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.