ALKALOIDS Alkaloids are a class of naturally occurring organic compounds that mostly contain basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Alkaloids are derived from plant sources they are basic they contain one or more nitrogen atoms (usually in a heterocyclic ring) and they usually have a marked physiological action. Function of alkaloids they may function as stimulants or regulators in activities like growth, metabolism and reproduction. They may act as reservoirs for protein synthesis Properties of alkaloids Alkaloids are colourless, crystalline, non-volatile, solids, a few such as coniine and nicotine are liquids and a few even coloured, viz. berberine is yellow. the alkaloids are bitter in taste and have pronounced physiological activity Classification of alkaloids a. Taxonomic classification- On the basis of taxonomic profile of the drug. For ex. Solanaceous alkaloids. b. Biogenetic classification- On the basis of amino acid precursor. For ex. Phenylalanine, Tyrosine alkaloids c. Pharmacological classification- On the basis therapeutic activity of the alkaloid For ex. Morphine as analgesic, Quinine as antimalarial. d. Chemical classification- On the basis of basic chemical structure of alkaloid. It is of further three types- 1. True alkaloid- The alkaloids which have all basic properties of alkaloids, derived from amino acid and contain Nitrogen in heterocyclic ring. Ex. Atropine, Morphine. 2. Proto alkaloid- The alkaloid in which nitrogen atom is not present in the ring, but it is present outside the ring I form of amino group, so also called amino alkaloids or biological amines. Ex. Ephedrine. 3. Pseudo alkaloids- Actually these are not alkaloids. These are not derived from amino acid and not give basic identification tests of alkaloids. These are Steroidal (Solanine), Terpenoidal (Diterpene alkaloid) and Purine alkaloid (Caffeine). chemical classification of alkaloids

1. ALKALOIDS
Mr Nandakishor B. Deshmukh.
Assistant Professor
Shraddha Institute Of Pharmacy, Kondala Zambre ,
Washim.
Subject - Pharmacognosy And Phytochemistry -I
Class- B-pharm- II Sem IV
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SR NO Content
01 Introduction
02 Function Of Alkaloids
03 Properties Of Alkaloids
04 Classification Of Alkaloids
05 Chemical Tests

3. ALKALOIDS
Alkaloids are a class of naturally occurring organic
compounds that mostly contain basic nitrogen atoms.
This group also includes some related compounds with neutral
and even weakly acidic properties.
Alkaloids are derived from plant sources they are basic they
contain one or more nitrogen atoms (usually in a heterocyclic
ring) and they usually have a marked physiological action.
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4. Function of alkaloids
they may function as stimulants or regulators
in activities like growth, metabolism and
reproduction.
They may act as reservoirs for protein
synthesis.
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5. Properties of alkaloids
Alkaloids are colourless, crystalline, non-volatile, solids, a few
such as coniine and nicotine are liquids and a few even coloured,
viz. berberine is yellow.
The free bases (i.e. alkaloids themselves) are insoluble in water
but soluble in most of the organic solvents. Most of the alkaloids
are laevorotatory (optically active), although a few are
dextrorotatory (e.g. coniine), while a few are even optically
inactive, viz. papaverine.
the alkaloids are bitter in taste and have pronounced physiological
activity.
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6. Classification of alkaloids
a. Taxonomic classification- On the basis of taxonomic profile of the
drug. For ex. Solanaceous alkaloids.
b. Biogenetic classification- On the basis of amino acid precursor. For
ex. Phenylalanine, Tyrosine alkaloids
c. Pharmacological classification- On the basis therapeutic activity of
the alkaloid For ex. Morphine as analgesic, Quinine as antimalarial.
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7. d. Chemical classification- On the basis of basic chemical structure of alkaloid. It is of
further three types-
1. True alkaloid- The alkaloids which have all basic properties of alkaloids, derived from
amino acid and contain Nitrogen in heterocyclic ring. Ex. Atropine, Morphine.
2. Proto alkaloid- The alkaloid in which nitrogen atom is not present in the ring, but it is
present outside the ring I form of amino group, so also called amino alkaloids or
biological amines. Ex. Ephedrine.
3. Pseudo alkaloids- Actually these are not alkaloids. These are not derived from amino
acid and not give basic identification tests of alkaloids. These are Steroidal (Solanine),
Terpenoidal (Diterpene alkaloid) and Purine alkaloid (Caffeine).
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8. chemical classification of alkaloids
1. Non-Heterocyclic Alkaloids
Groups Example Source Uses
Phenyl ethyl amine
alkaloid
Ephedrine, Mescaline
Hordenine
Ephedra sp.
Lophophora wiliamsoil
Asthama
Tropolone alkaloids Colchicine Colchicum sp. Gout
Modified diterpene Taxol Taxus sp. Anti cancer
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9. 2. Heterocyclic Alkaloids
A. Mono-nuclear Heterocyclic Alkaloids
Groups Example Source Uses
Pyridine Lobeline Lobelia sp. Asthama
Piperidine Piperine Piper sp Antioxidant
Pyrrole Hygrine Coca sp. CNS Stimulant
Pyrrolidine Nicotine Tobbaco sp CNS Stimulant
Imidazole Pilocarpine Pilocarpus Contraction pupil of
B. Poly-nuclear Hetero-cyclic alkaloids
Isoquinoline Morphine, papaverine Opium Narcotic analgesic
Quinoline Quinidine, quinidine Cinchona Anti-malarial
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10. Chemical tests
Reagent Composition Remarks
Alkaloid Precipitants
Mayer's Potassium- mercuric iodide Immediate creamy white ppt.(+ve
with most alkaloids except Caffeine
and dil. Ephedrine
Wagner's Iodine in potassium Reddish brown
Hager's
Dragendorff's
Iodide
Saturated soln. of picric acid
Yellow
Orange-reddish brown
Marme's Potassium bismuth iodide
Potassium cadmium iodide
Yellow
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