Polysaccharides azhar 2020-1

Polysaccharides
Lecture-1
Ahmed M. Metwaly
Ass. Professor, Faculty of Pharmacy, Al-Azhar University
PAGE 1

Course
Outline
Introduction
Homosaccharides (holosides)
Heterosaccharides (heterosides)
Polysaccharides in pharmacy
Honey
PAGE 2

▪ Definition
▪ Distribution and Importance
▪ Classificaton
Introduction

Definition
▪ The polysaccharides are complex, high molecular weight monosaccharide polymers of very wide
distribution in nature.
Depending on their structure, polysaccharides can have a wide variety of functions in nature.
▪ Some polysaccharides are used for storing energy (starch and glycogen),
▪ some for sending cellular messages,
▪ and others for providing support to cells and tissues (cellulose and chitin )
PAGE 4Introduction
Second Skill Third Skill ConclusionHomopolysaccharides Heteropolysacchrides Polysaccharides in pharmacy Honey
Function

Distribution and Importance
PAGE 5
Third Skill Conclusion
Introduction
Homopolysaccharides Heteropolysacchrides Polysaccharides in pharmacy Honey
Cellular Communication
▪ polysaccharides become glycoconjugates when they become covalently bonded to proteins
or lipids. Glycolipids and glycoproteins can be used to send signals between and within cells

Classification
PAGE 6
First Skill Second Skill Conclusion
Polysaccharides
> 10 sugar units.
Homosaccharides
Glucans
Starch Dextrin Dextran Sephadex Glycogen Cellulose
Fructosans
Inulin
Heterosaccharides
Dissimilar
monosaccharides
Derived carbohydrates
Polyuronides Mucopolysaccharides
Introduction
Homopolysaccharides Heteropolysacchrides Polysaccharides in pharmacy Honey

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)
Introduction
Homopolysaccharides
Heteropolysacchrides Polysaccharides in pharmacy Honey

Amylose
Amylopectin
Introduction
Homopolysaccharides
Starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight

Amylose
Amylopectin
Introduction
Homopolysaccharides

Characters of starch components
AmylopectinAmylose
Forms the outer layers of the starch granulesForms the inner layers of the starch
granules
Sparingly soluble in waterSoluble in water
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 consists mainly of linear chain of α-D
glucose linked 1-4 from 1000 to 4000 units,
Give bluish red color with iodine solutionGive Blue color with iodine solution
Introduction
Homopolysaccharides

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.
Raw starch is digested poorly in the duodenum and small intestine, while bacterial
degradation takes place mainly in the colon. When starch is cooked, the digestibility is
increased.
Introduction
Homopolysaccharides

Introduction
Homopolysaccharides
The US produced about 27.5 million tons of starch in 2017, of which about
8.2 million tons was high fructose syrup,
6.2 million tons was glucose syrups, and
2.5 million tons were starch products.
The rest of the starch was used for producing ethanol (1.6 billion gallons)

1) Hetastarch
■ It is hydroxyethyl starch (semisynthetic material)
■ Used as plasma expander in case of shock but it
increases bleeding time and cause allergy.
Introduction
Homopolysaccharides
Drugs derived from starch
(Starch) OH +
O OH
alkali
Starch O CH2 CH2OH
Etylene oxide Hetastarch

Mechanism of Action
Ethoxylated amylopectins; colloidally expands plasma volume
Pharmacokinetics
Onset: 30 min
Duration: 6-36 hr
Half-life, Elimination: 17 days
Metabolism: Enzymatically degraded by reticuloendothelial system or amylases in blood
Excretion: Urine, feces (by biliary excretion)
Administration: IV
Introduction
Homopolysaccharides

Adverse Effects
Anaphylaxis (periorbital edema,
urticaria, wheezing, mild termperature
elevation)
Chills
Flu-like symptoms
Myalgia
Peripheral edema
Headache
Pruritus
Vomitting
Salivary gland enlargement
Warnings
Do not use in critically ill adult patients including
those with sepsis, and those admitted to the ICU
Avoid use in patients with pre-existing renal dysfunction
Discontinue use at the first sign of renal injury
Need for renal replacement therapy has been reported
up to 90 days after administration; continue to monitor
renal function for at least 90 days in all patients
Avoid use in patients undergoing open heart surgery
in association with cardiopulmonary bypass due to
excess bleeding
Discontinue at the first sign of coagulopathy
Introduction
Homopolysaccharides

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
Introduction
Homopolysaccharides

Maltodextrin
is a polysaccharide that is used as a food
additive.
It is produced from vegetable starch by partial
hydrolysis and is usually found as a white
hygroscopic spray-dried powder.
Maltodextrin is easily digestible, being
absorbed as rapidly as glucose and may be
either moderately sweet or almost flavorless
(depending on the degree of polymerisation)
Introduction
Homopolysaccharides

Cyclodextrins
• are a family of cyclic oligosaccharides, consisting of a macrocyclic ring of glucose subunits
joined by α-1,4 glycosidic bonds.
• Cyclodextrins are produced from starch by enzymatic conversion, Commonly
cyclodextrin glycosyltransferase (CGTase) is employed along with α-amylas.
• They are used in food, pharmaceutical, drug delivery, and chemical industries, as well as
agriculture and environmental engineering.
• Cyclodextrins are composed of 5 or more α-D-glucopyranoside units linked 1-4, as in
amylose (a fragment of starch).
• Typical cyclodextrins contain a number of glucose monomers ranging from six to eight units
in a ring, creating a cone shape:
α (alpha)-cyclodextrin: 6 glucose subunits.
β (beta)-cyclodextrin: 7 glucose subunits
γ (gamma)-cyclodextrin: 8 glucose subunits
• β-cyclodextrin is ideal for complexation due to perfect cavity size, efficient drug
complexation and loading, availability, and relatively low cost
• Some containing 9, 10, 11, 12 and 13 glucopyranose units have also been reported.
• Some derivatives containing the hydroxypropyl (HP), methyl (M) and sulfobutylether (SBE)
substituents have been commercially used as new pharmaceutical excipients.
Introduction
Homopolysaccharides

Introduction
Homopolysaccharides

Cyclodextrins are cyclic oligosaccharides of a
glucopyranose, containing a relatively hydrophobic
central cavity and hydrophilic outer surface.
Owing to the lack of free rotation around the bonds
connecting the glucopyranose units, the CDs are not
perfectly cylindrical molecules but are toroidal or
cone shaped.
• As a result it act as molecular containers by
entrapping guest molecules in their internal cavity.
No covalent bonds are formed or broken during drug
CD complex formation.
• Once included in the cyclodextrin cavity, the drug
molecules may be dissociated from the
cyclodextrin molecules through complex dilution in
the aqueous tear fluid. Since no covalent bonds
are formed or broken during the guest–host
complex formation, the complexes are in dynamic
equilibrium with free drug and cyclodextrin
molecules.
Introduction
Homopolysaccharides

Uses of cyclodextrins
Enhancement of solubility:
• The resulting complex hides most of the hydrophobic functionality in the interior cavity, while
the hydrophilic hydroxyl groups on the external surface remain exposed to the environment.
Enhancement of bioavailability:
• When poor bioavailability is due to low solubility. Orally, when drug is complexed with CD,
dissolution rate and, consequently, absorption are enhanced.
• Reducing the hydrophobicity of drugs by CD complexation also improves their percutaneous
or rectal absorption.
• CDs also prevent crystallization of active ingredients by complexing individual drug molecules
so that they can no longer self-assemble into a crystal lattice.
Improvement of stability:
• CD complexation improving the chemical, physical and thermal stability of drugs. For an active
molecule to degrade upon exposure to oxygen, water, radiation or heat, chemical reactions
must take place. When a molecule is entrapped within the CD cavity, it is difficult for the
reactants to diffuse into the cavity and react with the protected guest.
Introduction
Homopolysaccharides

Reduction of irritation:
• Drug substances that irritate the stomach, skin or eye can be encapsulated within a CD
cavity to reduce their irritancy. Inclusion complexation with CDs reduces the local
concentration of the free drug, below the irritancy threshold. As the complex gradually
dissociates and the free drug is released
Prevention of incompatibility:
• Drugs are often incompatible with each other or with other inactive ingredients present in a
formulation. Encapsulating one of the incompatible ingredients within a CD molecule
stabilizes the formulation by physically separating the components.
Odor and taste masking:
• Unpleasant odor and bitter taste of drugs can be masked by complexation with CDs by
hiding from the sensory receptors by encapsulating within the CD cavity.
Material handling benefits:
• Substances that are oils/liquids at room temperature can be difficult to handle and formulate
into stable solid dosage forms.
• Complexation with CDs may convert such substances into microcrystalline or amorphous
powders which can be conveniently handled and formulated into solid dosage forms by
conventional production processes and equipment
Introduction
Homopolysaccharides

Cyclodextrins are of wide
interest in part because they
are nontoxic. The LD50 (oral,
rats) is on the order of grams
per kilogram
Introduction
Homopolysaccharides

Cyclodextrins in rectal drug delivery system Cyclodextrins in nasal drug delivery system
Introduction
Homopolysaccharides

Cyclodextrins in transdermal drug delivery system
Introduction
Homopolysaccharides

Cyclodextrins in ocular drug delivery system
• In an ocular drug delivery system, the major
disadvantage is its inability to sustain high
local concentration of drug.
• CDs have been used to increase the solubility
and/ or stability of drugs and to prevent side
effects of drugs such as irritation and
discomfort.
Introduction
Homopolysaccharides

They have been applied for delivery of a variety of drugs, including hydrocortisone,
prostaglandin, nitroglycerin, itraconazol, chloramphenicol. The cyclodextrin confers
solubility and stability to these drugs
Introduction
Homopolysaccharides

Chromatography
• β-cyclodextrins are used to produce stationary phase media for HPLC separations.[6]
Other uses
• Cyclodextrins bind fragrances. Such devices are capable of releasing fragrances during
ironing or when heated by human body that the β-cyclodextrins "trap" odor causing
compounds, thereby reducing the odor.
Introduction
Homopolysaccharides

Dextrans
Introduction
Homopolysaccharides

Dextran is a water soluble α-1-6 linked polyglucan.
Dextran chains are of varying lengths (from 3 to
2000 kilodaltons).
• The polymer main chain consists of α-1,6
glycosidic linkages between glucose monomers,
with branches from α-1,3 linkages.
• This characteristic branching distinguishes a
dextran from a dextrin, which is a straight chain
glucose polymer tethered by α-1,4 or α-1,6
linkages
• Dextran is now produced from sucrose by certain
lactic acid bacteria of the family lactobacillus.
Species as Leuconostoc mesenteroides and
Streptococcus mutans. The structure of dextran
produced depends on the family, species and the
strain.
• They are separated by fractional precipitation
from protein-free extracts using ethanol.
Introduction
Homopolysaccharides

Medicinally, dextran used as an antithrombotic (antiplatelet),
to reduce blood viscosity, and as a volume expander in
hypovolaemia.
• Dextran 70 is on the WHO Model List of (Essential
Medicines), the most important medications needed in a
health system
• Dextran used commonly by microsurgeons to decrease
vascular thrombosis. The antithrombotic effect of dextran
is mediated through its binding of erythrocytes,
platelets, and vascular endothelium, increasing their
electronegativity and thus reducing erythrocyte
aggregation and platelet adhesiveness. Dextrans also
reduce factor VIII-Ag (Von Willebrand factor), thereby
decreasing platelet function. Clots formed after
administration of dextrans are more easily lysed due to an
altered thrombus structure.
• It is used in some eye drops as a lubricant.
Introduction
Homopolysaccharides

In certain intravenous fluids to solubilize other factors,
such as iron (in a solution known as Iron Dextran).
• Iron dextran is a dark brown, slightly viscous liquid
complex of ferric oxide and hydrolyzed dextran.
• After injection, it is slowly absorbed after IM
administration into the lymphatic system. It may take 3
weeks for complete absorption
• After iron dextran is injected, the circulating iron dextran
is removed from the plasma by cells of the
reticuloendothelial system, which split the complex into
its components of iron and dextran
• 50 Mg/Ml Injection Solution. This medication is usually
injected deep into the muscle of the buttock or slowly
into a vein as directed by your doctor. When injecting
into the buttock, the next injection is given on the
opposite side from the last injection.
• The reactions start 24-48 hours after administration and
symptoms generally subside within 3-4 days.
Introduction
Homopolysaccharides

Sephadex
Source
Sephadex is a modified dextran in which dextran
macromolecules are cross-linked to give a three-
dimensional network of polysaccharide chains.
Properties
Sephadex is water insoluble and strongly
hydrophilic.
Its beads swell in water. The degree of swelling is
varied to give different types of sephadex gels.
Uses
It is used in chromatographic separation of
biological compounds e.g. enzymes, protein and
carbohydrates and as a molecular sieve.
Introduction
Homopolysaccharides

Glycogen (or animal starch)
Source
• Glycogen is the principal reserve polysaccharide
of animals, found in muscles and liver.
• It also occurs in certain fungi, algae and bacteria.
Introduction
Homopolysaccharides

Structure
• Glycogen is a branched biopolymer consisting of linear
chains of glucose residues with an average chain
length of approximately 8–12 glucose units.
• Glucose units are linked together linearly by α(1→4)
glycosidic bonds from one glucose to the next.
Branches are linked to the chains from which they are
branching off by α(1→6) glycosidic bonds between the
first glucose of the new branch and a glucose on the
stem chain
• The molecular structure of glycogen appears to be
similar to that of amylopectin of starch, but more
branched.
• The main difference is that the average chain-length in
amylopectin is 20-25 glucose units and in glycogen
about 8-12 glucose units.
Introduction
Homopolysaccharides

Cellulose
■ Cellulose is a linear polymer, made of  (1-4) linked D-glucose
(-glucan).
■ Cellulose is the chief polysaccharide of plant cell walls.
■ It constitutes 50% in wood, 50% in paper and 90% cotton hairs.
■ Complete acid hydrolysis of cellulose with hydrochloric acid
gives → -D-glucose
-(1 4) linked D-glucose
O
OH
O
OH
CH2OH
O
OH
OH
CH2OH
O
O OH
OH
OH
CH2OH
OH
1
4
4
1
n
Cellulose
Introduction
Homopolysaccharides

Carboxymethyl cellulose
Introduction
Homopolysaccharides
It is synthesized by the alkali-catalyzed reaction of cellulose
with chloroacetic acid.
• CMC is used in food as a viscosity modifier or thickener, and to stabilize
emulsions in various products including ice cream.
• It is also a constituent of many non-food products, such as toothpaste,
laxatives, diet pills, water-based paints, detergents, textile sizing, reusable heat
packs, and various paper products.
Medical uses
• Device for epistaxis (soaked in water to form a gel), this is inserted into the nose
and the balloon inflated. The combination of the inflated balloon and the
therapeutic effect of the CMC stops the bleeding.
• Fabric used as a dressing following ear nose and throat surgery.
• Water is added to form a gel, and this gel is inserted into the sinus cavity
following surgery
• Eye drops to relieve dry, irritated eyes.

Cellulose ethers
Methylcellulose is prepared by methylation of cellulose with methyl chloride under
pressure. It is a whitish, fibrous powder that swells in water to produce a clear to
opalescent, viscous, colloidal solution.
• It is used to increase the viscosity and to stabilize lotions, suspensions, pastes,
and some ointments and ophthalmic preparations.
• It is also used bulk laxative in chronic constipation and in treatment of obesity as it
gives feeling of fullness.
Introduction
Homopolysaccharides

Introduction
Homopolysaccharides
Inulin is a linear fructose polymer built from 2–60 d-
fructose units connected through β(2→1) glycosidic
linkages with a terminal α(1→2) bonded d-glucose
• Inulin is a natural, storage carbohydrate present in
more than 36,000 species of plants, including wheat,
onion, bananas, garlic, asparagus, Jerusalem
artichoke, and chicory as an energy reserve.
Properties
• Inulin is a white, amorphous and granular powder.
• Its solution in water is levorotatory.
• It gives a deep red color with rapid furfural test.
Inulin
Uses
It is used in preparation of culture media as a fermentative identifying agent for certain
bacteria.
• It was used as a diagnostic agent for evaluation of renal function.

Inulin is a short-chain carbohydrate that is poorly absorbed in the
intestine, rapidly fermented by bacteria in the bowel, and draws
extra water into the intestine.
• Inulin approved by the FDA as an ingredient to enhance the
dietary fiber value of manufactured foods.
• Inulin provides nutritional advantages by increasing calcium
absorption and possibly magnesium absorption, while promoting
the growth of intestinal bacteria.
• Inulin is classified as a prebiotic because of its ability to stimulate
the growth of beneficial bacteria such as Bifidobacteria.
• Inulin, a type of fiber, may also help to control appetite by
increasing feelings of fullness. It is thought that this occurs due
to short-chain fatty acids and their ability to increase appetite
suppressing hormones such as glucagon-like peptide 1 (GLP-1).
Contraindications
• Contraindicated in case of irritable bowel syndrome (IBS).
• Side effects include gas, bloating, diarrhea, constipation, and cramps.
Introduction
Homopolysaccharides

Polysaccharides azhar 2020-1

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Polysaccharides azhar 2020-1

Similar to Polysaccharides azhar 2020-1 (20)

More from Ahmed Metwaly

More from Ahmed Metwaly (20)

Recently uploaded

Recently uploaded (20)

Polysaccharides azhar 2020-1