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Chemical Tests and Thin Layer Chromatography (TLC) of anthra

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Paula Ramos

on 15 December 2013

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Transcript of Chemical Tests and Thin Layer Chromatography (TLC) of anthra

Chemical Tests and Thin Layer Chromatography (TLC) of anthraquinones
Ramos, PA
Salazar, SE
San Andres, H

Sources of Glycoside Anthquinones
Famous for their laxative properties
Laxative effect is caused by two independent mechanisms
Cascara Sagrada
-recently introduced to Modern Medicine
- known to early Spanish and Mexican priests in California
-Rhamnus californica
-Its bark was not introduced to medicine until 1877
Officially recognized in the USP XXII, as the dried bark of
Rhamnus purshianus
De Candolle (Rhamnaceae)
-to allow natural oxidation of some reduced emodin glycosides (anthrones) to less active monomeric anthraquinone glycosides.
- should be collected at least one year prior to use
owes its action
to a mixture of principles consisting largely of
cascarosides A, B, C, and D,
with other anthraquinone glycosides in minor amounts
Bark of USP quality contains
not less than 7 percent total hydroxyanthracene derivatives
calculated as
cascaroside A
on a
dried basis
. The
cascarosides should make up at least 60 percent of this total.
Cascaroside A
Cascaroside B
Cascaroside C
Cascaroside D
Being the
of the anthraquinone stimulant laxatives, it is the
least likely to produce undesirable effects
such as

Active principles, however, are
mother's milk
Pharmaceutical dosage forms
- extract
- fluidextract
- aromatic fluidextract
- capsule
Average dose is
1 g (about ½ teaspoonful).

Cascara tea is not popular because of its
extremely bitter taste
The herb is an ingredient in several popular OTC laxatives
Most widely used of the anthraquinone-containing stimulant laxatives.
Official in the USP XXII, senna is described as consisting of the dried leaflet of Cassia acutifolia Delile, known in commerce as Alexandria senna, or of Cassia angustifolia Vahl, known in commerce as Tinnevelly senna
Dianthrone glycosides, particularly sennosides A, A1, B, C, D, and G, together with various other anthraquinone derivates, account for the laxative action of senna.
- not as mild in its action as cascara but more widely used because it is considerably cheaper
Available as fluidextracts, syrups, or tablets
Obtained from:

- A. barbadensis
Mill. (
A. vera
L.), known in commerce as Curaçao aloe
- A. ferox Mill., and hybrids of these species with
A. africana
Mill. and
A. spicata
Bak., known in commerce as Cape aloe.
The anthraquinone glycosides aloin A and B (formerly designated barbaloin) render aloe an extremely potent laxative.
Its use in the United States has declined in recent years, rendering it of relatively minor therapeutic significance.
Its use in the United States has declined in recent years, rendering it of relatively minor therapeutic significance.
Aloe is obtained from specialized cells, known as pericyclic tubules, that occur at the border of the outer and inner cortical layers of the mesophyll, located just beneath the epidermis of the leaves of the aloe plant.

The bitter yellow latex is drained and dried to a reddish black glistening mass.
USP Identification test for aloes
USP Identification test for cascara sagrada
USP Identification test for Senna
TLC Analysis
Figure 1. Formation of reddish brown solution upon the addition of concentrated nitric acid to powdered aloe

Reflects the characteristic color of the species Aloe barbadensis Miller (Family Liliaceae) upon addition of nitric acid

Other species of Aloe such as Cape Aloe, Socotrine Aloe and Zanzibar Aloe give varying colors to this test which are initial brownish color changing to green, pale brownish yellow and yellowish brown respectively

Boiling of senna leaves in ethanolic potassium hydroxide for two minutes facilitated hydrolysis and formation of potassium salts of aglycones as well as cleavage of C-C linkage
Sennosides, the dianthrones present in senna leaves, are the species responsible for the bluish red coloration obtained in the test.
Those present in greatest concentration are sennosides A and B, a pair of optical isomers whose aglycones are rhein dianthrone (sennidin A and B)
Sennosides C and D are minor constituents having dimeric aglycones composed of 1 molecule of rhein and 1 molecule of aloe-emodin
TLC Analysis
Thin Layer Chromatography of Senna tablets was conducted in which the spot for the senna leaves showed a higher Rf than the spot for senna tablets.
Figure 4. TLC of Senna tablets (left) and powdered Senna leaves (right) producing brown spots under 254 nm UV light
Figure 3. Formation of bluish red colored solution upon the reaction of powdered senna leaves with potassium hydroxide in ethanol, hydrochloric acid, ether and 6 N ammonium hydroxide
Figure 2. Formation of orange colored solution upon the addition of 6 N ammonium hydroxide to powdered Cascara Sagrada
Aloes were known to contain the anthraquinone glycosides, Aloin A and B. Cascara Sagrada was known to contain Cascarosides A, B C and D which are responsible for the herb's laxative effect. Cascaroside A is the most abundant cascaroside found in Rhamnus purshiana DC. Senna was known to contain sennosides which also exerts a laxative effect
The presence of various glycosides present in the abovementioned species were confirmed by the USP Identification tests designated for each herb being tested
TLC Analysis confirmed the presence of sennosides in
tablet and leaf samples
While the USP Identification test for sennosides served as a credible basis on the presence of sennosides in senna leaf, it is however noteworthy to use a well recognized standard for TLC Analysis for both samples
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