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Pharmacognosy Handouts [Tannins + Lipids + Oils + Waxes]. PDF Document for Printing. Lecture delivered by Muhammad Tanveer Khan to Batch:01093 (F09) in The University of Lahore, Pakistan.
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Pharmacognosy By Sir Tanveer Khan Lecture: Tannins + Lipids + Oils + Waxes
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TANNINS
Introduction
The term tannin was first time coined by Seguin in 1796. This term was used to
denote substances present in plant extract which react with protein of animal hide,
prevent their putrefaction (process of decay of organic materials) and convert hide
and skin into leather.
Definition
“Complex substances that usually occur as mixtures of polyphenols that are very
difficult to separate since they don't crystallize, are called tannins.”
OR
“Tannins are polyhydroxy phenolic compounds.”
Physical Properties
Color: Dark brown or reddish brown
Taste: Puckering taste
State: Non-crystalline
Solubility: Soluble in water, alcohol, dilute alkalis, glycerols and acetone.
Chemical properties
(i) Precipitation
(ii) Anti-oxidizing properties
(iii) Astringent
(iv) Carcinogenicity
(v) Reaction with salts
(vi) Reaction with potassium ferricyanide and ammonia
(i) Precipitation:
Tannins have ability to precipitate solutions of;
Gelatin.
Alkaloids.
Glycosides.
Heavy metals.
Proteins.
(ii) Anti-oxidizing properties:
Because of accumulation of OH group on small size nucleus, these agents have
anti-oxidant nature.
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(iii) Astringent:
Tannins have property to react with protein of mucous membrane and cause
precipitation
(iv) Carcinogenicity:
Prolong use of tannin containing plant material is hazardous because it causes
cancer. Habitual use of Areca catechu can cause oral and esophageal cancer.
(v) Reaction with Salts:
(vi) Reaction with Potassium ferricyanide and Ammonia:
Importance of Tannins
Medicinal Uses:
• Antidote.
• Antiseptic.
• Algicidals.
• Astringents.
• Anti-carcinogenic.
Industrial Uses:
• Ink manufacture.
• Vegetable tanning.
• Preservatives.
Biological Activities:
• Inhibition of lipid per oxidation.
• Decrease in blood urea nitrogen content.
• Inhibition of plasmin.
• Lipolysis in fat cells.
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Chemical Classification Based on identity of phenolic nuclei involved and on the way they are joined.
(i) Hydrolysable Tannins:
These tannins are hydrolyzed by enzymes or acids.
Precursors:
• Phenolic acid (Gallic acid, Ellagic acid)
• Glucose residue
• Between phenolic acids and glucose sugar, there is ester linkage.
Properties:
Types:
Tannins
Hydrolysable
tannins
Condensed
tannins
Complex
tannins
Hydrolysable tannins
Gallitannins Ellagitannins
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Ellagitannins Gallitannins
Pomegranate
Eucalyptus
Rhubarb
Clove
Hamamelis
Occurrence
Upon acid hydrolysis of
Ellagitannins, Ellagic acid is
produces.
Upon acid hydrolysis of
Gallitannins, Gallic acid
is produces.
Hydrolysis
* Slowly soluble in water.
* Present in plants in open and
ring forms as Hexa hydroxy
diphenic acid.
* Rapidly soluble in
water.
* Free Gallic acid, in
plant, is converted to
gluco Gallitannins.
Properties
(ii) Condensed Tannins
These tannins are derivatives of Flavonoid, catechin, flavonol-3-4-diol.
Precursors:
• Flavonoid
• Catechin
• Flavonol-3-4-diol
Properties:
When heated with acids, these are self condensated, polymerized and
converted to insoluble red colored complexes, called Phlobaphenes.
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Tannins
True tannins Pseudo tannins
Examples
• Hamamelis
• Cinchona
• Cinnamon
(iii) Complex Tannins
These tannins are mixtures of both, hydrolysable and condensed tannins
Examples:
• Tea
• Quercus
• Castanea
Types (2nd Classification of tannins based on complexity):
Tannin is a substance which is detected qualitatively by tanning test (The
Gold Beater’s skin test) and quantitatively by its adsorption on standard
hide powder.
Depending upon this, tannins are of two types;
1) True tannins.
2) Pseudo tannins.
Difference:
Pseudo tannins True tannins
Phenolic compounds of plant origin that
don't convert animal hide to leather but
do give positive Gold beater’s skin test,
are called pseudo tannins.
Polyhydroxy phenolic compounds
which convert animal hide to leather
by precipitating proteins and give
positive Gold beater’s skin test, are
called true tannins.
Molecular weight is less than true
tannins.
Molecular weight is 1000-5000
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Identification Tests (for Tannins)
1. Color reaction:
Tannins give color reaction with iron.
2. Matchstick test:
• Dip matchstick in plant extract.
• Dry it.
• Moisten it with hydrochloric acid. And warm near flame.
• Wood will turn pink or red in color due to phloroglucinol.
3. Gelatin test:
Solution of tannin (0.5%-1%) precipitates 1% solution of gelatin containing
10% sodium chloride.
4. Phenazone test:
• Take 5ml of aqueous extract of drug.
• Add 0.5grams of sodium acid phosphate.
• Warm it and cool.
• Filter solution.
• To the filtrate, add 2%solution of Phenazone.
• Tannins will be precipitated.
• Precipitates will be bulky and colored.
5. Gold beater’s skin test:
Gold beater’s skin is a membrane prepared from intestine of Ox and behaves
similarly to un tanned skin.
• Soak a small piece of Gold beater’s skin in 2% hydrochloric acid.
• Rinse it with distilled water.
• Place it in solution to be tested for 5 minutes.
• Wash in water and transfer to 1% solution of ferrous sulphate.
• Black or brown color of skin indicates presence of tannins.
*** It is a quantitative test and +ive only for true tannins.
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6. Catechin test:
Catechin when heated with acid produce phloroglucinol. Phloroglucinol can be
detected with matchstick test.
7. Test for chlorogenic acid:
Treat extract containing chlorogenic acid with aqueous ammonia and expose it to
air. Green color will appear gradually.
Plants, Containing Tannins
a) Hamamelis
Botanical origin: Hamamelis virginiana.
Family: Hamamelidaceae.
Part used: Dried leaves.
Collection:
Leaves are collected throughout summers. Drying is done in open air,
preferably under shade to preserve green color.
Constituents:
• Gallitannins
• Ellagitannins
• Free gallic acid
• Pro-anthocyanadins
• Hamamelase
Uses:
• Astringent
• Anti-hemorrhagic
• Anti-inflammatory
• Anti-carcinogenic
b) Catechu
Botanical origin: Uncaria gambir
Family: Rubiaceae
Part used: Dried aqueous extract from leaves and young twigs.
Collection:
Boil leaves and twigs in water. Evaporate to a pasty consistency. Paste is put
in cubes and dried in sun.
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Constituents:
• Catechin
• Catechutannic acid
• Catechu red
• Quercitin
• Gambir flourescin
Uses:
• Astringent
• Dying
• Tanning industry
c) Nutt gall
Botanical origin: Quercus infectoria.
Family: Fagaceae.
Part used: Galls obtained from twigs.
Formation of galls:
Galls are pathological outgrowth formed on twigs of tree. Galls arise due to
deposition of eggs by small insect Adleria galactinctoria.
Steps are;
• Early summers, insects lay eggs on twigs
• Larvae come out from eggs and enter soft epidermis.
• Larvae secretes enzyme that stimulates abnormal growth around larvae.
• Starch in the tissue gets converted to sugars and stimulate cell division.
• Disappearance of starch causes cell shrinkage.
• Central cavity is formed in which larvae and pupae grows.
• Larvae remains in gall for 5-6months.
• Mature insect bores the covering of gall and escapes away.
• Galls are collected before escaping of insect.
Constituents:
• Tannic acid
• Gallic acid
• Ellagic acid
• Roburic acid
• Syringic acid
• Calcium oxalate crystals
Uses:
• Haemostatic
• Antidote for alkaloidal poisoning
• Astringent
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LIPIDS
INTRODUCTION
Lipids constitute a broad group of naturally occurring molecules which include waxes, fats,
sterols, fat-soluble vitamins, monoglycerides, diglycerides, phospholipids and others.
FIXED OILS
Fixed oils are esters of fatty acid with glycerol.
PROPERTIES
Non-irritant
Odorless
Tasteless
Non-volatile
Insoluble in water and soluble in organic solvents
Produce greasy mark on paper
Upon heating strongly, undergo decomposition
Upon hydrolysis, yield glycerol and fatty acid
CHEMISTRY
Fixed oils are esters of fatty acid with glycerol. These may be;
Monoglycerides
Diglycerides
Triglycerides
CLASSIFICATION
On the basis of their ability to absorb Oxygen from air; these are classified as:
a) Drying oil
b) Non-drying oil
c) Semi-drying oil
a) Drying oil
when exposed to air, undergo oxidation and form tough and hard film. These are usually
used in paints and varnishes.
For example; Linseed oil
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b) Non-Drying oil
These oils neither undergo oxidation nor form tough and hard film.
For example; Olive oil
c) Semi-Drying oil
When exposed to air, undergo little bit oxidation and form tough and thin film.
For example; Cotton seed oil
METHODS OF OBTAINING FIXED OILS
Direct expression
Solvent extraction
Steam treatment + extraction
COTTON SEED OIL
Botanical origin: Gossypium herbaceum
Family: Malvaceae
Part used: Seeds
Collection:
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Constituents:
Glycerides of;
Linoleic acid
Oleic acid
Palmitic acid
Stearic acid
Arachidic acid
Myristic acid
Toxicity:
Occur due to intravenous administration of
Cottonseed oil emulsion.
Acute toxicity includes following symptoms;
Fever
Pain in back or chest
Nausea
Vomiting
Headache
Tachycardia
Dizziness
Chronic toxicity includes following symptoms;
GIT bleeding
Mild anemia
Defects in blood clotting
Treatment of toxicity:
IV hydrocortisone sodium succinate 50grams
Promethazine 50mg
Heparin (to aid clearance of fat from circulation)
Uses:
Food
Emollient
Vehicle for injections
Preparation of hydrogenated
vegetable oils
Soap manufacture
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CASTER OIL
Botanical origin: Ricinus communis
Family: Euphorbeaceae
Part used: seeds
Collection:
Constituents:
Glycerides of;
Ricinoleic acid
Oleic acid
Linoleic acid
Stearic acid
Toxicity:
Excessive oral administration in larger doses Results in toxicity
Symptoms include;
Nausea
Colic
Vomiting
severe purgation
Electrolyte imbalance
Uses:
Purgative
Emollient
Preparation of zinc and castor
oil ointment
Sterilized castor oil as
soothing agent in eye
Oily vehicle for eye drops
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LINSEED OIL
Botanical origin: Linum usitatissimum
Family: Linaceae
Part used: Seeds
Constituents:
Glycerides of;
Isolinoleic acid
Linoleic acid
Stearic acid
Myristic acid
Palmitic acid
OLIVE OIL
Botanical origin: Olea europaea
Family: Oleaceae
Part used: Ripe fruit
Constituents:
Glycerides of;
Oleic acid
Linoleic acid
Stearic acid
Arachidic acid
Palmitic acid
PEANUT OIL
Botanical origin: Arachis hypogaea
Family: Leguminosae
Part used: Seeds
Uses:
In veterinary medicine as Purgative
Uses:
Laxative
Nutrient
Emollient
Demulcent
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Constituents:
Glycerides of;
Oleic acid
Linoleic acid
Stearic acid
Arachidic acid
Behenic acid
Lignoceric acid
Palmitic acid
CORN OIL
Botanical origin: Zea mays
Family: Gramineae
Part used: Embryo
Constituents:
Glycerides of;
1. Oleic acid
2. Linoleic acid
3. Stearic acid
4. Arachidic acid
5. Palmitic acid
6. Myristic acid
7. Lignoceric acid
Uses:
1. Vehicles in pharmaceutical and cosmetic preparation
2. Solvent for injections
3. Nutrient
Uses:
Vehicles in emulsions, liniments, plasters, soap
Ink manufacture
Preparation of hydrogenated vegetable oil
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SWEET ALMOND OIL
Botanical origin: Prunus amygdalus
Family: Rosaceae
Part used: Seeds
Constituents:
Glycerides of;
1. Oleic acid
2. Linoleic acid
3. Palmitic acid
4. Myristic acid
Uses:
5. Nutrient
6. Demulcent
7. Emollient
8. Preparation of cold creams, hair lotions and toilet articles
COCONUT OIL
Botanical origin: Cocos nucifera
Family: Palmae
Part used: Dried solid part of endosperm
Constituents:
Glycerides of;
1. Lauric acid
2. Myristic acid
3. Capric acid
4. Caprylied acid
5. Caproic acid
6. Oleic acid
7. Palmitic acid
8. Stearic acid
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Uses:
Nutrient
Confectionaries
Cosmetics
Ointment base
MUSTARD OIL
Botanical origin: Brassica juncea
Family: Cruciferae
Part used: Seeds
Constituents:
Glycerides of;
Linoleic acid
Oleic acid
Erucic acid
Uses:
Nutrient
Rubefacient
In preparation of liniments
In massages
SESAME OIL
Botanical origin: Sesamum indicum
Family: Pedaliaceae
Part used: Seeds
Constituents:
Glycerides of;
Linoleic acid
Oleic acid
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Stearic acid
Palmitic acid
Arachidic acid
And other components include;
Sesamin
sesamolin
SAFFLOWER OIL
Botanical origin: Carthamus tinctorius
Family: Compositae
Part used: Seeds
Constituents:
Glycerides of;
Palmitic acid
Stearic acid
Arachidic acid
Oleic acid
Linoleic acid
Linolenic acid
Uses:
Nutritive
SUNFLOWER OIL
Botanical origin: Helianthus annus
Family: Compositae
Part used: Seeds
Constituents:
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Glycerides of;
Palmitic acid
Stearic acid
Arachidic acid
Oleic acid
Linoleic acid
Behenic acid
Uses:
Nutritive
Preparation of hydrogenated products
Preparation of paints, varnishes and soap
THEOBROMA OIL
Botanical origin: Theobroma cacao
Family: Sterculiaceae
Part used: Seeds
Constituents:
2% Theobromine
40-60% solid fat
Mucilage
Uses:
Ingredient in cosmetic ointment
in pharmacy for coating pills
Preparation of suppositories
Diuretic
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LENOLIN
Lanolin is also called wool wax or wool grease. It is a yellow waxy substance secreted by
the sebaceous glands of wool bearing animals. Most lanolin used by humans comes from
domestic sheep.
Constituents:
A typical high purity grade of lanolin
is composed predominantly of;
long chain waxy esters
lanolin alcohols
lanolin acids
lanolin hydrocarbons
It has been estimated that there may be between 8,000 and 20,000 different types of lanolin ester
present in lanolin.
Production:
Lanolin is extracted by washing the wool in hot water with a special wool scouring
detergent to remove dirt, wool grease (crude lanolin), suint (sweat salts), and anything else stuck
to the wool. The wool grease is continuously removed during this washing process
by centrifugal separators, which concentrate the wool grease into a wax-like substance melting at
approximately 38 °C (100 °F).
Applications:
Lanolin and its many derivatives are used extensively in high value cosmetics, facial
cosmetics, lip products etc
Lanolin is used commercially in many industrial products ranging from rust-proof
coatings to lubricants.
Lanolin is often used as a raw material for producing cholecalciferol (vitamin D3).
Anhydrous lanolin is also used as a lubricant for brass instrument tuning slides.
Lanolin can also be restored to woolen garments to make them water and dirt
repellent.
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BEES WAX
Zoological origin: Apis mellifera/ Apis dosarta/ Apis cerana/ Apis indica/ Apis florea
Family: Apidae
Source: Bee hives
Production:
Worker bees have eight wax-producing mirror glands. The size of
these wax glands depends on the age of the worker and after daily
flights begin these glands gradually atrophies. The new wax scales
are initially glass-clear and colorless becoming opaque afterwards.
The wax of honeycomb is nearly white, but becomes
progressively more yellow or brown by incorporation of pollen oils and propels.Honey bees use
the beeswax to build honeycomb cells. In which their young are raised and honey and pollen are
stored. For the wax-making bees to secrete wax, the ambient temperature in the hive has to be 33
to 36°C (91 to 97 °F).To produce their wax, bees must consume about eight times as much honey
by mass. When beekeeper extracts the honey, they cut off the wax caps from each honeycomb
cell with an uncapping knife or machine. The wax may further be clarified by heating in water.
Constituents:
Beeswax is a tough wax formed from a mixture of several compounds.
Its main components are;
Palmitate
Palmitoleate
Hydroxypalmitate
oleate esters of long-chain (30-32 carbons)
Aliphatic alcohols with the ratio of triacontanyl Palmitate to cerotic acid, the two
principal components, being 6:1.
Applications:
Making of honeycomb foundation
Beeswax is an ingredient in surgical bone wax
Purified and bleached beeswax is used as:
Coating for cheese
Protectant of the food as it ages
Food additive
As a component of shoe polish, furniture polish
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As a component of modelling waxes
JOJOBA OIL
Botanical origin: Simmondsia chinensis
Family: Simmondsiaceae
Part used: seeds
Constituents:
This oil is rare in that it is an extremely long (C36-C46) straight-chain wax ester
Uses:
In cosmetics as a moisturizer
As a carrier oil for specialty fragrances
Bio-diesel fuel for cars and trucks
Biodegradable lubricant.
SPERMACETI
Source:
Spermaceti is a wax present in the head cavities of
the whale i.e. Physeter macrocephalus.
Extraction:
Spermaceti is extracted from oil by Crystallization at
6 °C. When treated by pressure and a chemical solution
of caustic alkali, spermaceti forms brilliant white crystals
that are hard but oily to the touch, and are devoid of taste
or smell.
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Uses:
Ingredient in cosmetics
Leather working
Lubricants
Making of candles
Dressing of fabrics
Pharmaceutical excipient (in ointments)
CARNAUBA WAX
Botanical origin: Copernicia cerifera/ Copernicia prunifera
Family: Arecaceae
Part used: Leaves
Constituents:
Carnauba consists mostly of;
Aliphatic esters
Diesters of 4-hydroxycinnamic acid
ω-hydroxycarboxylic acids
Fatty acid alcohols
Methoxy cinnamic acid
FATS VS FIXED OILS
Fixed oils Fats
Liquid at room temperature Solid at room temperature
Contain unsaturated glycerides e.g.
glyceryl oleate
Contain saturated glycerides e.g.
glyceryl stearate
Uses:
Automobile waxes
Shoe polishes
Dental floss
Food products such as sweets,
Floor and furniture waxes
and polishes
Use for paper coatings
Emollient
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VOLATILE OILS VS FIXED OILS
Fixed oils Volatile oils
Don't get volatiles at room
temperature
Volatilize at room temperature
Obtained by extraction Obtained by distillation
After evaporation, do leave spot Leave no spot after evaporation
Can be saponified Cannot be saponified
Esters of fatty acid with glycerol Mixtures of oleoptenes and
stereoptenes
Low refractive index High refractive index