Page 129 - Medicinal Plants_PharmD general

Properties:
Flavonoids are often yellow (Latin. flavus, yellow), they dissolve in

alkalies giving yellow solutions.

Test for flavonoids:
Addition of potassium hydroxide to powdered plant gives a yellow

colour which on addition of acid become colourless.

Uses:
1- They have been used in certain disease conditions to reduce capillary
bleeding e.g. diosmin, rutin, hesperidin.
2- Antioxidant e.g.
3- Antinflamatory e.g.

4. Cyanogenic or Cyanophore glycosides:

Definition:
Cyanogenic glycosides are glycosides yielding hydrocyanic acid as

one of the product of hydrolysis and are commonly found in rosaceous
plants e.g. amygdalin from bitter almond, linamarin from linseed and
prunasin from wild cherry bark

Test for Cyanogenic glycosides:
The material is well-broken and placed in a small flask with

sufficient water; in the neck of the flask a strip of filter paper impregnated
with sodium picrate (yellow) is suspended by means of a cork. After
hydrolysis the colour of the sodium picrate paper is changed into brick red
(sodium isopurpurate).

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