Tannins best slides

1. Tannins
Safdar munir

2. 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 and c . onvert hide and skin into leather

3. 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“

4. Structure of tannic acid

5. Occurrence
They are commonly found in gymnosperms as well as 
.inangiosperms
The best known families that contain tannins 
are;Aceraceae,actnidiaceae,Bixaceae,Burseraceae,Ericaeae

6. Localization in plant organs
Tannins are found inleaf,seed,root.bud and stems.They are 
often found in growth areas of plants like secondary phloem
and xylem and layer between cortex and epidermis.They help
.regulate growth of these tissues
Cellular localization 
Tannins are manufactured by chloroplast derived 
organelle the tannosome.Tannins are physically located in
the vacoules or surface wax. These storage keep them
active against predators.They are called ergastic
.substances the non protoplasmic materials found in plants

7. Presence in soils Water and
.Wood
The decaying of tannin rich vegetation causes leaching of 
water slouble tannins to rivers and lakes.it produces black
water river.The presence of tannins in well water causes bad
taste and smell but it is safe to drink.Soft wood of plants have
less tannin than hard wood.As tannic acid are brownin colour
so white wood has less tannin.Wood that have yellow ,red or
.brown colour has large quantitiy of tannins

8. Tannins in drinks.
The best known human dietry sources of tannins are tea and 
.wine
Wine;Most wines aged in charred wooden oak barrels 
possess tannins absorbed from naturally occuring tannins in
wood which seep in wine.This concentration gives wine its
.signature bitterness
Effect;the tannins draw residual proteins from tongue and 
mouth which gives wine its aftertaste

9. Tannins in fruits
Persimmons;These contain tannins in high quantity when 
are not ripened makinf them highly astringents and cannot be
.eaten.When ripened they contain less tannins
Berries;Strwberries and blue berries contain both 
.hydrolyzable and condensed tannins
.Nuts;like almond ,walnuts contain tannins in less quantity 
Herbs and spices;Clove vanilla,cinnamon cumin have 
.tannins
Chocolate;It contain about 6% tannins 

10. Physical Properties
:Color
Dark brown or reddish brown
:Taste
Puckering taste
:State
Non-crystalline
:Solubility
.Soluble in water, alcohol, dilute alkalis, glycerols and acetone

11. Chemical properties
i) Precipitation)
ii) Anti-oxidizing properties)
iii) Astringent)
iv) Carcinogenicity)
v) Reaction with salts)
vi) Reaction with potassium ferricyanide and ammonia)

12. 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

13. 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

14. v) Reaction with salts)
vi) Reaction with potassium )
ferricyanide and ammonia

15. 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

16. Chemical Classification
Based on identity of phenolic nuclei involved and on the way they
.are joined
Tannins
Hydrolysable tannins Condensed tannins Complex tannins

17. 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

18. :Properties
:Types
Hydrolysable tannins
Gallitannins Ellagitannins

19. Gallitannins Ellagitannins
Occurrence Rhubarb
Clove
Hamamelis
Pomegranate
Eucalyptus
Hydrolysis Upon acid hydrolysis
of Gallitannins, Gallic
.acid is produces
Upon acid hydrolysis
of Ellagitannins,
Ellagic acid is
.produces
Properties Rapidly soluble in *
.water
Free Gallic acid, in *
plant, is converted to
.gluco Gallitannins
Slowly soluble in *
.water
Present in plants in *
open and ring forms
as Hexa hydroxy
.diphenic acid

20. ii) Condensed tannins)
These tannins are derivatives of Flavonoid, catechin, flavonol-
.3-4-diol
:Precursors
Flavonoid
Catechin
Flavonol-3-4-diol

21. :Properties
When heated with acids, these are self condensated,
polymerized and converted to insoluble red colored
.complexes, called Phlobaphenes
:Examples
Hamamelis
Cinchona
Cinnamon

22. iii) Complex tannins)
These tannins are mixtures of both, hydrolysable and
condensed tannins
:Examples
Tea
Quercus
Castanea

23. 2nd Classification
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
True tannins
Pseudo tannins
Tannins
True tannins Pseudo tannins

24. True tannins 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
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
Molecular weight is 1000-5000 Molecular weight is less than
.true tannins

25. Identification tests
:Color reaction
.Tannins give color reaction with iron

26. Identification tests
: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
:Gelatin test
Solution of tannin (0.5%-1%) precipitates 1% solution of gelatin
.containing 10% sodium chloride

27. Identification tests
: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

28. Identification tests
:Gold beater’s skin test
Gold beater’s skin is a membrane prepared from intestine of Ox
.and I 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

29. Identification tests
:Catechin test
Catechin when heated with acid produce phloroglucinol.
.Phloroglucinol can be detected with matchstick test
:Test for chlorogenic acid
Treat extract containing chlorogenic acid with aqueous ammonia
.and expose it to air. Green color will appear gradually

30. Uses of Tannins
Natural tannins are used to Get leather from animal skin in :1 
(.tanneries.(now a days synthetic tannins are used
Tannic acis is used as clarifing agent in alcohlic drinks:2 
tannic acid is used as aroma ingredient:3
. Tannins are used in wine industry:4
tannins produce different colours with ferricchloride according to :5
type of tannin.Iron gall ink is produced by treating solution of
.tannins with iron sulphate

31. Uses
.Tannins are components of industrial particle adhesive:6 
Tanninsa are used for production of anti corrosive :7 
.primer,for rusted steel surfaces prior to painting
Immobilized tannins have been tested to remove uranium :8
.from sea water

32. ;Medical uses
When incubated with red grape juice and red wines with a ;< 
high quantity of condensed tannins the Polio virus,Herpes
.simplex virus and various enteric viruses are inactivated
In tissue cultured cell assays tannins have shown ;< 
.antiviral,anti bacterial,and anti parasitic effects
Tannin rich food can be used to treat HFE hereditary < 
hemochromatosis ,a hereditary disease that causes excessive
absorption of dietry iron resulting in pathalogical increase in
.total body iron stores

33. 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

34. :Constituents
Gallitannins
Ellagitannins
Free gallic acid
Pro-anthocyanadins
Hamamelase
:Uses
Astringent
Anti-hemorrhagic
Anti-inflammatory
Anti-carcinogenic

35. 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

36. :Constituents
Catechin
Catechutannic acid
Catechu red
Quercitin
Gambir flourescin
:Uses
Astringent
Dying
Tanning industry

37. c) Nutt gall
:Botanical origin
Quercus infectoria
:Family
Fagaceae
:Part used
Galls obtained from
twigs

38. :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

39. 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

40. :Constituents
Tannic acid
Gallic acid
Ellagic acid
Roburic acid
Syringic acid
Calcium oxalate crystals
:Uses
Haemostatic
Antidote for alkaloidal poisoning
Astringent

41. The end
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