Page 239 - Pharmacognosy 2 PG303

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

compound of 2-5 components, 20-30 µ in diameter, with a central cleft or
radiate hilum. Cork, fibers and sclereids are absent.

Powdered Rhubarb; 1, isolated cluster; 2, cluster in parenchyma; 3,
isolated starch granules; 4, starch granules in cells; 5, reticulated xylem

vessels.

Tests for Identity

Micro-sublimation of powdered rhubarb gives a yellow needle-shaped sublimate
that dissolves in KOH T. S. with reddish color.

Test for Anthraquinone derivatives: Boil about 0.2 gm. of powdered rhubarb with
4 cc. of alcoholic KOH T. S. for about 2-3 minutes in a test tube; dilute with 4 cc.
of water and filter. Acidify 5 cc. of the filtrate with dilute HCl, cool and shake well
with 5 cc. of ether or benzene; pipette off as much of the clear upper (ethereal) layer
as possible into a clean test tube and shake with 2 cc. of dilute ammonia solution,
a rose red to intense red color is produced in the aqueous layer.

Constituents
3-12 % hydroxy-anthracene derivatives. The figures indicated not only reflect

the variable content but also depend greatly on the substance (aglycone, glycoside)

196