Botanic characteristics
Podophyllum
Consists of nearly cylindrical rhizomes, jointed, compressed or flattened somewhat on upper and lower surfaces, and sometimes branched. It occurs as pieces of rhizome up to 20 cm in length, with internodes from 2 mm to 9 mm in diameter, some of the nodes being somewhat thickened. The rhizome is dusky red to light yellowish brown, longitudinally wrinkled or nearly smooth, with irregular, somewhat V-shaped scars of scale leaves; some of the nodes are annulate, the upper portion having large, circular, depressed stem-scars and buds or stem-bases. On the lower portion there are numerous root-scars or roots, the latter from 2 cm to 7 cm in length and about 2 mm in thickness. The fracture is short and weak, the fractured surface being yellowish orange to pale yellow or grayish white.
Histology
The rhizome shows an outer portion consisting of a brown epidermis, often necrosed, and 1 to 3 layers of brown to olive-brown suberized cells; a cortex about 20 cells in width, consisting chiefly of nearly isodiametric cells, the cells containing single or compound starch grains and resin masses and, in scattered cells of the nodes, rosette aggregates of calcium oxalate; a circle of from 16 to 34 open collateral vascular bundles, separated by rather wide medullary rays, each bundle containing a few lignified vessels, a more or less distinct cambium, and a rather large phloem. The pith is large, the cells being more or less rounded and containing starch grains and reddish brown resin masses. The roots show an epidermal layer of brownish suberized cells and a single row of hypodermal cells; a broad cortex of thin-walled nearly isodiametric cells; a distinct endodermis of tangentially elongated cells having uniformly thickened walls; and a 4- to 7-rayed vascular bundle.
Powdered Podophyllum
It is pale brown to weak yellow and has a slight odor. It contains numerous starch grains, simple or 2- to 6-compound, the individual grains being spheroidal, plano- to angular-convex, or polygonal, up to 20 µm in diameter; occasional rosette aggregates of calcium oxalate, up to 80 µm in diameter; vessels with simple pits or reticulate thickenings; fragments of starch- and resin-bearing parenchyma and reddish brown to yellow cork cells.
Assay
Place 10 g of Podophyllum, in fine powder, in a 125-mL conical flask, add 35 mL of alcohol, and reflux on a steam bath for 3 hours. Transfer the mixture to a small percolator, and percolate slowly with warm alcohol until the percolate measures 95 mL. Cool, add sufficient alcohol to the percolate to make it measure 100.0 mL, and mix. Transfer 10.0 mL of this percolate to a separator, and add 10 mL of chloroform and 10 mL of dilute hydrochloric acid (7 in 500). Shake the mixture, allow it to separate, draw off the alcohol-chloroform layer into a second separator, and wash the acid layer with three 15-mL portions of a mixture of chloroform and alcohol (2:1), adding the washings to the second separator. Add 10 mL of dilute hydrochloric acid (7 in 500) to the combined extract and washings, again shake the mixture, allow it to separate, and draw off the alcohol-chloroform layer into a tared vessel. Wash the acid layer three times with 15-mL portions of the alcohol-chloroform mixture, adding the washings to the tared vessel. Evaporate the combined extracts on a steam bath to approximately 1 mL, add 5 mL of dehydrated alcohol, again evaporate to dryness, and dry the residue at 80
for 4 hours: the weight of this residue is the weight of resin in 1 g of the Podophyllum taken.