Thevetia. Yccotli.—Inhabiting the damp, hot valleys of the Mexican Cordilleras is a large tree belonging to the Apocynaceae, whose fruits are known by the natives as huesos o codos de fraile, or friar's elbow bones, and are used as a topical application in hemorrhoids. The tree is the Thevetia Yccotli A. DC. In the seeds Herrera found a glucoside, thevetin. (A. J. P., 1877, 145.) Closely allied to T. Yccotli is T. nereifolia Juss., a tree which probably grows also in Mexico, but has been found by botanists chiefly, if not solely, in the West Indian Islands, Colombia, Peru and other parts of South America. De Vrij very many years ago discovered in its seeds a glucoside which was closely studied by Bias. (Neues Jahrb. f. Pharmacie, Bd. xxxiv, 1854, 1.) He gave it the name of thevetin and the formula C54H84O24 and believed it to be identical with cerberin, previously found by Oudemann in Cerbera Odallam Ham., also an apocynaceous plant, but Plugge (A Pharm., 1893, 10) after a thorough study found that cerberin was not identical with either tanghinin or thevetin. With the former it is isomeric, showing the same percentage composition, but has different crystalline form and melting point—cerberin 192° C. (377.6° F.), tanghinin 182° C. (359.6° F.). From thevetin it differs not only in composition, but in the nature of the decomposition products. Cerberin, C27H40O8, is decomposed into cerberetin, C19H26O4, a citron-yellow amorphous powder melting at 85.5° C. (186° F.), and glucose, while thevetin, C54H84O24, is split into theveresin, C48H70O17, a white powder, and glucose.
Merck (Jahresb. fur, 1892, 57) described a glucoside cerberin to which he gives the formula C25H38O12, which name he changed to cerberid in 1911. He states that it was obtained from a Mexican plant, probably Thevetia Yccotli. Whether this glucoside is identical with the thevetin of Bias cannot be definitely stated. Bias found that the thevetin of De Vrij boiled in diluted sulphuric acid splits into glucose and theveresin, which has the formula C48H70O17. Thevetin occurs in minute crystals, odorless, of a bitter taste, slightly soluble in cold water (twelve parts), freely so in boiling water, diluted and strong alcohol, acetic acid, insoluble in ether. Its most characteristic reaction appears to be its dissolving in concentrated sulphuric acid, with the production of a reddish-brown color, changing to a cherry-red, and after some hours to a violet color. In commerce it occurs as a yellowish-white, amorphous bitter powder, easily soluble in water and alcohol. Theveresin is only slightly soluble in boiling water. These substances are active poisons. Thevetosin, a crystalline glucoside, was made by Herrera from the seeds of T. Yccotli. It is a cardiac poison. (M. R., 1911.) A number of cases of poisoning by the seeds of the East Indian thevetia has occurred; the symptoms have been repeated vomiting, a slow, very feeble pulse, delirium, convulsive movements and coma. The physiological action of the thevetin from T. nereifolia has been investigated chiefly by Konig. (A. E. P. P., Bd. v, 228.)
David Cerna finds that the glucoside of T. Yccotli (P. M. T., ix, 396) with sulphuric acid affords a clear greenish-yellow solution gradually passing to brown and brownish-violet and finally becoming a permanent cherry-brown color, which changes on the addition of potassium bicarbonate to an emerald-green; also that it is in moderate doses stimulant both to the circulation and respiration, but finally paralyzes the heart muscle and the respiratory apparatus; that it causes cerebral convulsions and spinal paralysis, abolishing sensation and reflex activity before voluntary movement by an influence upon the sensory nerves or spinal tract. Zotos N. Zotos (In. Dis., Dorpat, 1892) states that cerberin belongs physiologically to the digitalin group.
The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.