Tannins Tannins are complex substances that usually occur as mixtures of polyphenols that are very difficult to separate since they do not crystallize. OR Tannins are polyhydroxy phenolic compounds. Tannins are found commonly in the bark of trees, wood, leaves, buds, stems, fruits, seeds, roots and plant galls. Tannins are complex chemical substances derived from phenolic acids (sometimes called tannic acid). They are classified as phenolic compounds, which are found in many species of plants. Tannins are high molecular weight phenolic compounds commonly found in plants with molecular weights ranging from 500 to over 3000 Dalton and up to 20,000 Dalton. Examples of plant species used to obtain tannins for tanning purposes are wattle (Acacia sp.), oak (Quercus sp.), eucalyptus (Eucalyptus sp.), birch (Betula sp.), willow (Salix caprea), pine (Pinus sp.), quebracho (Scinopsis balansae) .

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2. Tannins are complex substances that usually occur as mixtures
of polyphenols that are very difficult to separate since they
do not crystallize.
OR
Tannins are polyhydroxy
phenolic compounds.
Tannins are found commonly
in the bark of trees, wood,
leaves, buds, stems, fruits,
seeds, roots and plant galls.
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3.  Tannins are complex chemical substances derived from
phenolic acids (sometimes called tannic acid). They are
classified as phenolic compounds, which are found in
many species of plants.
 Tannins are high molecular weight phenolic
compounds commonly found in plants with molecular
weights ranging from 500 to over 3000 Dalton and up
to 20,000 Dalton.
 Examples of plant species used to obtain tannins for
tanning purposes are wattle (Acacia sp.), oak (Quercus
sp.), eucalyptus (Eucalyptus sp.), birch (Betula sp.),
willow (Salix caprea), pine (Pinus sp.), quebracho
(Scinopsis balansae) .
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4. Tannins
True tannins Pseudo tannins
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5. 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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6. True
tannins
Hydrolysable
tannins
Condensed
tannins
Complex
tannins
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8.  Color:
Dark brown or reddish brown
 Taste:
Puckering taste
 State:
Non-crystalline
 Solubility:
Soluble in water, alcohol, dilute alkalis,
glycerols and acetone.
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9.  Precipitation
 Anti-oxidizing properties
 Astringent
 Reaction with salts
 Reaction with potassium ferricyanide and ammonia
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Identification
of plant
Collection of
plant
Drying of
plant parts
Grinding
Stored the
powder in
cool and dry
place
Prepare the
extract with a
suitable
solvent
Filtration
Identification
test
Storage and
packaging
Flow chart of Tannin extraction
and processing

11.  Maceration
 Decoction
 Pressurized water extraction
 Ultrasound method
 Microwave assisted extraction
 Infrared assisted extraction
 Soxhlet extraction
 Super critical extraction
 Enzyme assisted extraction
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12.  Color reactions
 Alkaloid precipitation
 Gelatin test
 Goldbeater’s skin test
 Ferric chloride test
 Matchstick test
 Chlorogenic acid test
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13.  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.
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14.  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 +ve only for true tannins.
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15.  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.
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16. Take 1 ml of the extract in a test tube and added 1ml of
gelatin (1%solution) and NaCl. The formation of a
white precipitate will show The presence of tannins.
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Biological activities of Tannins
Anti -
inflammatory
Anti-oxidant
Biological
activities of
Tannins
Anti -
hyperglycemic
Anti -
apoptotic
Anti-aging
Anti-
bacterial

18. Medicinal plant Plant part Activity of Tannins
Mimosa arenosa Stem bark Antibacterial activity
against Gram +ve and
Gram-ve bacteria
Mimosa tenuiflora Stem bark Wound healing, gastric
ulcer, inflammation and
burns etc
Piptadenia stipulacea Stem Antimicrobial activity
Anacardium occidentale Leaves Antimicrobial and non
stick activity
Anadenanthera colubrina Leaves, seeds and stem
bark
Anti-inflammatory,
antioxidant, astringent
activity
Solanum paniculatum Roots and stem Treat chronic hepatitis
and chronic arthritis etc
Uncaria gambir Leaves Astringent
Quercus infectoria Galls obtained from
twigs
Antidote for alkaloidal
poisoning
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19.  Currently, tannins have been applied
into many different fields including
medicine, food, beverage,
manufacture of ink and adhesives, dye
and tanning industry, plastic resins,
water purification, and surface
coatings.
 The tannin-containing plant extracts
are used as astringents, against
diarrhea, as diuretics, against stomach
and duodenal tumors, as anti-
inflammatory, antiseptic, antioxidant
and haemostatic pharmaceuticals etc.
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20. Medicinal and biological properties
of Tannins
Medical research has shown that tannin found in cranberries
is highly effective in preventing urinary tract infections by
preventing E. coli bacteria from adhering to walls of the
urinary tract.
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21.  Tannin-containing drugs precipitate proteins and have
been traditionally used as styptics (stop hemorrhage)
and internally for the protection of inflamed surfaces of
mouth and throat.
 They play an important role in the treatment of burns.
They form a mild antiseptic protective layer on the
surface of the injured skin below which regeneration of
new tissue takes place.
 They act as anti-diarrhea although not recommended in
this respect as they usually delay elimination of
bacterial toxins from the body.
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22.  Tannins have been employed as antidote in
poisoning by heavy metals, alkaloids and certain
glycosides due to their precipitation as tenants.
 Recently tannins as most polyphenols were proved
to have a potent antioxidant effect.
 Studies on the antitumor effect of tannins proved
that a strong activity is obtained with ellagitannins
having galloyl groups at the O-2 and O-3 positions
of the glucose core, as in the tellimagrandins.
 Certain tannins were proved to have anti-HIV
activities.
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26. Taninal
Taninal is traditionally applied
in diarrheas and in case of
food poisoning.
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