1 Sugar derivatives There are many important compounds that are derived from monosaccharides. They include sugar acids, sugar alcohols, deoxy sugars and amino sugars 1- Sugar acids They are the oxidation products of monosaccharides. According to the site of oxidation sugar acids are classified into: a- Aldonic acids It is produced by oxidation of carbonyl group (C1 in aldoses) to carboxylic group e.g. gluconic acid from glucose. H C O COOH H C OH H C OH HO C H HO C H H C OH H C OH H C OH H C OH CH2 OH CH2 OH Glucose Gluconic acid b- Uronic acids It is produced by oxidation of the last carbon e.g. glucuronic acid from glucose. H C O H C O H C OH H C OH HO C H HO C H H C OH H C OH H C OH H C OH CH2 OH COOH Glucose Glucuronic acid 2 Glucunonic acid is important in: - Detoxication reactions - Biosynthesis of mucopolysaccharides - Metabolism of bilirubin - Excretion of steroids. c- Aldaric acid (Saccharic acid) It is a dicarboxylic acid resulting from oxidation of both carbonyl carbon and last carbon e.g. glucaric acid from glucose. H C O COOH H C OH H C OH HO C H HO C H H C OH H C OH H C OH H C OH CH2 OH COOH Glucose Saccharic acid d- L-Ascorbic acid (vitamin C) It is a water soluble vitamin. It is a 6-carbon sugar acid derived from glonic acid. 2- Sugar alcohols Aldoses and Ketoses may be reduced at the carbonyl carbon to the corresponding sugar alcohols D-Sorbitol from D-glucose D-mannitol from D-mannose D-ribitol from D-ribose Inositol is a cyclic alcohol derived from glucose. OH OH H H H H H H OH OH OH OH 3 It is a member of vitamin B complex that acts as a lipotropic factor preventing accumulation of fats in the liver Also, inositol triphosphate has a role in the mechanism of action of some hormones. 3- Deoxysugars These are monosaccharides with one hydroxyl group (usually at C2) is replaced by hydrogen e.g. 2-deoxyribose which is a constituent of DNA. 4- Amino sugars These are monosaccharides in which the hydroxyl group at C2 is replaced by amino group. Glucosamine and galactosamine are examples of amino sugars. H C O H C O H C OH H C NH2 HO C H HO C H H C OH H C OH H C OH H C OH CH2 OH CH2 OH Glucose Glucosamine Amino sugars are important for biosynthesis of mucopolysaccharides and glycoproteins. Glucosamine which is derived from glucose is a constituent of heparin and hyaluronic acid Galactosamine which is derived from galactose is a constituent of chondriotin sulphate. .