Page 91 - phytochemistry II -pharmD general
P. 91
Hydrolysis
On hydrolysis: reserpine yields reserpic acid, trimethoxybenzoic acid and
methanol while recinnamine gives reserpic acid, trimethoxycinnamic acid and
methanol.
Deserpedine is the demethoxylated derivative of reserpine. It lacks the
methoxyl group on ring "A". On hydrolysis it yields deserpic acid,
trimethoxybenzoic and methanol.
Estimation of reserpine
Reserpine is a weakly basic alkaloid that could not be determined by the
usual titrimetric methods. Several other techniques have been deviced for its
estimation including:
▪Non-aqueous titration.
▪Fluorimetric estimation.
▪Spectrophotometric determination.
▪Biological assay.
Tests for identification
▪ Vanillin /HCl reagent (1%): gives a violet color with reserpine.
▪ p-Dimethylaminobenzaldehyde reagent (PDAB): gives with reserpine in
presence of glacial acetic acid and H2SO4 a green color that turns red in excess
of acids.
▪ Froehd’s reagent gives a yellow color that turns to blue.
▪ Marqui’s reagent gives a grayish green color that turns to brown.
Uses
The above mentioned alkaloids, as well as rauwolfia and its pharmaceutical
preparations are useful hypotensive agents. They are also applied as sedatives,
tranquilizers, and in the treatment of various mental diseases.
The alkaloid reserpine is superior for the treatment of various mental
diseases.
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