Biochemistry for Health science students

1. Major Medicinally Important 1o and 2o
Metabolites
1

2. Carbohydrates
2

3. Session outline
• Introduction
• Classification
• Relations among different carbohydrates
• Sugars
• Polysaccharides
• Compounds related to sugars
• Qualitative tests for carbohydrates
3

4. Four Major Types of Biological Macromolecules
Type of Polymer Monomers making up
Polymer Example
I. Carbohydrates
(Polysaccharides) Monosaccharides Sugars, Starch,
Cellulose
II. Lipids Fatty acids and glycerol Fats, steroids,
cholesterol
III. Proteins Amino acids
Enzymes,
structural
components
IV. Nucleic Acids Nucleotides DNA, RNA
Introduction

5. Introduction
Definition
– carbohydrate(hydrated carbon)
– Is a polyhydroxy aldehyde or ketone or a larger
molecule which can be hydrolyzed to a polyhydroxy
aldehyde or ketone or their derivatives
5

6. Introduction…
– Are the most abundant compounds found in plant
(cellulose, starch, sugars) and animals (glycogen)
– In most cases, composed of only C, H and O , with
general formula of (CH2O)n
– Usually the ratio of H to O is 2:1
6

7. Introduction…
However there are exceptions for this rule
 There are compounds that conform to the hydrate
rule (2:1 ratio of H and O) but not carbohydrates
E.g. Formaldehyde, HCHO; Acetic acid, CH3COOH
7

8. Introduction…
 There are compounds that do not conform to the
hydrate rule but have chemical properties of
carbohydrates
E.g. Deoxy sugars like:Rhamnose(C6H12O5),
digitoxose(C6H12O4)
8

9. Introduction…
Why do we study carbohydrates in pharmacognosy?
• Widely used in pharmaceuticals as additives
(suspending agents, emulsifiers, fillers, binders,
absorbents/ adsorbents)
• Starting material in the synthesis of various
compounds
9

10. Introduction…
• Many of them have pharmacological activity
– Anticoagulant
– Hypoglycemic activity
– Anti-inflammatory activity
– Antimicrobial
10

11. Role in living organism
• Storage of energy (e.g., starch and glycogen)
• Structural components (e.g., cellulose in plants and
chitin in arthropods)
• The 5-carbon monosaccharide ribose is an important
component of coenzymes (e.g., ATP ) and the
backbone of the genetic molecule known as RNA.
11
Introduction…

12. 12
Sources
• Major sources of carbohydrates are plants
• E.g Glucose is produced in plants through photosynthesis
from CO2 and H2O
• Glucose is converted in plants to other small sugars and
polymers (cellulose, starch)
Introduction…

13. 13
Classification of Carbohydrates
I. Number of carbohydrate units
• Monosaccharides
• Oligosaccharides
• Polysaccharides

14. 14
II. Position of carbonyl group
aldose: Sugars that contain an aldehyde group
ketose: Sugars that contain a ketone group

15. An aldose: Glucose
III. Cyclic form
• Less then 1% of CHO exist in an open chain form
• Pyranose (6-membered ring) and furanose (5-membere)

16. from
http://ntri.tamuk.edu/cell/carbohydrates.html
A ketose: Fructose

17. Classification…
17

18. 18
IV. Number of carbons

19. Classification…
• Monosaccharides or simple sugars
– They contain one sugar units
– They cannot be hydrolyzed further
• Monosaccharides are classified according to three
different characteristics:
– The placement of its carbonyl
– The number of carbon atoms it contains, and
– Its chirality (D- or L-)
19

20. • Trioses – 3 carbon atom e.g. glyceraldehydes
• Tetroses – 4 carbon atom e.g. threose, erythrose
• Pentoses – 5 carbon atom e.g. Arabinose, Xylose,
Ribose
• Hexoses – 6 carbon atom e.g. glucose, fructose,
mannose and galactose.
• Heptoses – 7 carbon atom e.g. Digitoxose, Cymarose
Classification…
20

21. Classification…
• Oligosaccharides
– Contain usually 2-12 sugar units linked to each
other by what is known as glycosidic linkage
– Can be hydrolyzed by dilute acids or enzymes to
give 2-12 monosaccharide units
• Classified based on their number of sugar units.
• 2 monosaccharides = disaccharides
• 3 monosaccharides = trisaccharides
21

22. Classification…
22
C
CHOH
CHOH
C
CHOH
O H
CH2OH
C
CHOH
CHOH
C
CHOH
O H
CH2OH
O H
H
+ H2O
H or OH
C
CHOH
CHOH
C
CHOH
O H
CH2OH
C
CHOH
CHOH
C
CHOH
O H
CH2OH
OH
HO
OH
H
- H2O
glycosidic bond

23. Classification…
Disaccharides
• Can be hydrolyzed to two monosaccharides
• Examples
– Sucrose:- composed of glucose and fructose
– Maltose:- composed of two molecules of glucose
– Lactose:- composed of glucose and galactose &
glucose
23

24. Formation of Disaccharides
24

25. Hydrolysis of a Disaccharide
25

26. Classification…
Trisaccharides
– Can be hydrolyzed to three monosaccharides
Examples
– Raffinose: can be hydrolyzed by enzymes of
intestinal bacteria to glucose, fructose, and
galactose.
26

27. Classification…
Polysaccharides
– Consist of many monosaccharide units linked to each
other by glycosidic bond.
– Could be;
 Homopolysacchrides, composed of only one type
of monosaccharide
 e.g.: starch, cellulose, glycogen, inulin and chitin.
27

28. Classification…
• Heteropolysaccharides, more than one type of
monosaccharides …. Also called heteroglycans
• Mucopolysaccharides or Glycosaminoglycans (GAGs)
are the heteroglycans consistis of a repeating
disaccharide unit.
• The repeating unit consists of an amino sugar along
with a uronic sugar (glucuronic acid or iduronic acid)
or galactose.
E.g hyaluronic acid, chondroitin sulphate and heparin. made of
repeating units of sugar derivatives like amino sugars and uronic
acids
28

29. Chondroitin sulfate
• Composed of a chain of alternating sugars (N-
acetylgalactosamine and glucuronic acid)
• Important structural component of cartilage and
provides much of its resistance to compression
• Used as dietary supplement for treatment of
osteoarthritis.
29
Classification…

30. 30
Chemical structure of one unit in a chondroitin
sulfate chain.
Chondroitin-4-sulfate: R1 = H; R2 = SO3H; R3 = H.
Chondroitin-6-sulfate: R1 = SO3H; R2, R3 = H.
Acetylgalactosamine
Glucuronic acid

31. Hyaluronan/ hyaluronic acid
• Non-sulfated glycosaminoglycan distributed widely
throughout connective, epithelial, and neural tissues.
• Hyaluronan is a polymer of disaccharides, composed
of D-glucuronic acid and acetylglucosamine
• It is component of articular cartilage, skin
31
Classification…

32. 32
Hyaluronan/ hyaluronic acid

33. • The FDA has approved the use of hyaluronic acid
during certain eye surgeries
– It is injected into the eye during the procedure to
help replace natural fluids.
• For various joint disorders, including osteoarthritis.
• For healing wounds, burns, skin ulcers, as a
moisturizer.
33
Classification…

34. Relations among different carbohydrates
Isomers
• Isomers are molecules that have the same molecular
formula, but have a different arrangement of the
atoms in space (different structures).
• Examples of isomers: Glucose, Fructose, Galactose,
Mannose ………..the same chemical formula C6 H12
O6
34

35. Relations among…..
Epimers
• Epimers are sugars that differ in configuration at only
1 position.
• Examples of epimers :
– D-glucose & D-galactose (epimeric at C4)
– D-glucose & D-mannose (epimeric at C2)
35

36. Relations among…..
36

37. Enantiomers
1. Monosaccharides contain one or more asymmetric C-
atoms: get D- and L-forms, where D- and L- designate
absolute configuration
2. D-form: -OH group is attached to the right of the
asymmetric carbon
3. L-form: -OH group is attached to the left of the
asymmetric carbon
4. If there is more than one chiral C-atom: absolute
configuration of chiral C furthest away from carbonyl
group determines whether D- or L-
Relations among…..
37

38. e.g
of
chiral
Carbon
atoms
38

39. Sugars
Monosachrides
Ribose:
• Is an aldopentose that, in its open chain form, has an
aldehyde functional group at one end
• Ribose exists in an equilibrium among 5 forms:
– the linear form and
– either of the two ring forms: alpha- or beta-
ribofuranose, with a 5-membered ring, and alpha- or
beta-ribopyranose
39

40. 40
• The ribose β-D-ribofuranose forms part of the backbone of
RNA.
• It is related to deoxyribose, which is found in DNA

41. Uses:
• D-ribose is often marketed as a supplement for
bodybuilders, for recovery or increasing muscle mass
in healthy people.
• D-ribose has also been used to reduce fatigue in
fibromyalgia.
41
Sugars …

42. Xylose
• Xylose or wood sugar, is an aldopentose -- a
monosaccharide.
• Xylose is found in straw, oat hulls and in most woods.
• In animal medicine, xylose is used to test for
malabsorption (if 25 g po of D-xylose is given to
normal patients 4.5 g in 5 hrs will be excreted in the
urine ) .
42
Sugars …

43. 43
Oat hulls
Sugars …

44. Mannose
• Sugar monomer of the aldohexose series of
carbohydrates.
• Mannose is a C-2 epimer of glucose.
• Mannose commonly exists as two different sized rings,
the pyranose form and the furanose form.
• Mannose is widely distributed in nature in the form of
anhydride-like condensation products termed
mannosans
44
Sugars…

45. • Sugar extract from the sap is extracted by making a
cut in the bark Fraxinus ornus
45
Fraxinus ornus
Sugars…

46. Galactose
• Galactose is a type of sugar which is less sweet than
glucose.
• It is a C-4 epimer of glucose
• It is considered a nutritive sweetener because it has
food energy
46
Sugars …

47. • Galactose is found in dairy products, tomatoes, sugar
beets, etc
• It is also synthesized by the body, where it forms part
of glycolipids and glycoproteins in several tissues
47
Sugars…

48. Sugars…
D-glucose (dextrose , α-D-glucopyranose, grape sugar)
• C6H12O6 , It is found in honey and the juices of many
fruits
• Glucose is made industrially by the hydrolysis of
starch under the influence of dilute acid.
48

49. 49
• Glucose is stored as a polymer, in plants as starch
and in animals as glycogen.
• Many crops can be used as the source of starch.
• Maize, rice, wheat, cassava, are all used in various
parts of the world
Sugars…

50. 50
Cassava, Beta vulgaris, sugar beet
Sugars…

51. Uses
– As sweetener ….In the preparation of syrups and
elixirs
– For coating tablets and as tablet binder
– It is used as a nutrient in food and dextrose
injection in replacement therapy usually at 5% and
10%.
51
Sugars…

52. Sugars…
– It is used as a fluid and nutrient replenisher.
– It also present in anticoagulant citrate phosphate
dextrose solution.
– Used commercially in the manufacture of candy,
carbonated beverages, ice cream,etc.
52

53. 53
Sugars…

54. Sugars…
D-fructose (levulose)
• Is present practically in all fruits and honey
• Commercially, fructose is frequently derived from
sugar cane, sugar beets, and corn.
54

55. Sugars…
• It is the sweetest of all naturally occurring
carbohydrates.
• In general, fructose is regarded as being 1.73 times
as sweet as sucrose.
• However, it is the 6-membered ring form of fructose
that is sweeter
55

56. Crude drug containing sugar
Honey
• Honey is thick, syrupy, translucent liquid when fresh
but becomes opaque and granular through time due
to crystallization of glucose
• It is pale yellow to reddish brown
• It posses sweet taste and usually pleasant flavor
(odor & taste) that varies depending on the nectar
source
56
Sugars…

57. Chemical constituents:
• Honey contains chiefly D-glucose (30-40%), fructose
(40-50%) and small amounts of sucrose (0.1-10%),
pollen grains, and volatile oil
57
Sugars…

58. Medicinal uses and health effects of honey
• Honey has antibacterial activity
• Diabetic ulcers when the patient cannot use other
topical antibiotics
• Mild forms of conjunctivitis
• Due to its antiseptic properties, it can be taken orally
by Pharyngitis and Laryngitis sufferers, in order to
soothe them
• Mild laxative (for constipation)
• Sedative (for mild insomnia)
58
Sugars…

59. Cymarose and Digitoxose
– Cymarose is closely resembles to digitoxose in
behaviour and is considered to be a methylether
of digitoxose.
– Cymarose are obtained on hydrolysis of the
glucosides cymarin (from the root of apocyanum)
59
Sugars …

60. Digitoxose, (C 6 H 12 O 4)
• The leaves of Digitalis purpurea contain apparently
more than five glycosides which form the active
constituents of digitalis
• Digitoxin the most active principle, is insoluble in
water; on hydrolysis it forms digitoxigenin and a
sugar, digitoxose.
60
Sugars and…

61. Disaccharides
Sucrose (saccharum, sugar or table sugar)
• It is O-β-D- fructofuranosyl-(2 ↔ 1)-α-D-glucopyranose
• Sucrose is a disaccharide composed of D-glucose and
D-fructose.
• It is a the most abundant disaccharide and the main
form in which carbohydrates are transported in
plant.
61
Sugars and…

62. Sugars…
• Important commercial sources of sucrose are
– Sugar cane: Saccharum officinarum
– Sugar beet: Beta vulgaris
62

63. Sugars…
• When sucrose is hydrolyzed by dilute acid solution, it
produces equal amounts of D-glucose and D-
fructose.
• This mixture is commonly known as invert sugar.
63

64. Sugars…
Uses
– As sweetener
– In the preparation of syrups and elixirs
– For coating tablets and as tablet binder
– For manufacturing lozenges and pastilles
– As a demulcent and as a nutrient
– Act as bacteriostatic agent and preservative if
used in high concentration
64

65. Lactose, milk sugar
• Lactose is a disaccharide composed of D-galactose
and D-glucose units
• It found most notably in milk .Lactose makes up
around 2–8% of milk (by weight)
• It is only faintly sweet, and its principal use is as a
diluent in tablet formulations
65
Sugars…

66. Polysaccharides
Polysaccharides
• They consist of repeat units of monosaccharides or
their derivatives.
• They are colourless and tasteless.
• They are concerned with two important functions -
structural and storage of energy.
66

67. Starch
• Starch for medicinal and pharmaceutical use consists
of polysaccharide carbohydrate occurring as discrete
granules in:
– The mature grain of maize or corn (Zea mays)
– The mature grain of wheat (Triticum aestivum)
– The mature grain of rice (Oryza sativa)
– Tubers of potato (Solanum tuberosum)
67
Polysaccharides…

68. 68
Polysaccharides…
Starch

69. Character:
• Starch occurs as granules with different shapes,
patterns and size (diameter = 2-100 μm) depending
on the botanical source.
– Wheat starch: 2-23 μm
– Corn starch: 25-32 μm
– Potato starch 30-100 μm
• Starch granules are insoluble in water
69
Polysaccharides…

70. Chemical composition:
Starch granules are composed of two glucans known as
amylose and amylopectin
Characteristics Amylose Amylopectin
Average amount 20-25% 75-80%
Average no of glucose
units
250-300 More than 1000
Structure Linear non-
branching
Linear branching
Connectivity of
glucose units
Exclusively by
α(1→4) linkage
α(1→4) linkage in the main
chain and α(1→6) linkage
at branching points
Water solubility Water soluble Water insoluble but swells
in water
Color with iodine Deep-blue Blue-violet or purple 70
Polysaccharides…

71. Amylose – a straight chain structure formed by 1,4
glycosidic bonds between α-D-glucose molecules.
H O
OH
H
OH
H
OH
CH2OH
H
O H
H
OH
H
OH
CH2OH
H
O
H
H H O
O
H
OH
H
OH
CH2OH
H
H H O
H
OH
H
OH
CH2OH
H
OH
H
H O
O
H
OH
H
OH
CH2OH
H
O
H
1
6
5
4
3
1
2
amylose
Structure of Amylose Fraction of Starch
71
Polysaccharides…

72. Amylopectin-a glucose polymer with mainly α -(14)
linkages, but it also has branches formed by α -(16)
linkages.
H O
OH
H
OH
H
OH
CH2OH
H
O H
H
OH
H
OH
CH2OH
H
O
H
H H O
O
H
OH
H
OH
CH2
H
H H O
H
OH
H
OH
CH2OH
H
OH
H
H O
O
H
OH
H
OH
CH2OH
H
O
H
O
1 4
6
H O
H
OH
H
OH
CH2OH
H
H H O
H
OH
H
OH
CH2OH
H
H
O
1
OH
3
4
5
2
amylopectin
Structure of Amylopectin Fraction of Starch
72
Branch
Polysaccharides…

73. Medicinal uses:
– As binder (because of amylose…. Water soluble)
– As disintegrants (because of amylopectin.. Swell in
water)
– As tablet filler
– As absorbent in dusting powders
73
Polysaccharides…

74. Dextran
• Dextran contains from 200-400 glucose units with
predominant linkage is α(1,6)
• 3.5 or 10% solution dextran is used for plasma
volume expansion in the treatment of shock, means
of parenteral nutrition
• Dextran is also used in lubricant eye drops designed
to minimize discomfort from contact lens
74
Polysaccharides…

75. Cellulose
• The β-glucose molecules are joined together forming
β-(1,4) glycosidic linkages.
• The glucose units are linked into straight chains each
100-1000 units long.
• Weak hydrogen bonds form between parallel chains
binding them into cellulose microfibrils.
• Cellulose microfibrils arrange themselves into thicker
bundles called microfibrils…….fibres
75
Polysaccharides…

76. • The cellulose fibres are often “glued” together by
other compounds such as hemicelluloses and
calcium pectate ……..plant cell walls.
• Cellulose is the principal structural element of higher
plant cell walls
• Cellulose is commercially obtained from:
– Hair of the seed of cotton plant
– Wood
76
Polysaccharides…

77. 77
Polysaccharides…

78. 78
Polysaccharides…

79. 79

80. Cellulose
80
Polysaccharides…

81. Use
• Surgical dressing
• For preparing absorbent gauze
• Powdered cellulose is used as tablet diluent and
disintegrants
81
Polysaccharides…

82. Cellulose
Cellulose acetate phtalate (CAP)
- entricoating tablets
Hydroxypropylmethylcellulose
- suspending agent
- thickening agent
Ethylcellulose
- tablet binder
Methylcellulose
- bulk laxative
- suspending agent
- Artificial tear
+ for xerophtalmia
+ contact lens
Sodium carbonylmethylcellulose (CMC)
- thickening agent
- bulk laxative
Cellulose is extensively modified;
82
Polysaccharides…

83. Glycogen
• Is a polysaccharide of glucose which functions as the
secondary short term energy storage in animal cells
• It is made primarily by the liver and the muscle, but
can also be made by the brain and stomach
• Glycogen is the analogue of starch commonly
referred to as animal starch
83
Polysaccharides…

84. Gums and mucilage
Consists of Ca, Mg and K salts of polyuronoides that
are hydrolyzed by boiling with acids to monosaccharide
and uronic acid or galactouronic acid
84
Polysaccharides…

85. • Gums are considered to be pathological products
formed upon injury of the plant or owing to
unfavorable conditions such as drought
• The formation of gums is known as gummosis which
involves the break down of cell walls and thus it is an
extracellular process
• Mucilages are normal products of metabolism,
formed with in cells (intracellular formation)
85
Polysaccharides…

86. • Mucilages usually serve as storage materials, water-
storage reservoirs, or may provide protection for
germinating seeds
• Insoluble in alcohol and in most organic solvents but
soluble in water yielding viscous, usually adhesive
colloidal solutions
86
Polysaccharides…

87. Pharmaceutically important gums
• Acacia gum is the dried gummy exudate obtained
from the stem and branches of Acacia senegal and
some related species like Acacia arabica
• Acacia gum contains chiefly arabin (mixture of
calcium, magnesium and potassium salts of arabic
acid)
• On hydrolysis arabic acid yields L-rhamnose, L-
arabinose, D-galactose and D-glucuronic acid 87
Polysaccharides…

88. 88
mucilage
Polysaccharides…

89. Acacia gum is used:
• As demulcent (added in formulations for cough,
diarrhea and throat problems)
• As emollient (to cover burns, sore nipples etc)
• As emulsifying agent (for oil in water emulsions)
• As binder in tablets especially in lozenges.
• Commercially as adhesive
89
Polysaccharides…

90. Gum tragacanth
• Tragacanth is the dried gummy exudate obtained
from the stems of Astragalus gummifer and other
related species
• Gum tragacanth contains targacanthin and bassorin
– Targacanthin is the water soluble portion and is
1/3 of the mass
– Bassorin is the water insoluble portion and is 2/3
of the mass…….Bassorin swells to from a gel
90
Polysaccharides…

91. 91
Astragalus gummifer
Polysaccharides…

92. • Gum tragacanth is used
– As suspending and emulsifying agent
– As binder in pills and tablets
– As a bulk laxative
– Gum tragacanth is resistant to acid hydrolysis so it
is preferred in acidic preparations.
92
Polysaccharides…

93. Pharmaceutically important mucilages
Agar
• Agar is the dried, acidic, hydrophilic colloidal
polysaccharide complex extracted from different red
algae species such as:
– Gelidium cartilagineum
– Gracilaria confervoides
• Agar is composed of acidic polysaccharides that could be
resolved into two fractions:
– Agarose is the gelling fraction
– Agaropectin is the non-gelling fraction
93
Polysaccharides…

94. 94
Polysaccharides…
Gelidium cartilagineum
culture media

95. Agar is used
• As suspending and emulsifying agent
• As gelling agent for suppositories
• As tablet filler and disintegrant
• For the treatment chronic constipation (bulk laxative)
• For the preparation of culture media (1% solution)
95
Polysaccharides…

96. Algin (Sodium alginate)
• Algin is a polysaccharide extracted from different
strains of brown seaweed by the use of dilute alkali
• It is chiefly obtained from Macrocystis pyrifera
• Sodium alginate yields D-mannuronic acid and L-
glucuronic acid
• Algin is readily water-soluble
96
Polysaccharides…

97. 97
Macrocystis pyrifera
Polysaccharides…

98. Algin is used
• As suspending and emulsifying agent
• As thickening agent
• As tablet binder
• Food (ice cream)
• Commercially it s widely used in cosmetics and
textile
98
Polysaccharides…

99. Pectin
• Cell walls of higher
plants
• Largely a linear polymer
of polygalacturonic acid
with varying degrees of
methyl esterification.
99
Polysaccharides…

100. Use
• as gelling agent
• Thickeners
• Laxative
• used in throat lozenges as a demulcent
100
Polysaccharides…

101. Chitin
• Chitin is the second most abundant carbohydrate
polymer
• It is modified polysaccharide that contains
nitrogen;………..units of N-acetylglucosamine
• Cellulose with one hydroxyl group on each monomer
replaced with an acetyl amine group.
• Present in the cell wall of fungi and in the
exoskeletons of crustaceans, insects and spiders
101
Polysaccharides…

102. 102
Polysaccharides…

103. • Chitin is used commercially in coatings (extends the
shelf life of fruits and meats)
• Chitin's flexibility and strength make it favorable as
surgical thread
103
Polysaccharides…

104. Plant acids such as citric, lactic, and tartaric acid find
wide application in the formulation of food and
medicine.
Citric acid
Weak organic acid with the formula C6H8O7
104
Sugar related compounds

105. Sugar related…
– It is a tricarbixylic acid
– First isolated from lemon juice
– Present in many fruits and plants
– Commercially obtained from lemons, pineapples
– Colorless, odorless, translucent crystal and soluble
in water and alcohol
105

106. Uses
– Useful in buffering system
– Used as an acidulant in effervescent formulation
– An ingredient in anticoagulant, citrate phosphate
dextrose solution
106
Sugar related…

107. Lactic acid
– Colorless or yellowish, odorless, syrupy liquid
– Miscible with water, alcohol and ether
Uses:
– As acidulant especially in infant feeding formulas
– Sodium lactate injection is a fluid and electrolyte
replenisher
– Calcium lactate - a calcium replenisher
– In topical preparations and cosmetics to adjust acidity and
for its disinfectant and keratolytic properties.
107
Sugar related…

108. 108
Sugar related…

109. Tartaric acid
– Dicarboxylic acid byproduct of wine industry
– Freely soluble in water
– Used as a substitute for citric acid in buffer system
in effervescent formulations
109
Sugar related…

110. Mannitol (D-mannitol)
110
• Obtained by the reduction of
mannose or by isolation from
manna
• Manna is the dried saccharine
exudate of barks of Fraxinus ornus
and contains 50-60% of mannitol
Sugar related…

111. 111
Fraxinus ornus

112. • Occurs as white crystalline powders.
• Odorless and sweetish taste.
• Mannitol is not absorbed in GIT……When
administered parentally, it is not metabolized and
eliminated by glomerular filtration (80% of 100 in 3
hrs)
112
Sugar related…

113. Medicinal use:
• For diagnosis of kidney function
• As osmotic diuretic
• Also as osmotic laxative for constipation
• As sweetener for diabetics
113
Sugar related…

114. Sorbitol (D-glucitol or D-sorbitol)
114
Sugar related…
Most sorbitol is made from corn syrup, but
it is also found in apples, also occurs in
many fruits
Sorbitol is an isomer of mannitol

115. • Commercially it is prepared from glucose by chemical
or electrolytic reduction
• Sorbitol is half as sweet as sucrose and it is not
absorbed from the GIT
115
Sugar related…

116. Pharmaceutical use:
• Used as osmotic laxative for constipation.
• As sweetener for diabetics
• It is commonly used in toothpastes, chewing gums
116
Sugar related…

117. Qualitative Test to Detect CHOs
• Is concerned with determining the identity of a
substance.
– Molisch Test- carbohydrates
– I2 Test - Cellulose, Starch, Dextrin
– Seliwanoff’s Test- Ketose from Aldose
– Test for Reducing Sugars (Barfoed’s TestFT )
117

118. Qualitative test…
Molisch test
• Aqueous solution of carbohydrate mixed with few
drops of Molisch reagent (alpha naphthol) and Conc.
H2SO4 was added from sidewall of test tube.
• Formation of purple coloured ring at junction
indicates presence of carbohydrates.
118

119. 119
Qualitative test…

120. Iodine test
• It is specific for polysacchrides.
• Few drops of Iodine solution is added to aqueous
solution of polysaccharide.
• Formation of blue colour, which disappears on
heating and reappears on cooling, indicates the
presence of starch.
Qualitative test…
120

121. 121
Qualitative test…

122. Barford test
• This test is used to distinguish between monosacchride
and disacchrides.
• Two ml of Barford reagent (Cupric acetate, acetic acid
and water) was added to 1 ml aqueous solution of
carbohydrates and boil.
• Formation of brick red precipitate in 5 minutes indicates
presence of monosacchride while in 7 minutes indicates
disaccharide.
Qualitative test…
122

123. 123
Qualitative test…

124. Seliwanoff’s test
• This test is used for identification of keto-hexoses or
to distinguish between ketoses and aldoses.
• To 1 ml aqueous solution of drug, 5 ml of
Seliwanoff’s reagent (resorcinol in 6M HCl) was
added and boiled.
• Formation of cherry red colour in presence of ketose
(e.g fructose) due to formation of hydroxyl methyl
furfural
Qualitative test…
124

125. 125
Qualitative test…

126. Fehling solution test
• It is generally used for reducing sugars and
composed of two solutions, which are mixed in situ.
• Fehling solution A composed of 0.5% of copper
sulphate whereas Fehling solution B composed of
Sodium Potassium Tartarate.
Qualitative test…
126

127. • Equal volumes of Fehling A and Fehling B solutions
were mixed (1 ml each) and 2 ml of aqueous solution
of drug was added followed by boiling for 5-10
minutes on water bath.
• Formation of reddish brown coloured precipitate due
to formation of Cuprous oxide indicates presence of
reducing sugar.
127
Qualitative test…

128. 128
Qualitative test…

129. 129
Qualitative test…

130. Benedict’s test
• It is used for reducing sugars and composed of mainly
Copper sulphate and sodium hydroxide.
• To the 4 ml of aqueous solution of drug, 1 ml of
Benedicts solution was added and heated almost to
boiling.
• Formation of green, yellow, orange, red or brown colour
in order of increasing concentration of simple sugar in
the test solution, due to formation of cuprous oxide.
Qualitative test…
130

131. 131
Qualitative test…