1. ALKALOIDS
#AN OVERVIEW
Dr. S. Nayak
Principal & Professor
Bansal College of Pharmacy, Bhopal
www.bansalpharmacy.com
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2. Alkaloids
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OBJECTIVES
To know --
What are alkaloids
Sources of alkaloids
Importance of alkaloids
Test to detect the presence of alkaloids
Classification of alkaloids
Plants containing alkaloids and their therapeutic
uses
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Alkaloids
Alkaloids are metabolic by-products, commonly
applied to basic nitrogenous compounds of plant
origin that are physiologically active.
They are organic nitrogenous compounds with a
limited distribution in native nature.
More than 10000 alkaloids are found from over 300
families of plant.
Usually they are derivatives from amino acids
4. Occurrence of Alkaloids
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Alkaloids occurs in plant kingdom
The Leguminosae , Papaveraceae , Ranunculaceae ,
Rubiaceae , Solanaceae , and Berberidaceae .
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Occurs in fungi (Ergot, Claviceps purpurea )
Occurs in various parts of the plant;
Seeds ( Physostigma , Areca),
Leaves (Vasaca, Dhatura )
Underground stems ( Sanguinaria ),
Roots (Belladonna root),
Rhizomes and Roots (Ipecac, Hydrastis ),
Barks (Cinchona).
8. Uses of Alkaloids in Plants
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Poisonous agents protect plants against insects
and herbivores end products of detoxification
reactions representing a metabolic locking-up of
compounds otherwise harmful to the plants.
9. Characters of alkaloids
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Mostly colorless, crystalline solid.
Bitter taste
Have definite melting point
Few bases are soluble in organic solvents and insoluble in
water.
Alkaloidal salts are soluble in water.
10. Extraction of alkaloids
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Method A :-
Powdered material moistened with alkaline subs
( sodium bicarbonate, ammonia, calcium
hydroxide)
Extract with organic solvent
Concentrate the organic extract
Shake with aqueous acid
Allow to separate
Alkaloid salt present in aqueous phase
Purification
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Method B :-
Powdered material extract with water or aqueous
alcohol containing dilute acid
Add chloroform or other organic solvent
Few alkaloids are then precipitated by addition of
excess alkaline substance (sodium bicarbonate or
ammonia)
Separate by filtration or by extraction with organic
solvent
Purification
21. Test for Alkaloids
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Wagner’s Test -Reddish brown precipitate Reagent
used: Wagner’s Reagent
[Solution of iodine in potassium iodide]
Mayer’s Test - Cream color precipitates Reagent
used: Mayer’s Reagent
[Potassium mercuric iodide solution]
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Dragendorff’s test - Orange precipitate
Reagent : Dragendorff’s reagent
[Potassium bismuth iodide solution]
Hager's test - Yellow color precipitate
Reagent : Hager's reagent
[saturated solution of Picric acid ]
Tannic acid test- buff color precipitate
Reagent
[10% Tannic acid solution ]