Page 154 - PG 504-theoretical notes-phyto-1-2024-2025..

Clinical pharmacy PharmD program Third level Phytochemistry-1 (PG-504)

• Dianthrones and dianthranols also respond negatively to Borntrager’s reaction. However, if
they are cleaved and then oxidized to afford anthraquinones, then, they give a positive color
reaction .

Quantitative determination of anthracene glycosides
Colorimetric method:
After hydrolysis with acid, the aglycone is allowed to react with KOH to give red or violet color.
The intensity of this color is directly proportional to the concentration of anthraquione, and can be
measured colorimetrically.

Anthranol contents can, similarly, be determined but after oxidation with FeCl 3 or H 2 O . 2

Pharmacological properties:
1, 8-anthraquinone derivatives exert a laxative or purgative activity.
Anthraquinone glycosides may be considered pro - drugs: the sugar moiety is essential for the
pharmacological action, as it serves to transport the aglycone to the site of action in the large
intestine.
They exert their action by :
(A) Increasing the peristaltic movement of the large intestine causing soft evacuation.
(B) Stimulate the secretion of water and electrolytes into the large intestine.
Side effect:
Habit-forming, and long-term use may result in laxative dependence and loss of normal bowel
function.

1-Anthraquinones
i) Emodins:
Frangulin: gives on hydrolysis frangula-emodin and rhamnose.
ii) Aloe - emodin : in Cascara bark, Senna leaves and Aloes
iii) Rhein : found in rhubarb.

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