Title: TANNINS
1TANNINS
2- Tannins
- Tannins is a substance found naturally in many
different plants, most in grapes and tea leaves
,precipitate proteins from their aqueous
solutions.
3(No Transcript)
4(No Transcript)
5Base Unit Gallic acid Flavone
Class/Polymer Hydrolysable tannins condensed tannins
Sources Plants Plants
6Condensed tannin  Hydrolysable Tannin
On dry distillation they give catechol. their structures are related to flavonoids and they lack sugar in their structures Present in cinnamon, cinchona and tea. consist of several molecules of phenolic acids united by ester linkage to a central glucose residue.Also have potential antibacterial effects against Helicobacter pylori.
7 Types of hydrolysable tannin A- Gallitannin
On hydrolysis , it gives gallic acid and
glucose. Present in clove.. Â B- Ellagitannin Â
On hydrolysis it gives ellagic acid and glucose
 Present in pomegranate. Pseudotannins
Pseudo tannins are low molecular weight compounds
found in Rhubarb , tea and coffee
8Identification of Tannins
- 1-tannin ferric chloride (FeCl3)
- Bluish black colour with hydrolysable tannin.
- Brownish black colour with catechol.
9- 2-
- 2-Gelatin test Solution of tannins (about 5-1)
precipitate 1 Solution of gelatin containing l0
sodium chloride Gallic acid and other
pseudotannins also precipitate. gelatin if the
solutions are sufficiently concentrated. - 3- Bromine water only condensed tannin gives
ppt. with bromine water.
104-Gold beater's skin test
- a soak a small piece of Gold beater's skin
membrane in 2 hydrochloric acid ( HCL). - b- rinse with distilled water.
- c- place the piece for 5 minutes in the tannin
solution to be tested. - d- wash with distilled water
11-
- e- transfer to 1 ferrous sulfate (FeSO4)
solution. - f- a brown or black colour in the skin denote
the presence of tannins.
12Quantitative determination of tannin
- 1- Hide powder methodThe difference in the dry
weight of the extract before and after treatment
with hide powder is taken as a measure for tannin
content. - 2- Copper acetate method Gravimetric method
using copper acetate as precipitant.
13Uses of Tannins
- IndustriallyIn leather tanning, ink manufacture.
- MedicinallyAstringent, haemostatic,
antidiarrheal, antidote in alkaloid and heavy
metals toxicity. - In labs Reagent for detection of proteins,
alkaloids and heavy metals because of their
precipitating properties.
14Tannin containing drugs
- Galls (Blue Galls, Aleppo Galls, Turkish Galls)
Turkish galls are vegetable growths formed on the
Young twigs of the dyers oak.
15Origin of galls
- (pathological outgrowth) as a result of the
deposition of the eggs of the gall-wasp Cynips
gallae tinctoriae on the young twigs of Quercus
infectoria (Fagaceae). They are Collected before
the escape of the insect and known as blue galls.
16Characters of galls
- 1- galls are globular in shape and form l0 to 25
mm in Diameter . - 2-They have a short basal stalk and numerous
rounded projection on the surface. - 3-Galls are hard and heavy, usually sinking in
water. - 4-external surface is bluish green to olive green
in color .Internally it is buff in color. - 5- The so-called blue' variety are actually of a
grey or brownish-grey color. - Â
17Constituents of galls
- Galls contain 50-70 of the tannin known as
gallotannic acid. Galls also contain Gallic acid
and ellagic acid.
18Uses of galls
- Medicinally
- 1-It is used as astringent
- 2- haemostatic used in treatment of hemorrhoids
in form of suppository or ointment. - Industrially
- 1- in manufacture of ink and paints.
- 2- in tanning of leather.
19Commercial test
- Galls fecl3
- Bluish Black color.