Inositols naturally occurring

Amphotropic behavior can be found for a large number of different chemical structures. Additional information is given in other chapters of this Handbook. Typical classes of amphotropic materials are for instance classical soaps (see lyotropics), transition metal soaps (see metallomesogens), viologens, quartemary amines and other ionic surfactants (see lyotropics), block copolymers (see polymer liquid crystals), cellulose derivatives (see cellulose liquid crystals) and partially fluorinated paraffines, diols, peptide surfactants, lecithins, lipids, alkylated sugars and inositols, naturally occurring glycosides and silanols, which are discussed in this chapter. 

The deoxyinositols (quercitols, cyclohexanepentols) are useful model compounds which display many of the physical and chemical properties of true deoxy sugars. Although (-b)-proto-quercitol, the best known isomer, was isolated from nature 118 years ago, no synthesis has been reported up until now. The synthesis here described is actually that of the (-)-enantiomer, starting with (-)-inositol however, identical procedures applied to the readily available ( + ) or dl-inositol would give (- -) or DL-proto-quercitol, respectively. The natural occurence of, )-proto-quercitol has... 

An equally simple chemical study was carried out on phytic acid-aluminosilicate cements (Prosser et al., 1983). Phytic acid, myo-inositol hexakis(dihydrogen phosphate), is a naturally occurring substance found in seeds, and it is a stronger acid than phosphoric acid. Cements were prepared using aqueous solutions of phytic acid, concentrated to 50 wt%, and with 5 wt % zinc dissolved in the acid to moderate the rate of reaction with the glass powder. Discs of cement were prepared and these were... 

Glycosylphosphatidylinositols are naturally occurring glycophospholipids on a cell surface. Full structural assignment was reported by Ferguson et al. in 1988 [142,143]. The core structure was composed of a carbohydrate residue with an ethanolamine side chain, inositol residue, and a phosphoglycerolipid residue (O Fig. 11). The carbohydrate residue, ethanolamine side chain or lipid moiety is species specific [144,145,146,147,148], and depends on species and... 

Inositol hexaphospate (IP6) is a naturally occurring compound found in com, sesame, wheat, and rice. In human trials, this substance inhibited prostate cancer, and in laboratory studies, it caused cancer cells to revert to normal cells. 

The stability constant of D-ribose has been determined more frequently than that of any other sugar, presumably because it is the only naturally occurring aldose that complexes readily. Most of the known stability constants are shown in Table IV. Some further stability constants are listed herewith myo-inositol with Ca " ", 0.2 3-0-methyl-4pi-inositol with Ca ", 1.6 3-O-methyl-a-D-allo-pyranose and -fiuant with Ca, —0.6 and —3.0, respectively D- /yc ro-a-D- /o-heptopyianose with La, ... 

The commonest naturally-occurring inositol is myu-inositol, and its structure is readily memorised because in the preferred conformation only one hydroxyl group is axial. Its 1-L phosphate ester is biosynthesised from its isomer glucose-1-phosphate by an oxidation-intramolecular aldol condensation-reduction sequence, see Section 6.8.4. 

A long series of papers by Shvets and co-workers is devoted to synthesis of asymmetrically substituted myo-inositols and, in particular, inositolphos-phatides. Their route to optically active compounds from wyo-inositol consists of the formation of diastereoisomeric orthoesters in the reaction of a suitably protected racemic myo-inositol derivative with the orthoacetate of D-mannose, followed by the separation of the diastereoisomers and hydrolysis. Naturally occurring ( + ) and (-) bomesitols (3- and 1-0-methyl-sn-myo-inositols) were obtained in this way, among many other enantiomerically pure chiral myo-inositol derivatives. ... 

Research on liquid crystals with a disc-like shape started in 1977 [130] when hexa(hep-tanoyl)benzene (38, first synthesized forty years earlier [131]) was proved to form a columnar mesophase (m.p.=/tj, 81.2°C, cl.p.=/ci 87.0°C) [132]. Disc-shaped amphiphilic molecules with saturated cores, such as the hexaesters 39 or even the hexa-ethers 40 of the naturally occurring scyllo-inositol [9, 109, 133-137] form columnar liquid crystals much more easily with me-sophases more stable and very much wider in range than known for the mentioned benzene derivatives. 

A new silylatlng reagent, "trlmethylsllyl-N,N-dimethylcarbam-inate", has been shown to be superior to the previous best reagent (BSTFA) for derivatlzlng rlbonucleosides for g.c. It can be used as the solvent for derivatization (at 60°C, 0.5 h). The g.c. separation of naturally occurring inositols and their mono-0-... 

Myoinositol is a naturally occurring vitamin with a hexahydroxycyclohexane structure its phosphorylated forms are readily converted to trimethylsilyl derivatives which, as has been observed for alkyl ethoxy phosphates, can be separated by SFC at temperatures some hundreds of degrees below those necessary for GC of such compounds [14]. Both silylated inositol triphosphate and phytic acid (inositol hexaphosphate) were eluted... 

Inositols are cyclohexanehexols that naturally occur as free, methylated, or phosphorylated forms. Of the nine possible isomers (Figure 2A), three are synthetic epi-, alio-, and ds-inositol), seven are optically inactive as meso forms, and two are enantio-morphs (d- and L-chiro inositol). However, phosphorylation or methylation of the inositol isomer most widely distributed in the nature, myo-inositol, at one of the hydroxyl groups 1, 3, 4, or 6 lead to chiral compounds, as shown in Figure 2B. Inositol... 

A number of cyclic polyols also are known to occur (Fig. 15.13). myo-Inositol (62), widespread in animals, is a growth factor in yeasts and a group B vitamin. This compound, one of nine possible stereoisomers, is widespread in plants (six other isomers also are naturally occurring). When plant cells are incubated with radiolabeled myo-inositol, a large portion of the label appears in the pentose and uronic acid residues of the cell wall (Karr, 1976 Loewus and Loewus, 1980). myo-Inositol serves as a precursor for o-glucuronic acid (3). Furthermore, when glucose and other monosaccharides are incorporated into cell walls, myo-inositol appears to be an intermediate (Karr, 1976 Loewus and Loewus, 1980). Analytical techniques for the study of cyclitols and sugar alcohols (polyols) have been reviewed (Beck and Hopf, 1990 Loewus, 1990). 

An easy conversion of naturally occurring quebrachitol (2-0-methyl-L-c/u>o-inositol) to mwco-inositol has been described, involving oxidative removal of the methyl group from the perbenzoyl derivative and inversion at C-2 by solvolysis of the corresponding tosylate with concomitant benzoate neighbouring-group participation. ... 

In view of the wide distribution of the cyclohexanehexols (called inositols or cyclitols) and the importance of one in particular (myo-inositol) to certain bacteria, plants, and perhaps even to warm-blooded animals, the naturally occurring and synthetic compounds of this carbocyclic class have received considerable study. Naturally occurring members include four inositols, monomethyl ethers, a dimethyl ether, monodeoxy derivatives, one dideoxy derivative, a methyl homolog, and deoxy carboxylic acids. Five inositols and many other synthetic members, including ketones (cycloses or inososes), are known. 

Trivial names serve to identify the inositols and the related naturally occurring compounds. It is also possible to identify the inositols by a numerical system, wherein the orientation of hydroxyl groups above and below the ring is represented by a fraction. neo-Inositol (IV), for example, may be designated as 123/456-inositol and allo-inositol (III) as 1234/56-inositol. Formerly the conmion inositol, mi/o-inositol (V), was often called meso-inositol, but use of the latter term is discouraged because all but two... 

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