Derived carbohydrates

Carbohydrates
Deoxyribose sugar
amino sugar
amino sugar acid
oxidation/reduction of monosaccahrides

1. 1

2. Carbohydrates Monosaccharides : Pentose (Ribose) Hexose (Glucose, Fructose, Galactose) Derived Carbohydrates: (Deoxy Sugar, Amino Sugar, Oxidation/Reduction) Disaccharides Maltose Lactose Sucrose Polysaccharides Homopolysaccharides (Starch, Glycogen , Cellulose) Heteropolysaccharides ( Glycosaminoglycans ) 2

3. Derived Carbohydrates Single units of  carbohydrates  called Monosaccharides Monosaccharides may undergo various reactions to form Carbohydrate Derivatives .  3

4. Derived Carbohydrates Oxidation Deoxy S ugar Addition Reduction Amino group Non-carbohydrate residues 4

5. 1- Oxidation to produce Sugar A cids Aldoses are oxidized to form A cid 5

6. 1- Oxidation to produce Sugar A cids Aldoses are oxidized to form Acid E.g.: oxidation of glucose Uronic acid Glucuronic acid Galacuronic acid Aldonic acid Gluconic acid Galaconic acid Dicarboxylic acid / Saccharic acid Glucosaccharic acid 6

7. Biomedical importance of D-Glucuronic Acid Uronic acid pathway : Pathway for glucose oxidation . In liver: Gluc uronic acid is formed from Glucose (a) Conjugates with toxic substances Drugs Hormones Bilirubin (a break down product of Hb ) 7

8. Biomedical importance of D-Glucuronic Acid D-Gluc uronic acid is converted to a soluble non-toxic substance, a glucuronide , which is excreted in urine. 8

9. 2- Reduction of sugars to form sugar alcohols Monosaccharides may be reduced to their corresponding alcohols by reducing agents 9

10. 2- Reduction of sugars to form sugar alcohols Examples: Glucose yields D-Sorbitol ( G lucitol ) 10

11. 2- Reduction of sugars to form sugar alcohols D-Glucose yields D- Sorbitol ( Glucitol ) • D-Galactose yields D- Dulcitol • D-Mannose yields D- Mannitol Examples: Erythritol Lactitol Maltitol Mannitol Sorbitol Xylitol 11

12. Biomedical Importance of sugar alcohols In microbiology, used to identify type of bacteria. Different bacteria gives different pattern . Example: E. coli Xylose reductase in Escherichia coli for the production of xylitol 12

13. Addition : 3-Amino S ugars Sugars containing an – NH2 group in their structure are called amino sugars Two types of amino sugars of physiological importance are: Glycosylamine Glycosamine 13

14. (a) Glycosylamine : A nomeric –OH group is replaced by an –NH2 group. Example: Ribosylamine , a derivative involved in the synthesis of purines (A/G) . 5-phospho-β-D- ribosylamine 14

15. (b) Glycosamine ( Glycamine ) Alcoholic – OH group of the sugar molecule is replaced by – NH2 group . Two naturally occurring members are derived from Glucose ---------> Glucos amine Galactose ---------> Galactos amine 15

16. Biomedical Importance • Glucosamine is the chief organic constituent of Cell wall of F ungi Shells of crustaceae (crabs , Lobsters), as Chitin • Antibiotics: Amino sugars are related to the antibiotic activity of these drugs. Erythromycin contains dimethyl amino sugar C arbomycin contains 3-amino-D-Ribose . 16

17. Acetylated Amino Sugar A mino group may be Acetylated as N - acetylglucosamine 17

18. Biomedical Importance N-acetyl derivative of D-Glucosamine occur as a constituent of certain M ucopolysaccharides (MPS )/ Glycosaminoglycan • N-acetyl-Galactosamine in chondroitin sulphates present in Cartilages Bones Tendons Heart valves 18

19. Amino Sugar Acids • Derivatives of amine containing sugars, E.g :   N - acetylglucosamine  and  sialic acid , whose nitrogens are part of more complex functional groups   19

20. Amino Sugar Acids • Neuraminic Acid Muramic Acid 20

21. Neuraminic Acid   9-carbon monosaccharide  Neuraminic acid is unstable found in nature in the form of acylated derivatives N-acetyl Neuraminic acid — NANA , ( Sialic acids) found as a terminal residue of oligosaccharide chains of glycoproteins 21

22. Muramic acid A condensation product of D Glucosamine and Lactic Acid .  It occurs as   N - acetylmuramic acid  in  peptidoglycan , whose primary function is a structural component of many typical bacterial cell walls 22

23. Biomedical Importance of Amino Sugar Acids • A number of nitrogenous oligosaccharides contain N euraminic acid are found in human milk . • Certain bacterial cell walls contain M uramic acid . • Neuraminic acid & Sialic acids occur in mucopolysaccharides and in glycolipids like gangliosides . 23

24. Biomedical Importance of Amino Sugar Acids • Neuraminidase are enzymes that cleave sialic acid groups from glycoproteins Neuraminidase are required for influenza virus replication . found on the surface of influenza viruses that enables the virus to be released from the host cell. 24

25. 4. Glycosides   Glycosides = Carbohydrate + Non-carbohydrate ( sugar) ( Aglycone ) glycerol, phenol sterols, hydroquinones 25

26. 4. Glycosides Glycosides are named according to the carbohydrate contain. Glucose = G lucoside Galactose = G alactoside 26

27. Biomedical Importance of Glycosides found in many drugs, spices and in the constituents of animal tissues • Cardiac glycosides: It is important in medicine because of their action on heart and thus used in cardiac insufficiency. They all contain steroids as aglycone component in combination with sugar molecules . Digitonin 4 Galactose + Xylose + Digitogenin ( Aglycone ) 27

28. Biomedical Importance of Glycosides Ouabain : Inhibits active transport of Na+ in cardiac muscle in vivo (Sodium Pump inhibitor ). • A ntibiotics: Streptomycin 28

29. 5- Deoxy sugars Deoxy sugars of biological importance are : • 2-deoxy-D-Ribose is found in nucleic acid (DNA ). • 6-deoxy-L-Galactose common component of many N- and O-linked polysaccharides and glycolipids produced by mammalian cells. Glycoproteins Blood group substances Bacterial polysaccharides 29

30. Derived Carbohydrates Oxidation Deoxy S ugar Addition Reduction Amino group Non-carbohydrate residues Gluconic acid Glucuronic acid Glucaric acid Sorbitol Amino sugar Glucosamine Galactoseamine Mannoseamine Amino Sugar Acids Neuraminic Acid Muramic Acid Galactoside Glucoside 2-deoxy-D-Ribose 6-deoxy-L-Galactose 30

31. 31 Reference: Textbook Medical Biochemistry by Chatterjea , Eight Edition, Chapter 3 https://www.amazon.com/Textbook-Medical-Biochemistry-M-D-Chatterjea/dp/9350254840