Arabinitol

Fig. 1. Stmctures of the tetritols (a) erythritol, (b) D-threitol, and (c) L-threitol and the pentitols (d) ribitol, (e) D-arabinitol, (f) L-arabinitol, and (g) xyhtol.

Xyhtol (Fig. Ig) is found in the primrose (38) and in minor quantity in mushrooms (39). It can be obtained from glucose in 11.6% overall yield by a sequential fermentation process through D-arabinitol and D-xylulose (28). 

Sweetness is often an important characteristic of sugar alcohols in food and pharmaceutical applications. The property of sweetness is measured in a variety of ways and has a corresponding variability in ratings (218). Based on one or more test methods, erythritol and xyfitol are similar to or sweeter than sucrose (218,219). Sorbitol is about 60% as sweet as sucrose, and mannitol, D-arabinitol, ribitol, maltitol, isomalt, and lactitol are generally comparable to sorbitol (see Sweeteners). 

The addition of COg to ribulose-l,5-bisphosphate results in the formation of an enzyme-bound intermediate, 2-carboxy,3-keto-arabinitol (Figure 22.24). This intermediate arises when COg adds to the enediol intermediate gener-... 

R = H 3.5-Q-benzylidene-l-deoxy-2-C-phenyl-D-arabinitol yield 77% d.r. (39/40) 100 0 40 R = TBDMS 3,5-0-benzylidene-4-0-tert-butyldimethylsilvl-t-deoxy-2-C-phenyl-D-ribitol yield 89% d.r. (39/40) 0 100... 

The latter were further converted in one step to l,4-dideoxy-l,4-imino-D-arabinitol [(2R,3 A,4A)-3,4-dihydroxy-2-(hydroxymethyl (pyrrolidine] and fagomine (l,2,5-trideoxy-l,5-iminohexitol), respectively, by palladium-catalyzed hydration23 27. These compounds are extremely efficient inhibitors of glycosidases24. 

GC separation of the acetate derivatives rhamnitol, fucitol. ribi-tol, arabinitol, mannitol, galacitol, glucitol, and inositol... 

Initially, attempts to grow the organism on sodium acetate as the sole source of carbon were unsuccessful, but the difficulties were overcome and mannitol, arabinitol, erythritol, glycerol, maltose, and a,a-trehalose were produced. This was a useful development because conditions were established for the incorporation of [14C] acetate, thereby making labeled polyols and disaccharides available. 

Conformational depictions of acyclic sugar chains are conveniently expressed by locating certain atoms in the plane of the paper and orientating the remaining atoms or groups appropriately above and below that plane, as shown for D-arabinitol and xylitol (it should be recognized that the favoured conformation does not necessarily have all the carbon atoms in the same plane) ... 

For an alternative approach to naming carbohydrate residues as substituents see 2-Carb-31.2 [which would give the name (II )- or (lS)-L-arabinitol-l-C-yl for the above example, depending on the ligands at the branch point]. 

Arabinitol, galactitol, sorbitol, mannitol, xylitol, lactitol, etc. 

There are solitary examples of other alditol phosphates as components of this class of polymers. Arabinitol 1-phosphate is part of the S. pneumoniae type 17F capsular polysaccharide. o-Glucitol 6-phosphate is a component of the group-specific polysaccharide from group B Streptococcus, which has a most unusual, ramified structure. In a polysaccharide from Nocardia... 

---