pharmacognosy handouts [tannins + lipids + oils + waxes] by, sir tanveer khan

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

pharmacognosy handouts [tannins + lipids + oils + waxes] by, sir tanveer khan

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