_Radix podophylli_; _Podophyllum Root_.
=Botanical Origin=—_Podophyllum peltatum_ L., a perennial herb growing
in moist shady situations throughout the eastern side of the North
American continent from Hudson’s Bay to New Orleans and Florida.
The stem about a foot high, bears a large, solitary, white flower,
rising from between two leaves of the size of the hand composed of 5
to 7 wedge-shaped divisions, somewhat lobed and toothed at the apex.
The yellowish pulpy fruit of the size of a pigeon’s egg is slightly
acid and is sometimes eaten under the name of _May Apple_. The leaves
partake of the active properties of the root.
=History=—The virtues of the rhizome as an anthelminthic and emetic
have been long known to the Indians of North America. The plant was
figured in 1731 by Catesby[166] who remarks that its root is an
excellent emetic. Its cathartic properties were noticed by Schöpf[167]
and Barton[168] and have been commented upon by many subsequent
writers. In 1820, podophyllum was introduced into the _United States
Pharmacopœia_, and in 1864 into the _British Pharmacopœia_. Hodgson
published in 1832 in the _Journal of the Philadelphia College of
Pharmacy_[169] the first attempt of a chemical examination of the
rhizome, which now furnishes one of the most popular purgatives, the
so-called _Podophyllin_, manufactured on a large scale at Cincinnati
and in other places in America, as well as in England.
=Description=—The drug consists of the rhizome and rootlets. The
former creeps to a length of several feet, but as imported is mostly
in somewhat flattened pieces of 1 to 8 inches in length and 2 to 4
lines in longest diameter: it is marked by knotty joints showing a
depressed scar at intervals of a few inches which marks the place of a
fallen stem. Each joint is in fact the growth of one year, the terminal
bud being enclosed in papery brownish sheaths. Sometimes the knots
produce one, two, or even three lateral buds and the rhizome is bi-
or tri-furcate. The reddish-brown or grey surface is obscurely marked
at intervals by oblique wrinkles indicating the former attachment of
rudimentary leaves. The rootlets are about ½ a line thick and arise
from below the knots and adjacent parts of the rhizome, the internodal
space being bare. They are brittle, easily detached, and commonly of a
paler colour. The rhizome is mostly smooth, but some of the branched
pieces are deeply furrowed. Both rootstock and rootlets have a short,
smooth, mealy fracture; the transverse section is white, exhibiting
only an extremely small corky layer and a thin simple circle of about
20 to 40 yellow, vascular bundles, enclosing a central pith which in
the larger pieces is often 2 lines in diameter.
The drug has a heavy narcotic, disagreeable odour, and a bitter, acrid,
nauseous taste.
=Microscopic Structure=—The vascular bundles are composed of spiral and
scalariform vessels intermixed with cambial tissue. From each bundle a
narrow-tissued, wedge-or crescent-shaped liber-bundle projects a little
into the cortical layer. This, as well as the pith, exhibits large
thin-walled cells. The rootlets are as usual of a different structure,
their central part consisting of one group of vascular bundles more or
less scattered.[170] The parenchymatous cells of the drug are loaded
with starch granules; some also contain stellate tufts of oxalate of
calcium.
[166] _Nat. Hist. of Carolina_, i. tab. 24.
[167] _Materia Med. Americ._ Erlangæ, 1787, p. 86. Schöpf was physician
to German troops fighting in the War of Independence.
[168] _Collections for an Essay on Mat. Med. of U.S._ Philad. 1798, 31.
[169] Vol. iii. 273.
[170] Figured by Power, _Proc. American Phar. Assoc._, 1877. 420-433.
=Chemical Composition=—The active principles of podophyllum exist in
the resin, which according to Squibb[171] is best prepared by the
process termed _re-percolation_. The powdered drug is exhausted by
alcohol which is made to percolate through successive portions. The
strong tincture thus obtained is slowly poured into a large quantity
of water acidulated with hydrochloric acid (one measure of acid to
70 of water), and the precipitated resin dried at a temperature not
exceeding 32° C. The acid is used to facilitate the subsidence of the
pulverulent resin which according to Maisch settles down but very
slowly if precipitated by cold water simply, and if thrown down by hot
water fuses into a dark brown cake. The resin redissolved in alcohol
and again precipitated by acidulated water, after thorough washing with
distilled water and finally drying over sulphuric acid, amounts to
about 2 per cent.
[171] _American Journ. of Pharm._ xvi. (1868) 1-10.
Resin of podophyllum is a light, brownish-yellow powder with a tinge
of green, devoid of crystalline appearance, becoming darker if exposed
to a heat above 32° C., and having an acrid, bitter taste; it is very
incorrectly called _Podophyllin_. The product is the same whether the
rhizome or the rootlets are exclusively employed.[172] It is soluble
in caustic, less freely in carbonated alkalis, even in ammonia, and is
precipitated, apparently without alteration, on addition of an acid.
Ether separates it into two nearly equal portions, the one soluble in
the menstruum, the other not, but both energetically purgative. From
the statements of Credner[173] it appears that if caustic lye is shaken
with the ethereal solution, about half the resin combines with the
potash, while the other half remains dissolved in the ether. If an acid
is added to the potassic solution a red-brown precipitate is produced
which is no longer soluble in ether nor possessed of purgative power.
According to Credner, the body of greatest purgative activity was
precipitated by ether from an alcoholic solution of crude podophyllin.
By exhausting the resin with boiling water, Power found that finally
not more than 20 per cent. of the resin remained undissolved. By
melting the crude resin with caustic soda, a little protocatechuic acid
was obtained.
F. F. Mayer[174] of New York stated podophyllum to contain, beside
the resin already mentioned, a large proportion of _Berberine_, a
colourless alkaloid, an odoriferous principle which might be obtained
by sublimation in colourless scales, and finally _Saponin_. From all
these bodies the resin as prepared by Power,[175] was ascertained by
him to be destitute; he especially proved the absence of berberine in
Podophyllum.
=Uses=—Podophyllum is only employed for the preparation of the resin
(_Resina Podophylli_) which is now much prescribed as a purgative.
[172] Saunders in _Am. Journ. of Pharm._ xvi. 75.
[173] _Ueber Podophyllin_ (_Dissertation_), Giessen, 1869.
[174] _Am. Journ. of Pharmacy_, xxxv. (1863) 97.
[175] L. cit., also _Am. Journ. of Pharm._ (1878) 370.