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

These mentioned subgroups may occur in the form :

1) Free aglycones: e.g: anthraquinones.

2) O-glycosides. 3) C- glycosides

Properties of Anthrquinone derivatives:

▪ They are usually red or yellow colored.

▪ When free, they are of low solubility in water.

▪ glycosides show greater solubility in water.

▪ Anthraquinone derivatives give reddish coloration with alkali, a fact on which
Borntrager’s Reaction is based.

Tests for identity:

1) Bornträger’s test: pink or red in aqueous layer.

• The glycosides are extracted and hydrolyzed by boiling the drug with mineral acids.
• The aglycones are extracted from the acidic solution with ether or benzene.

• Upon shaking the ether or benzene layer with aqueous alkali or ammonia solution,
the aqueous layer assumes a deep-red colour, because of the formation of
anthraquinone salts.

2) Modified Borntrager’s reaction :
• Borntrager’s reaction can distinguish anthraquinones from anthrones and anthranols which
do not give the test unless they are converted to anthraquinone by oxidation with mild
oxidants such as hydrogen peroxide or ferric chloride.

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