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

Oligosaccharides

Introduction:

When two or more monosaccharide are jointed together, the bond that holds

them together is known as the glycosidic bond. This is formed between the

hydroxyl-group at the anomeric carbon atom of one monosaccharide and any

hydroxyl-group on another monosaccharide through formation of an acetal.

Molecule of oligosaccharide contains 2-10 monosaccharide units. The

commonest of oligosaccharides have only 2, 3 or 4 units; and hexose units are by
far the most frequent. They are classified according to the number of

monosaccharide units in the molecule into di-, tri, tetra-....etc. -saccharides.

In general, they are crystalline solids, soluble in water, with sweet taste.

They can be hydrolyzed by acid or by some specific enzymes. The ease of acid

hydrolysis varies from each other; e.g., sucrose is easier to be acid-hydrolyzed in

comparison to lactose.

Disaccharides

If two monosoccharide units; e.g., 2 x glucose; combine together through a

glycosidic linkage; i.e., acetal linkage; to form a disaccaharide, the product may

be reducing or non-reducing disaccharide according to the site of the glycosidic

linkage “acetal linkage”.

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