Page 204 - Pharmacognosy 2 PG303 (1)

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

Colchicum Corm: A., flat surface of a corn gathered in June, after removal
of brown outer scale; B, transverse section of the same; C, longitudinal
section of the same; D, commercial dried slices of the corm; Starch
grains at bottom of drawing; b, bud for next season's flowering stem; e,
brown outer envelope f, remains of the flowering stem of last season;
f.v.b., vascular bundle; a, scar where corm has broken away from the
parent corm; a,, region when much shrinkage occurs during drying.

The dried slices are from 2-5 mm. thick about 3 cm. wide, sub-renifom to
oval in shape, the groove on one side being due to the shrinkage of the more
aqueous parenchyma occurring in the centre of the straight edge. The surface of
the edge of the slice is dark brown, the transverse surface shows a white, mealy
ground tissue in which are numerous scattered vascular bundles, appearing as
grayish points . Pieces from the apex and base of the corm are sub-conical and
plano-convex, respectively. The fracture is short and starchy, the drug is in
odorous and has a bitter taste. The transverse surface assumes a yellow color
when treated with hydrochloric acid or with sulphuric acid, 20%. This is a
reaction for colchicine.

Microscopical Characters
The epidermis consists of rectangular to polygonal tabular cells, about 40-
60-95 microns in width or length with brown, indistinctly pitted moderately
thick, slightly wavy walls; it contains occasional stomata, nearly circular in
outline. The mass of the corm consists of a thin-walled, round-celled parenchyma
filled with starch grains which are simple or more usually compound with 2 or 3
or sometimes 4-7 components which are often muller-shaped,, the hilum is
central and often a radiate split. The vascular bundles are slender, collateral and
run longitudinally through the corm; the xylem vessels are narrow, spiral or
annular and about 30 microns in diameter. Colchicine is found in the epidermis
and in a sheath, one cell thick, surrounding each vascular bundle.

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