Catechu (U. S. P.)—Catechu.
"An extract prepared from the wood of Acacia Catechu (Linné filius) Willdenow"—(U. S. P.). (Mimosa Catechu).
COMMON NAMES: Catechu, Black catechu, Cutch.
ILLUSTRATION: Bentley and Trimen, Med. Plants, 95.
Botanical Source.—Acacia Catechu is a small-sized tree, from 15 to 20 feet high. The bark is thick, scabrous, rust-colored, slightly bitter, and exceedingly astringent; the branches are spreading, armed with strong, black, stipulary spines, and downy toward their extremities. The leaves are bipinnate; pinnae 10 to 20 pairs; leaflets 30 to 50 pairs, linear, bluntish, unequal, and auricled on the lower side of the base, and ciliated; the petiole angular, and channeled above, downy, with 1 orbicular urceolate green gland below the lowest pair, smaller ones between the two, and has 3 or 4 terminal pairs of pinnae. The spikes are axillary, 1 or 2 together, slender, cylindrical, and borne on downy stalks. The flowers are numerous, white or pale-yellow, and sessile. The calyx is downy, tubular, and 5-toothed; the teeth erect. Corolla rather longer than the calyx, 5-petaled, and glabrous. Stamens twice the length of the corolla, very numerous and distinct, anthers roundish. The ovary is green, glabrous, and shortly stipitate; the style capillary, and as long as the Stamens; stigma simple. The legumes are flat, linear, thin, straight, glabrous, and contain about 6 orbicular, compressed seeds (L.).
History.—The catechu tree is common to the East Indian continent, thriving in Bengal, on the Coromandel and Malabar coasts, etc., and, according to Pereira, in Jamaica. According to Dr. Royle, the extract (catechu), is prepared by concentrating a strong aqueous decoction of the reddish inner wood, and pouring it into square clay molds to dry. Catechu is likewise obtained from the Areca Catechu (see Areca), and Uncaria Gambier (see below). There are several kinds of it met with in commerce, but the best are those which are the most astringent. It was named Terra japonica at a time when its source was unknown, the general belief being that it came from Japan.
Description and Tests.—Catechu is met with in square, round, and irregular pieces, pale-red, pale-brown, dark-brown, or blackish in color, friable, odorless, astringent, and sometimes having a sweetish after-taste. The specific gravity of catechu is 1.28 to 1.39. It is soluble in hot water, which takes up its tannic and catechuic acids, but a reddish matter is deposited as the solution cools. It is imperfectly soluble in cold water. The tannic acid of catechu is easily soluble in water and alcohol, but very slightly so in ether. Alcohol or ether dissolves its catechuic acid. Its solutions are not precipitated by alkalies. The official catechu is described as occurring "in irregular masses, containing fragments of leaves, dark-brown, brittle, somewhat porous and glossy when freshly broken. It is nearly inodorous, and has a strongly astringent and sweetish taste. If a portion of catechu be digested with 10 times it weight of alcohol, and the liquid filtered, the undissolved matter, after being dried at 100° C. (212° F.), should not exceed 15 per cent of the original weight. The tincture, diluted with 100 parts of water, acquires a green color on the addition of ferric chloride T.S. If 2 parts of catechu be boiled. with 20 parts of water, a brownish-red, turbid liquid will be obtained which turns blue litmus paper red. Upon incineration, catechu should not leave more than 6 per cent of ash"—(U. S. P.). Catechu is incompatible with solutions of the pure earths, with sulphuric or hydrochloric acid, salts of aluminum, lead, copper, and with ferric salts; also with gelatin, opium, cinchona, and those salts of the vegetable alkaloids which form insoluble salts with tannin.
Chemical Composition.—Successive treatment of catechu with ether and absolute alcohol abstracts the two principal constituents, namely, from 13 to 33 per cent of crude catechin, also called catechuic acid, and from 22 to 50 per cent of a peculiar tannic acid, called catechu-tannic acid. Besides there are present water-soluble extractive matter, gum, and mineral substances. Catechin is not soluble in cold water. When pure, it forms minute, colorless crystals, which are acted on by alkalies, causing them to absorb oxygen, giving a yellow, then red, and finally a black color. Its formula is variously given as C19H18O8 (Hlasiwetz), C21H18O9 (Gautier), C18H12O5 (Rochleder), C21H20O9+5H2O (Liebermann and Tauchert). When subjected to dry distillation, it yields pyrocatechin (C6H6O2), while phloroglucin and protocatechuic acid are produced by fusing it with caustic potash. By the action of sulphuric acid, catechuretin is produced.
The catechu-tannic acid of catechu, sometimes termed mimmotannic acid and catechu-red, differs from ordinary tannic acid by giving a greenish-gray precipitate with the iron salts, by not precipitating a solution of tartar emetic, and by not furnishing pyrogallic acid on exposure to heat. It is an amorphous, deep-red powder, dissolving in alcohol, alcoholized ether, and water, but little soluble in absolute ether, and is regarded as an anhydrid of catechin.
Quercetin was obtained from the aqueous solution of catechu by means of ether, by Löwe, in 1873.
Pyrocatechin (C6H6O2), or catechol, may be obtained from many tannins and extracts by means of destructive distillation. It forms short, prismatic crystals, readily soluble in water, ether, and alcohol. Ferric chloride colors its solution in water a deep green, which, when treated with sodium bicarbonate, ammonia, or tartaric acid, changes to a violet hue. Catechol fuses at 104° C. (219.2° F.). Its boiling point is 245° C. (473° F.). Its methylic ether is guaiacol. Certain gum-resins, resins, and tannins, when fused with caustic potash, produce protocatechuic acid (C7H6O4) (dioxybenzoic acid). It forms shining, acicular crystals, or may form scales, readily soluble in hot water, alcohol, and ether. When heated above 199° C. (390.2° F.) it is resolved into pyrocatechin and carbonic acid gas. When treated with ferric chloride its aqueous solution gives a deep-green color, changing successively to blue and red by sal soda solution much diluted.
Action, Medical Uses, and Dosage.—Catechu possesses strong astringent properties. It is used for arresting mucous discharges when excessive, for removing relaxation or congestion of mucous membranes, and for checking hemorrhages. In chronic diarrhoea, chronic catarrh, colliquative diarrhoea, and chronic dysentery, it has proved beneficial, especially when combined with opium. As a local application, it is a valuable agent for removing cynanche tonsillaris, aphthous ulcerations of the mouth, elongation of the uvula, and relaxation and congestion of the mucous membrane of the fauces, especially of the kind to which public singers are subject; it is also useful in congestion, tenderness and sponginess of the gums, particularly when the result of mercurial ptyalism. The tincture of catechu is often beneficial in fissure of the nipples, when applied twice a day with a fine hair pencil. An ointment composed of 4 ounces of catechu, 9 drachms of alum, 4 ounces of white resin, and 10 fluid ounces of olive oil, with a sufficient quantity of water, is in great repute in India as an application to ulcers (Thomson, Lond. Dis.). Chronic and phagedenic ulcers are frequently benefited by the application of catechu to them. Chronic gonorrhoea, old gleets, and fluor albus, as well as hemorrhage from the nose and other parts, have been cured by the local application of an aqueous solution of catechu. Powdered catechu may be given in a dose of from 5 to 20 grains, or more, repeated as often as required; it may be administered in pill form, in syrup, or in gum mucilage. The dose of the tincture is from 20 minims to ½ fluid ounce. Dr. E. Hopkins states that catechu is not incompatible with opium and quinine, as no precipitate ensues when their respective solutions are united. He recommends, in diarrhoea, a compound of catechu 10 grains, opium 1 grain, sulphate of quinine 2 grains; mix, and make into 1 or 2 powders, according to the urgency of the case. CATECHU PALLIDUM (see below), has similar properties, but is less astringent.
Related Drugs.—CATECHU PALLIDUM. Pale catechu (Catechu of Br. Ph.).—This is also known as Terra Japonica, Gambir, Gambier, and Gambeer. Pale catechu is the official catechu of the British Pharmacopoeia, and one of the official kinds of the German Pharmacopoeia. It is extracted from the young leaves and shoots of Uncaria Gambier, Roxburgh (Nauclea Gambir, Hunter). Nat. Ord.: Rubiaceae. This is a climbing plant bearing pink flowers, and grows in Sumatra, Ceylon, and in the countries bordering the straits of Malacca. At Singapore it is extensively cultivated. A species thought to be a variety, Uncaria acida, Roxburgh, also furnishes a portion of pale catechu. Gambier is prepared by boiling the fresh young twigs and leaves for 1 hour, after which they are taken out and placed in a trough which allows the decoction to flow back into the boiling pan, and the liquor from the exhausted shoots and leaves is squeezed out by hand. The fluid is then evaporated to a thin, syrupy consistence, and dipped into vessels to cool, and instead of stirring round and round, the operator passes a soft piece of wood in and out of the liquid, in a sloping manner. This, he asserts, will cause it to thicken when ordinary stirring will have no effect on it. It is then poured into shallow, rectangular molds, and allowed to harden sufficiently to be cut into cubical blocks to be dried in a shady situation (see Pharmacographia). Gambier is an earthy-appearing mass of pale-brown color. It occurs in small cubes, or may come in irregular, compact masses. It is lighter in color than cutch, which it resembles, and when broken (for it is porous, dry, and friable), it presents an irregular surface of an earthy, brownish-gray hue, interspersed with darker streaks. It is odorless, but has a bitter, astringent, and afterwards sweetish taste. The microscope shows it to be made up of minute, crystalline needles. It dissolves in alcohol, giving a deep-brown solution. Water does not dissolve it wholly, and with hot water a turbid mixture is produced. Impurities to the extent of 15 per cent of the whole weight are allowed by the German Pharmacopoeia. The same work limits its ash to not more than 6 per cent. Its chemical composition agrees with that of cutch (catechu), the proportion of tannin being less than in the latter. The coloring principle is quercetin and the chief constituent is catechin, which gives to it a crystalline appearance. Quinovic acid is probably present in gambir, having been found in other species of Nauclea. It contains from 25 to 38 per cent of tannin, and from 20 to 29 per cent of catechin. The ash consists largely of calcium and magnesium carbonates (Pharmacographia). Prof. Trimble (Am. Jour. Pharm., 1888) making a comparative determination of catechin, catechu-tannic acid and other constituents in 3 representative samples each, of cutch and of gambier, finds a decidedly higher percentage of available tannin in gambier than in cutch. He therefore recommends the official use of gambier in preference to cutch for several reasons: Gambier, as he finds, has more available astringency, and being put up in the form of cubes, can not be so easily adulterated, and is not liable to contain mordants added for the use of dyers.