Inositols proof

Cautious nitric acid oxidation of meso-inositol afforded Postemak a pentahydroxycyclohexanone. Reduction of this compound or its pentaacetate gave a new inositol which Postemak named epi-inositol. Proof of the structure of the pentahydroxycyclohexanone epi-meao-inosose, see the following section) as a racemic mixture of 1-keto- and 3-keto-meso-inositol (XXXIII and XXXIV) demonstrated that ept-inositol corresponds to formula II. 

In addition to the above water-soluble vitamins, other compounds are present in milk, such as choline, myo-inositol, and para-aminoben-zoic acid, compounds for which there is no proof of a dietary requirement for humans (NAS 1980A). 

Ms. Pat Hall and Drs. J. Nowacki and E. Epstein have provided our knowledge of the amounts and rate of metabolic turnover of the indolylic components of the kernels of lea mays (cf. 27, 28 Nowacki, unpublished Epstein, unpublished). This knowledge Fas enabled us, 1) to identify the "seed auxin precursor"—that is the compound which is transported from the seed to the growing shoot (39J, and 2) has provided a portion of the proof that IAA-myo-inositol and IAA are in reversible equilibrium in the shoot tissue. Proving that IAA and IAA esters are in reversible equilibrium in the tissue is essential if we wish to postulate hormonal homeostasis. 

Additional proof of the proposed formula for (—)-quebrachitol was furnished by the synthesis of 1 -O-methy 1-Zeyo-inositol (2-O-methyl-feao-inositoI)... 

Sequoyitol, which is optically inactive, was presumed to be one of the meso forms, and this presumption was eventually verified by the finding that the infrared spectrum of its pentaacetate differs from those of the (optically active) bornesitol pentaacetate and ononitol pentaacetate.66 Many unsuccessful attempts were made to decide between the two possibilities (LXXI and LXXII) by indirect means,78 83 by synthesis,164 and by degradation.68 Proof that sequoyitol is actually 5-O-methyl-myo-inositol (LXXI) was finally obtained by synthesizing it from (+)-pinitol.M The only myoinositol methyl ethers which could be derived from pinitol by the inversion of one of its hydroxyl groups are LXXI and LXXIV formula LXXIV is excluded because it must be optically active. The synthesis of sequoyitol from (+)-l, 2-anhydro-neoinositol (see p. 183) confirms the formula LXXI.7-166... 

PREPARATION OF GLYCEROPHOSPHOINOSITOLS WITH CONCOMITANT FORMATION of long-chain fatty acid derivatives. A primary approach used for structure proof and identification studies on the inositol-containing phos-phoglycerides has been to effect the cleavage of the fatty acid ester groups and at the same time lead to the formation of glycerophosphoinositol. Base-catalyzed methanolysis of the parent molecule has been the procedure of choice. 

In the budding yeast, inositol polyphosphate synthesis proceeds via what is likely to be one of the earliest incarnations of a PLC-dependent pathway for higher inositol polyphosphate metabolism in eukaryotes. Early biochemical studies in yeast (and plants) failed to identify a calcium-sensitive Ins(l,4,5)P3 3-kinase activity analogous to that found in mammalian cells. Instead, these studies identified C6-hydroxyl phosphorylation of Ins(l,4,5)P3 and formation of Ins(l,4,5,6)P4 as the most likely first anabolic step in the production of higher inositol polyphosphates (22). Additional biochemical studies identified the sequential phosphorylation of Ins(l,4,5,6)P4 to Ins(l,3,4,5,6)P5 followed by Ins(l,2,3,4,5,6)P6 (23). These findings were interpreted as proof of the existence of disparate pathways in yeast and mammals for the metabolism and functionality of Ins(l,4,5)P3. In contrast, the eventual cloning of the yeast Ins(l,4,5)P3 kinase activity found that mammalian and yeast inositol metabolism were more closely related than initially suspected. 

The difficult proof of the configuration of meso-inositol has come only recently from two independent sources, each proof representing the culmination of a long series of researches. The work of T. Posternak, although second in actual priority, will be described first. 

In 1942, however, Mrs. Gerda Dangschat announced the isolation of D,L-idosaccharic acid from the oxidation of a derivative of meso-inositol. Several months later Posternak published proof that his hexaric acid from the oxidation of inosose was actually n,L-idosaccharic acid and not n,L-glucosaccharic acid. Thus, by two separate paths meso-... 

The proof of configuration was not accomplished until many years later. By independent means, the configuration of mi/o-inositol was established by Dangschat 79) and by Posternak 49). Previously, S. and T. Posternak 80) had narrowed the possibilities for m /o-inositol to... 

The proofs of structure of these two deoxyinositols are considered together since they afford a good illustration of the interrelationships of inositols. 

Systematic investigations of sugars [266-268] have provided additional proof of the presence of associated building units in discotic structures. Several isomers, differing in the steric positions of the hydroxyl groups, of inositol are known. Because inositols contain six hydroxyl groups, many derivatives differing in the number and positions of the substituents are possible. By suitable substitution the derivatives can be mesomorphic. The kind of mesophase... 

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