TANNINS

1
TANNINS
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)
5
Base Unit Gallic acid Flavone
Class/Polymer Hydrolysable tannins condensed tannins
Sources Plants Plants
6
Condensed 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..  B- Ellagitannin  
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
8
Identification 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.

10
4-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.

12
Quantitative 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.

13
Uses 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.

14
Tannin containing drugs

• Galls (Blue Galls, Aleppo Galls, Turkish Galls)
  Turkish galls are vegetable growths formed on the
  Young twigs of the dyers oak.

15
Origin 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.

16
Characters 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.
•  

17
Constituents of galls

• Galls contain 50-70 of the tannin known as
  gallotannic acid. Galls also contain Gallic acid
  and ellagic acid.

18
Uses 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.

19
Commercial test

• Galls fecl3
• Bluish Black color.