This document provides information on various types of tannins. It discusses true tannins, which are divided into hydrolysable tannins and non-hydrolysable tannins. Hydrolysable tannins can be further divided into gallotannins and ellagitannins. Pseudo tannins like gallic acid, catechin, and chlorogenic acid are also mentioned. Extraction methods and chemical properties of specific tannins are outlined, including catechu, pale catechu, and pterocarpus. Key uses of tannins include as astringents, anti-diarrheals, dyeing/tanning agents, and in leather industry.

1. TANNINS
Amla Hirda Bheda Arjun
bark
11/7/2023
Dr. Sutar N.G., Associate Prof., HOD, Dept of Pharmacognosy, Sanjivani College of Pharmaceutical Education and Research,
Kopargaon

2. TANNINS
Introduction
These are natural compounds which are polyphenolic in nature, polyhydroxy benzoic
acid, having astringent action.
They have large molecular weight but some have low molecular weight.
They provide protection to the plants especially during growth
from herbivorous animals, insects, bacteria and others.
Uses of tannins are:
1. Anti-diarrheal
2. Anti-bacterial
3. Antidote in alkaloidal
poisoning
4. Haemostatic
5. Mild diuretic
6. Leather industry
7. Astringent for inflamed mucous
membrane
8. Stomachic etc.
They are found in
Leaves,
Barks,
Immature fruits
but, they disappear
during ripening
process.
Goldbeater's skin test: skin is
a Membrane produced from the
intestine of Ox
Soak in 2% HCL
Wash with water
place in tannin solution 5 min
Wash with water
Place in 1% FeSO4
Skin colour changes to brown or black
11/7/2023
Dr. Sutar N.G., Associate Prof.,HOD, Dept of Pharmacognosy,
Sanjivani College of Pharmaceutical Education and Research,
Kopargaon

3. CLASSIFICATION Tannin
True tannins:
Hydrolysable group: Non hydrolysable / Condensed
tannin
1. Hydrolyzed by acids or enzymes
2. The tannins from Gallic acid called
Gallo-tannin Eg. Rhubarb, Clove
3.Tannis from ellagic are ellagotannin
Eg. Pomegranate roots bark and
Eucalyptus leaves
4. They form dark blue color with FeClз
1.Not hydrolyzed by acids or enzymes
2. In barks like: Cinnamon Cinchona
3. They produce dark green color with
FeClз.
Pseudo tannins:
They have low molecular weight.
Gallic acid -Rhubarb
rhizomes.
o catechin like in Cacao,
Acacia.
o chlorogenic acid like in
coffee
11/7/2023
Dr. Sutar N.G., Associate Prof.,HOD, Dept of Pharmacognosy,
Sanjivani College of Pharmaceutical Education and Research,
Kopargaon

4. PHYSICO-CHEMICAL PROPERTIES of TANNIN
1. They form colloidal solutions with water.
2. They are non crystalline substances.
3. Their aqueous solution is acidic.
4. They have sharp puckering taste.
5. They have astringent property.
6. They are precipitated by: alkaloids, gelatin, salts of
heavy metals, proteins (enzymes).
CHEMICAL TESTS
1. Tannin + FeClз: -
Hydrolysable -Dark blue colour.
Non Hydrolysable tannins - Dark green colour.
2. It forms precipitate with alkaloids, gelatin, proteins,
heavy metals like lead acetate, copper acetate.
3. Tannins give yellow colour with H2SO4
4. When vanillin hydrochloride is added in tannin solution,
red to pink colour
EXTRACTION AND ISOLATION OF TANNINS
11/7/2023
Dr. Sutar N.G., Associate Prof.,HOD, Dept of Pharmacognosy,
Sanjivani College of Pharmaceutical Education and Research,
Kopargaon

5. CATECHU (BLACK CATECHU)
Synonyms: Kattha, Cutch,Catechu
Biological Source: Black catechu
or cutch is an aqueous extract of
the heartwood of Acacia catechu
Family: Leguminosae.
Geographical Source: Myanmar and
India
Catechu consist of two parts i.e. kattha and
cutch.
Catechu is used in India as a masticatory from
ancient time. The female used catechu for
colouring purpose of their feet
Extraction / Preparation:
Bark and sapwood are stripped off from trunk. Then the dark red
heartwood is cut into chips
Boiled with water into earthen vessels
.
Filter and again boiled in iron vessels with continuous
stirring until it gets syrupy consistency
. The syrupy liquid is poured in a wooden frame or mould and allowed
to cool.
. Next morning the cutch will be dry and forms brick like
masses having weight about 20 kg.
Colour: Dull brownish to black.
Odour: Odourless.
Taste: Astringent and subsequently
sweet.
Size: Near about 2.0 cm × 5.0 cm.
Shape: Cube like or brick shaped pieces.
Chemical Constituents:
It shows catechutannic acid (25-33%) and
acacatechin (10-12%). Other are catechu red,
gum, quercitin and quercitrin.
Chem. Test-
1. Drug + with vanillin and
hydrochloric - Red colour
2. drug, + lime water - brown colour
3. Drug + NH4SO4- Green colour
Uses
Astringent,
Cooling and
Digestive dyeing
and tanning
purposes
11/7/2023
Dr. Sutar N.G., Associate Prof.,HOD, Dept of Pharmacognosy,
Sanjivani College of Pharmaceutical Education and Research,
Kopargaon

6. PALE
CATECHU
Synonyms: Gambier,
Catechu
Biological source:
It is an aqueous extract of the
leaves and young shoots of
Uncaria gambier
Family: Rubiaceae
Geographical source: Singapore and
Sumatra. This drug was used in India for the
chewing purpose with Piper betle (betel) leaf.
Extraction / Preparation:
Leaves and young shoot are boiled in a water in Cauldron ( a wooden
vessel with iron bottom
. Concentrate with continuous stirring until green colour syrupy
consistency
. The syrupy liquid is poured in a wooden frame or mould and allowed
to cool.
. When form semisolid mass cut by knife
Much amount of Gambier is filled into kerosene tins to solidify to obtain
large blocks
Form: Cubes, rectangular blocks
Colour: Dark reddish brown.
Odour: None.
Taste: First bitter and astringent afterwards
sweetish.
Chemical Constituent:
It contains (+)-catechin (7-33%),
catechutannic acid (22-50%). Other
are catechu red, quercitin and gambier
fluorescin, a fluorescent substance.
Chem test-
1. Dip a matchstick in tannin solution, dry +
conc. HCL. warm stick near flame.
colour of the wood changes to pink due
to the formation of phloroglucinol.
2. Drug + with vanillin and hydrochloric –
Red colour
USES-
Astringent in the
treatment of
diarrhoea
Local astringents
11/7/2023
Dr. Sutar N.G., Associate Prof.,HOD, Dept of Pharmacognosy,
Sanjivani College of Pharmaceutical Education and Research,
Kopargaon

7. PTEROCARPUS
Synonyms: Malbar Kino, Indian kino tree, Cochin
Kino.
Biological Source
It is unorganized drug obtained in dried juice of
Pterocarpus marsupium Linn. The juice is
collected by making incision on the stem bark.
Family: Leguminosae.
Geographical source: found in Ceylon and in
India
(forest of Kerala,
West Bengal,
Assam,
Madhya Pradesh,
Gujarat,
Uttar Pradesh,
Bihar & Orissa.
Form: Small, glistering, angular grain.
Size: Grains are 3 to 5 mm in diameter and
sometimes more than 10 mm.
Colour: Transparent or dark ruby red.
Odour: Odourless.
Taste: Astringent.
Solubility: Partially soluble in cold water,
soluble in hot water and alcohol.
Constituents:
The chief constituent of kino is kinotannic acid (70 to 80 %).
Other constituents are
kino red, Catechol (κ-pyrocatechin), tannin (gallic acid) and
resins.
Chemical Test:
1. Drug + FeSO4 - green colour.
2. Drug solution +KOH - purple or violet colour develops.
3. Drug +mineral acid -PPT.
Uses:
It is used as astringent, in the treatment of diarrhea and
dysentery, bleeding gums and
toothache and diabetes. It is also used in dyeing, painting and
tanning industries.
11/7/2023
Dr. Sutar N.G., Associate Prof.,HOD, Dept of Pharmacognosy,
Sanjivani College of Pharmaceutical Education and Research,
Kopargaon