RUTACEÆ.
CORTEX ANGOSTURÆ.
Cortex Cuspariæ; Angostura Bark, Cusparia Bark, Carony Bark; F. Ecorce d’Angusture de Colombie; G. Angostura-Rinde.
Botanical Origin—Galipea Cusparia St. Hilaire (G. officinalis Hancock, Bonplandia trifoliata Willd., Cusparia trifoliata Engler 1874, Flora Brasil. 113), a small tree, 12 to 15 feet high, with a trunk 3 to 5 inches in diameter, growing in abundance on the mountains of San Joaquin de Caroni in Venezuela, between 7° and 8° N. lat., also according to Bonpland[419] near Cumana. According to Hancock,[420] who was well acquainted with the tree, it is also found in the Missions of Tumeremo, Uri, Alta Gracia, and Cupapui, districts lying eastward of the Caroni and near its junction with the Orinoko. The bark is brought into commerce by way of Trinidad.
History—Angostura Bark is said to have been used in Madrid by Mutis as early as 1759[421] (the year before he left Spain for South America,) but it was certainly unknown to the rest of Europe until much later. Its real introducer was Brande, apothecary to Queen Charlotte, and father of the distinguished chemist of the same name, who drew attention to some parcels of the bark imported into England in 1788.[422] In the same year a quantity was sent to a London drug firm by Dr. Ewer of Trinidad, who describes it[423] as brought to that island from Angostura by the Spaniards. The drug continued to arrive in Europe either by way of Spain or England, and its use was gradually diffused. In South America it is known as Quina de Caroni and Cascarilla del Angostura.
Description—The bark occurs in flattish or channelled pieces, or in quills rarely as much as 6 inches in length and mostly shorter. The flatter pieces are an inch or more in width and ⅛ of an inch in thickness. The outer side of the bark is coated with a yellowish-grey corky layer, often soft enough to be removeable with the nail, and then displaying a dark brown, resinous under surface. The inner side is light brown with a rough, slightly exfoliating surface indicating close adhesion to the wood, strips of which are occasionally found attached to it; the obliquely cut edge also shows that it is not very easily detached. The bark has a short, resinous fracture, and displays on its transverse edge sharply defined white points, due to deposite of oxalate of calcium. It has a bitter taste and a nauseous musty odour.
Microscopic Structure—The most striking peculiarity is the great number of oil-cells scattered through the tissue of the bark. They are not much larger than the neighbouring parenchymatous cells, and are loaded with yellowish essential oil or small granules of resin. Numerous other cells contain bundles of needle-shaped crystals of oxalate of calcium or small starch granules. The liber exhibits bundles of yellow fibres, to which the foliaceous fracture of the inner bark is due. The structure of the bark under notice has been very minutely described and figured by Oberlin and Schlagdenhauffen.[424]
Chemical Composition—Angostura bark owes its peculiar odour to an essential oil which it was found by Herzog[425] to yield to the extent of ¾ per cent. It is probably a mixture of a hydrocarbon (C₁₀H₁₆) with an oxygenated oil. Its boiling point is 266° C. Oberlin and Schlagdenhauffen obtained 0·19 per cent. of the oil, and found it to be slightly dextrogyre; it assumes a fine red colour when shaken with aqueous ferric chloride, and turns yellow with concentrated sulphuric acid.
The bitter taste of the bark is attributed to a substance pointed out in 1833 by Saladin and named Cusparin. It is said to be crystalline, neutral, melting at 45° C., soluble in alcohol, sparingly in water, precipitable by tannic acid. The bark is stated to yield it to the extent of 1·3 per cent. Herzog endeavoured to prepare it but without success, nor have Oberlin and Schlagdenhauffen met with it. The latter chemists, on the other hand, isolated an alkaloid Angosturine C₁₀H₄₀NO₁₄. It is in thin prisms, melting at 85° and yielding a crystallized chlorhydrate or sulphate. Angosturine turns red when touched with concentrated sulphuric acid, or green if nitric acid or iodic acid, or other oxydizing substances, have been previously mixed with the sulphuric acid. The alcoholic solution of the alkaloid is of decidedly alkaline reaction. A cold aqueous infusion of angostura bark yields an abundant red-brown precipitate with ferric chloride. Thin slices of the bark are not coloured by solution of ferrous sulphate, so that tannin appears to be absent.
Uses—Angostura bark is a valuable tonic in dyspepsia, dysentery and chronic diarrhœa, but is falling into disuse.