Page 75 - phytochemistry II -pharmD general

following childbirth and spontaneous or elective abortion. It also causes uterine
contractions to aid in expulsion of retained products of conception after a missed
abortion (miscarriage in which all or part of the fetus remains in the uterus) and to
help deliver the placenta after child birth child birth. It is available as tablets or
injection and is contraindicated in pregnancy and hypertension.

Lysergic acid diethylamide (LSD)

Another example of this class of simple amides is the famous hallucinogen
(LSD) which is lysergic acid diethylamide (in German lyserg saure diethyamide
(L.S.D.). It is a semi synthetic drug with a very potent action on the CNS in
extremely small doses.

ii. The polypeptide alkaloids
These polypeptide alkaloids, together with the simple lysergic amide,
ergometrine, represent the most important medicinally utilized ergot alkaloids.

The polypeptide alkaloids are more complex, high molecular weight, water-
insoluble alkaloids. Though they are also amides of lysergic acid, they are built up
from a lysergic acid moiety forming an amide with a complex polycyclic polypeptide
moiety. The latter moiety is formed up of three different amino acids.

(a) R1 HO

(b)

CO NH O
N

H N O
O
NCH3

R2 (c)

NH

General structure of the polypeptide alkaloids

(Showing the three amino acids part structures a, b and c)
(Linked together and to the lysergic moiety by three amide linkages)

Amino acid (a) = α-hydroxyalanine or α-hydroxyvaline
Amino acid (b) = Proline
Amino acid (c) = Valine or Leucine or Phenylalanine

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