indicated that the polysaccharides significantly lowered the contents of plasma total cholesterol, low-density lipoprotein cholesterol, triglyceride and markedly increased the contents of serum high-density lipoprotein cholesterol, compared with the hyperlipidemia control group (p<0.01). Moreover, administration of polysaccharides significantly decreased the atherogenic index. The present results suggest that the polysaccharides from Ulva pertusa have great potential for preventing ischemic cardiovascular and cerebrovascular diseases.

Extension of life span and improvement of vitality of Drosophila melanogaster by long-term supplementation with different molecular weight polysaccharides from Porphyra haitanensis

Polysaccharides isolated from Porphyra (porphyran) have been known to have diverse biological activities, including immunomodulatory and antioxidant activities. The molecular weight-antiaging activity relationship of degraded porphyrans was examined in this study. Natural porphyran was extracted from P. haitanensis, and then was degraded into different molecular weight fractions, P1 molecular weight 49 kDa, P2 molecular weight 30 kDa, P3 molecular weight 8.2 kDa, by free radical. The influence on life span and vitality of porphyrans were carried out on Drosophila melanogaster. We found that all the degraded porphyrans and natural porphyran (P), added daily to the diet, can significantly increase the life span of D. melanogaster, except for P3. Among them, P1 exhibited the most prolonging life span activity. Furthermore, vitality of middle-aged flies (assessed by measuring their mating capacity) receiving porphyrans was increased considerably in comparison with the controls. Finally, in the heat-stress test, we observed a remarkable increase in survival time, especially in P3-diet groups. These results suggest that porphyrans may be effective in reducing the rate of the aging process and molecular weight has important influence on the effects. It seems that P1 and P2, possessed higher molecular weight, may be more useful in normal metabolic condition and P3, possessed the lowest molecular weight, may be more beneficial for D. melanogaster in stress condition. (C) 2007 Elsevier Ltd. All rights reserved.

Extraction of the polysaccharides from five algae and their potential antioxidant activity in vitro

The sulfated polysaccharides extracted from algae possess excellent antioxidant activities. In this study, we prepared five polysaccharides extracted from five algae including one brown alga Laminaria japonica. one red alga Porphyra haitanensis and three green algae Ulva pertusa, Enteromorpha linza and Bryopsis plumose. And then the antioxidant activities of all the samples were investigated including scavenging effects of superoxide and hydroxyl radicals, and reducing power. The chemical analysis and FT-IR spectrum showed these extracts were polysaccharides. And in addition, we found that certain polysaccharide exhibited stronger antioxidant activity in certain antioxidant activity. Factors effecting and attributing to radical scavenging effect need to be further studied. (C) 2010 Elsevier Ltd. All rights reserved.

The intraocular lens: challenges in the prevention and therapy of infectious endophthalmitis and posterior capsular opacification

Cataract is the leading cause of visual impairment worldwide. In the UK, some 30% of the population over 65 years of age have visually impairing cataract. Importantly, 88% of those with treatable visual impairment from cataract are not in contact with any ocular healthcare service, representing a major potential healthcare need [1]. In the USA, it has been estimated that 17.2% of the population (approximately 20.5 million) over 40 years of age have cataract in either eye and by 2020, this number is expected to rise to 30.1 million. Currently, cataract is responsible for 60% of Medicare costs associated with vision [2]. Furthermore, as the populations of industrialized countries such as the UK and the USA continue to age, the costs associated with treatment of cataract can only be expected to increase. Consequently, the development of the intraocular lens to replace the cataractous lens and the advances in intraocular lens design and implantation represent a major development in cataract treatment. However, despite such advances, cataract surgery is not without complications, such as postoperative infectious endophthalmitis, a rare but potentially devastating condition, and posterior capsular opacification, a less serious but much more common problem. This review will examine the epidemiology of cataracts, the polymeric construction of intraocular lenses implanted during cataract surgery and the complications of postoperative infectious endophthalmitis and posterior capsular opacification with regard to therapeutic interventions and prophylactic strategies. Advances in biomaterial design and function will be discussed as novel approaches to prevent such postoperative complications.

Repertoire of HLA-DR1-restricted CD4 T cell responses to capsular Caf1 antigen of Y. pestis HLA-transgenic mice

Yersinia pestis is the causative agent of plague, a rapidly fatal infectious disease that has not been eradicated worldwide. The capsular Caf1 protein of Y. pestis is a protective antigen under development as a recombinant vaccine. However, little is known about the specificity of human T cell responses for Caf1. We characterized CD4 T cell epitopes of Caf1 in 'humanized'-HLA-DR1 transgenic mice lacking endogenous MHC class II molecules. Mice were immunized with Caf1 or each of a complete set of overlapping synthetic peptides, and CD4 T cell immunity was measured with respect to proliferative and IFNgamma T cell responses and recognition by a panel of T cell hybridomas, as well as direct determination of binding affinities of Caf1 peptides to purified HLA-DR molecules. Although a number of DR1-restricted epitopes were identified following Caf1 immunization, the response was biased towards a single immunodominant epitope near the C-terminus of Caf1. In addition, potential promiscuous epitopes, including the immunodominant epitope, were identified by their ability to bind multiple common HLA alleles, with implications for the generation of multivalent vaccines against plague for use in humans.

Role of the rfe gene in the biosynthesis of the Escherichia coli O7-specific lipopolysaccharide and other O-specific polysaccharides containing N-acetylglucosamine

We report that rfe mutants of wild-type strains of Escherichia coli O7, O18, O75, and O111 did not express O-specific polysaccharide unless the rfe mutation was complemented by a cloned rfe gene supplied in a plasmid. The O polysaccharides in these strains are known to have N-acetylglucosamine (GlcNAc) in their O repeats. In addition, in vitro transferase assays with bacterial membranes from either the O7 wild-type strain or its isogenic rfe mutant showed that GlcNAc is the first carbohydrate added onto the lipid acceptor in the assembly of the O7 repeat and that this function is inhibited by tunicamycin. Our results indicate that the rfe gene product is a general requirement for the synthesis of O polysaccharides containing GlcNAc.