Page 186 - Pharmacognosy 2 PG303 (1)

Pharmacognosy-2 (PG303) Level 2 Clinical Pharmacy-Pharm D

RADIX IPOMOEA

Orizaba Jalap Root. Mexican Scammony,

Orizaba jalap root is obtained from Ipomoea orizabensis (Pellet.) Ledanois,
family Convolvulaceae, a plant growing near Orizaba in the Mexican Andes, about
sixty-five 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, is imported in considerable quantities,
under the name of Mexican Scammony.

Macroscopical Characters
The tubercles of Mexican Scammony or Ipomoea are large and
fusiform, about 15-20 cm. long and 4-10 cm. thick, and compared with jalap,
they are light in density. Entire tubercles, sometimes slashed longitudinally
to facilitate drying, are occasionally imported, but usually they are cut into
transverse slices about 0.5-2 cm. thick or sometimes as much as 4 cm. and
more or less wedge shaped. Externally the tubercles are grayish-black and
very coarsely wrinkled. The transverse surface of the slices is rough and
fibrous from the projection of numerous woody strands arranged in concentric
circles, of which five or six are often present, in the tissue phloem and
parenchyma between the woody rings there are numerous scattered resin-
cells. The slices are tough and the fracture is short, irregular and resinous; the
odor is slight and the taste faintly acrid. Ipomea fluoresces in ultra-violet light
with a deep bluish-violet color (cf. Jalap).

Microscopical Characters
The numerous rings of vascular bundles arise by the limited activity of
successive cambia. At the centre of the root is a small woody core consisting
of the primary xylem surrounded by the secondary xylem formed by the
original cambium, which ceases to function after a limited period, •a new
accessory cambium now arises in the pericycle and forms a ring of tertiary
bundles surrounding the first secondary tissues and separated from one another
and from the central group by parenchyma. After a short time this cambium
also ceases to function and accessory cambia are formed successively in the
pericycle, producing additional rings of bundles as the tubercle increases in
size.

Abundant starch grains are present in the parenchyma, most of them
being two- to six- compound, individual grains being mostly muller-shaped
and up to 35 microns in diameter.

Numerous cluster crystals of calcium oxalate, 15-45 microns in

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