Page 63 - phytochemistry II -pharmD general
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Identification of solanaceous tropane alkaloid
1- Vitali-Morine's test
The alkaloid is treated with fuming nitric acid. The mixture is evaporated to
dryness on a water bath. The yellow residue is cooled then treated with few drops
of 3 % alcoholic KOH solution, it gives a bright purple or violet color.
It is the most useful, although it is non-specific test. This test is sensitive and
can be used for colorimetric estimation of tropane alkaloids.
2- Gerrard's reaction
When few mg of the alkaloids are treated with 2% HgCl2 in 50% ethanol, a
red color is formed in case of hyoscyamine and a white precipitate in case of
hyoscine.
3- Test with p-dimethylaminobenzaldehyde reagent (PDMAB).
The alkaloid is treated with PDMAB /H2SO4. On warming in a water bath a
red color is produced that turns to cherry red color on cooling.
Natural tropane N-oxides
Me O
ON Me N
H H
OR OR
Hyoscyamine N-oxides
R = tropoyl
Two isomers of hyoscyamine N-oxide were isolated from the roots, stems,
leaves, flowers, pericarp and seeds of Atropa belladonna, Hyoscyamus niger and
Datura stramonium.
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