Source, Etc

The May-apple, Podophyllum peltatum, Linne (N.O. Berberidece), is a small herb with a long perennial creeping rhizome. It is a native of and common in the eastern United States and Canada, producing, when it flowers, but two leaves and a single flower. The drug was well known to the North American Indians as an emetic and vermifuge; it was introduced into the British Pharmacopoeia in 1864. The rhizome, which grows to a length of several feet, is collected in the late summer and dried; it is usually cut into pieces about 10 cm. in length.

Description

Podophyllum root, or more correctly rhizome, is seen in commerce usually in nearly cylindrical pieces 10 or more cm. in length and about 5 mm. in thickness. These are of a dark reddish brown colour, and are nearly smooth or slightly longitudinally wrinkled. Summer rhizomes contain less starch and are flatter and more deeply wrinkled. At intervals of about 5 cm. the rhizome is enlarged and bears on the upper surface a concave scar surrounded by several circular leaf-scars; these have been left by an aerial flowering stem and its cataphyllary leaves. Below the stem-scar, on the under surface of the rhizome, are the scars of several stout roots, which are occasionally left attached to the rhizome, but which more commonly have been removed. The rhizome occasionally forks, but produces very few lateral branches. When a flowering stem is produced the growth of the main axis is terminated; a bud in the axil of one of the cataphyllary leaves then develops, forming a sympodial system and continuing the growth of the plant.

Fig. 154. - Podophyllum rhizome. A, plump autumnal rhizome without roots showing the scar left by the aerial stem. B, transverse section of the same. C, shrivelled summer rhizome with roots attached. All natural size.

The rhizome breaks with a short fracture. The transverse section is usually white and starchy, but if the heat employed in drying the rhizome has been sufficient to gelatinise the starch it is yellowish and horny; it exhibits a very thin cork and a circle of small, oval, distant, fibro-vascular bundles.

The drug has a characteristic but not strong odour, and a bitter acrid taste.

The student should observe

(a) The straight cylindrical rhizome with occasional stem, root, and leaf scars,

(b) The structure shown by the transverse section.

Constituents

The most important constituents of podophyllum rhizome are a neutral crystalline substance, podophyllotoxin, and a resin, podophylloresin, both of which are purgative. In addition the drug contains picropodophyllin, quercetin, and starch. It yields about 3 per cent, of ash on incineration.

Podophyllotoxin, C15H1406 (0.2 to 1.0 per cent.) crystallises in colourless needles melting at 117°, and easily soluble in alcohol, chloroform, and boiling benzene, but very sparingly in water. Alkalies convert it readily into salts of an unstable gelatinous acid, podophyllic acid, which easily loses water and passes into crystalline, non-toxic picropodophyllin (m.pt. 227°), which is isomeric with podophyllotoxin.

Podophylloresin is an amorphous resin of the nature of which little definite is known.

Quercetin, C15H10O7,2H1O, is contained in bearberry leaves and other drugs (see p. 42).

A concentrated alcoholic tincture of the drug poured into 10 volumes of acidified water throws down a copious resinous precipitate, podo-phyllin (yield from 3 to 7.7 or even 16 per cent.; roots as rich as rhizome). This podophyllin contains as its chief constituents podophyllotoxin (about 20 per cent.), podophylloresin, and picropodophyllin, together with quercetin and other bodies. The yield of podophyllin is very variable, but whether this is due to the time at which the rhizome is collected or to other conditions is not at present definitely known. The rhizome is said to be most active in the spring when beginning to shoot.

Uses

Podophyllum rhizome, or at least the podophyllin obtained from it, is a gastro-intestinal irritant. In large doses it produces inflammation of the stomach and intestines which has proved fatal. In moderate doses it is a drastic purgative with some cholagoguic action, and is much used in cases of constipation from hepatic trouble.