Gluco

Linamarin, acetonecyanhydrin, -D>gluco-pyranoside, CeH, 0j 0 C CH3)2 CN. M.p. I43-I45°C. Present in young flax plants and in Phaseolus lunatus and is also the glycoside of rubber seeds. Such glycosides may be regarded as primary materials for synthesis. 

By saccharic acid is usually meant D-gluco-saccharic acid, m.p. 125-126°C, obtained by the oxidation of glucose or starch. This exists in water solution in equilibrium with its two y lactones, both of which can be obtained crystalline, though the acid itself does not crystallize readily. 

Deoxy-1-N-octadecylamlno-D-fructose (2). A solution of N-octadecyl-O-gluco-sylamlne 1 (2 5 g, 5 8 mmol) in pyridine (25 mL] was mixed with 0 28 N HCI (21 mL) in pyridine (5 8 mmoO- Next day, water (200 mL) was added and the product was extracted with a rnixture of 41 BOAc BuOH (200 mL) The organic layer was washed wrth water and dried (Na2S04)... 

From the plant Escallonia pulvemlenta (Escalloniaceae), which grows in Chile, an iridoid gluco-side of elemental composition CigZ/j On was isolated. Formula / gives the structure of the iridoid glucoside skeleton... 

When the juice of the fresh berries of the same plant was examined it yielded a gluco-alkaloid, m.p. 269-270° dec.), which appeared to be solauricine, m.p. 270° (dec.), but on hydrolysis it furnished a crude aglycone, m.p. 219-220°, which, after a long series of recrystallisations from a variety of solvents, gave a fraction of pure solasodine, m.p. 199-5-202°, and another of pure solauricidine,m.p. 213-7°. 

The major difference between the two gluco-alkaloids and also between the two aglycones, lies in their melting-points and those of their derivatives. For convenience of comparison these are summarised in the following table, which includes mixed melting-points to illustrate the difficulty met with in this series, that a mixture of two distinct members of the group may not show depression of melting-point. 

Anchusa officinalis L. Cynoglossine B. HCl, crystalline. Paralyses peripheral nerve terminations. Consolidine gluco-alkaloid hydrolysed to glucose and consolicine (also present as such). Paralyses the central nervous system. The same alkaloids are also present in Echium vulgare L. and Cynoglossum offikinale L. (Greiner, Arch. Pharm., 1900, 238, 505). 

Achillea spp. A. millefolium L. contains achilleine, amorphous hydrolysed to achUletine, CnHj,04N, also amorphous, ammonia and a reducing sugar. A. moschata contains achilleine and moschatine, CjiHjjOjN, an ill-defined gluco-alkaloid.2 ((1) Zanon, Annalen, 1846, 58, 21. (2) von Planta, ibid., 1870,... 

Ipomosa sidcefolia Choisy. The seeds, piule, contain a gluco-alkaloid with narcotic properties. (Santesson, Arch. Pharm., 1937, 275, 532.)... 

Gould, G. W., and Bell, G. I., 1990. Facilitative gluco.se transporters An expanding family. Trends in Biochemical Sciences 15 18-23. 

Gluco.se is kept in the cell by pho.sphorylation to G6P, which cannot easily cross the plasma membrane... 

Reaction.s 1 through 15 con.stitute the cycle that lead.s to die formation of one equivalent of gluco.se. The enzyme catalyzing each step, a concise reaction, and die overall carbon balance is given. Numbers in parendieses show die numbers of carbon atoms in the substrate and product molecules. Prefix numbers indicate in a. stoichiometric fashion how many times each step is carried out in order to provide a balanced net reacdon. 

In essence, this series of four reactions has yielded a fatty acid (as a CoA ester) that has been shortened by two carbons, and one molecule of acetyl-CoA. The shortened fatty acyl-CoA can now go through another /3-oxidation cycle, as shown in Figure 24.10. Repetition of this cycle with a fatty acid with an even number of carbons eventually yields two molecules of acetyl-CoA in the final step. As noted in the first reaction in Table 24.2, complete /3-oxidation of palmitic acid yields eight molecules of acetyl-CoA as well as seven molecules of FADHg and seven molecules of NADFI. The acetyl-CoA can be further metabolized in the TCA cycle (as we have already seen). Alternatively, acetyl-CoA can also be used as a substrate in amino acid biosynthesis (Chapter 26). As noted in Chapter 23, however, acetyl-CoA cannot be used as a substrate for gluco-neogenesis. 

The 3-deoxy 1,2-O-isopropylidene D-gluco- (37) and D-galacto-furanoses (17) have been used (53, 58) in yet another way to prepare deoxy sugars phosphorylated in the terminal position. If either of these compounds is treated with one molar equivalent of periodate, carbon 6... 

Hydrogenation of exocyclic, pyranoid vinyl ethers could afford a mixture of both possible 6-deoxy-D and L-hexoses. Our observations show that the proportion of each isomer is dependent upon the catalyst and the substituents on the vinyl ether. Thus, treatment of a methanol solution of l,2,3,4-tetra-0-acetyl-6-deoxy-/ -D-xylo-hex-5-eno-pyranose (12) with hydrogen in the presence of a palladium catalyst afforded a mixture which was shown by gas chromatography to contain 96% of the 6-deoxy-D-gluco isomer (11) and 4% of the 6-deoxy-L-ido isomer (13). In this... 

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