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.
Orizaba jalap root is obtained from Ipomoea orizabensis, Ledanois, a Convolvulaceous plant growing near Orizaba in the Mexican Andes (about 65 miles south-west of Vera Cruz). It produces a large, woody root which is cut into pieces of varying size, and shape and dried. The drug, which has long been known as light, woody, stalk, or male jalap has largely been imported in considerable quantities under the name of Mexican Scammony.
Orizaba jalap root occurs mostly in large transverse slices, 5 to 10 cm. in diameter, and 1 to 2 cm. thick, or in irregular rectangular portions of larger slices. It is greyish-black in colour and coarsely wrinkled; internally it is greyish or brownish and more or less horny. From the transverse surfaces coarse woody fibres protrude in irregular, concentric circles. The odour is slight and the taste faintly acrid. Occasionally small tapering roots 2 to 3 cm. in diameter and 8 to 10 cm. long are met with.
Like jalap and scammony root the chief constituent of Orizaba jalap root is the 'resin' it contains; other constituents of less importance are sugar, β-methylaesculetin, dihydroxycinnamic acid, fatty acids, phytosterol, starch and calcium oxalate. The amount of crude resin determined as described under 'Jalap Root' varies from 6 to 22 per cent., averaging 12 to 18 per cent.
The crude resin is a very complex mixture. It contains about 6 per cent. of fatty substances, 64.8 per cent. of resin soluble in ether, 24.8 per cent. soluble in ethyl acetate and 2.3 per cent. soluble in chloroform. The ether-soluble portion is not identical with the ether-soluble portion of jalap resin. By alkaline hydrolysis it yields ipuranol. d-a-methylbutyric acid, tiglic acid and a product which, by acid hydrolysis, yields dextrose, methylpentose, jalapinolic acid and methyl jalapinolate. The resin soluble in ethyl acetate gives similar results. The chief constituents, therefore, appear to be the glucoside and methylpentoside of jalapinolic acid and its methyl ester; these are very similar to those of scammony resin (see p. 351). The following table shows the solubility of certain Convolvulaceous resins when treated with various solvents in success.
Ethyl Acetate .
The therapeutic action of Orizaba jalap resin appears to be very similar to that of scammony resin and although the two resins are not identical the British Pharmacopoeia permits both roots to be used in the preparation of scammony resin.
Brazilian jalap, which has lately appeared on the market, is the root of Piptostegia Pisonis, Martius (N.O. Convolvulaceoe). It occurs in the form of transverse, circular slices about 3 to 5 cm. in diameter, and 1 cm. thick, pale greyish brown, with several concentric rings and exhibiting pale resin cells; it contains 20 per cent. of resin, very little of which is soluble in ether.
The root of Ipomoea purpurea, Linne (N. America), contains 4.8 per cent. of a purgative resin.