This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
Cusparia bark is obtained from Galipea officinalis, Hancock (N.O. Rutaceoe), a tree indigenous to the mountains of Venezuela. It was introduced into European medicine about the end of the eighteenth century, being brought from Angostura (on the Orinoco) to Trinidad, whence its name 'Angostura' bark. It was long considered to be derived from Cusparia febrifuga, de Candolle, a tree closely allied to G. officinalis botanically, but characterised by the presence of calcium oxalate in rosettes, while in Galipea this takes the form of acicular crystals.
Cusparia bark occurs in somewhat thin curved or channelled pieces or single quills, usually about 8 or 10 cm. long and 1.5 to 3 mm. thick, but sometimes much longer, one of the longitudinal margins being frequently obliquely cut. The outer layer (cork) is sometimes buff-coloured, friable, and easily removed by the finger-nail, sometimes dark grey, thin and firmly adherent, a difference due to the alternate production of layers of thin and thick-walled cork cells.
Below the cork is a hard, dark brown middle layer (cortex), whilst the inner surface of the bark (bast) is of a cinnamon or chocolate brown colour and finely striated. This portion frequently exhibits a laminated structure and bears numerous minute short white lines, longitudinally arranged, which are usually easily visible under a lens, especially after the inner surface has been smoothed with a knife. They are caused by axially elongated cells filled with acicular crystals of calcium oxalate. Similar white masses of calcium oxalate may be seen on the smoothed radial and transverse sections.
The fracture is short and resinous, the transverse section exhibiting a whitish cork, a yellowish brown cortex, and, in the bast, yellowish oblique or wavy medullary rays alternating with darker bast-rays. Throughout both cortex and bast numerous cells filled with white crystals of calcium oxalate, as well as minute dark ones filled with oil, may be distinguished under the lens.
Fig. 118. - Cusparia bark, showing buff spongy cork and obliquely cut edges. Natural size.
A transverse section examined under the microscope shows a cork varying in thickness and in the nature of the cells, layers with thin-walled cells alternating with thick-walled. The primary cortex usually contains but few sclerenchymatous cells; when present they are generally near the cork and probably belong to the phelloderm. The secondary bast contains occasional tangentially elongated groups of bast fibres and slender axially elongated prisms of calcium oxalate. All the tissues except the cork contain small oil-cells with droplets of yellowish oil, and tangentially elongated cells filled with acicular crystals of calcium oxalate.
The bark has an unpleasant musty odour and a bitter taste. The student should observe
(a) The cork, which is often spongy,
(b) The laminated inner portion,
(c) The calcium oxalate,
(d) The characteristic odour.
The bitterness of cusparia bark is due chiefly to angosturin, C9H1205, a substance that has been obtained in colourless pulverulent crystals melting at 58°, easily soluble in water, alcohol, and ether. The bark also contains a number of alkaloids (2.4 per cent.), - viz. galipine, cusparine, galipoidine, and a fourth which has not yet been closely examined. A glucoside yielding by hydrolysis a fluorescent substance is also present. By distillation the drug yields about 1.5 per cent. of an aromatic volatile oil, the most important constituent of which is the aromatic sesquiterpene alcohol, galipol. Cusparidine and galipidine, alkaloids reported to be present, are probably mixtures of galipine and cusparine.
Fig. 119. - Cusparia bark. Transverse section, showing oil-cells and groups of bast-fibres. Magnified. (Planchon and Collin).
Fig. 120. - Nux Vomica bark. Transverse section, showing band of sclerenchymatous cells. Magnified. (Planchon and Collin).
Cusparine, C20H19NO3, forms colourless needles or compact crystalline masses, readily soluble in alcohol, ether, and chloroform; its salts are sparingly soluble in water.
Galipine, C20H11NO3, crystallises in colourless needles, but yields deep yellow salts.
Cusparia belongs to the group of aromatic bitters. It formerly had a high reputation as a febrifuge and tonic, being preferred to cinchona bark on account of its freedom from astringency.
The accidental substitution in Hamburg in 1804 of the bark of Strychnos nux-vomica, Linne, for cusparia bark led to several cases of poisoning. Such a substitution or admixture is not likely to occur again, and would moreover be easily detected, as the barks do not bear much resemblance to one another. Nux vomica bark is harder and thicker; it occurs in small, often recurved, pieces, with dark greyish, yellowish, or rusty-red cork, usually bearing numerous greyish warts. The dark transverse section exhibits under the lens a distinct paler line of sclerenchymatous cells separating the cortex from the bast; this line of sclerenchymatous cells is never found in cusparia bark.
Brazilian Angostura bark; Esenbeckia febrifuga, A. Jussieu (N.O. Rutaceoe); greyish brown with reddish brown patches; internally brown; taste bitter.