Derived Monosaccharide

Derived monosaccharides differ from normal monosaccharides with respect to aldoses and ketoses. They include the glycosides, sugar phosphates, gluconic acid, glucruonic acid, amino sugars and vitamin C.

1. Glycosides. The hydroxyl group on carbon 1 in the sugar molecule can be replaced by other radicals, forming compound known as glycosides. There are two methyl glucosides possible, α and β, corresponding to the α and β forms of glucose. Glucosides formed from galactose are known as galactosides.

2. Sugar phosphates. C-1 or C-6 of glucoase can react with phosphoric acid (H3PO4) to yield glucose-1-phosphate and glucose-6-phosphate, respectively. These compounds play an important part in carbohydrate metabolism.

3. Gluconic acid glucuronic acid. Oxidation of C-1 of the glucose molecule to a carboxyl group yields gluconic acid. Production of a carboxyl group at C-6 yields glucronic acid. The corresponding terms for any hexoses are hexonic acid and hexuronic acid.
Glucuronic acid is an important constituent of complex polysaccharides and is also an important coupling agent. Many drugs, pesticides, and environmental pollutants and harmones are coupled with glucuronic acid and excreted in urine or bile as glucuronides.

4. Amino sugars or hexosaminues are formed when an amino sugar is introduced into hexoses. Thus glucose with NH2 at C-2 forms glucosamine. This compound is extensively found in complex polysaccharides, usually in the form of its acetyl derivative N-acetyl glucosamine. N-acetyl galactosamine, the amino derivative of galactose is found in glycoproteins and glycolipids.

5. Vitamin C (ascorbic acid) is a sugar acid of biological importance.