2.1.1.2
Simple Lysergic Acid Derivatives
The derivatives of lysergic acid are amides in which the amidic moiety is
formed by a small peptide or an alkylamide. The derivatives of (+)-lysergic acid
with 8b-configuration are pharmacologically active. Nonpeptide amides of lysergic acids isolated from ergot fungi are ergometrine, lysergic acid 2-hydroxyethylamide, lysergic acid amide, and paspalic acid (Fig. 3). Further information
is available in [2, 3, 7].
4
J. Mukherjee · M. Menge
a
b
Fig. 3. a Paspalic acid. b Simple derivatives of lysergic acid: R=OH, lysergic acid; R=NH 2 ,
lysergic acid amide; R=NHCHOHCH 3 , lysergic acid 2-hydroxyethylamide; R=NHCHCH 3
CH 2 OH, ergometrine
Fig. 4. General structure of ergopeptines. (R 1 = substituent of amino acid I; R 2 = substituent of
amino acid II; amino acid III is l-proline)
2.1.1.3
Ergopeptines
The ergopeptines, also called cyclol ergot alkaloids (CEA) are composed of two
parts, namely lysergic acid and a tripeptide moiety. Figure 4 shows the general
structure of the ergopeptines.
Their characteristic feature is the cyclol part which results from the reaction
of an a-hydroxy-amino acid adjacent to lysergic acid with a carboxyl group of
proline. Amino acid III of this tripeptide is l-proline and is common to all the
naturally occurring ergopeptines. Their molecular structures have been
described by the exchangeability of the l-amino acid I and the l-amino acid II
between alanine, valine, phenylalanine, leucine, isoleucine, homoleucine, and
a-aminobutyric acid. The groups of the ergopeptines formed by the combination of these amino acids are ergotamine, ergotoxine, ergoxine, and
ergoannines [2, 7].