Cahinca. David's Root. Radix Caincae. Cainga, Fr. Kainkawurzel, G.—This medicine attracted at one time considerable attention. The name of Cahinca or cainca was adopted from the language of the Brazilian Indians. The Portuguese of Brazil call the medicine raiz pretta, or black root. When first noticed in Europe, it was supposed to be derived from the Chiococca racemosa (Fam. Rubiaceae), which was known to botanists as an inhabitant of the West Indies. But Martins, in his work on Materia Medica Brasiliensis, describes two other species of Chiococca, C. anguifuga Mart. and C. densifolia Mart., both of which are now known as C. brachiata Ruiz and Pav., which afford roots having the properties of the root ascribed to C. racemosa. A. Richard, however, received from Brazil specimens of C. racemosa as the Cahinca plant.

A specimen brought to Philadelphia consisted of cylindrical pieces, from 1 to 2 cm. thick somewhat bent or contorted, slightly wrinkled longitudinally, and more or less roughened, internally ligneous, externally covered with a thin, brittle, reddish-brown bark, having a light brown or brownish ash-colored epidermis. The cortical portion, which was of a resinous character, had a bitter disagreeable, somewhat acrid and astringent taste; the ligneous part was quite tasteless. The virtues of the root reside almost exclusively in its bark. They are extracted by water and alcohol. Four distinct principles were discovered in it by Pelletier and Caventou—

(1) a crystallizable, bitter substance, believed to be the active principle, and called cahincic acid, C40H64O18 (also called caincic acid and caincin);
(2) a green, fatty matter of a nauseous odor;
(3) a yellow coloring matter; and
(4) a colored viscid substance. Rochleder and Hiasiwetz found also caffe-tannic acid.

Cahincic acid is white, without odor, of a taste at first scarcely perceptible, but afterwards extremely bitter and slightly astringent, slightly soluble in water, but readily soluble in alcohol, permanent in the air, and unaltered at 100° C. (212° F.). It reddens vegetable blues, and unites with the alkalies, but does not form crystallizable salts. It is thought to exist in the root as calcium subcahinate. When treated with diluted hydrochloric acid it is decomposed into glucose and other products, of which is obtained at first chiococcaic acid, C28H42O7 (thought by some to be identical with quinovic acid), and later, by boiling with alcoholic hydrochloric acid, caincetin, C22H34O3.

Cahinca is tonic, diuretic, purgative, emetic, and is capable of producing serious gastro-intestinal irritation. In Brazil it has long been used by the natives as a remedy for the bites of serpents, also in rheumatism and in dropsy. Dose, of the powdered bark, from twenty grains to a drachm (1.3-3.9 Gm.); of the aqueous or spirituous extract, from ten to twenty grains (0.65-1.3 Gm.).

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.