Tannins – Pharmacognosy B Pharmacy 5th Semester


  • Derived from the Frenck work “Tanin” means tanning substance.
  • These are chemically Natural Polyphenols – It contains sufficient hydroxyl group and other suitable group such as carboxyl, to form strong complex with protein and other macromolecules. This term first used by Seguin (1796).
  • Tannins are Complex Non nitrogenous Plant product.
  • Astringent property – Precipitate tissue protein.
  • Mostly high molecular weight compounds
  • Water Soluble
Definition: Tannins are secondary metabolites which are non-nitrogenous, complex polyphenolic organic compound having high molecular weight, water soluble and astringent property.
Gallic Acid



  • Tannins are widely distributed in Plant Kingdom. Such as Higher Plant, Combretaceae(Arjuna, Bahera, Myrobalan),  Leguminosae(Pterocarpus, Black Catechu, Ashoka).
  • Found in seed, root, stem, bark, leaf.
  • Tannins are present in the solution form in the distinct vacuoles of the cell sap in plants.

Medicinal Use of Tannin

  • Used mainly due to its astringent property.
  • Externally used as a healing agent which helps in formation of new tissue and healing of inflamed mucosa, minor burns, ulcers, haemorrhoids, wounds, antiseptic, haemostatic.
  • Internally used as Diarrhoea
  • Antidote in heavy metal poisoning and alkaloid(tannins make complex with heavy metals and alkaloids.)

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