Alkaloids are basic organic compounds containing nitrogen atoms, derived from amino acids, and can have significant physiological effects, ranging from medicinal uses to toxicity. They can be classified into true alkaloids, protoalkaloids, and pseudoalkaloids based on their chemical structure and properties. Extraction methods utilize their basic nature and solubility characteristics to isolate them for various applications.

1. ALKALOIDS: Definition,
classification, properties and test
for identification

2. DEFINITION
1. It is originate from alkali like word because of
resemblance with the characters of naturally
occurring complex amines.
2. Alkaloids are basic in nature.
3. These are organic products of natural or
synthetic origin which contain one or more
nitrogen atom usually in heterocyclic ring and it
has marked physiological effect on human or
other animal when used in small quantities.

3. • Usually alkaloids are derivatives from amino
acids.
• Even though many alkaloids are poisonous (e.g.
strychnine or coniine), some are used in
medicine as analgesics (pain relievers) or
anaesthetics, particularly morphine and
codeine.
• Most alkaloids have a very bitter taste.

4. Functions in plants
1. Act as protective against insects and
herbivores due to their bitterness and
toxicity.
2. Source of nitrogen in nitrogen deficiency
3. Sometimes act as growth regulator

5. Types of alkaloids: There are three main types of
alkaloids:
(1) true alkaloids/ typical/ heterocyclic alkaloids
(2) protoalkaloids/ non-heterocyclic/ atypical
alkaloids
(3) pseudoalkaloids.

6. 1. True alkaloids:
• These are present in plants as salts of organic
acids.
• They are basic in nature
• Toxic in nature
• Derived from amino acids
• Presence of nitrogen in the heterocyclic ring
• Example: Morphine and Quinine

7. 2. Protoalkaloids:
• Nitrogen is not present in the heterocyclic ring
but present in the side chain
• These are simple amines and basic in nature.
Example: Ephedrine

8. 3. Pseudoalkaloids:
• These are steroidal, terpenoidal and purines
alkaloids.
• Not derived from amino acids
• They do not show typical characters of alkaloids
but give standard test for alkaloids.
Example: Caffeine (Murexide test)

9. PROPERTIES
1.Physical properties:
• Colourless
• Crystalline solid
• It has sharp melting point
• Some are Amorphous gums example: Opium.
• Some are volatile and liquid Example is
Nicotine
• Some are colored Example: Betadine is red in
colour, berberrine is yellow in colour.

10. PROPERTIES
2. Chemical properties:
• Most of the alkaloids are basic in nature due
to the availability of non-pair of electron on
nitrogen.
• Alkaloids become neutral/ acidic when
adjacent functional groups are electron
withdrawing. Example: Amide group.

11. Decomposition of alkaloids:
• Alkaloids show basic character and due to this
they are very much sensitive to decomposition
and cause a problem during storage because of
this reason they are made into salt form.
• Alkaloids are insoluble in water
• Pseudo and proto alkaloids show more
solubility in water.
Example: Caffiene (freely soluble in water)

12. CLASSIFICATION OF ALKALOIDS:

16. CHEMICAL TESTS:

17. • EXTRACTION/ ISOLATION:
• The extraction of alkaloids is based on their
basic character and solubility profiles. Generally
alkaloids are extracted mainly using two
methods.