1. COURSE CODE : PHR 103 COURSE TEACHER : ZARA SHEIKH
CARBOHYDRATES
COURSE CODE : PHR 103
COURSE TEACHER : ZARA SHEIKH

2. Definition:
Carbohydrates are:
universal constituents of living organisms, they are aldehyde-or ketone-polyalcohols with hydrogen and oxygen present in the same ratio as in water (2:1)with some exceptions (deoxy-sugars) .
a major source of energy from our diet.
also called saccharides, which means “sugars.”

3. Carbohydrates’ Synthesis
produced by photosynthesis[glucose (the primary unit of carbohydrates) is synthesized in the chloroplasts in plants from CO2, H2O, and energy from the sun].
are oxidized in living cells to produce CO2, H2O, and energy.

4. Carbohydrates’ Synthesis

5. Importance to Plants
In plants, they are found:
as support elements; participating in the structure of the organism (cellulose and other parietal polysaccharides);
as energy reserves; in the form of polymers (starch or inulin);
as constituents of various metabolites; nucleic acids, coenzymes and glycosides;
as required precursors for all other metabolites.

6. Pharmaceutical Importance of carbohydrates
Carbohydrates are used in pharmacy:
for the preparation of simple syrup( sucrose).
as diluents& binders for the preparation of tablets(lactose, starch, gums) & for coating sugar-coated tablets(liquid glucose).
for preparation of infants’ food(starch & dextrin).
for preparation of sterile iv solutions(dextrose).
In anti-diarrheal drugs (pectin).

7. Pharmaceutical Importance of carbohydrates
Carbohydrates are used in pharmacy:
As laxatives (mucilage, lactulose),antacids(sucralfate) or diuretic drugs (mannitol & sorbitol).
as emulsifying agents(gums).
as nutrient media for both bacteria and tissue cultures (agar).
In the preparation of surgical dressing(cellulose) & plasters( gums).
Some carbohydrate derivatives have various therapeutic use such as ascorbic acid, glucosamine, dextran and others.

8. Classification of Carbohydrates
Monosaccharides:
of the general formula Cn(H2O)n , characterized by the presence of an aldehyde (aldoses)or ketone (Ketoses)carbonyl function.
According to Cn are named tetroses, pentoses, hexoses,---.
Those with 3 carbon atoms are called trioses, those with 4 carbon atoms are called tetroses, those with 5 carbon atoms are called pentoses, those with 6 carbon atoms are called hexoses.

9. Classification of Carbohydrates
Disaccharides:
On hydrolysis give 2molecules of monosaccharides, further classified to reducing & non-reducing disaccharides.
Oligosaccharides:
On hydrolysis give 3-10molecules of monosaccharides
Polysaccharides:
On hydrolysis give large number of molecules (>10), can be homopolysaccharides consisting of one type of monosaccharides( e. g. cellulose) or heteropolyccharides consisting of more than one type (e.g. gums).

10. Polysaccharides:
The more complex high molecular weight polysaccharides are represented by starch, inulin and celluloses.
These polysaccharides are usually hydrolyzed to a component hexose and are therefore called hexosans – starch which yields glucose is called a glucosan and inulin which yields fructose is called a fructosan.

11. Chemical Structure of monosaccharides
Monosaccharides( aldoses and ketoses) show many isomers due to the existence of one or more asymmetric (chiral) carbon atoms as well as the different geometric arrangement of the atoms within the molecules.
In carbohydrate chemistry, The D and L describes the configuration of the asymmetric carbon atom farthest away from the reducing group.

12. Structure of D and L- glucose

13. Physical properties of carbohydrates
Simple sugars: are water soluble, crystalline, sweet tasting, have sharp melting points with decomposition. They are optically active and exhibit mutarotation phenomenon.
Polysaccharides: are amorphous mixture of variable molecular weight. They are slightly soluble or insoluble in cold water and may be soluble in hot water and are precipitated with alcohol from their aqueous solution.

26. Gums and Mucilages
Gums are complex heterogeneous, branched and uronic acid containing polysaccharide macromolecules.
These are translucent, amorphous substances, exudates of plants and produced as the result of trauma.
Gums are insoluble in organic solvents but most of them are soluble in water and forms colloidal viscous solutions.
These are optically active and dilute solutions (<1%) precipitates upon addition of ethanol or lead sub acetate.
Gums on hydrolysis yields sugars (arabinose, galactose, glucose, mannose and xylose) with sugar acids (glucoronic acid and galacto-uronic acid).

27. Gums and Mucilages
Mucilages are normal cell constituents of high molecular weight compounds, composed mainly of sulphuric acid esters of sugar.
These neither dissolves in water to form clear colloidal solutions but swells nor precipitates by addition of alcohol.
Mucilages on hydrolysis yields sugar (galactose and arabinose) and sugar acids (uronic acids).
Seaweed agar and carrageenan contains mucilage composed of salts of sulphate esters of polysaccharides.

28. Seaweed agar

29. Carragenan agar – Carrageenan is a seaweed extract common in the Atlantic Ocean near Britain, Continental Europe and North America.