Page 83 - Phytochemistry 2 (06-PG 605)

Lysergic acid alkaloids Alcoholic KOH Isolysergic acid alkaloids
Active ergot alkaloids H3PO4 or CH3COOH Inactive Lumi-derivatives

Light or UV

Ergot alkaloids are subclassified into 3 main groups, according
to their hydrolytic products:

- Alkaloids of the ergometrine group that yield 2-amino
propanol,

- Alkaloids of the ergotamine group that yield pyruvic acid,
- Alkaloids of the ergotoxine group that yield dimethyl pyruvic

acid
Tests for identification
1. Van-Urk's test: to a solution of the alkaloids add Van Urk's

reagent (solution of p-dimethyl aminobenzaldehyde, PDAB, in
15% H2SO4, containing traces of FeCl3) a deep blue colour is
obtained.
2. Keller’s test: to a solution of the alkaloids in acetic acid add
drops of FeCl3 followed by careful addition of concentrated
H2SO4 on the wall of the test tube a blue layer is formed
between the two phases.
Estimation of ergot alkaloids

The total ergot alkaloids can be determined in the powdered
drugs or pharmaceutical preparations by one of the following
techniques:
1. Colorimetrically, based on that the blue color produced with

using Van Urk's reagent is concentration dependent. The
absorbance is measured at 590 nm and compared with a with a
standard reference alkaloid.
2. Fluoremetrically, based on that the alkaloids are fluorescent.

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