PRESENTAION ON POLYSACCHARIDE DELIVERED BY: SANGH PARTAP M.PHARM

Definition of POLYSACCHARIDE Polysaccharides are high molecular weight polymers build up by repeated condensation of monosaccharides which are joined together by glycosidic linkages.

EXAMPLE OF POLYSACCHARIDE CELLULOSE INULIN STARCH HEPARIN HYALURONIC ACID

Types of POLYSACCHARIDE Homopolysaccharides :-also k/as homoglycans. On hydrolysis yield only one type of monosaccharide unit. Example- cellulose, inulin, starch etc.

Heteropolysaccharides :- also k/as homoglycans Heteropolysaccharides :- also k/as homoglycans. On hydrolysis yield more than one type of monosaccharide unit. Example- α- heparin,hyaluronic acid etc.

Cellulose Cellulose is the chief constituent of the cell wall Of plant and most widely distributed carbohydrate. Cellulose is an organic compound with the formula (C6H10O5)n, a polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4) linked D-glucose units.

Types of cellulose γ- Cellulose:- is insoluble in both. α- Cellulose :- is very much less degraded and does not dissolve in aqueous NaOH. β- Cellulose:- is soluble in aqueous NaOH but insoluble in dill. Acid. γ- Cellulose:- is insoluble in both.

cellulose Structure and properties Cellulose has no taste, is odourless, is hydrophilic, is insoluble in water and most organic solvents.

Constitutions Mol.formula of Cellulose has been found to be (C6H10O5)n from analytical data. When Cellulose is hydrolysed with fuming HCL it give D- glucose in 95-96% yield.This reaction reveal that Cellulose is made up of glucose unit.It means that the structure of Cellulose is based on the D- glucose unit.

Methylation,acetylation and nitration of Cellulose produce trisubstitution product as a max. substituted product, it means that each glucose unit present possesses 3 OH group in an uncombined state.

Fully methylated cellulose, when subjected to hydrolysis yield 2,3,6 tri-O-methyl D- glucose (90%) as main product and also 2,3,4,6 tetra-O-methyl D- glucose 0.6% as minor product.

Chemical method Determination of the proportion of end group and comparing with the total no. of unit in molecule. Haworth methylation method:- cellulose is completely methylated in inert atmosphere then methylated cellulose is hydrolysed by dill. Acid to cleave the glycosidic linkage.the nonreducing end will yield 2,3,4,6 tetra-O-methyl D- glucose whereas all other will undergo hydrolysis to yield 2,3, tri-O-methyl D- glucose. The two hydrolytic product are seprated by chromatographic tech. Hence by knowing the % of tetra methyl derivative or ratio of tetra methyl- tri methyl derivative. This method is known as the end-group assay.

Periodic oxidation method When cellulose is treated with sodium periodate or periodic acid,two mole of formic acids are obtained from reducing end whereas one mole of formic acid from the non-reducing end. the amount of formic acid is estimated by the titration method. This estimation gives the value of chain length.

starch Starch is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store. It is the most important carbohydrate in the human diet and is contained in such staple foods as potatoes, wheat, maize (corn), rice, and cassava.

Pure starch is a white, tasteless and odorless powder that is insoluble in cold water or alcohol. It is produced in the green plant by the reaction b/w water and oxygen under catalytic effect of chlorophyll and sunlight.

It consists of two types of molecules: the linear and helical amylose:-Amylose is a linear polymer made up of D-glucose units. the branched amylopectin: Branching takes place with α(1→6) bonds occurring every 24 to 30 glucose units. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin.

Amylose

Amylopectin

Constitutions of amylose It is empirical formula is C6H10O5 . On complete hydrolysis amylose give D-glucose units .this indicate that amylose is composed of only D-glucose units.

Enzymatic hydrolysis amylose give maltose Enzymatic hydrolysis amylose give maltose. Maltose is 4-o-(α-glucopyranosyl) –D-glucopyranose, all the glucose unit in starch are linked through C1α and C4. hence amylose posesses the foolowing str. Which explain the hydrolysis product.

The amylose is confirmed by hydrolysis of its fully methylated derivative to 2,3,6 tri-o-methyl-D-glucopyranose and 0.32% of 2,3,4,6 tetra-o-methyl-D-glucopyranose

Constitutions of amylOPECTIN It is empirical formula is C6H10O5 On complete hydrolysis amylopectin give D-glucose units .this indicate that amylose is composed of only D-glucose units.

Fully methylated amylopectin on hydrolysis gives 2,3,6 tri-o-methyl-d-glucose and 0.32% of 2,3,4,6 tetra-o-methyl-d-glucose.

Differences between starch & cellulose It is reserve food material of plant and is found mainly in seeds, roots and tubers of the plant. Wheat , maize, patatoes and rice are its main commercial source. It can be separated in two components, amylose and amylopectin. CELLULOSE It is very widely distribution in nature as the chief component of wood and plant fibres. Cotton, wood and juite are its main source. It is single compound which can not be separated into or more components.

STARCH CELLULOSE Both amylose and amylopectin consists of D-(+) glucose unit linked through α-glucoside linkage. It gives blue colour with iodine. It is also made up of D-(+) glucose unbrached chain but they are interlinked by β-glucoside linkage. It does not give blue colour with iodine.

Hetropolysaccharides 1-Hyaluronic acid 2-Heparin

Hyaluronic acid Hyaluronic acid -Hyaluronic acid is an important GAG (Glycosamonoglycan) found in the ground substance of synovial fluid of joints and vitreous humor eye. - Hyaluronic acid serves as a lubricant and shock absorbant in joints. -Hyaluronic acid is composed of alternate unit of D-gluconic acidN-acetyl D-glucosaamine.

Heparin Heparin is an anticoagulant( prevant blood clothing) produced by basophils and mast cells that occur in blood, lung, liver, kidney, spleen etc. Heparin is composed of alternate unit of N-sulfo D-glucosamine 6-sulfate and glu 2-sulfate.