Page 82 - Pharmd general phytochemistry I-Final2024_LEUCTERS

Quantitative determination of anthracene glycosides
Colorimetric method:
• After hydrolysis with acid, the aglycone is allowed to react with

KOH to give red color. The intensity of this color is directly
proportional to the concentration of anthraquinone, and can
be measured colorimetry.
• Anthrones contents can, similarly, be determined but after
oxidation with mild oxidants such as hydrogen peroxide or
ferric chloride.
•????? (Oxidative hydrolysis using FeCl3/HCl)

• Anthracene-bearing purgative drugs are much advantageous
over many other laxatives and cathartics, because:
– They do not irritate the small bowel .
– They do not produce watery stools.
– They do not also affect the intestinal epithelium .
– No colitis was reported with anthracene laxatives.
– They do not cause any griping action; thus no
antispasmodic, such
as belladonna preparations, is prescribed with them.

The most widely used drugs that contain anthracene compounds
are :

1- Senna Leaves and Pods :
The most important constituents of which are the SennosidesA,B,C

and D.
2- Cascara Bark :
• It contains the cascarosides A,B,C and D as well as
barbaloin and chrysaloin
3- Aloes :
• It contains the aforementioned C-glycosides barbaloin and
chrysaloin

80