3. The first individual alkaloid, morphine, was isolated in 1804
from the opium poppy (Papaver somniferum).
4. Alkaloid - Definition
• Alkaloid is defined as organic products of
natural or synthetic origin which are basic in
nature, and contain one or more nitrogen
atoms, normally heterocyclic nature, and
possess specific physiological actions on
human or animal body, when used in small
6. Alkaloids - History
• “Alkaloids" was introduced in 1819 by the German chemist Carl Friedrich
Wilhelm Meißner, ('ashes of plants').
• The term came into wide use only after the publication, by Oscar
Jacobsen in the 1880s.
• In 1804, the German chemist Friedrich Sertürner isolated from opium,
which he called "morphium“ (Greek god of dreams).
• The term "morphine", used by the French physicist Joseph Louis Gay.
• The first complete synthesis of an alkaloid was achieved in 1886 by the
German chemist Albert Ladenburg (coniine ).
7. Occurrence of Alkaloids
• Alkaloids are produced by a large variety of organisms
8. Occurrence of Alkaloids
• Distribution in nature:
• Alkaloids are found:
in certain types of fungi, such as psilocybin,
in animals, such as bufotenin in the skin of some toads and
a number of insects, markedly ants.
Many marine organisms also contain alkaloids.
• Some amines, such as adrenaline and serotonin, which play an
important role in higher animals, are similar to alkaloids in their
structure and biosynthesis and are sometimes called alkaloids.
9. Occurrence of Alkaloids
• Distribution in nature:
• Alkaloids are generated by various living organisms, especially by higher
plants – about 10 to 25% of those contain alkaloids.
• Depending on the type of plants, the maximum concentration is observed
in the leaves (black henbane),
fruits or seeds (Strychnine tree),
root (Rauvolfia serpentina) or
• Furthermore, different tissues of the same plants may contain different
10. Distribution and Occurrence
o Rare in lower plants.
o Dicots are more rich in alkaloids than Monocots.
o Families rich in Alkaloids: Apocyanaceae,
Rubiaceae, Solanaceae, and Papavercea.
o Families free from Alkaloids: Rosaceae,
11. Distribution and Occurrence
All parts e.g. Datura
Barks e.g. Cinchona
Seeds e.g. Nux vomica
Roots e.g. Aconite
Fruits e.g. Black pepper
Leaves e.g. Tobacco
Latex e.g. Opium
14. Classification of Alkaloids
I. Alkaloids are often classified on the basis of their chemical structure.
• Eg: Alkaloids that contain a ring system indole are known as indole
• On this basis, the principal classes of alkaloids are:
quinolines, terpenoids and steroids.
15. Classification of Alkaloids
I. Chemical classification:
• The alkaloids are categorised into three divisions.
a. True alkaloids: These have heterocyclic ring with nitrogen and
derived from amino acids.
b. Proto alkaloids: These does not have heterocyclic ring with nitrogen
and derive from amino acids, e.g. colchicine.
c. Pseudo alkaloids: These have heterocyclic ring with nitrogen and
derived from terpenoids or purines but not derived from amino acids.
18. Classification of Alkaloids
II. Taxonomical classification:
• This classification is based on the distribution of alkaloids in
various plant families:
• Some times they are grouped as per the name of grouped
genus in which they occur, e.g. ephedra, cinchona, etc.
19. Classification of Alkaloids
II. Alternatively, alkaloids can be classified according
to the biological system in which they occur.
• For example, the opium alkaloids occur in the opium
poppy (Papaver somniferum).
25. Classification of Alkaloids
IV. The medicinal properties of alkaloids are quite diverse.
• Morphine is a powerful narcotic used for the relief of pain.
• Codeine, the methyl ether derivative of morphine found in the
opium poppy, is an excellent analgesic that is relatively
• Certain alkaloids act as cardiac or respiratory stimulants.
• Quinidine, which is obtained from plants of the genus Cinchona, is
used to treat arrhythmias, or irregular rhythms of the heartbeat.