Related entries: Jalap
Synonyms.—Convolvulin; Jalapurgin; Rhodeoretin.
Jalapin is one of two homologous glucosides obtained from the tubercles of Ipomoea Purga, Hayne. The term jalapin is applied in England to the ether-insoluble portion of the resin obtained from jalap. It may be prepared by precipitating an alcoholic solution of the purified resin with ether. It occurs as a pure white, odourless powder, and has an acrid and nauseating taste in alcoholic solution. The alcoholic solution is neutral, and reduces an ammoniacal solution of silver nitrate on gentle heating. It also reduces Fehling's solution after first heating with diluted mineral acid. Melting-point, 150° to 155°. It dissolves in alkalies with decomposition. On boiling with diluted mineral acid it yields glucose and jalapinol (convolvulinic acid). Concentrated sulphuric acid produces a red colouration. Oxidation with nitric acid converts it into oxalic and sebacic acids. Jalapin is said to be identical with pharbitisin, obtained from the seeds of Ipomoea hederacea, Jacq. (see under Kaladana). The name jalapin is also applied in Germany to the ether-soluble resin obtained from Convolvulus Scammonia, Linn., and Ipomoea orizabensis, Ledenois.
Soluble in alcohol, glacial acetic acid, or acetic ether slightly soluble in chloroform; insoluble in ether, petroleum ether, benzol, or water.
Action and Uses.—Jalapin possesses similar properties to jalap resin, but is considered to be less active. It may be administered in cachets, or in pills prepared with syrup of glucose, and containing preferably soap and oleoresin of ginger or capsicum. It is sometimes prescribed with calomel as a brisk purge, and as an anthelmintic. When given by the mouth it cannot be found in either the faeces or urine, and would seem, therefore, to be destroyed.
Dose.—6 to 30 centigrams (1 to 5 grains).