Page 62 - phytochemistry general program
P. 62
It is used in medicine as mydriatic, antispasmodic, preanesthetic
medication and antidote to organophosphorus insecticides.
Hyoscyamine .1
It has the same structure as atropine but differs in having an optically
active l-tropic acid moiety.
Occurrence
It occurs in Atropa belladona, Datura and Hyoscyamus species, family
Solanaceae.
Properties
It is the most common tropane alkaloid. The major source is Hyoscyamus
muticus, (indigenous to Egypt). It is laevorotatory, (due to the optically active
tropic acid moiety). Hyoscyamine is crystalline solid, occurs in silky needles, m.p.
108-111 oC; very soluble in ethanol (1:3), chloroform (1:2), less soluble in ether
and benzene. Hyoscyamine is readily racemized by alcoholic potash to give
atropine. Racemization is brought about even when hyoscyamine is heated under
vacuum or boiled in chloroform. Hyoscyamine is hydrolyzed by dil. alkali or dil.
acids to yield tropic acid and tropine base.
Uses
As atropine but more active.
Minor alkaloids and related atropine analogues
Apo-atropine .1
It occurs in Belladonna roots, it is optically inactive (as apotropic acid
has no asymmetric carbon).
It is freely soluble in alcohol, ether, chloroform, benzene. It is used as
antispasmodic
Belladonnine .2
Belladonnine occurs, as minor alkaloid, in Atropa belladonna. It is a dimer of
apo-atropine. It can be prepared by dimerizing apo-atropine by heating at 110 oC
for 48 hours. It gives positive Vitali’s test. It is soluble in alcohol, benzene,
chloroform, ethyl acetate.
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