Page 88 - Phytochemistry 2 (06-PG 605)

Nux vomica alkaloids
In the seeds strychnine is usually located in the inner parts of
the endosperm, while brucine occurs largely in the outer layers of
the endosperm.
The total alkaloidal contents of Nux vomica varies from 0.2 to
5%; and for pharmaceutical purposes the seed is required to
contain not less than 1.2 % of strychnine; so, the seed is assayed
for its strychnine content and not for total alkaloids.

Strychnos nux-vomica Alkaloids

N

R Strychnine; R = H

RN Brucine (2,3-Dimethoxystrychnine); R = OCH3

OO

Properties
Strychnine occurs as colourless rhombic crystals, or white

crystalline powder, m.p. 286-288 ˚C. It is soluble in alcohol,
chloroform and benzene but insoluble in water. It is a mono-acidic
base (only the N atom, farthest from the benzene ring forms salts,
while the other N, is an amide and has no basic characters).

Brucine crystallizes from water or aqueous alcohol as
prisms, m.p. 178oC. It is soluble in alcohol, chloroform and
acetone, but insoluble in water. Brucine is a mono-acidic base, it is
dimethoxy strychnine, and is much less poisonous.

Separation of a mixture of strychnine and brucine
Strychnine can be separated from brucine by one of the
following methods:
1. Shaking with acetone, where only brucine will dissolve.
2. Shaking with 25% ethanol, where only brucine will dissolve.

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