Anti-Amoebic Agents – Medicinal Chemistry



People living in the tropical countries with poor sanitizations

Infection due to microbe’s viz. Bacteria, fungi, protozoa virus
and rickettisia.

Infection due to paralytic worms and insects.


Amoebiasis is the parasitic protozoal infection caused by
entamoeba hysstolytica, with or without clinical manifestations.

This disease is due to poor hygienic condition and transmitted by
faecal –oral route. Amoebae are present in the lumen or wall of the gut of
human beings.

Classification of Antiamoebic drugs:

A) Chemical
classification of Antiamoebic drugs:

Alkaloid:  -e.g.
Emetine and Dihydro emetine.

Amaroids: – Quassin

Antibiotics: – Promomycine

Quinoline derivatives:

a) Halogenated hydroxy Quinoline :-diiodohydroxyquinoline
(Iodoquinol) ,Iodochlorhyquinoline (clioquinol)

b) Amino Quinoline: chloroquine, amodiaquine.

Heterocyclic compound:

a) Furan derivatives: Diloxanide

b) Imidazole derivatives: Metronidazole.

Organometalic compound:  Acetarsol


B) On the basis of site of action they are
grouped as follows:

Luminal amoebicides: e.g. Diloxinide furoate, Paromomycin
Halogenated hydroquinolines.

Tissue or systemic amoebicides:-Emetine and its derivatives.

Mixed amoebicide:  Metronidazole.


Emetine is an alkaloid obtained from ipecacuhana.

It can be obtained by methylation of cephaeline; the other
alkaloid is also present which can be prepared by synthetically.

It contains tetra hydro Quinoline heterocycle.

Physical properties of Emetine:

Emetine hydro chloride is a dihydro salt
of emetine.

It is white or slightly yellow
crystalline powder.

It is odourless.

It is tasteless.

It is soluble in water and alcohol. 

Emetine is levo rotetory

Chemical properties of Emetine:

It gives bright green colour when a
mixture of molybdenum trioxide and sulphuric acid is sprinkled on it.

It contains two basic nitrogen atom
.hence it form salt quite readily with two molecules of hydrochloric acid gives
an emetine hydro chloride.

Stability and storage of Emetine:

It becomes faintly yellow on exposure to
light .it is stored in tightly closed light resistant containers.

Uses of Emetine:

Intestinal Amoebiasis (amoebic dysentery)

Hepatic Amoebiasis (amoebic hepatitis)

Amoebic infection of lung, brain and other tissues

Pharmaceutical formulations: Emetine

Brand names: Stembin,


Structure of Metronidazole: