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.
The yellow jasmine, Gelsemium nitidum, Michaux (G. sempervirens, Aiton) (N.O. Loganiaceoe), is an elegant climbing plant indigenous to the southern United States; it ascends lofty trees and forms festoons, scenting the atmosphere with its fragrant yellow flowers. It has long been known, but its medicinal use is of recent date. The rhizome and roots should be collected in the autumn.
This plant should not be confounded with Jasminum nudiflorum, Lindley, a yellow-flowering jasmine commonly cultivated in this country.
The drug consists of the rhizomes, to which portions of both slender aerial stems and small and large roots are sometimes attached; usually the rhizomes and larger roots, cut into pieces about 15 cm. in length, constitute the commercial drug.
The rhizomes are generally in nearly straight cylindrical pieces varying from 5 to about 20 mm. in thickness, of a dark purplish brown colour, or at least marked with a more or less distinct network of purplish lines, the intervening spaces being yellowish brown. This difference in colour is due to the fact that the outer cork-cells are filled with a dark reddish brown substance, the inner with a yellowish deposit; by the growth of the rhizome the outer dark layer is fissured, disclosing the paler inner layer. The rhizomes are hard and woody, and break with an irregular splintery fracture, frequently exhibiting in the bast silky fibres, which, however, are much more conspicuous in the aerial stems.
The roots are, on the average, rather smaller than the rhizomes; they may be distinguished by their uniform yellowish brown colour and finely wrinkled surface, and by their rather more sinuous course.
The aerial stems are usually slender, but may attain 15 mm. in-thickness. They are of a dark purplish brown colour, longitudinally wrinkled or nearly smooth, internally whitish and hollow in the centre. The fractured bark exhibits projecting strands of bast fibres.
Both rhizome and root exhibit in transverse section a comparatively narrow bark enclosing a large yellowish white wood; the latter consists of narrow wood-bundles with small vessels alternating with distinct, straight, whitish medullary rays, the section thus assuming an elegant radiate appearance. The section of the rhizome is distinguished from that of the root by the presence of a small pith, which, however, is more evident in the smaller (younger) than in the larger (older) pieces; it differs also from that of the aerial stem in the arrangement of the fibres in the bark; in the stem these are grouped into bundles, whilst in the rhizome they form an interrupted ring of isolated fibres or groups of two or three (Sayre, 1897).
The drug has a bitter taste, especially conspicuous in the bark, and a very slight aromatic odour.
The student should observe
(a) The splintery fracture,
(b) The radiate structure of the transverse section,
(c) The purplish colour and small pith of the rhizome,
(d) The yellowish colour and slightly tortuous appearance of the root.
Gelsemium rhizome contains three alkaloids, one only of which, gelsemine, has been obtained crystalline, the others (gelsemi-nine and gelsemoidine) being amorphous. Other constituents are β-methylgesculetin, emodin monomethyl ether, phytosterol, resin and fixed oil.
Gelsemine, C20H12N2O2, has been reported to owe any toxicity it may possess to the presence of accompanying gelseminine but this has been denied; both of the amorphous alkaloids are strongly toxic.
β-methylaesculetin, C9H5(CH3)04 (gelsemic or gelseminic acid, scopoletin, chrysatropic acid), is a product of the hydrolysis of methyl-aesculin, aesculin being a fluorescent substance found in horse-chestnut bark. β-methylaesculetin is present in belladonna root and in scopola rhizome; in alkaline solution it exhibits an intense bluish green fluorescence, and its presence in the drug may easily be demonstrated by shaking a little of the powder with lime water or, better, by shaking with chloroform, filtering and shaking the filtrate with very dilute solution of ammonia.
Gelsemine must be carefully distinguished from gelsemin, which is a powdered alcoholic extract.
Gelsemium resembles hemlock in action but is more strongly depressant. It has been much used for, and appears to relieve, certain forms of neuralgia and sick headache as well as rheumatic and ovarian pains.