Page 59 - phytochemistry II -pharmD general
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Properties
It is the racemic form (dl-mixture) of hyoscyamine, so it is optically inactive
(consisting of equimolar mixture of d-tropic & l-tropic esters). It is formed from
hyoscyamine during the process of extraction.
Atropine is readily hydrolysed by treatment with alkali or dilute acid yielding
tropic acid and tropine. Atropine SO4 is the most commonly used form among its
salts for medicinal purposes.
Uses
It is used in medicine as mydriatic, antispasmodic, preanesthetic
medication and antidote to organophosphorus insecticides.
B. Hyoscyamine
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.
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