Fructans

Fructans are polymers of fructose stored in some plants as reserve material instead of starch. They have much lower molecular weight than starch, and are water soluble. The branched fructans are found mainly in the grass (Poaceae) and lily (Liliaceae) families while linear fructans (specifically inulin) are particularly common in the Aster-aceae. Fructans are composed almost entirely of fructosyl-fructose linkages, and in some cases glucose molecules are present in the chain (Cseke and Kaufman 1999). 

Bruneton, J. 1995, Pharmacognosy Phytochemistry Medicinal Plants, Lavoisier Pubs, Paris. 

Ganoderma polysaccharides current concepts and applications , Proceedings, International Symposium on Ganoderma Research, Beijing. 

Bioactive polysaccharides from traditional Chinese medicine herbs as anticancer adjuvants , Journal of Alternative and Complementary Therapies 8 559-565. 

and Cribb, J. 1981, Wild Medicine in Australia, Collins, Sydney. 

Fructans can occur as oligosaccharides and polysaccharides. This means that their degree of polymerization can vary from below 20 sugar units to well above 20 sugar units. As a food ingredient, fructans often have a degree of polymerization of 25 or less. Thus, they are discussed as oligosaccharides. 

There are essentially two kinds of fructans, inulin and levan. Both are found in plants and are produced extracellularly by certain species of bacteria. 

Levans are polysaccharides containing D-fructofuranosyl units linked P-2 6 

It has been suggested that a rich source of inulin, such as Jerusalem artichokes, might be a source of D-fructose for use as a sweetening agent. However, 

In water, inulin undergoes reversion from a more soluble to a less soluble form, in the manner of retrograding starch (Whistler and Smart, 1953) it is slightly soluble in organic solvents. Fructans are easily hydrolyzed by acid. Levan is the branched isomer of inulin. 

A historical review on some resolved and unresolved questions in wood chemistry, particularly related to cellulose and lignin, has been published. A review on the basic trends in the present-day study of cellulose (and other polysaccharides) has been published. The chemical modification of cellulose has been reviewed from a historical perspective.  

The crystal structure of native ramie cellulose was shown to be similar to that recently reported for Valonia cellulose. The earlier conclusion that the ramie diffraction data could not be satisfied by a conventional cellulose model is refuted. R (an indication of diffraction error) values of 0.158, 0.185, and 0.175 were obtained for anti-parallel, parallel up, and parallel down alignments respectively. The author considers that the anti-parallel model provides the best accounting for the ramie data and is therefore probably the correct model for both cotton and ramie cellulose. The changes in crystallinity and physical characteristics of microcrystalline cellulose which occur on grinding have been studied. Under one set of grinding conditions, the specific surface area rose 

Fukuoka, S. Nakajima, and K. Yamamoto, Chem. and Pharm. Bull. Japan), 1977, 25, 2490. 

High resolution electron microscopy showed that ot-cellulose could be split into smaller fibrillar elements by heating and that an elementary fibril with a uniform diameter did not exist within the cell wall, although certain fibril diameters were dominant. In addition to the cellulose fibrils, supramolecular structures of polyoses and lignin were detected in the holocellulose as coils either attached to cellulose chains or deposited within fibre bundles. 

The reactions of dichlorotriazinyl dyes with cellulose have been studied and the diffusion coefficient was shown to decrease with an increase in pH. The rate constants of the reaction were pseudo first order. The pH dependence was similar to that of hydrolysis of the dye. 

Cycloamyloses have been separated by h.p.l.c. on a /u-Bondapak-carbohydrate column using acetonitrile-water mixtures as eluant. The molecular dynamics of the inclusion complexes formed between cyclohexa-amylose and some aromatic amino-acids and dipeptides have been studied by n.m.r. spectroscopy. The forces binding the complexes were found to be weak. The c.d. spectra of cyclohepta-amylose which had been complexed with 2-substituted naphthalenes were measured at various concentrations of cyclohepta-amylase and temperatures between 10-70 C. The complex with 2-naphthoxyacetic acid showed 1 1 stoicheiometry. The molar ellipticity and thermodynamic parameters were determined and enthalpy and entropy ranges calculated. The correlation was explained by a cyclohepta-amylose guest molecule interaction where the guest molecule was highly solvated. The induced c.d. spectra of cyclohepta-amylose complexes with substituted benzenes confirmed that an axial inclusion 

The dielectric constant and dielectric loss for moist cellulose fibres was measured over a frequency band, a temperature range, and relative humidity range.The dielectric constant increased with increasing frequency and temperature owing to an increase in the rotation and polarization of the flexible part of the fibre. As the relative humidity was increased, the dielectric constant 

spectra of peracetylated cello-oligosaccharides have been recorded and compared with that of cellulose acetate.All of the signals from cellulose acetate were only observed in the spectra of cellotetraose and cello-pentaose peracetates. Some signals were not observed in the spectra of cellobiose and cellotriose peracetates. 

A bioengineering approach has been used for the separation of cellodextrins. Cellulose was hydrolysed with HCl and a combination of columns of Sephedex G15 and Dowex AG50W X 4 allowed a one step desalting and separation of the hydrolysate using water as the eluant. The column was stable and did not require to be regenerated after every run. Up to 3 g of cellodextrins could be produced per day. 

A method for the gel permeation chromatographic analysis of the molecular weight distribution of wood pulp holocellulose as the carbanilate derivative has been applied to red maple Acer rubrum) and loblolly pine Pinus taeda). Either the chlorine-ethanolamine or acid-chlorite method could be used to prepare the holocellulose and the derivative was obtained by heating at 80 with phenylisocyanate in pyridine. Higher temperatures caused depolymerization. 

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From the organochemical point of view, carbohydrates/polysaccharides are more or less substituted polyhydroxy aldehydes (e.g., glucose—>glucans) or polyhydroxy ketons (e.g., fructose-n fructans). From the physicochemical point of view, an enormous heterogeneity also exists in... 

Degree of polymerization distribution of a plant fructan (inulin) at increasing physiological age of the source remarkable performance of S-200 in the low dp range degree of polymerization distribution obtained from bad (P-6) and good (S-200 / P-6) resolution of high dp components... 

Bio-Gel P-6 and a combined system of P-6/S-200 were utilized for investigations of inulin-type /3(2- l)-linked nb fructans. With a flow rate of 0.33 mP min, each separation of a sample volume of 1 ml of a 20- to 30-mg/ml concentrated solution typically lasted 20 hr, i.e., one run per day. Both systems (P-6 and P-6/S-200) maintained stability for approximately 1 year, equivalent to approximately 100 runs. 

The remarkable performance of P-6 in the separation of oligosaccharides, particularly of glucans and fructans, is well known (31,32) and is illustrated... 

The biosynthesis and degradation of fructans by microbial organisms has been reviewed in detail recently.35 Additionally, a review of the production of di-D-fructose dianhydrides from inulin and levan by enzymes has been published in Japanese.36 This account is therefore limited to a general overview. 

Little information is available on the specific control of fructan metabolism in higher plants73 or in microorganisms.35 If a regulatory role is envisaged for the di-D-fructose dianhydride enzymes, as has been suggested for microorganisms,71 then more detailed studies are required. 

Two extracellular D-fructans, (2- 6)-linked S-D-fructofuranan or levan and the less common corresponding (2 l)-linked polysaccharide, of the inulin type, are elaborated by different bacteria. These polysaccharides are formed from sucrose by the action of sucrose fructosyltransferases. Terminal )S-D-fructofuranosyl groups are present in some bacterial heteropolysacchar-... 

The idea that inulin-type fructans are fermented by bacteria colonising the large bowel is supported by many in vitro (both analytic and microbiological) and in vivo studies, which, in addition, confirm the production of lactic and short-chain carboxylic acids as end products of the fermentation (Tanner, 2005). Furthermore, it was shown inhuman in vivo studies that this fermentation leads to the selective stimulation of growth of the bifidobacteria population, making inulin-type fructans the prototypes of prebiotics (Roberfroid, 1997 Roberfroid, 2001). 

Interestingly, W271N synthesized larger fructan products as compared to the WT enzyme.97 B. megaterium LS residue Asn252 (subsite +2) clearly plays an important... 

B. C. Tungland, Fructooligosaccharides and other fructans, in G. Eggleston and G. L. Cote, (Eds.), Oligosaccharides in Food and Agriculture, ACS Symp. Ser., Vol. 849, American Chemical Society, Washington, DC. 

From sedimentation and diffusion measurements, Ogston has determined the molecular weight of the fructans from both leafy cocksfoot grass (Dacty-lis glomerata) and Italian rye grass (Lolium italicum) to be 5,500.261 Both polysaccharides were polymolecular, and the data indicated a singly-branched structure for each. 

Stahl, B. Linos, A. Karas, M. Hillenk-amp, F. Steup, M. Analysis of Fructans From Higher Plants by MALDI-MS. Anal Biochem. 1997, 246, 195-204. 

Polymers of D-fructose are important carbohydrate reserves in a number of plants. Inulins and levans are two major types that differ in structure. D-Fructans require only relatively mild conditions for their hydrolysis, for example, levan was qualitatively hydrolyzed by hot, dilute, aqueous oxalic acid. Permethylated fructans could be hydrolyzed with 2 M CF3CO2H for 30 min at 60°. Fructan oligosaccharides were hydrolyzed in dilute sulfuric acid (pH 2) at 70 (see Ref. 53) or 95° (0.1 M). D-Fructans from timothy haplocorm (where they comprise 63% of the water-soluble carbohydrates) could be hydrolyzed with 0.01 M hydrochloric acid at 98°. 

A fructan-produclng bacterium was Isolated from soils and characterized for polysaccharide synthesis. The composition and properties of the polysaccharide produced were studied. The organism. Identified as a strain of Bacillus polvmvxa. produced a large quantity of polysaccharide when grown on sucrose. 

The polysaccharide consisted entirely of fructose methylatlon analysis showed that the primary fructose linkages were P(2- 6) fructofuranosyl linkages. Carbon 13 nmr showed the product to be a levan type fructan. 

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