GENTIANEÆ.
RADIX GENTIANÆ.
Gentian Root; F. Racine de Gentiane; G. Enzianwurzel.
Botanical Origin—Gentiana lutea L., a handsome perennial herb, growing 3 feet high, indigenous to open grassy places on the mountains of Middle and Southern Europe. It occurs in Portugal, Spain, the Pyrenees, in the islands of Sardinia and Corsica, in the Apennines, the mountains of Auvergne, the Jura, the Vosges, the Black Forest, and throughout the chain of the Alps as far as Bosnia and the Danubian Principalities. Among the mountains of Germany, it is found on the Suabian Alps near Würzburg, and here and there in Thuringia, but not further north, nor does it occur in the British Islands.
History—The name Gentiana is said to be derived from Gentius, a king of the Illyrians, living b.c. 180-167, by whom, according to both Pliny and Dioscorides, the plant was noticed. Whether the species thus named was Gentiana lutea is doubtful. During the middle ages, gentian was commonly employed for the cure of disease, and as an antidote to poison. Tragus in 1552 mentions it as a means of diluting wounds, an application which has been resorted to in modern medical practice.
Description—The plant has a cylindrical, fleshy, simple root, of pale colour, occasionally almost as much as 4 feet in length by 1½ inches in thickness, producing 1 to 4 aerial stems.
The dried root of commerce is in irregular, contorted pieces, several inches in length, and ½ to 1 inch in thickness; the pieces are much wrinkled longitudinally, and marked transversely, especially in their upper portion, with numerous rings. Very often they are split to facilitate drying. They are of a yellowish-brown; internally of a more orange tint, spongy, with a peculiar, disagreeable, heavy odour, and intensely bitter taste. The crown of the root, which is somewhat thickened, is clothed with the scaly bases of leaves. The root is tough and flexible,—brittle only immediately after drying. We found it to lose in weight about 18 per cent.; by complete drying in a water-bath it regained 16 per cent. by being afterwards exposed to the air.
Microscopic Structure—A transverse section shows the bark separated by a dark cambial zone from the central column; the radial arrangement of the tissues is only obvious in the latter part. In the bark, liber-fibres are wanting; and in the centre there is no distinct pith. The fibro-vascular bundles are devoid of thick-walled ligneous prosenchyme; this may explain the consistence, and the short even fracture of the root. It is moreover remarkable on account of the absence both of starch and oxalate of calcium; the cells appear to contain chiefly sugar and a little fat oil.
Chemical Composition—The bitter taste of gentian is due to a substance called Gentiopicrin or Gentian-bitter, C₂₀H₃₀O₁₂. Several chemists, as Henry, Caventou, Trommsdorff, Leconte and Dulk have described the bitter principle of gentian in an impure state, under the name of Gentianin, but Kromayer in 1862 first obtained it in a state of purity. Gentiopicrin is a neutral body crystallizing in colourless needles, which readily dissolve in water. It is soluble in spirit of wine, but in absolute alcohol only when aided by heat; it does not dissolve in ether. A solution of caustic potash or soda forms with it a yellow solution. Under the influence of a dilute mineral acid, gentiopicrin is resolved into glucose, and an amorphous, yellowish-brown, neutral substance, named Gentiogenin. Fresh gentian roots yield somewhat more than ⅒ per cent. of gentiopicrin; from the dried root it could not be obtained in a crystallized state. The medicinal Tincture of Gentian, mixed with solution of caustic potash, loses its bitterness in a few days, probably in consequence of the destruction of the gentiopicrin.
Another constituent of gentian root is Gentianin or gentisin
| CH₃ | ||
| C₁₄H₁₀O₅ or (OH)₂C₆H₃·CO·C₆H₂ | O \ . | |
| O / |
It forms tasteless yellowish prisms, sparingly soluble in alcohol, requiring about 5000 parts of water for solution. With alkalis it yields intensely yellow crystallizable compounds, which, however, are easily decomposed already by carbonic acid. Gentianin may be sublimed if carefully heated at 250° C. By melting it with caustic potash, acetic acid, phloroglucin, C₆H₃(OH)₃, and oxysalicylic acid, C₆H₃(OH)₂COOH, are produced, as shown in 1875 by Hlasiwetz and Habermann. The name of gentianic acid or gentisinic acid had been applied to the oxysalicylic acid obtained by the above decomposition before it was identified with oxysalicylic acid from other sources.
Gentian root abounds in pectin; it also contains, to the extent of 12 to 15 per cent., an uncrystallizable sugar, of which advantage is taken in Southern Bavaria and Switzerland for the manufacture by fermentation and distillation of a potable spirit.[1616] This use of gentian and its consumption in medicine have led to the plant being almost extirpated in some parts of Switzerland where it formerly abounded.
The experiments of Maisch (1876) and Ville (1877) have shown tannic matters to be absent from the root.
Commerce—Gentian root finds its way into English commerce through the German houses; and some is shipped from Marseilles. The quantity imported into the United Kingdom in 1870 was 1100 cwt.
Uses—Gentian is much used in medicine as a bitter tonic. Ground to powder, the root is an ingredient in some of the compositions sold for feeding cattle.
Substitutes—It can hardly be said that gentian is adulterated, yet the roots of several other species possessing similar properties are occasionally collected; of these we may name the following:—
1. Gentiana purpurea L.—This species is found in Alpine meadows of the Apennines, Savoy and Switzerland, in Transylvania, and in South-western Norway; a variety also in Kamtchatka.[1617] The root is frequently collected;[1618] it attains at most 18 inches in length and a diameter of about 1 inch at the summit, from which arise 8 to 10 aerial stems, clothed below with many scaly remains of leaves. The top of the root has thus a peculiar branched appearance, never found in the root of G. lutea, with which in all other respects that of G. purpurea agrees. The latter is perhaps even more intensely bitter.
2. G. punctata L.—Nearly the same description applies to this species, which is a native of the Alps of South-Eastern France, Savoy, the southern parts of Switzerland, extending eastward to Austria, Hungary and Roumelia.
3. G. pannonica Scop.—a plant of the mountains of Austria, unknown in the Swiss Alps, has a root which does not attain the length or the thickness of the root of G. purpurea, with which it agrees in other respects. It is officinal in the Austrian Pharmacopœia.
4. G. Catesbœi Walter (G. Saponaria L.)—indigenous in the United States. Its root, usually not exceeding 3 inches in length by ⅓ inch in diameter, has a very thin woody column within a spongy whitish cortical tissue and a bright yellow epidermis. This root is less bitter than the above enumerated drugs; the same remark applies also to those European Gentianæ which like G. Catesbœi are provided with blue flowers.
HERBA CHIRATÆ.
Herba Chirettæ vel Chiraytæ; Chiretta or Chirayta.
Botanical Origin—Ophelia[1619] Chirata Grisebach (Gentiana Chirayita Roxb.), an annual herb of the mountainous regions of Northern India from Simla through Kumaon to the Murung district in South-eastern Nepal.
History—Chiretta has long been held in high esteem by the Hindus, and is frequently mentioned in the writings of Susruta. It is called in Sanscrit Kirāta-tikta, which means the bitter plant of the Kirātus, the Kirātas being an outcast race of mountaineers in the north of India. In England, it began to attract some attention about the year 1829; and in 1839 was introduced into the Edinburgh Pharmacopœia. The plant was first described by Roxburgh in 1814.
Chiretta was regarded by Guibourt as the Calamus aromaticus of the ancients, but the improbability of this being correct was well pointed out by Fée[1620] and by Royle, and is now generally admitted.
Description—The entire plant is collected when in flower, or more commonly when the capsules are fully formed, and tied up with a slip of bamboo into flattish bundles of about 3 feet long,[1621] each weighing when dry from 1½ to 2 lb. The stem, ²/₁₀ to ³/₁₀ of an inch in thickness, is of an orange-brown, sometimes of a dark purplish colour; the tapering simple root, often much exceeding the stem in thickness, is 2 to 4 inches long and up to ½ an inch thick. It is less frequently branched, but always provided with some rootlets. In stronger specimens, the root is somewhat oblique or geniculate; perhaps the stem is in this case the product of a second year’s growth and the plant not strictly annual. Each plant usually consists of a single stem, yet occasionally two or more spring from a single root. The stem rises to a height of 2 to 3 feet, and is cylindrical in its lower and middle portion, but bluntly quadrangular in its upper, the four edges being each marked with a prominent decurrent line, as in Erythræa Centaurium and many other plants of the order. The decussate ramification resembles that of other gentians; its stems are jointed at intervals of 1½ to 3 or 4 inches, bearing opposite semi-amplexicaul leaves on their cicatrices. The stem consists in its lower portion of a large woody column, coated with a very thin rind, and enclosing a comparatively large pith. The upper parts of the stem and branches contain a broad ring of thick-walled woody parenchyme. The numerous slender axillary and opposite branches are elongated, and thus constitute a dense umbellate panicle. They are smooth and glabrous, of a greenish or brownish grey colour.
The leaves are ovate-acuminate, cordate at the base, entire, sessile, the largest 1 inch or more in length, 3-to 5-or 7-nerved, the midrib being strongest. At each division of the panicle there are two small bracts. The yellow corolla is rotate, 4-lobed, with glandular pits above the base; the calyx is one-third the length of the petals, which are about half an inch long. The one-celled, bivalved capsule contains numerous seeds.
The flowers share the intense bitterness of the whole drug. The wood of stronger stems is devoid of the bitter principles.
Chemical Composition—A chemical examination of chiretta has been made at our request under the direction of Professor Ludwig of Jena, by his assistant Mr. Höhn. The chief results of this careful and elaborate investigation may be thus described.[1622]
Among the bitter principles of the drug, Ophelic Acid, C₁₃H₂₀O₁₀, occurs in the largest proportion. It is an amorphous, viscid, yellow substance, of an acidulous, persistently bitter taste, and a faint gentian-like odour. With basic acetate of lead, it produces an abundant yellow precipitate. Ophelic acid does not form an insoluble compound with tannin; it dissolves in water, alcohol and ether. The first solution causes the separation of protoxide of copper from an alkaline tartrate of that metal.
A second bitter principle, Chiratin, C₂₆H₄₈O₁₅, may be removed by means of tannic acid, with which it forms an insoluble compound. Chiratin is a neutral, not distinctly crystalline, light yellow, hygroscopic powder, soluble in alcohol, ether and in warm water. By boiling hydrochloric acid, it is decomposed into Chiratogenin, C₁₃H₂₄O₃, and ophelic acid. Chiratogenin is a brownish, amorphous substance, soluble in alcohol but not in water, nor yielding a tannic compound. No sugar is formed in this decomposition.
These results exhibit no analogy to those obtained in the analysis of the European gentians. Finally, Höhn remarked in chiretta a crystallizable, tasteless, yellow substance, but its quantity was so minute that no investigation of it could be made.
The leaves of chiretta, dried at 100° C., afforded 7·5 per cent. of ash; the stems 3·7; salts of potassium and calcium prevailing in both.
Uses—Chiretta is a pure bitter tonic, devoid of aroma and astringency. In intense bitterness it exceeds gentian, Erythræa and other European plants of the same order. It is much valued in India, but is not very extensively used in England, and not at all on the Continent. It is said to be employed when cheap, in place of gentian, to impart flavour to the compositions now sold as Cattle Foods.
Substitutes and Adulteration—Some other species of Ophelia, namely, O. angustifolia Don, O. densifolia Griseb., O. elegans Wight, O. pulchella Don, and O. multiflora Dalz, two or three species of Exacum, besides Andrographis paniculata Wall., are more or less known in the Indian bazaars by the name of Chiretta[1623] and possess to a greater or less degree the bitter tonic properties of that drug. Another Gentianacea, Slevogtia orientalis Griseb., is called Chota Chiretta, i.e. small chiretta. It would exceed due limits were we to describe each of these plants: we have therefore given a somewhat detailed description of the true chiretta, which will suffice for its identification. We have frequently examined the chiretta found in the English market, but have never met with any other than the legitimate sort.[1624] Bentley noticed in 1874 the substitution of Ophelia angustifolia, which he found to be by far less bitter than true chiretta.