Catechu and tannic acid are plant-derived tannins. Catechu comes from the leaves of Uncaria gambier and consists of dried aqueous extract containing tannins like catechins. Black catechu comes from the heartwood of Acacia catechu and Acacia chundra. Tannic acid is obtained from nutgalls, which are outgrowths on oak tree twigs, and yields gallic acid and glucose upon hydrolysis. Both catechu and tannic acid are used as astringents.

2. CATECHU
 Synonyms – Pale catechu, gambier, kattha
 Biological source – It consists of the dried
aqueous extract prepared from the leaves of
Uncaria gambier
 Family - Rubiaceae

3.  Chemical constituents –
 It contains tannins like catechins and
catechu tannic acid
 It contains flavonoids like quercetin and
fluorescent substances Gambier fluorescein.
 It also contains catechu- red, pyrogallol, fixed
oil and waxes

4.  Uses –
 Used as an astringent
 Used in the treatment of diarrhoea
 Used in the preparation of lozenges

5. BLACK CATECHU
 Biological source –
 It consists of the dried aqueous extract
prepared from heart wood of Acacia catechu
and Acacia chundra
 Family - Leguminosae

6.  Chemical constituents –
 It contains tannins like catechins and catechu
tannic acid
 It contains flavonoids like quercetin.
 Others like Catechu- red and gum
 Uses –
 Used as an astringent, used in diarrhoea
 Used as a cooling and digestive agent

7. CHEMICAL TESTS FOR CATECHU
 1. Gambir Fluorescin test-
 Alcoholic extract of drug, few drops of
sodium hydroxide mix and add petroleum
ether, shake and kept aside for few minutes
– petroleum ether layer shows green
fluorescence ( + ve for pale catechu due
Gambir Fluorescin )

8.  2. Match stick test ( Catechins test) –
A match stick is dipped in aqueous plant
extract , dried near burner and moistened
with Hcl. On warming near flame , the
match stick wood turns pink or red due to
the formation of phloroglucinol.

9.  3. Vanillin – Hydrochloric acid test –
 Test solution and few drops of Vanillin –
Hydrochloric acid reagent – A red or pink is
formed due the formation of phloroglucinol.
 4. Chlorophyll test -
 Powdered drug is heated with chloroform on a
water bath for 1-2 minutes .The organic layer
is filtered in a china dish and evaporated on
the water bath– green residue

10. TANNIC ACID
 Biological source –
It is obtained from the nutgalls. Galls are
vegetable outgrowths found on the young
twigs of Quercus infectoria
 Family - Fagaceae
 Tannic acid is a hydrolysable tannin and
yields Gallic acid and glucose on hydrolysis

11.  Uses –
 Used as an astringent
 Used externally in the treatment of burns
 Used as an antidote for alkaloid poisoning

12. NUTGALL
 Synonym – Turkey galls
 Biological source – Galls are the pathological
outgrowths formed on the twigs of the oak
tree Quercus infectoria
 Family - Fagaceae
 Chemical constituents – 40-60% of tannic acid
 Uses- Used as an astringent, used in the
manufacture of tannic acid

13.  QUESTIONS –
 Define tannins and explain various methods of estimation
of tannins.10 M
 Write a note on general properties and method of isolation
of tannins. 10M
 Write the source, active constituents and uses of Catechu
and Nutgall.5M
 Explain the different types of tannins with examples.5M
 Write a note on Goldbeaters’ test and its significances.5M

14.  Write a note on estimation of Hydrolysable tannins.5M
 Give the chemical tests for the identification of Catechu
and Tannic acid.5M
 Give an account of Catechu.5M
 What are tannins? Give general chemical tests to identify
them.5M
 Define Tannins. How will you differentiate True tannins
from pseudo tannins ? 5M

15.  Write in brief about Nut gall. 2M
 Chemical tests for the identification of tannins.2M
 What is tannic acid and give its uses.2M
 Gambir- Flurorescin test and its significances.2M
 Define Pseudo- tannins and give examples. 2M