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.
Chiretta, Swertia Chirata, Hamilton (N.O. Gentianeoe), is an erect annual herb growing to a height of about a metre, and indigenous to the mountainous districts of Northern India. It has long been used by the Hindus, but was not introduced into European medicine till about 1830. The entire plant is collected when the flowering is well advanced, and made into bundles about a metre long, weighing nearly a kilogramme each, which are often compressed for exportation.
The stem, which attains about 6 mm. in thickness, is of a yellowish brown or purplish brown colour, glabrous, and slightly winged. The lower part is rounded, and exhibits, when cut longitudinally, a narrow wood enclosing a large, continuous, easily separable pith; the upper part of the stem produces in the axils of opposite leaves numerous slender, elongated, decussate branches which ramify further, bearing numerous fruits and occasional flowers.
The few leaves to be found are opposite and sessile, ovate or lanceolate in outline, acuminate, entire, and glabrous. The fruits are superior, ovoid and pointed; they are formed from two carpels, but are one-celled and contain numerous, minute, reticulated seeds. There are not many flowers present in the drug.
The tapering root attains about 10 cm. in length and 12 mm. in thickness at the crown, and is frequently oblique.
The drug has no marked odour, but all parts have an extremely bitter taste.
The student should observe
(a) The purplish brown colour of the stem,
(b) The large continuous pith,
(c) The intensely bitter taste,
(d) The opposite leaves,
(e) The bicarpellary, unilocular fruits.
The first three characters will suffice to distinguish the genuine drug from other species of Swertia, which sometimes are mixed with it or substituted for it, as well as from other substitutions that have been occasionally noticed. The last two are characteristic of the natural order Gentianeoe and are also useful in identifying the drug.
Fig. 108. - Chiretta. A, portion of flowering panicle; B, pistil; C, fruit with persistent calyx; D, transverse section of fruit; E, seeds. A, natural size. B, C, D,enlarged; E, highly magnified. (Bentley and Trimen).
Chiretta contains two intensely bitter principles, ophelic acid and chiratin, both amorphous or indistinctly crystalline yellow substances.
Ophelic acid exists in the larger proportion; it has been obtained as a viscid yellow substance with a persistent bitter taste, soluble in water, alcohol, and ether. Chiratin is a yellow powder soluble in warm water, alcohol, and ether. Boiled with hydrochloric acid it yields ophelic acid and chiratogenin but no sugar, and is therefore not a glucoside.
This drug, which has bitter and tonic properties, is highly esteemed in India, and much used as a tonic. In this country it is now but seldom prescribed, probably on account of the very disagreeable nature of its bitterness.
The name chiretta being applied in India to a number of bitter plants, it is not surprising that other more or less similar bitter drugs are occasionally mixed with or substituted for the official chiretta. Sometimes, too, plants that resemble true chiretta in appearance but are much less bitter make their appearance under the name of chiretta. Among the substitutions and adulterations may be mentioned Swertia angustifolia, Buch-Hamilton; S. alata, Royle; S. trichotoma, Wallich, etc.; Andrographis paniculata, Nees; the root of Rubia cordifolia, Linne, etc. The large continuous pith, dark colour, and intensely bitter taste are sufficient to distinguish S. Chirata from other species of the same genus; the opposite leaves and bicarpellary, unilocular fruits, from plants belonging to natural orders not possessing these characters.
Japanese Chiretta, derived from S. chinensis, Franchet, is a much smaller plant; the stem varies from 10 to 35 cm. in length and 1 to 2 mm. in thickness, and is brown or purplish brown; the root is straight or only slightly oblique; it yields more alcoholic extract and is more bitter than S. Chirata.