POLYSACCHARIDES . By SANGH PARTAP Department of Pharmacy Teerthanker Mahaveer University, Moradabad, U.P., INDIA. Definition.
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Department of Pharmacy
TeerthankerMahaveer University, Moradabad, U.P., INDIA
On hydrolysis yield only one type of monosaccharide unit.
Example- cellulose, inulin, starch etc.
On hydrolysis yield more than one type of monosaccharide unit.
Example- α- heparin, hyaluronic acid etc.
Of plant and most widely distributed carbohydrate.
Structure and properties
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.
Haworth methylation method:-
Cellulose is completely methylated in inert atmosphere then methylated cellulose is hydrolysed by dill. Acid to cleave the glycosidiclinkage.thenonreducing 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.
the amount of formic acid is estimated by the titration method. This estimation gives the value of chain length.
The repeating unit consists of D-galactose (β 1 4)-linked to 3,6-anhydro-L-galactose (in which an ether ring connects C-3 and C-6). These units are joined by ((α1 3)-) glycosidic links to form a polymer 600 to 700 residues long. A small fraction of the 3,6-anhydrogalactose residues have a sulfate ester at