Source, Etc

The nux vomica tree, Strychnos Nux-vomica, Linne (N.O. Loganiacoe). is a small tree widely distributed in India, and occurring also in Ceylon, Siam, and northern Australia. Notwithstanding the wide distribution of the tree, and the poisonous properties of the seeds, the Hindus appear to have been unaware of its medicinal action. It was introduced into Europe in the sixteenth century, but was not much used in medicine, being chiefly employed to poison dogs, cats, crows, etc.

Fig. 93.   Nux Vomica. A, corolla opened, magnified. B, ovary with style, magnified. C, ovary cut longitudinally, more highly magnified. D, ripe fruit, cut transversely, showing seeds; reduced to about one half. E, seed, entire, natural size: a, hilum; b, micropyle. F, the same, cut vertically: a, endosperm; b, radicle; c, cotyledon. (Luerssen.)

Fig. 93. - Nux Vomica. A, corolla opened, magnified. B, ovary with style, magnified. C, ovary cut longitudinally, more highly magnified. D, ripe fruit, cut transversely, showing seeds; reduced to about one-half. E, seed, entire, natural size: a, hilum; b, micropyle. F, the same, cut vertically: a, endosperm; b, radicle; c, cotyledon. (Luerssen).

The ripe fruit, which resembles an orange, contains usually from three to five seeds embedded in a bitter whitish pulp. The seeds are washed free from adhering pulp, dried in the sun and sorted. They are collected extensively in the Eastern Ghat mountains and in the Travancore hills, and are exported from various Indian ports (Madras, Bombay, Cochin, Coconada, &c).

Description

The seeds have the shape of small discs, 20 to 25 mm. in diameter and about 4 mm. thick, of an ash-grey or greenish grey colour, and possessing a distinct sheen. They are usually not quite flat, being a little depressed on one side and arched on the other, or sometimes irregularly bent. They are covered with numerous, closely appressed hairs, radiating from the centre to the circumference, to which the satiny sheen of the seeds is due. The edge of the seed is sometimes rounded, sometimes acute, according to the variety; at one point on the margin there is a distinct prominence (micropyle) from which a raised line passes to the centre of the seed. This line does not exist in the fresh seed, but makes its appearance during the drying; it has frequently been mistaken for the raphe. The hilum is in the centre of either the raised or depressed surface, and may be recognised by the scar left by the funicle.

The dry seed is hard and horny, but softens when soaked in water; it can then easily be split into two thinner discs, exhibiting the small embryo, consisting of a radicle and two leafy cotyledons, embedded in a copious, grey, translucent, horny endosperm.

The seeds are almost odourless, but have a persistent, intensely bitter taste.

The student should not fail to observe

(a) The characteristic shape and satiny appressed hairs,

(b) The horny endosperm and characteristic cotyledons.

(c) The bitter taste.

Microscopical Characters

The seed-coat is very thin and consists of a narrow layer of brown, collapsed parenchyma covered with an epidermis, the cells of which have developed into hairs. These are bent near the base and thus lie close to the surface of the seed. The base is thick-walled and marked with oblique pits; above it passes into a tubular hair bearing longitudinal rod-like thickenings. The endosperm consists of large cells with very thick walls which swell in boiling water or in solution of potassium hydroxide. These cells contain the alkaloids.

In powdered nux vomica the hairs are broken up into the thick-walled bases and rod-like fragments of the upper part.

Constituents

The principal constituents of nux vomica are the two alkaloids, strychnine and brucine, in addition to which they contain a small percentage of a glucoside, loganin, which is much more abundant in the pulp, and an acid that has been termed igasuric acid, but is probably identical with caffeotannic acid. The alkaloid strych-nicine which occurs in the leaves may also occur in minute quantity in the commercial drug (Boorsma, 1902). An alkaloid, struxine, has been obtained during the separation of strychnine from more or less decomposed Cochin-China seeds; it is probably not a normal constituent of the seeds.

The cell-wall of the endosperm, which is very thick, appears to consist of galactan and mannan, the former preponderating; it yields by hydrolysis galactose and marinose.

The seeds contain, further, about 3 per cent, of a viscous oil which appears to reside chiefly in the hairs. A trace of copper is also invariably present, and passes into solution when the seeds are exhausted with alcohol, giving rise to the green reaction often observed when the diluted tincture is mixed with ammonia.

The proportion of total alkaloid varies from 1.84 to 5.3 per cent., averaging in seeds of good quality about 2.8 per cent. This total alkaloid contains a variable proportion, ranging from 35 to 50 per cent, of strychnine, the average amount of strychnine in the drug being 1.23 per cent., and of brucine 1.55 per cent. As the toxicity of brucine is only one-eighth that of strychnine, the drug and its preparations are assayed for strychnine and not for the total alkaloid present.

Strychnine, C21H12N202, crystallises in colourless, odourless prisms melting at 265°, and having an intensely bitter taste, though very slightly soluble in water (1 in 7000). The hydrochloride crystallises in needles which are soluble in water, but less soluble in water acidified with hydrochloric acid.

Brucine, C23H16N204,4H10, is also crystalline and more soluble in water than strychnine (1 in 320); melting-point 178°; is probably dimethoxystrychnine.

Caffeotannic acid (chlorogenic acid) is also found in the leaves and seeds of Caffea arabica, Linne, and in other plants; exposed to the air in the presence of ammonia it turns green (viridic acid).

Action And Uses

Nux vomica is largely used as a bitter stomachic and tonic, its action being practically identical with (although slower than) that of the alkaloid strychnine. It stimulates the muscular coat of the intestine, increasing peristalsis, and hence is given in constipation from an atonic condition of the intestine. It increases the blood pressure, and is therefore valuable in certain cases of cardiac failure. In large doses the excitability of the motor nerve cells is so much increased that violent convulsions may occur; these involve the respiratory muscles, and death ensues from asphyxiation.

Note

The seeds of Strychnos potatorum, Linne, and of 8. Nux-blanda, Hill, have been offered as nux vomica. The former are smaller, thicker and free from bitterness; they are used in India for clearing turbid water. The latter closely resemble nux vomica, but may be distinguished by the small ridge on the edge; they are also free from bitterness (and consequently from strychnine and brucine).