RESUMO
L-Xylulose is an intermediate in certain metabolic pathways and is classified as a rare sugar. It shows important physiological effects such as acting as an inhibitor of α-glucosidase and decreasing blood glucose, and it can be employed to produce other significant rare sugars, such as L-ribose and L-xylose which contribute to the production of antiviral drugs. Chemical synthesis of L-xylulose was performed, but it is difficult and low yielding. The biotransformation from xylitol to L-xylulose by xylitol 4-dehydrogenase was studied intensively. This review describes the occurrence of L-xylulose in certain metabolic pathways, its bioproduction, and application potential.
Assuntos
Biotecnologia/métodos , D-Xilulose Redutase/metabolismo , Redes e Vias Metabólicas , Xilulose/metabolismo , Antivirais , Biotecnologia/tendências , Biotransformação , Glucose/metabolismo , Ribose/metabolismo , Desidrogenase do Álcool de Açúcar/metabolismo , Álcoois Açúcares/metabolismo , Xilitol/metabolismo , Xilose/metabolismo , Xilulose/síntese química , Xilulose/farmacologia , alfa-Glucosidases/metabolismoRESUMO
[reaction: see text] A new route, of potential strategic importance, to a difluorosugar analogue has been developed. Key steps included a Stille coupling and a highly regio- and enantioselective dihydroxylation of a highly substituted diene. Protecting groups were chosen to enhance the reactivity of the disubstituted allylic fragment in the AD reaction and allow deprotection under orthogonal conditions.
Assuntos
Xilulose/análogos & derivados , Xilulose/síntese química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Estereoisomerismo , Xilulose/químicaRESUMO
1-Deoxy-D-xylulose has been prepared in seven steps and approximately 21% overall yield from 2,3-O-isopropylidene-D-erythrono-1,4-lactone. The key reaction involves transformation of a branched-chain aldotetrose to the 1-deoxy-2-ketopentose catalyzed by molybdic acid. Other branched-chain aldotetroses containing bulkier substituents at C2 also engage in the conversion, suggesting routes to protected 2-ketoses and alpha-ketoacids/esters. This synthetic route mimics reactions of the non-mevalonate isoprenoid pathway in plants and bacteria. [reaction: see text]
Assuntos
Molibdênio/química , Tetroses/química , Xilulose/análogos & derivados , Xilulose/síntese química , Catálise , Espectroscopia de Ressonância Magnética , Modelos MolecularesRESUMO
The pentuloses D-erythro-2-pentulose (1) and D-threo-2-pentulose (2) and their 1-13C- and 2-13C-substituted derivatives were prepared by hydrogenating the corresponding isotopically normal and 13C-substituted D-pentos-2-uloses with a Pd-carbon catalyst. The threo isomer and its labeled derivatives were alternatively prepared from isotopically normal and 13C-substituted D-xyloses with immobilized D-xylose (D-glucose) isomerase (E.C.5.3.1.5). The equilibrium compositions of 1 and 2 (furanose anomers and acyclic keto forms) in 2H2O were determined from 13C-n.m.r. spectra (75 MHz) of the 2-13C-labeled derivatives. The conformational properties of the cyclic and acyclic forms in 2H2O were assessed with the use of 1H-1H, 13C-1H, and 13C-13C spin-coupling constants obtained from 1H-n.m.r. (620 MHz) and 13C-n.m.r. (75 MHz) spectra. Compared with the structurally related aldotetrofuranoses the 2-pentulofuranoses more strongly prefer conformations in which the anomeric hydroxyl group is oriented quasi-axially. The strongly dipolarized carbonyl group in the acyclic keto forms of 1 and 2 appears to stabilize chain conformations having O-1 and O-3 eclipsed with the carbonyl oxygen.