Black Catechu

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Chapter: Pharmacognosy and Phytochemistry : Drugs Containing Tannins

Black catechu is the dried aqueous extract prepared from the heartwood of Acacia catechu Willdenow, belonging to family, Leguminosae.


BLACK CATECHU

 

 

Synonym

 

Cutch, black catechu, kattha.

 

Biological Source

 

Black catechu is the dried aqueous extract prepared from the heartwood of Acacia catechu Willdenow, belonging to family, Leguminosae.

 

Geographical Source

 

A. catechu is common throughout the tract from Punjab to Assam ascending to an altitude of 300 m. It is also quite common in drier regions of peninsula such as Madhya Pradesh, Maharashtra, Gujarat, Rajasthan, Bihar, and Tamil Nadu.

 

History

 

Possibly, the use of black catechu could be traced back in history from the time of chewing betel leaf, in which it has been used as adjuvant. In old days, it was used by women as a colouring agent for the feet. Since 15th century, this natural material has been exported to Europe. The old information about catechu is by a Portuguese writer Garcia de Orta in 1574. Dr. Wrath first used the scientific process to extract catechu, and showed that catechu consists of two parts, such as, kattha and cutch.

 

Collection and Preparation

 

catechu is a medium-sized tree with thorns. For preparation of the drug the tree is cut off from the ground. The main trunk and branches are cleared of foliage and thorns. The bark is stripped off, and the heartwood is made into chips. Heartwood is boiled in water in large earthen pots. The decoction is then strained and boiled in an iron pot with continuous stirring till it forms the syrupy mass. When the extract is cool enough, it is spread in the shallow wooden trays and kept for over night. When sufficiently dry, it is cut into pieces. Since the decoction is concentrated in iron vessels, the colour of the catechu becomes darker due to its reaction with iron salts. If the syrupy extract is stirred during cooling, it develops the shining crystals of catechin and produces translucent black catechu. Nowadays stainless steel vessels are used for the manufacture of catechu that produces a lighter coloured product.



 

Microscopy

 

A transverse section of A. catechu heartwood shows numerous uniseriate and biseriate medullary rays, with vessels occurring isolated or in small groups of two or four. Xylem fibres with narrow lumen occupy major portion of wood and xylem parenchyma is usually predominantly paratracheal, forming a sheath around vessels. Wood consists of crystal fibres having prismatic crystals of calcium oxalate. A few tracheids with scalariform thickening and some cells including vessels are also present.

 

Chemical Constituents

 

Cutch or black catechu resembles pale catechu or gambier in its composition. It contains about 2–12% of catechin and about 25 to 33% of phlobatannin catechutannic acid. The principle fraction of cutch has been identified as a mixture of catechin isomers which includes (-) epicatechin, acatechin, DL-acacatechin, L-acacatechin and D-isoacacatechin. It also contains 20–30% gummy matter, catechin red, quercetin and querecitin. It yields 2–3% of ash.


 

Chemical Tests

 

1.     Because of the presence of catechin, black catechu gives pink or red colour with vanillin and HCl.

 

2.     Catechin when treated with HCl produces phlorogucinol, which burns along with lignin to give purple or magenta colour. For this purpose, tannin extract is taken on match stick dipped in HCl and heated near the flame.

 

3.     Lime water when added to aqueous extract of black catechu gives brown colour, which turns to red precipitate on standing for some time.

 

4.     Green colour is produced when ferric ammonium sulphate is added to dilute solution of black catechu. By the addition of sodium hydroxide, the green colour turns to purple.

 

Uses

 

Cutch is used in medicine as astringent. It cures troubles of mouth, diseases of the throat and diarrhoea. It also increases appetite. In India and eastern countries, it is used in betel leaves for chewing. In dyeing industries, cutch I used for dyeing fabrics brown or black. It is also used in calico printing.

 

Marketed Products

 

It is one of the ingredients of the preparation known as Koflet lozenge (Himalaya Drug Company) as cough expectorant, and Gum tone (Charak Pharma Pvt. Ltd.).

 

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