Page 59 - final Practical handout PG 303-Cogno-2- 2024-2025

Clinical Pharm D Level 2 Pharmacognosy-2 (PG 303)

Dried Juices

Juices are fluid plant saps being usually aqueous liquids containing dissolved substances
and are usually present in plants in special structures. They occur either in cells e.g., Aloes
or in cavities e.g., Eucalyptus…etc.

Aloe ‫الصبر‬

Chemical tests:

1- Bromine water test for barbaloin
Br₂ water gives yellow precipitate due to tetrabromoaloin.

2- Borax test for anthranols

Green fluorescence is produced. The fluorescence is due to formation of Aloe-emodin
anthranol liberated from barbaloin by hydrolysis with borax.

3- Test for free anthraquinone (Aloe-emodin) (Borntrager's test).

with 10 ml of dilute solution of NH4OH, a rose red color is produced in the ammoniacal
layer.

Resin and resin combinations

Resins are hard, solid or semisolid amorphous (mostly) organic substances of complex
nature. They are insoluble in water and hence have slight taste; they are usually insoluble in
petroleum ether, with few exceptions (colophony, mastic and copaiba). They dissolve more
or less completely in alcohol, chloroform, ether.

Resins: e.g. colophony.

Oleo-gum resins: e.g. Asafoetida and Myrrh.

Colophony (rosin) ‫راتنج التربنتينا‬

Chemical tests:

1- Test for abietic acid: shake powdered colophony with petroleum ether for few minutes,
and filter. Shake the filtrate with equal volume of dilute cupper acetate; the petroleum ether
layer assumes a bright bluish green (emerald green).

2- Test for terpenes: dissolve colophony in glacial acetic acid, heat gently, cooling + H2SO4
(one drop on wall), a bright purplish red color is produced, which rapidly changes to violet.

47