Catechu. Catechu pallidum. Catechu nigrum. Black Catechu.
CATECHU [Catechu Pallidum]
"Catechu is an extract of the leaves and young shoots of Uncaria Gambier, Roxb." Br.
Catechu is described in the Br. Pharm., 1914, as follows: "In cubes, sometimes more or less agglutinated, each side measuring about twenty-five millimetres. Dark reddish-brown externally, pale cinnamon-brown internally, porous and friable. When examined under the microscope they are found to consist chiefly of minute acicular crystals. No odor; taste at first bitter and very astringent, but subsequently sweetish. Almost entirely soluble in boiling water. Not less than 80 per cent. is soluble in alcohol (90 per cent.); the alcoholic solution made strongly alkaline with solution of sodium hydroxide and shaken with petroleum spirit imparts to the latter a brilliant green fluorescence (distinction from Black Catechu); the residue insoluble in alcohol (90 per cent.) exhibits no starch grains when examined under the microscope. Ash not more than 5 per cent.; ash of the powder not more than 8 per cent." Br.
CATECHU NIGRUM. Br.
Related entry: Gambir
"Black Catechu is an extract prepared from the wood of Acacia Catechu, Willd." Br.
Cutch, Cachou, Fr.: Phgu, Katechu, G; Caticu, Catto, It.; Catecu, Sp.; Cutt, Hindostanee.
The U. S. P. (8th Rev.) dismissed catechu and introduced gambir because of the greater uniformity in quality of the latter. See Gambir.
The U. S. P. 1890 defined catechu as "an extract prepared from the wood of Acacia Catechu (Linné fil.) Willdenow (Fam. Leguminosae)."
Acacia Catechu is a small tree, seldom more than twelve feet in height, with a trunk one foot in diameter, dividing towards the top into many close branches, and covered with a thick, rough, brown bark. This species of Acacia is a native of the East Indies, growing abundantly in various provinces of Hindostan, and in the Burmese Empire. It is also common in eastern Africa where it is valued for its wood; but no extract appears to be made from it. Pereira says that its is common in Jamaica.
This drug had been long known before its source was discovered. It was at first called Terra japonica, under the erroneous impression that it was an earthy substance derived from Japan. When ascertained by analysis to be of vegetable origin, it was generally considered by writers on the Materia Medica to be an extract of the betel nut. Its true origin was made known by Kerr, assistant surgeon of the civil hospital in Bengal. According to Kerr, the manufacturer, having cut off the exterior white part of the wood, reduces the interior brown or reddish-colored portion into chips, which he then boils in water in unglazed earthen vessels until all the soluble matter is dissolved. The decoction thus obtained is evaporated first by artificial heat, and afterward in the sun, until it has assumed a thick consistence, when it is spread out to dry upon a mat or cloth, being, while yet soft, divided by means of a string into square or quadrangular pieces. The account subsequently given by Royle, of the preparation of the extract in Northern India, is essentially the same. The process, as he observed it, was completed by the pouring of the extract into quadrangular earthen moulds. It is said that the unripe fruit and leaves are also sometimes submitted to decoction. Three colors of catechu are prepared; the light red or red, which is considered best and is especially employed in Burma and India to chew with the betel nut; the dark red and black, which are made especially for European and American markets, and which are apt to suffer adulteration en route in China.
The name catechu in the native language signifies the juice of a tree, and appears to have been applied to astringent extracts obtained from various plants. Commerce is chiefly supplied with catechu from Bahar, Northern India, and Nepaul through Calcutta, from Canara through Bombay, and from the Burmese dominions. It is frequently called cutch by the English traders, a name derived from the Hindostanee word cutt.
It enters commerce in large masses, sometimes of one cwt., consisting of layers of flat cakes, frequently wrapped in the leaves of the Dipterocarpus tuberculatus Roxb. In this form, however, we do not see it in drug stores, but almost always in angular, irregular fragments, in which portions of two layers sometimes cohere with leaves between them, indicating their origin. It is characterized by its compactness, shining fracture, and blackish-brown or dark port-wine color, so that when finally broken it bears considerable resemblance to kino. This is an excellent variety of catechu.
Catechu is inodorous, with an astringent and bitter taste, followed by a sense of sweetness. It is brittle, and breaks with a fracture which is rough in some specimens, in others uniform, resinous, and shining. That which is preferred in our market is of a dark color, easily broken into small angular fragments, with a smooth. glossy surface, bearing some resemblance to kino. Catechu is often mixed with sand, sticks, and other impurities.
Black catechu is described in the Br. Pharm., 1914, as follows: "In irregular masses of a dark brown color; brittle, having a porous, glossy, somewhat conchoidal fracture. Partially soluble in cold water, almost entirely soluble in boiling water. Not less than 60 per cent. is soluble in alcohol (90 per cent.). No odor; taste sweetish, astringent. Its dilute aqueous solution gives a dark green color with T. Sol. of ferric chloride, changing to purple when made slightly alkaline with solution of sodium hydroxide. Ash not more than 5 per cent.; ash of the powder not more than 8 per cent. In India, in the Eastern, and in the North American Divisions of the Empire, Black Catechu may be employed in making the official preparations for which Catechu is directed to be used." Br.
The proportion of tannic acid, which may be considered the efficient principle, varies from about 45 to 55 per cent. in catechu or cutch, and from 36 to 40 per cent. in gambir. The portion designated by Davy as extractive is said to contain, if it does not chiefly consist, of a principle discovered by Buchner, and now called catechin, catechuin, or catechuic acid, to which Etti gives the formula C18H18O8, and catechu red, C36H34O15, which is evidently the first anhydride of catechin. The catechu tannic acid is of the variety which precipitates iron of a greenish-black color, and differs from most of the other varieties in not yielding grape sugar when digested with diluted sulphuric acid. It is not, therefore, a glucoside. It precipitates gelatin, but not tartar emetic (Kane), and is not, like the tannic acid exposure of galls, converted into gallic acid by the access of the air. Catechu is almost wholly soluble in a large quantity of water, to which it imparts a brown color. The extractive or catechuic acid is much less soluble than the astringent principle, which may be almost entirely separated from it by the frequent application of small quantities of cold water. Boiling water dissolves it much more readily than cold, and deposits it of a reddish-brown color upon cooling. Both principles are readily dissolved by alcohol or proof spirit, and also by ether.
De Meyer affirms that the best method of detecting adulteration of catechu is to treat the suspected drug with ether. Catechu of good quality, after repeated treatment with ether, loses 53 per cent. of its weight, and the dried residue weighs only 47 per cent. of the catechu employed. If this be exceeded, the drug must be proportionately impure. (J. P. C., June, 1870, 479.) A. Jossart (J. P. A., 1881, 41) examined a catechu which was adulterated with from 60 to 65 per cent. of ferrous carbonate. For methods of assaying catechu and gambir, see Trimble's The Tannins, 43; also Ph. Rev., 1897, 27. (See also Gambir, p. 507, and U. S. D., 19th ed., p. 1436.)
Catechu is used for the same purposes and in the same proportions as Gambir, see page 507.
Dose, five to fifteen grains (0.3-1.0 Gm.).