257. Catechu. Gambir.
An extract prepared from the heart-wood of Aca'cia cat'echu Linné.
BOTANICAL CHARACTERISTICS.—Small tree with straggling, thorny branches, and compact, dark red wood. Leaves bipinnate; petiole angular, with prickles on its under side. Flowers pale yellow. Legume about three-seeded.
SOURCE.—The tree is common in most parts of India and Burmah, where the export of cutch forms, next to the sale of timber, the most important item of forest revenue. It abounds in the forests of tropical Eastern Africa, but in many places where the tree abounds it is only valued for its wood. In comparatively few regions is any extract manufactured. From Acacia suma, a nearly related species growing in Southern India, catechu is also made. The extract from these two species of acacia furnishes a variety of catechu, but a catechu formerly prescribed as Catechu pallidum (pale catechu), gambir, is official in the present Pharmacopoeia and is described as follows:
Related entry: Catechu pallidum
An extract prepared from the leaves and twigs of Ourouparia Gambir (Hunter) Baillon (Fam. Rubiaceae).
Irregular masses of cubes about 25 mm. in diameter; externally reddish-brown, pale brownish-gray or light brown; fracture dullearthy, friable, crystalline; inodorous, bitterish, very astringent with a sweetish af ter-taste.
Not less than 70 per cent. should be soluble in alcohol; the ash should not be more than 5 per cent., and starch should not be present.
CONSTITUENTS.—Mainly catechu-tannic acid, 45 to 55 per cent., which does not produce gallic acid on exposure to air as does the tannin of galls; it is turned blackish-green by ferric salts. Catechin is an interesting principle which, by dry distillation, yields pyrocatechin, or catechol, C6H6O2, which, with ferric chloride, gives a dark green color by ammonia changing to violet. Ash, not more than 9 per cent.
Preparation of Catechin.—On allowing the decoction of catechu to stand several days, crude catechin is deposited. This deposit is purified to white silky needles by dissolving in dilute alcohol, washing with ether, and evaporating from hot aqueous solution. It has a sweetish taste, is precipitated by albumen, but not by gelatin.
ACTION AND USES.—A powerful astringent like kino. Dose: 8 to 30 gr. (0.5 to 2 Gm.).
Tinctura Gambir Composita (5 per cent., with saigon cinammon 2.5 per cent.), Dose: 15 to 60 drops (1 to 4 mils)