Page 95 - Phytochemistry 2 (06-PG 605)

Carboline alkaloids
The most prominent examples are:
 Rauwolfia alkaloids (mainly reserpine).
 Yohimba alkaloids (mainly yohimbine),
 Peganum harmala alkaloids (mainly harmine and harmaline).

The alkaloids of this group are more correctly considered as
β-carboline derivatives, rather than indole derivatives.

From Rauwolfia and some Yohimbe species, a number of β-
carboline alkaloids were isolated and identified (during the past 50
years).

Rauwolfia alkaloids
Occurrence
Rauwolfia roots (Rauwolfia serpentina, family Apocynaceae)
contain several alkaloids, the most important of which is reserpine.
Rauwolfia alkaloids are subclassified as follows:
 The weakly basic tertiary colourless alkaloids e.g. reserpine,

deserpidine and recinnamine.
 The intermediately basic tertiary colourless alkaloids e.g.

ajmaline and rauwolfine.
 The strongly basic quaternary yellow alkaloids e.g. serpentine

and serpentinine.

R1 N H R1 R2

NH Reserpine OCH3 Trimethoxybenzoyl
H Rescinamine OCH3 Trimethoxycinnamyl
H OR2 Deserpedine H Trimethoxybenzoyl

H3COOC OCH3

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