Deoxy sugars, 6-Deoxy-hexoses
(methyl pentoses or hexomethyloses)
alpha-L-Rhamnose (6-deoxy-L-mannose),D-Digitoxose
a component of the sugar part of Digitalis glycosides
Keller Killiane test ,DISACCHARIDES, Maltose (malt sugar)
Lactose (milk sugar) LACTULOSE, Polysaccharide
3. 6-Deoxy-hexoses
(methyl pentoses or hexomethyloses)
α-L-Rhamnose (6-deoxy-L-mannose),
D-Mannose
HHO
HHO
OHH
OHH
CH2OH
CHO
OOH OH
OHOH
CH3
L-rhamnose
4. 2, 6-Deoxy-hexoses
D-Digitoxose
a component of the sugar part of Digitalis glycosides
6
2
D-Allose
O
OH OH
OH
CH3
OHH
OHH
OHH
OHH
CH2OH
CHO
HH
OHH
OHH
OHH
CH3
CHO
D-Digitoxose
5. Keller Killiane test (for 2,6-Deoxy sugar)
70% alcoholic digitalis extract, heat and filter.
- 5 mL lead acetate solution.
- Separate the chloroform layer
- Evaporate the chloroform layer to dryness
- Add cautinously on the wall of test tube Conc. H2SO4
Intense blue color develop at the surface between the two layer
- 3 mL glacial acetic acid and 2 drops of FeCl3
Residue
- Shake the filtrate with chloroform,
- Shake and filter
7. DISACCHARIDES
■Formed between monosaccharides via a glycosidic
bond
■involves OH of anomeric carbon and any other OH
■In the reaction, lose elements of H2O
■Anomeric carbon gets fixed/locked into either α or β
configuration (can’t mutarotate)
■alpha (1→4)
■alpha = configuration of anomeric carbon
■1=number of anomeric carbon
■→4=denotes other carbon involved in glycosidic bond
8. General format to describe a disaccharide is:
■1st Sugar name – OH type (Carbon # 1st sugar –
Carbon # 2nd sugar)
■2nd Sugar name (α or β)
■example: glucose (α1 → 4) glucose
For example
O
OH
OH
H
OH
OH
CH2OH
O H
OH
OH
OH
OH
CH2OH
α-D-glucose
+
H2O
1
4
Maltose
α-(1 4) glycosidic bond
O
OH
H
OH
OH
CH2OH
O H
OH
OH
OH
O
CH2OH
α-D-glucose
10. Maltose (malt sugar( Lactose (milksugar(
4-O-α-(D-glucopyranosyl)-D-
glucopyranose
4-O-β-(D-galactopyranosyl)-D-
glucopyranose
Source
It is the main constituent of malt
and germinating cereals and as
hydrolytic product of
polysaccharides, e.g.
starch and dextrin
Source
Lactose is the principal sugar of
mammalian milk and is not
present in higher plants.
consists of two glucose units
linked through α 1-4 linkage
consists of galactose and
glucose, linked by β 1-4 linkage
It is hydrolyzed by maltase enzyme
(α -glucosidase).
It is hydrolyzed by emulsion enzyme
(β-galactosidases)
It undergoes mutarotation It undergoes mutarotation
11. Preparation
Maltose is prepared from
starch by partial acid
hydrolysis, or by using
α -amylase enzyme isolated
from green malt.
Preparation
Lactose is obtained from
whey (a by-product from
cheese manufacture) after
concentration, upon which
deposits of lactose
crystallize out.
In Lactose The enzyme (Lactase) needed to digest this beta
glycosidic bond is lacking in many people and, also, tends to
disappear with age. This leads to so-called lactose intolerance
12. CELLOBIOSE
(4-O-β-D-glucopyranosyl-D-
glucose) results from the
hydrolysis of cellulose by
bacteria.
LACTULOSE Galactose-β-(1,4)-fructose.
Nature and uses: it is a semi-synthetic
disaccharide, not absorbed in the GI tract. It is
metabolized by bacteria to lactic acid, formic
acid and acetic acid. It is used either as a
laxative or in the management of portal
systemic encephalopathy.
GENTIOBIOSE
Is an example of C-6 dihexoses. 1,6-β-D-glucopyranosyl-β-D-
glucopyranoside.
13. Non-reducing disaccharides:
Sucrose (Saccharum, Table sugar, Cane Sugar- Beet
Sugar). commercially obtained from sugar cane or sugar beet
Sucrose
α-D-glucopyranosyl-β-D-fructofuranose
[Glu-1α−2β-Fru]
1
O
OH
H
OH
OH
CH2OH
O
CH2OH
CH2OH
OH
HO
O
2
6
6
α-D-glucose
β-D-fructose
• Anomeric carbon (C1) on glucose is linked
to the anomeric carbon (C2) on fructose
• BOTH anomeric carbons are involved in
glycosidic bonds
• Therefore, sucrose is NOT a reducing sugar
15. Hydrolysis of sucrose
The enzymatic (α-glucosidase and invertase) or
dilute acid hydrolysis of sucrose is called “inversion”
due to the fact that:
The sign of rotation being changed from (+) in the original solution of
sucrose into (-) in the hydrolyzed solution,
the process is called inversion
Sucrose
([α]25
D = + 66.5o
)
acid hydrolysis
(α-glucosidase or invertase)
enzyme hydrolysis
or
D-(+)-glucose
([α]25
D = + 52.7o
)
D-(-)-fructose
([α]25
D = - 92o
)
50% 50%
([α]25
D = - 20.4o
)
16. Chemical tests for Sucrose
(1) Sucrose
used as flavoring and
colouring matter).
200-250 o
C
amorphous brown
substance (Caramel)
(2) Sucrose Cobalt nitrat Violet color
(3) Sucrose
Fehling's solution
- ve
(4) Sucrose
Osazon
- ve
(5) Sucrose solution does not undergo
mutarotation.
NaOH
17. Preparation of Sucrose
A) From sugar-cane (Saccharum officinarum)
B) From sugar beets (Beta vulgaris)
Uses of Sucrose
■Nutrients
■In the preparation of syrups and Excipient for tablets ( It
masks disagreable taste in tablets and pills)
■In sufficient concentration of sugar in aqueous
solution, is bacteriostatic and preservative (66%w/v)?.
■In preparation of dextran
(a polysaccharide used as plasma substitute)
18. Trehalose:
Trehalose is a disaccharide found in yeasts,
fungi, sea urchins, and algae. It is a
nonreducing sugar and does not found in
plants.
HONEY
Source: Sugar secretions are collected in honeycomb by honey bees Apis
mellifera L.
and other species Family Aapidae.
Chemical composition: Honey consists chiefly of dextrose and levulose (70-
80%) with small amounts of water, sucrose (2-10%), dextrin, wax, proteins,
volatile oils, minerals, acids and coloring and flavoring components, it contains
vitamin B1, B2, C, nicotinic acid and formic acid.
Uses:
1- As demulcent, sweetener in cough mixture.
2- As a biological additive in shampoos, face body and hand creams and
lotions.
3- It has been reported to have antimicrobial activity which is due to production
of locally high osmolality due to water activity in honey or due to enzymatic
production of hydrogen peroxide.
22. Classifications of Polysaccharides
polymers of more than
one type of monosaccharide
Homopolysaccharides Heteropolysaccharides
polymers of a single
monosaccharide
Starch
Cellulose
Dextrins
Dextran
Gums Mucilages
Agar Algin
Pectic substances
23. Polysaccharide containing only
monosaccharide units
A. Starch
Occurrence:
■Starch is widely distributed in plants.
■It constitutes from 50 to 65% of the dry weight of
cereals seeds and as much as 80% of the dry
matters of potato tubers. Although starch (oats,
wheat, Corn, rice, rye, and sorghum)
24. Amylose
Amylopectin
It is an α -glucan polysaccharide.
Structure of Starch
It consists of two components
Amylose
Amylopectin
25. Characters of starch components
Amylose Amylopectin
Forms the inner layers of the
starch granules
Forms the outer layers of the
starch granules
soluble in water Sparingly soluble in water
It consists mainly of linear chain
of α-D glucose linked 1-4 from
1000 to 4000 units,
higher molecular weight than
amylose and has chains of D-
glucose units linked α-1-4, with
branches of similar chain linked
through α-1-6 linkages (each 25-30
glucose units)
It hydrolyzed completely with
amylase enzyme produces 100%
maltose
With amylase enzyme gives 50%
of maltose and 50% dextrin ? (c.f.
amylose)
Give Blue color with iodine
solution
Give bluish red color with iodine
solution
26. Preparation of starch:
■Graminaceous fruits (wheat or rice) are
grounded and suspended in water.
■Glutin (protein of cereals) is removed by
addition of alkali followed by washing with
water.
■The starch is then dried and finally powdered
27. Uses of Starch
■Dusting powder
■Antidote for iodine poisoning.
■Diluent in powders and tablets manufacture.
■Nutrient, demulcent, protective and adsorbent.
■Starting material in the manufacture of
glucose, liquid glucose, maltose, and dextrins.
28. Soluble starch
Soluble starch is prepared by heating starch
with dilute HCl at 40 o
C for 30 min or
by maceration of starch for 7 days in dilute
HCl, followed by washing until neutrality and
drying. The product produced is soluble in
water and used as indicator in iodometric
assays.
29. Drugs derived fromstarch
1(Hetastarch
■It is hydroxyethyl starch (semisynthetic material(
■Used as plasma expander in case of shock
but it increases bleeding time and cause
allergy.
(Starch( OH +
O OH
alkali
Starch O CH2 CH2OH
Etylene oxide Hetastarch
30. 2(Dextrins (or artificial gums(
It is glucan polysaccharide consists of highly
branched chain (α-1-4 & 1-6(
They prepared by partial starch hydrolysis through:
Enzymatic degradation using amylase
Yellow dextrin
(British gum dextrin(
Heating starch with
dil HCl
110 o
C
White dextrin (high-grade(
Heating starch with
Steam
200-250o
C
31. Types of Dextrins
Achrodextrin
According to the method used for their preparation
Hydrolysis with dilute acids White dextrin
Hydrolysis with steam Yellow dextrin
According to the molecular weight of the degradation products
of starch
Amylodextrin High molecular weight polymer. It gives a blue color
with iodine and does not reduce Fehling's solution.
Erythrodextrin Medium molecular weight polymer. It gives a red color
with iodine and reduces Fehling's solution.
Low molecular weight polymer. No color
with iodine and reduces Fehling's solution.
32. Uses of Dextrins
1-In infant formulas as nutrient.
2-Substitutes for natural gums.
3-For sizing cloth or paper and
in cloth printing.
33. 3(Dextran
.
Preparation:
■Dextran is obtained from sucrose by the action of a
bacterial enzyme obtained from Leuconostic mesenteroides
■Dextran is an example of biochemical conversion of a
disaccharide into a polysaccharide.
Uses
■It is used as plasma expander for emergency treatment in cases
of shock due to hemorrhage, or severe burns.
■Dextran sulphate can be used as anticoagulant, in treatment of
ulcer and in preparation of sephadex.
It is water soluble α-1-6 linked polyglucan.