Turpethum. Br. Turpeth.
"Turpeth is the dried root and stem of Ipomoea Turpethum, R.Br." Br.
Turpeth Root, Indian Jalap, Trivrit, Nisoth.
Ipomoea Turpethum (operculina Turpethum (L.) Peter) (Fam. Convolvulaceae) is a convolvulaceous plant which is found throughout India, China, Ceylon, Australia, and is occasionally cultivated in botanical gardens as an ornamental plant. There are two varieties, viz., Sveta or white turpeth, and Kirshna or black turpeth, the former being preferred as a mild cathartic. The black variety is said to be a powerful drastic. (Watt, "Dictionary of the Economic Products of India.")
According to Merat and De Lens, the root itself formerly came into commerce, but at present turpeth consists of the root and stem of the plant cut into short lengths, usually from 1.5 to 5 cm. in diameter; the central woody portion is often removed by splitting the bark on one side. The pieces are cylindrical, somewhat twisted and externally of a dull gray color. A transverse section shows a porous central wood surrounded by a broad cortical portion, containing yellowish-brown resin cells, lactiferous vessels and crystals of calcium oxalate. The fracture is short in the cortex and fibrous in the central portion. The drug has a faint odor and a nauseous taste, which is perceptible only after it has been some time in the mouth.
"In cylindrical pieces of varying length, from one to five centimetres wide, often split on one side and deprived of the central portion; longitudinally furrowed; dull grey or brown. Fracture of the bark short, of the wood fibrous; internally usually pale grey. In transverse section, a porous wood surrounded by a thick bark in which abnormal wood-bundles are frequently present. Slight odor; taste nauseous, slowly developed." Br.
Boutron-Chalard found in turpeth root, resin, a fatty substance, volatile oil, albumen, starch, a yellow coloring matter, lignin, salts, and ferric oxide. (J. P. C., viii, 121.) The root contains 10 per cent. of resin. (Andouard, Ann. Ther., 1866, 118.) According to Spirgatis this resin is a glucoside, turpethin, C76H128O36 like that of other Convolvulaceae, insoluble in ether, but soluble in alcohol, to which it imparts a brown color not removable by animal charcoal. To obtain it pure, the alcoholic solution is concentrated; the resin precipitated by, and" afterwards boiled with, water, then dried, reduced to powder, digested with ether, and finally redissolved by absolute alcohol and thrown down by ether. After being treated several times in this way, it is obtained in the state of a brownish resin, yielding on pulverization a gray powder, which strongly irritates the mucous membrane of the nostrils and mouth, and is fusible at 182.2° C. (360° F.). It is inflammable, burning with a smoky flame and emitting irritant vapors. With strong bases it acts like jalapin, takes up water, and is transformed into a soluble acid, turpethic acid, C34H60O18, while with dilute acids it is decomposed into turpetholic acid, C16H32O4, and glucose. (J. P. C., 4e ser., i, 236.)
Turpeth root is purgative, somewhat less powerful than jalap, and rather slow in its action.
Dose, five to twenty grains (0.32-1.3 Gm.).
Off. Prep.—Tinctura Jalapae Composita, Br.