Polysaccharides laminarin

If branching is (1 —> 3), no glycol grouping will be present in any central unit and it may be seen that reaction will only occur on the terminal units. Such is the case with the polysaccharide laminarin, with the glucan of yeast membrane, and with a galactose-containing polysaccharide isolated from agar.146-148... 

A recently developed method for preparing the epimerie D-glucometasaccharinic acids is based on the action of lime-water on the seaweed polysaccharide, laminarin. The mixed D-glucometasaccharinic acids are obtainable from this source in practically pure condition, as their calcium salts, after separation from unchanged polysaccharide. The directions for their preparation from insoluble laminarin follow. 

Information on the hydrolytic activity in marine sediments has been obtained from the use of model substrates labeled with fluorescent dyes such as methylumbelliferone (MUF) or fluorescein. These substrates may be small dimeric molecules, the hydrolytic cleavage of which releases the fluorescence signal, which is then indicative of the activity of specific enzymes such as glucosidase, chitobiase, lipase, ami-nopeptidase or esterase (Chrost 1991). Also large fluorescently labeled polymers such as the polysaccharides laminarin or pullulan have been used in experiments to demonstrate the mechanism and kinetics of bacterial degradation (Amosti 1996). 

Experiments have been performed on enzymes likely to hydrolyze polysaccharides (laminarin and algin) more specific to brown algae. 

The polysaccharide laminarin is commerdally extraded mainly from kelp and fucoids and is a main form of food storage of brown algae. Sulfated laminarins have antilipidemic activities and capable of reducing serum cholesterol levels and total serum lipids (Kiriyama et al., 1969). The anticoagulant activity of this material is attributed to its antithrombotic... 

There have been few reports of the occurrence of D-mannitol in the combined form. A monoacetate and mono- and diglucosides of D-mannitol have been found in algae 42h)y and mannitol may be a terminal unit in the polysaccharide laminarin 2c). 

The reaction of these aldehydes, derived from periodate oxidation, with carbonyl reagents has also been investigated. Studies 147 148 were made on oxidized laminarin, a (1 —> 3)-linked polysaccharide, in which only the terminal residues had been oxidized. The addition of phenylhydrazine acetate detached the remainder of the terminal residue as glyoxal phenyl-osazone. When the aldehydic compounds derived from the periodate oxidation of raffinose and trehalose818a were reacted with p-nitrophenylhydrazine, the authors were surprised to find that one molecule of oxidized raffinose, containing six aldehydic functions, reacts with only three molecules of the reagent, and that the four aldehydic functions of the oxidized trehalose molecule react with only two. The reactions of periodate-oxidized carbo-... 

The same group investigated the separation of fluorescently labled sugars by different CDs as well as linear polysaccharides (dextrin 10, dextran, laminarin, and alginic acid) and oligosaccharides in the presence of borate... 

FIGURE 1 Potential hydrolysis rates of six structurally distinct polysaccharides in seawater (A) and surface sediments (B) from Skagerrak and Svalbard. Pull = pullulan, lam = laminarin, xyl = xylan, fu = fucoidan, ara = arabinogalactan, chon = chondroitin sulfate. Note the differences in scale on the y axes for sediments and for seawater. [Skagerrak data from Arnosti (2000).]... 

Laminarin. A beta-glucan polysaccharide produced by many chromists through photos)mthesis. 

Insoluble laminarin (50 g.) is treated with an oxygen-free suspension of calcium hydroxide (60 g.) in 1 liter of water. After 8 days at room temperature, the suspension is filtered, and calcium is precipitated by the addition of the equivalent amount of oxalic acid. Concentration of the filtrate to a volume of 500 ml. causes precipitation of polysaccharide (21.4 g.). After filtration, and concentration to a sirup, extraction with ethanol (3 X 100 ml.) leaves further polysaccharide (7.7 g.). Evaporation of the ethanol extract affords a mixture of the sirupy D-glucometasaocharinic lactones (13.8 g.). After their conversion to the calcium salts, and crystallization from water (finally with the gradual addition of ethanol), there is obtained calcium /3 -D-glucometasao-oharinate (5.8 g.), calcium a -D-glucometasaccharinate (0.6 g.), and a residue of the mixed salts (3.7 g., principally a epimer). 

Among the polysaccharide elicitors are 3,6-3-glucans from Phytophthora megasperma (84, 85) and yeast cell walls (59) and the algal glucan, laminarin (84)., which have structures comparable to those described for the wilt-inducing P. cinnamomi,... 

Dietary use of Laminaria dates back to the days of the First World War when it was used in raw form as a feed supplement for horses. It is used as a food, principally in Asian coimtries, where it is valued for its flavor, mineral content, and health giving benefits. The most important components with a medicinal point of view are Laminaria s polysaccharides. It contains alginates, laminarin, laminine, and fucoidan as well as a number of other polysaccharides and simple sugars. 

Carrageenans and semi-synthetic sulphated polysaccharides, like laminarin sulphate, wctc shown to be potent angiogenesis inhibitors [83]. 

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