Page 309 - Pharmacognosy 2 PG303

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

4- HCl test: Boil 1 g of Gum Tragacanth with 20 ml of water, until a mucilage is
obtained, then add 5 ml of HCl and again boil the mixture for 5 mins.; no red or
pink colour is produced (Indian Gum or Karaya Gum).

5- Lead acetate test: Boil 0.5 g of gum Tragacanth with 20 ml of water, until a
mucilage is obtained, add 10 ml of lead acetate T.S.; a flocculent precipitate is
formed, filter, and to the filtrate add 10 ml of lead sub-acetate solution; no
precipitate is formed, or at most a slight turbidity is produced (c.f. Gum Arabic).

6- Iodine test: Mix a small quantity of powdered gum tragacanth with few drops
of water, followed by few drops of N/50 iodine; the particles are coloured yellow
and may show minute scattered blue points. Examine microscopically; only few
groups of small, rounded starch granules are visible.

Constituents
Gum Tragacanth contains 60-70 % of bassorin, a complex of

polymethoxylated acids, which swells in water but does not dissolve and which gives
tragacanth mucilage its peculiar density, serving to distinguish it from acacia which
contains little or no bassorin. Tragacanth also contains tragacanthin, which is a
soluble constituent consists of 3 molecules of glucuronic acid and 1 molecule of
arabinose.

Uses
Tragacanth is employed pharmaceutically as a suspending agent for insoluble

powders in mixtures, as an emulsifying agent for oils and resins, and as an adhesive
in pill mass. It is employed in cosmetics (hand lotions), as a demulcent and an
emollient, and in cloth printing, confectionary, etc.

DRIED EXTRACTS

This group includes drugs which are prepared by evaporating the aqueous
decoction of parts of certain plants or animals, e.g., Agar-Agar, Gelatin and Gambir,
which are official in the Egyptian Pharmacopoeia.

Agar-Agar

Syn.: Agar; Japanese Isinglass

251