This document provides information about secondary metabolites called tannins. It discusses what tannins are, their functions in plants, classification into hydrolysable tannins, condensed tannins, and pseudotannins. Tests for identifying tannins are described. Examples of medicinal plants containing different types of tannins are given. The document also discusses properties and biological activities of tannins.

1. Secondary metabolites and
its detail information
Pooja H. Khanpara
Asst. professor
Pharmacognosy
Aksharpreet College of Pharmacy, Lakhabaval,
Jamnagar

2. Presented by
Mrs. Pooja khanpara
Asst. Professor , APIP, Jmnagar
Tannin
2

3. WHAT ARETANNINS?
■ Defination:It is a secondarymetabolite, non-nitrogenous,phenolic in
natureit canpresentin alltreesand plantcansows astringentand
antioxidantpropertyis known as tannin.
■ The termtanninwas first time coinedby Seguinin 1796.
■ This termwas used to denotesubstancespresentinplantextractwhich react
with proteinof animal hide,preventtheirputrefaction(decayor rotting)and
converthide and skinintoleather.
■ They have a propertyto tan animal skinto convert to leather or hide.
■ Conversion impartsresistanceto water,heat, abrasives.
■ Theycan be extracted usingwater-acetone/alcohol mixture.
■ Theyhave a propertyto precipitate gelatin & heavy metals.
■ Tanninsare widely distributedinseveralplant species and are found in
wood, bark,leaves and fruits

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2.1 Base Unit
Gallic acid Flavone Phloroglucinol

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3. Function of tannins in plants
Tannins are considered the source of energy through their oxygen
content.
They serve as a protective to the plant (plant antiseptics).
They may have function in respiratory activity, i.e. in the
mechanisms of hydrogen transfer in plant cells.
Tannins play an important part in the acceptance of many foods
and beverages by consumers e.g. tea, cocoa.

6. 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

7. TANNINCLASSES
HYDROLYSABLE
TANNINS
A hydrolyzable
tannin or pyrogallol-
type tannin is a type
of tannin that, on
heating with
hydrochloric or
sulfuric acids, yields
gallic or ellagicacids.
NON-HYDROLYSABLE
TANNINS
(Condensed tannins)
Non-hydrolysable
tannins on heating
with hydrochloric
acid yield
phlobaphenes like
phloroglucinol.
PSEUDO
TANNINS
Pseudo tannins are
low molecular
weight compounds
associated with
other compounds.
e.g.Chlorogenic
acid in coffee

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4. Classification of tannins
Hydrolysable tannins are esters of a sugar (or related polyol) and
of a variable number of phenolic acid moleculThe sugar is most
generally glucose.
The phenolic acid is either gallic acid, in the case of gallitannins, or
Ellagic acid, in the case of the tannins conventionally referred to as
ellagitannins.
Ellagic acid can arise by lactonization of hexahydroxydiphenic acid
(= HHDP) during chemical hydrolysis of the tannin.
Hydrolysable tannins were formerly known as pyrogallol tannins,
because on dry distillation gallic acid and similar components are
converted into pyrogallol.
4.1 Hydrolysable tannins

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4.2 Condensed tannins (proanthocyanidins)
Condensed tannins or proanthocyanidins are polymeric flavans. They
consist of flavan-3-ol units linked together by carbon-carbon bonds,
most often 48 or 46, which result from coupling between the
electrophilic C4 of a flavanyl unit from a flavan-4-ol or flavan-3,4-
diol and a nucleophilic position (C-8, less commonly C-6) of another
unit, generally a flavan-3-ol.
Biosynthetically, gallic acid (= 3,4,5-trihydroxybenzoic acid) arises
from the metabolism of shikimic acid.
Examples of drugs containing Hydrolysable tannins: Gallitannins:
rhubarb, cloves, Chinese galls, Turkish galls, hamamelis, chestnut and
maple.
Ellagitannins: pomegranate rind, pomegranate bark, eucalyptus
leaves, and oak bark

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Unlike hydrolysable tannins, these are not readily hydrolyzed to
simpler molecules and they do not contain a sugar moiety.
Biosynthetically, flavonoids are derived from acetate and
shikimate pathways.
Condensed tannins occur due to polymerization (condensation)
reactions between flavonoids.
The polymers may include up to 50 monomer units.
On treatment with acids or enzymes condensed tannins are
converted into red insoluble compounds known as
phlobaphenes. Phlobaphenes give the characteristic red colour
to many drugs such as red cinnamon bark.

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Examples of drugs containing Condensed tannins:
Some drugs (e.g. tea, hamamelis leaves and hamamelis bark)
contain both hydrolysable and condensed tannins. The following
are rich in condensed tannins.
(1) Barks: cinnamon, wild cherry, cinchona, willow, acacia, oak
and hamamelis
(2) Roots and rhizomes: krameria (rhatany) and male fern
(3) Flowers: lime and hawthorn
(4) Seeds: cocoa, guarana, and kola
(5) Leaves: hamamelis, hawthorn and tea, especially green tea
(6) Extracts and dried juices: catechu, acacia and mangrove
cutches

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4.3 Pseudotannins
They are compounds of lower molecular weight than true tannins and
they do not respond to the goldbeater's skin test.
Examples of drugs containing Pseudotannins are:
Gallic acid: Rhubarb
Catechins: Guarana, Cocoa
Chlorogenic acid: Mate, Coffee
Ipecacuanhic acid: ipecacuanha

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5. Properties and tests of tannins
 Tannins are soluble in water, dilute alkalis, alcohol, glycerol and
acetone, but generally only sparingly soluble in other organic
solvents.
 Solutions precipitate heavy metals, alkaloids, glycosides and
gelatin.
 With ferric salts, gallitannins and ellagitannins give blue-black
precipitates and condensed tannins brownish-green ones. If a very
dilute ferric chloride solution is gradually added to an aqueous
extract of hamamelis leaves (which contains both types of tannin), a
blue colour is produced which changes to olive-green as more ferric
chloride is added. Other useful tests are the following:

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1. Goldbeater's skin test
Soak a small piece of goldbeater's skin in 2% hydrochloric acid; rinse
with distilled water and place in the solution to be tested for 5 min. Wash
with distilled water and transfer to a 1% solution of ferrous sulphate. A
brown or black colour on the skin denotes the presence of tannins.
Goldbeater's skin is a membrane prepared from the intestine of the ox
and behaves similarly to an untanned hide.
2. Gelatin test
Solutions of tannins (about 0.5-1 %) precipitate a 1% solution of gelatin
containing 10% sodium chloride. Gallic acid and other pseudotannins
also precipitate gelatin if the solutions are sufficiently concentrated.
3. Phenazone test: 5 ml aq. Sol. Of tannin + 0.5 gm sodium acid
phosphate  warm it, cool it + 2% phenazone sol.  bulky colored
ppts. Produce.

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6. Medicinal and biological properties
The applications of tannin-containing drugs are limited, and result
from their affinity for proteins.
 Tannin-containing drugs will precipitate protein and have been
used traditionally as styptics and internally for the protection of
inflamed surfaces of mouth and throat.
 They act as antidiarrhoeals and have been employed as antidotes
in poisoning by heavy metals, alkaloids and glycosides.
4. Test for catechin (matchstick test) : dip the match stick in tannin
sol. Moist with Conc. HCl. Warm over the flame  pink, red or
majanta color(pholoroglucinol)
5. Test for chlorogenic acid: tannin sol. Treated with aq. Ammonia
 Green due to chlorogenic acid is present.

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Tannin contain in crude drug
 Hydrolysable tannin
1. Myrobalan
2. Bahera
3. Amla
4. Arjuna
 Non- hydrolysable tannine
1. Ashoka
2. Black catechu
3. Pale catechu
4. Pterocarpus

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9.2.2 Black catechu
Synonyms - catechu, Kattha, cutch,
Biologicale source – it consis of dried aq.extract of heart wood plant
acacia catechu belonging to family leguminosae.
Geographical source – India, Pakistan, U.S.A. Sri Lanka
Chemical constituents – it can contain 10% of acacatechin it is
diastreomer of 5, 7, 3’, 4’ tetrahydroxy flavan 3-ol, catechu tannic
acid, tannic acid.
Morphology-
Colour – light brown black
Odour – none
Taste – astringrnt
Solibility in water – completely. ; Solibility in alcohol –soluble.

19. Chemical test -
1]Catechu + alcoholic vanilline +hydrochloric acid -Pink colour
2]Aq.extract of drug + lime water - Brown colour tun to red
3]Dil.solution catechu + ferric ammonium sulphate solution -
Green colour
4]Dip matchstick in Hcl & heate near theflame -Purple colour
5]Potassium permagnet - Decolourisation
Use – astringent, for boiling, ulcers, it is used in cough and
diarrhea, cooling & digestive properties.

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9.2.3 Pale catechu
Synonyms – gambier ,gambir,catechu
Biologicale source – it is drird aq.extract of the leaves & young
shoots of uncaria gambier belonging to family of Rubiaceae.
Geographical source - plant native to south east Asian region like
arachipelago in Malaysia , sigapore and Indonesia.
Chemical constituents – drug containing catechu, catechu tannic acid
, catechu red
Morphology-
Colour – raddiish brown
Odour – none
Taste – astringrnt

21. Chemical test-
1]Lead acetate White Buff ppt (tests 1 to 5 same as above
black catechu)
2]Gambir florocin test [alcohol+sodium hydroxide solution+few
drops of light petroleum+shake] Green fluorescense observed
in petroleum layer
3]Chloroform extract evaporate to dryness Greenish yellow
colour
Use – it is used as astringent of diarrhoea and local astringent in
the form of lozenges.

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9.2.4 Pterocarpus
Synonyms-bijasal
Biological source- it can consist dried juce of plant pterocarpus
marsupium belonging to family Leguminosace.
Geographical source - Gujrat, Madhya predesh, uter predesh, bihar.
Morphology-
Colour – ruby red
Odour – characteristics
Taste – astringent
Size- 3 to 5 mm diameter
Shape- angular grains

23. Chemical constituents-70% to 80% kiotannic acid , kino red , k-
pyrocatechin.
Chemical test-drug treated with ferrous sulphate shows green
colour.
Drug + alkali shows violet colour.
Mineral acid shows ppt.
Use-– it is used as astringent of diarrhoea
and local astringent in the form of lozenges. dyspepsia , purgative.

24. Resins

25. Introduction
The term ‘resin’ is amorphous, transparent or translucent
solid, semisolid or liquid products of complex chemical
nature.
These are amorphous mixtures of essential oils,
oxygenated products of terpenes and carboxylic acids
On heating get soften then melt & form clear adhesive
fluids
Produced in plants during normal growth or secreted as a
result of injury to the plants

26. General Properties
Physical characters
1. All resins are heavier than water , they are usually
amorphous ,hard, and brittle solids.
2. They are insoluble in water and usually insoluble in
petroleum ether but dissolve more or less completely in
alcohol, chloroform and ether.
3. They are hard, electrically non-conductive &
combustible (flammable) masses.
4. High molecular wt. compound.
5. By the action of heat they soften yielding clear,
adhesive fluids , Resins burn with a characteristic,

27. General Properties
Chemical Properties
1. Resins are often associated with volatile oils
(oleoresins), with gums (gum-resins) or with oil and
gum (oleo-gum-resins).
2. Resins may also be combined in a glycosidal manner
with sugars.
3. Chemically, resins are complex mixtures of resin acids,
resin alcohols (resinols), resin phenols (resinotannols),
esters and chemically inert compounds known as
resenes.
4. Many resins ,when boiled with alkalies yield soaps
5. Resins do not contain nitrogen elements ( Non

28. Classification of resins
Resins are classified in three different ways:
1.Taxonomical classification, i.e. according to botanical
origin, e.g. Berberidaceae resins. (Podophyllum)
2.Classification according to chemical constituent;
e.g. Acid resins (Colophony), Ester resins (Benzoin),
Resin phenols (Tolu Balsum), Resin Alcohol (Peru),
Glycoresin (Podophyllum), Resene resins (Asafoetida) ,
etc.

29. 3. Occurance

30. Classification of resins
1. Acid resins – Mainly Carboxylic Acid
 Found in free state or as ester, soluble in alkali & form soap like
solution.
 Metalic salt known as resinates (in mfg of soap, paint, varnishes)
Examples –
Colophony – Abietic acid
Myrrh - Commiphoric acid
Copaiba - Copaivic acid

31. 2. Ester resins – alcohol & acid
Ester formed by combination of resin alcohol with resin
acid.
Examples
Benzoin contains Benzoic Acid + Benzoresinol +
Cinnamic Acid
Storax contains Cinnamyl Cinnamate

32. 3.Resin alcohols (Resinols)–
They are complex alcoholic compound, high mol. Wt.
Occur as free alcohol or combined as ester with balsamic
acid or resin acid
They are tetracyclic or pentacyclic compound (amyrin
derivatives)
Colorless, not respond when tested with ferrous salt.
Insoluble in aq. Alkali.
examples –
Storex – Storesinol
Benzoin - Benzoresinol

33. 4.Resin Phenols (Resinotannols)
They are combined with tannin.
Found in free state or as ester
Phenolic in nature so form phenoxoids & soluble in aq.
Alcoholic solution.
They give blue/green/violet color with Ferric chloride
solution.
examples –
Balsam of peru – perruresinotannol
Tolu Balsam – toluresinotannol
Benzoine – siaresinotannol

34. 5.Resenes:
They are complex neutral inert substance
Found in free state & never form ester or other
derivatives
Soluble in benzene, Chloroform & petroleum ether
where insoluble in water.
Not hydrolysed by alkali or acids
Not affected by moisture, light, Chemical reagent.
examples –
Asafoetida – asaresene, Dammar – dammaresene
colophony

35. On Basis of Occurance
1) Oleo resin:
Assosiated with Volatile Oil or Oily liquid
They possess essence due to volatile oil
Examples:
Copaiba, Ginger, Turmeric, Capsicum
2) Gum resin:
Mixture of resin with gum, look like acacia gum. It contain 2 or more
glycosidal acids.
Easily seperated from resine due to solubility of gum in water
Examples: Ammoniacum, Gamboage

36. 3) Oleogum resin:
Naturally occuring mix. Of gum, volatile oil, resin.
E.g.: Myrrh, Asafoetida
4) Glycoresins:
Sugar with resin
Hydrolysed by acid into sugars & complex resin acids
Found in Convolvulaceae Family
E.G.:
Jalap, Ipomoea, Podophyllum

37. 5) Balsams
Balsams are resinous mixtures that contain large
proportions of cinnamic acid, benzoic acid or both or
esters of these acids.
The term “balsam” is often wrongly applied to oleoresins
and should be reserved for such substances as balsam
of Peru, balsam of Tolu and storax, which contain a high
proportion of aromatic balsamic acids.

38. Acid Resin
1) COLOPHONY:

39. Cultivation & collection

43. Adultrants: Black resin or apic resin

44. Balsam
1) Tolu Balsam
Syn: Balsam of Tolu, Balsamum Tolutanum
B.S.: by incision of stem of Myroxylon
balsamum
Family: Leguminoceae
G.S.: South America, Colombia(tolu), Peru (Miami),
Venezuela, Argentina, Brazil
Cultivation & collection:
Tree, upto 35 mtr height, white flower with seed pods.
(20 yr old, 3 gm of gum obtain annually)

45. Tolu Balsam
Characters:
Size: varies
Shape: Semisolid or plastic solid thin layers
Color: yellowish brown
Odour: Vanilla like & slightly pungent
Taste: Aromatic
Soluble in alcohol, benzene & chloroform
Insoluble in water

46. use
Cough, bronchitis, swollen airways, cancer
In soap as cosmetic & flavoring agent
In skin disease
Food additive
Mild antiseptic & expectorant

47. 2) Peru Balsam

49. Ester Resin
Benzoin (Loban)

57. Oleo Gum Resin
1) Asafoetida

63. 2) Myrrh

69. 3) Guggul

72. Salaiguggul
Syn: Indian Frankincense, indian Olibanum, Shallaki
B.S.: Boswellia serrata
Family: Burseraceae
G.S.: India(Punjab), Pakistan
Characters:
Size: Varies
Shape: Tears
Color: Yellowish brown
Odor: Aromatic
Taste: Sweet

73. C & C:
Boswelic Acid (Boswelia)
V.oil (thujen (12%), Pinene (8%), sabinane (2.2%)
Myrcene & limonene
Use:
Analgesic, Antipyretic, antiinflamatory
In pitta, cough, asthama
Improve blood circulation
cosmetic

74. Oleo resin
1) Ginger

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