Page 320 - Pharmacognosy 2 PG303

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

brown or nearly black, opaque masses; fracture, uneven, porous; odour,
characteristic and disagreeable; taste, nauseous and very bitter. Zanzibar Aloes:
occurs in livery-brown opaque masses; fracture, nearly smooth and slightly porous;
odour, slight and not disagreeable; taste, nauseous and very bitter.

Powder
Powdered Aloes is yellowish-brown to dark reddish-brown in colour. The

determination of the particular variety of Aloes can be achieved by microscopical
examination in lactophenol. Cape Aloes appears as transparent brown irregular and
angular fragments. Curaçao Aloes shows fragments with numerous minute acicular
crystals embedded in an amorphous matrix. Zanzibar Aloes shows irregular lumps
with sphaerites. Socotrine Aloes shows fairly large prisms grouped into masses.
The particles gradually dissolve in the mount.

Powdered Aloes mounted in
lactophenol: Fragments of A, Cape; B,
Curaçao; C, Zanzibar and D, Socotrine
Aloes.

Solubility
Aloes is partially soluble in water; soluble in alcohol 60%, and in glycerol;

insoluble in chloroform, in ether and in petroleum ether. It is soluble in alkali and
in glacial acetic acid.

Tests for Identity
Boil about 0.5 g of powdered Aloes with 50 ml of water for about 2-3 min,

cool, then shake thoroughly with about 1 g of kieselguhr and filter. The clear filtrate
obtained responds to the following tests for identification of Aloes and for the
determination of the particular variety.

1- Borax test for anthranols (Schenteten’s reaction): Dissolve with the aid of
heat, about 0.2 g of borax in 5 ml of the filtrate; transfer 5-10 drops of the solution
to a test tube nearly filled with water; a green fluorescence is produced. The
fluorescence is due to the formation of aloe-emodine anthranol liberated from
barbaloin by hydrolysis with borax. The test is positive with the four varieties
of aloes, and negative with Natal aloe)

2- Test for free anthraquinones: Shake 30 ml of the filtrate with 20 ml of ether,
and allow to separate. Shake 10 ml of the ether layer with 10 ml of dilute solution

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