The fruit of Terminalia Chebula, Retzius; Myrobalanus Chebula, Gaertner.
COMMON NAME: Myrobalans.
Botanical Source.—Terminalia Chebula is a tree whose trunk towers from 40 to 70 feet, its verticillate branches giving the tree a symmetrical head. The leaves are short-petioled, alternate, entire, or slightly dentate, arranged on the ends of the branches (hence the name Terminalia), coriaceous and spotted. The 10-stamened flowers are white or yellowish, and borne in racemes or spikes. The fruit is a drupe about the size of a large plum.
History.—Several other species yield commercial myrobalans, but the fruit is almost unknown in Western commerce. In India and China, where the species are indigenous, the fruit is highly valued for almost every ill that flesh is heir to. The hard wood takes a fine polish and is useful in cabinet work. The creamy, fragrant juice of the T. angustifolia, Wight, when dried, is used in Indian temple worship as an incense. The tree is regarded sacred, and has interesting historical and mythological connections. The celebrated India Ink is the product of the bark and leaves of T. cattapa, Linné. All the species yield a tanning bark. The leaves, bark, and fruit yield a dye, which with iron gives a rich black, and with alum a fine yellow color.
Description.—Chebula myrobalans are ovoid or oblong, about the size of the prune, yellow-brown, marked with 5 or 6 obtuse angles, and ribbed. The light-brown endocarp is resin-dotted. The single seed is white. The Myrobalani citrinae, or Yellow myrobalans, are smaller, orange or yellow-hued, and of a more pronounced bitter taste. They have been sold as white galls. The unripe fruit is known as Myrobalani nigrae, or Black myrobalans. They are blackish, shrivelled and brittle, glossy on fracture, and contain either none or an imperfect seed. They are astringent and somewhat sour.
Chemical Composition.—The fruit, as well as all other parts of the tree, contains tannin. According to E. Mafat (Pharm. Jour. Trans., Vol. XXIII, 1892, p. 145), the amount of tannin in chebulic myrobalans varies from 18.2 to 52 per cent. Stenhouse (1843) found 45 per cent of tannin, gallic acid, mucilage, and a brown-yellow coloring matter. The black variety contains much sugar. Apéry, (1888) isolated from black myrobalans a green oleoresin soluble in alcohol, ether, petroleum spirit, and oil of turpentine. He named it myrobalanin. A. Campbell Stark (Pharm. Jour. Trans., 1892, Vol. XXIII, p. 253) making a complete analysis of myrobalans, observed the same oil and obtained only 20.6 per cent of tannin. Dr. G. Zölffel (Archiv der Pharm., 1891, p. 123) found the tannin matter of myrobalans to be identical with that of algarobilla, the astringent fruit of Caesalpinia brevifolia, Bentham, a Chilenian plant. It consists of two principles which differ in both plants only with regard to their relative proportions. Accordingly, the tannin matter of myrobalans is a mixture of predominating ellaggen-tannic acid (C14H10O10, Loewe, 1875, or C6H2.COOH.[OH]2.O.O.CO.C6H2[OH]3, Zölffel), and a smaller quantity of gallic acid glucosid, yielding, upon hydrolysis, gallic acid and dextrose. Gallic acid also preexists in part in myrobalans. Ellaggen-tannic acid, isolated by Loewe (1875) from the fruits of Caesalpinia Coriaria, Willdenow (Divi-divi), as well as from myrobalans, decomposes, upon hydrolysis, into water and ellagic acid (C14H6O8+2H2O). Fridolin's crystallizable chebulinic acid (1884), upon hydrolysis, splits into 2 molecules of gallic, and 1 molecule of tannic acid. It is no doubt closely related to the tannic principles aforenamed.
Action, Medical Uses, and Dosage.—Myrobalans were known to the ancients who appear to have valued them highly in innumerable complaints for which they are never now employed. They impart a green color to the saliva, and have an astringent, sourish taste. Like rhubarb, they have been found to possess both cathartic and astringent properties (Apéry), and are reputed of some value in the chronic forms of diarrhoea, dysentery, and catarrhal diseases of the bowels. The dose is from 2 to 5 grains, in pill or capsule, every 2 to 4 hours.
Other Myrobalans.—BELLERIC MYROBALANS. Subglobular, smaller than the chebulic myrobalans, short-stalked, tomentose, and of a red-brown color. The putamen is light-brown, 5-sided, odorless, bitter, and astringent. The fleshy part of the fruit is resinous. It is the product of Terminalia bellerica, Roxburgh (see its analysis in Pharmacographia Indica, Vol. II, 1890, p. 7). Several other species of Terminalia yield astringent barks and and employed in tanneries.
EMBLIC MYROBALANS.—This is furnished by an entirely different plant from the Terminalia, the Phyllanthus Emblica, Linné (Emblica officinalis Gaertner); Nat. Ord.—Euphorbiaceae. India. Subglobular, drupaceous fruit, having 6 grooves, deeply furrowed between grooves, 3-celled, each cell enclosing 2 glossy, brownish-red seeds. The taste of this fruit is astringent and sour.