Chitin

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.