chemical properties of monosaccharides

Chemical properties of monosaccharidesReaction with hydrazines to form osazones.Reduction to form sugar alcohols Name of monosaccharide Sugar derivative Glucose Sorbitol Mannose Mannitol Galactose Dulcitol Fructose Sorbitol and Mannitol Ribose Ribitol Glyceraldehyde Glycerol Dihydroxyacetone Glycerol

Mannitol acts as diuretic and used in the patients of cerebral edema.

Sorbitol gets deposited in the lens of the diabetic patient and contributes to an early cataract formation.

Oxidation to produce sugar acids Gluconic acid,Glucuronic acid,Glucaric acidGluconic acid is of great physiological

importance,used in the detoxification and inactivating many substances like benzoic acid,steroid hormones,bilirubin etc.

Reducing action of sugars in alkaline solutionsAction of acids and basesFormation of esters 1.Phosphates acetates,propionates,stearatesetc.2.Glucose catabolism3.Nucleoproteins

Several sugar esters importantin metabolism

Formation of amino sugars 1.Hexosamines(D-glucosamine,D-galactosamine

and D manosamine).2.Constituent of Glycosaminoglycans.

Fermentation

Special monosaccharides: amino sugarsConstituents of mucopolysaccharides

FORMATION OF GLYCOSIDES.Compounds in which carbohydrate residue is attatched by an acetal linkage at the anomeric carbon atom to an alcoholic residue called aglycone which is a non carbohydrate.

The aglycone may attach through to sugar through –OH or -NH2 group forming O and

N-glycosides.Aglycone may be methyl alcohol,a

sterol,phenol,a purine or a pyrimidine(sugar nucleosides),a protein(glycoproteins,GAG’s) and lipids(glycolipids).

Physiologically important glycosides.Cardiac glycosidesStreptomycinOuabainGlucovanillin

Deoxy sugars.Oxygen of the hydroxyl group is removed.Most important deoxy sugar is 2’-deoxy-D-

ribose.

Component of DNAL- fucose(deoxy L-galactose) in milk and blood

group substances.2-deoxy glucose is used in research.

Some important Monosaccharides.HEXOSESD-GLUCOSE.Grape sugar or dextrose.Form glycogen, starch and cellulose.Represents almost 100% of monosaccharides in blood

therefore known as blood sugar.Found in the urine of diabeticsSorbitol.sugar acidsCan occur in pyran and furan form74% as sweet as sucrose.

FRUCTOSEFruit sugar and levulose.Occurs in honey and plant kingdom.Source of energy for spermatozoa.Occur in pyran and furan formConstituent of sucrose.Sweetest of all sugars(173%) of sucrose

GALACTOSE.Part of lactose,seed coat of legumes.Constituent of glycolipids and glycoproteins.32% sweeter than sucrose.

MANNOSEConstituent of glycoproteinsIn the body turns into glucose

PENTOSESMonosaccharides contain ring of five atoms.Constituent of nucleic

acids,ATP,GTP,CTP,UTP,NAD+,NADP+,FMN,FAD and coenzyme A.

Phosphates as intermediates in the pentose phosphate pathway of glucose metabolism.

L-Xylulose is intermediate in uronic acid pathway of glucose metabolism.

D-lyxose is found in heart muscle.D-arabinose and D-Xylose is found in

glycoproteins.