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Clinical pharmacy PharmD program Third level Phytochemistry-1 (PG-504)

2) Cellobiose

• Chemically, it is: 4-O-(-D-Glucopyranosyl) -D-glucopyranose.

• It does not occur free in nature.

Preparation:

It may be obtained from cellulose by acetylating good filter paper, which is

almost pure cellulose, with acetic anhydride in the presence of concentrated

sulfuric acid.

Properties:

• Cellobiose is a white crystalline solid, soluble in water and dextrorotatory.

• It is a reducing sugar, forms an osazone: rosettes of plates or broad needles

(cellobiosazone), and undergoes mutarotation, reduces Fehling’s but does not

reduce Barfoed’s reagent.

• On hydrolysis with dilute acids or by enzyme emulsin, it yields D-glucose.

N.B: The only difference between cellobiose and maltose is the type of glycosidic

linkage, where:

• Cellobiose : the glycosidic linkage is (),

• Maltose the glycosidic linkage is ().

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