Tannins-Pharmacognosy

Tannins-Introduction,Defination,Property,Classification,Chemical test and Crude drugs are Black and Pale catechu,Pterocarpus

1. Tannins

2. Introduction Tannins are Polyphenolic substance found in many palnts product of secondary metabolites.Its water soluble nature allowes easy extraction And is usefull in various application in chemical and pharmaceutical industry. DEFINATION: The complex, organic, nitrogenous, Polyphenolic substance with higher molecular weight.They are use as astringent,antiseptic and in GIT disease like dirrhea and also use in lather idudtry.

3. Property: Pale yellow to light red brown amorphous substance widly distributed in plants. Their solution are acidic and astringent in taste. They are isolated from oak bark,sumac and falls. Tannins give tea astringency,color and flavor,they are phenol glycosides

4. Physical property: Tannins are non-crystalizable Compound. They are soluble in water forming colloidal solution with acidic reactionsand sharp astringent taste. They are soluble in dilute alkali, alcohol,glycerol and acetone,but only sparingly soluble in other organic solvant. Their solution precipitate heavy metal,alkaloid, glycosides and protein (e.g Gelatine)

5. Uses: Dye Fibres Glue Oil Waxes Flavouring agent Perfumes Drugs

6. Classification of tannins:

7. Hydrolysable tannins: These tannins are hydrolysed by acid or enzym and product of hydrolysis products are Gallic acid and ellagic acid. On dry distillation gallic acid and other compound are converted into pyrogallon. The response to ferric chloride solution producing blue color. E.g,Gallo tannins-rhubarh,amla,cloves,nutgall Ellago tannins-oak,myrobalans, pomegranate barks.

8. Pseudo tannins: This is not as such a separate group of tannins,but may be trated as subgroup because they do not obey to goldbitters skin test or and contain low molecular weight compound. Chlorogenic acid in coffee and nuxvomica,ipecacuahenic acid in ipecacuahen and cathechins in cocoa are exaple of pseudotannins.

9. Condensed tannins: They are also called as non-hydrolysable tannins phiobatannins or proanthocynidines. They are releted to flavanoid pigament,because they are form by the darivative of flavones,like cathechin or flavon-3-ol and flavon3-4-diones. This Tannis give brownish-green color with ferric chloride. On dry distillation that give a catechol. Ex-Cinchona,cinnamon,wild cherry bark,pale and black cathechu etc.

10. Identification test of tannins: Gelatine test: To a solution of tannins,add a solution of 1% gelatine and 10% sodium chloride solution.A white buff color of precipitate is form. Goldbeater’s skin test: A small peace of goldbeater’s skin is soaked in 20% of HCL,rinse with distilled water and place in a solution of tannins for 5 minutes.The skin piece is wash with distilled water and kept in solution of 1% solution of ferous sulphate.A black or brown color is produce on the skin.

11. Phenazone test: A 10 ml of aqueous extract of tannin and sodium acid phosphate is heated and cooled and filtered. A 2% of solution of phenazone is added to the filtrate,a bulky color precipitate is formed. Match stick test(Cathechin test): A match stick is dipped in aqueous plant extract,dried near burner and moistened conc.HCL.on warming near the flame the match stick wood turn pink or red Due to formation of floroglucinol.

12. Pterocarpus Black pale . Catechu. Catechu

13. Pterocarpus: Synonyms: Red sandle wood,Rakta chandan,Indian kino,malabar kino Biological source: it is obtain from the dried juice of the plant of pterocarpus marsupium. Family: leguminoseae Morphology: Color:Red Odour: Odour less Taste: Astringent Size:3-10mm Shape:angular/grains

14. Cont….. Chemical constituents: Kinotanic acid 70-80% Kino red K-pyrocatechin Gallic acid,resin etc. Use: Powerfull Astringent and in treatment of diarrhoea and dysentery Diabitish Purgative Dyspepsia Tanning Printing

15. Pale catechu: Synonyms: kattha, Gambier Biological source: it consists of a dried aqueous extract preapare from leaves of Uncaria Gambier. Family: Rubiaceae Morphology: Colour: Reddish brown Odour: Odourless Taste: Astringent Shape: Cubiodal Special function: Brittle in nature and easily soluble in nature

16. Chemical constituents: Catechin(7-33%) Catechu tannic acid and catechu red Quercetin Gambier fluorescein use: Use as an astringent Source of tannic acid Use in leather and febric industry Use in dying industry

17. Black catechu Synonyms: khair,kattha,catechu Biological source: Black catechu consists of the dried aqueous extract prepared from heart wood of Acacia catechu willed and Acacia chundra willd. Family: leguminoseae Morphology: Colour: Black or dark brown, Odour: Odourless Taste: Bitter to start with,turn sweet and finally astringent Shape: irregular mass of cubes

18. Chemical constitutes: 1. It contains tannins like catechins, catechu tannic acid, 2. It is also contains flavonoids like quercetin and it derivatives. 3. Others-Catechu red and gum, etc. Uses: 1. Astringent 2. Cooling and digestive agents. 3. It is used in relaxed conditions of throat, mouth and gums. 4. It is also used in diarrhoea and in preparation of lozenges