pharmacognosy of chitin and chitosen

1. CHITIN

2. Biological Source
It is a nitrogenous polysaccharide consisting of amino
and acetyl group found in the exoskeleton of the tarantula.
Its a tough semitransparent horny substance—the
principal component of the exoskeletons of arthropods and
the cell walls of certain fungi like Mycelia.
This product can be found in crustaceans, such as
crabs, lobsters, and shrimp.

3. Preparation
The shells are made into fine powder and treated with
5% hydrochloric acid for 24 h to remove the impurities and
calcium present in the shell.
The above extract is then treated with proteolytic
enzyme like pepsin for the removal of protein from the shell.
The product is then bleached with acidified hydrogen
peroxide for 4–6 h.

4. It is then deacetylated at 120°C with a mixture
containing two parts of potassium hydroxide, one part of
ethyl alcohol and one part of ethylene glycol.
The process of deacetylation is continued till the
test for acetylisation gives report of minimum acetyl
content. This deacetylated product is known as the
chitosan.

5. Solubility
Insoluble in water, dilute acid, alcohol and organic
solvents, Soluble in sulphuric acid and hydrochloric acid.
Chitin mainly consists of the aminosugar N-
acetylglu-cosamine.

6. Chemical Test
1. A Chitosan is soaked in iodine solution and to it
add 10% sulphuric acid. It gives deep violet colour.
2. Chitosan is dissolved in 50% nitric acid and
crystallized for the formation of spherecrystals of
chitosanitrate.
The crystals when observed under polarized light using
crossed nicol, a distinct cross is observed.

7. Uses
• It is used in wound healing preparations, cuts and burns.
• Chitin is also used as a sizing agent for rayon, cotton, wool
and even for synthetic fibres.
• It has adhesivity to glass and plastics.
• Industrially chitin is used in the process of water
treatment by separating organic compounds and heavy
metals.