Inulins structure

The new compounds were assigned structures by examination of their 13C NMR spectra and of the H NMR spectra of the peracetates. A similar mechanism to that previously postulated for fructose and inulin,31 and involving a sor-bofuranosyl fluoride was suggested for the formation of these isomers. In both Refs. 31 and 80, formation of the 2,3-linkage was associated with more-rigorous conditions. 

Inulin crystallizes in the form of doubly refracting sphero-crystals, the crystalline structure of which is indicated by x-ray patterns.6,4 In aqueous solution inulin has a specific rotation [ajo20 = — 39 to — 40° referred to the anhydrous substance. 

Difructose anhydride II reacts with one mole of per-iodic acid. Hydrolysis of its methyl derivative indicates that two different trimethyl-D-fructoses are formed whose combined specific rotations in water amount to between + 20° and + 30°. If we assume that this anhydride, like the other two derived from inulin, is made up of D-fructofuranoses, the facts that have been mentioned allow only three possible structures for this anhydride. 

Introns, 12 449 17 619 20 824 Intrusive uranium deposits, 17 520 Inulin, classification by structure, 4 723t In-use properties, of soap, 22 728, 730-731 Invention. See also Patents... 

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°. 

Structure. The nmr spectra, shown in Figure 2, indicates that essentially all fructose molecules in the polymers are in the same conformation. In Table I, nmr peaks from fructan are compared to peaks from known inulin 0-(l->2) linked) and bacterial levan (P-(2->6) linked). Data clearly show the fructan to be of the p-(2- 6) type (27). (Sec Table II.)... 

Distribution in the body is determined by the ability to penetrate membranous barriers (p. 20). Hydrophilic substances (e.g., inulin) are neither taken up into cells nor bound to cell surface structures and can, thus, be used to determine the extracellular fluid volume (2). Some lipophilic substances diffuse through the cell membrane and, as a result, achieve a uniform distribution (3). 

Fructans are polysaccharides composed of o-fructofuranose units. They are important in short-term energy reserves for grasses and some plants. Inulin, found in dahlias, and levans from grasses are examples of fructans. Levans are short linear polysaccharides composed of (3 2 1 linked fructose units as illustrated in structure 9.21. 

Inulin is soluble in water (maximum 10% at room temperature) and forms a gel-type structure. It does hydrolyse in acid conditions over time to produce fructose. It is heat stable. In soft drinks it can produce similar mouthfeel and technical properties to glucose syrup. 

The major part of inulin is composed of fructoses linked /3 (2-1). Draw the structure of inulin. 

Fig. 1.—Relation24 Between Movement in a Paper Chromatogram and Structure of Oligosaccharides. 1 = Galactan series (reducing) 2 = Dextran series 3 — Amyl-ose series 4 = Inulin series.

Detailed studies of the periodate oxidation of dextran and inulin (4-6) have shown evidence for the occurrence of hemiacetal structures formed by reaction of aldehydes with hydroxyl groups of either the same unit (intra-residual) or a neighbouring unit (inter-residual). Inter-residual hemiacetal formation reduces the number of diol struc-... 

The only dimethyl-D-fructose which has been characterized, 3,4-di-methyl-D-fructose, has been prepared by McDonald and Jackson141 from di-D-fructose anhydride I. Tritylation of this anhydride gives the 6,6 -ditrityl derivative which is methylated to 3,4,3, 4 -tetramethyl-6,6 -di-trityl-di-D-fructose anhydride I. Removal of the trityl groups followed by hydrolysis yields liquid 3,4-dimethyl-D-fructose, [ ]d —60.66° in water. It has also been obtained, with 4-methyl-D-fructose, from the hydrolysis of methylated di-D-fructose anhydride III. The structure of this dimethyl-D-fructose follows from its method of preparation from di-D-fructose anhydride I whose structure is known.10 McDonald and Jackson also prepared 3,4-dimethyl-D-fructose from inulin by the following method inulin — monotrityl inulin — monotrityl inulin diacetate — dimethyl monotrityl inulin — dimethyl isopropylidene-D-fructose — methyl dimethyl-D-fructoside —> 3,4-dimethyl-D-fructose. Its structure was confirmed by its oxidation without loss of methyl to the same lactol of the dimethyl dibasic acid obtained from 1,3,4-trimethyl-D-fructose (see page 78). The phenylosazone made from 3,4-dimethyl-D-fructose has m. p. 126° that from 3,4-dimethyl-D-glucose has not been recorded. 

Inulin would therefore appear to be an unbranched molecule consisting of about 30 D-fructose units, although the position regarding the D-glucose molecules which may be part of the structure is not definite. 

Compounds with different structures but with the same therapeutic activity isolated from different plant species act as active moieties for the treatment of particular diseases. Some of these compounds have been abandoned due to toxicity but these compounds apparently do not cause serious adverse effects. Some of these active principles originate from edible plants and their inclusion in the diet would undoubtedly be of some value because of their hypocholesterolemic potential. Several phytoconstituents including inulin, pectin, gugglu lipids, flavonoids, ginkoloids, saponins, tannins, and others obtained from various plant sources have proven hypolipidemic potentials as has been further explained in Tables I and II. The chemical structures of a few potential phytoconstituents with hypolipidemic activity are shown in Figure 2. It is hoped that as new additions are made to the list of these active compounds causing only minimum untoward side effects, these naturally... 

Many pioneer structural investigations were carried out in other groups of polysaccharides, notably on inulin, on the xylan from esparto, on the mannan from yeast and on a series of bacterial polysaccharides amongst the latter were included somatic and lipoid-bound polysaccharides from M. tuberculosis. Noteworthy also was the work on the dextran produced by strains of Leuconostoc, which is showing grqat promise as a blood plasma substitute. 

In 1895 Dull,9 who was studying inulin and its products of hydrolysis, found that when either fructose or sorbose was treated with an aqueous solution of oxalic acid under pressure, a substance was obtained which had the formula CeHeOa and resembled furfural in its properties. This substance was further investigated by Kiermayer4 who found that fructose and sucrose were the best sources when they were heated with 0.3% aqueous oxalic acid at 120°. It was however only the fructose portion of the sucrose molecule which was transformed since the glucose moiety was recovered unchanged. Kiermayer prepared several derivatives of CeH Os and from its reactions concluded that its structure was probably /3-hydroxy-S-methylfurfural (III). Van Ekenstein and... 

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