Ergot alkaloids structures

Common Name Dihydroergotoxine Dihydrogenated ergot alkaloids Structural Formula ... 

Wallwey C, Li SM (2011) Ergot Alkaloids Structure Diversity, Biosynthetic Gene Ousters and Functional Proof of Biosynthetic Genes. Nat Prod Rep 28 496... 

Wallwey C, Li S-M (2011) Ergot alkaloids structure diversity, biosynthetic gene clusters and functional proof of biosynthetic gores. Nat Prod Rep 28 496-510... 

Of the typical ergot alkaloids, six pairs f table, p. 526) are now known. The first five pairs are more complex in structure than the sixth pair, ergometrine and eigometrinine. 

The Structure of Ergot Alkaloid, Elymoclavine. Bull, agric. chem. Soc. Japan 19, 94 (1955). 

Fig. 1. Structural similarities between ergot alkaloids and CNS neurotransmitters.

Flieger, M. et al. (1997). Ergot alkaloids — sources, structures and analytical methods. Folia Microbiol. 42(1), 3-29. Glass, J. et al. (2002). Streptococcus pneumoniae as a genomics platform for broad spectrum antibiotic discovery. Curr. Opin. Microbiol. 5(3), 338—342. 

Cyclols Stable molecules obtained by the addition of a heteroatom nucleophile to the carbonyl group of lactams are not very common. The side-chain moiety of the ergot alkaloids (e.g., 50) is one of the earliest examples of such a cyclolic structure (75FOR51) identified. This has given rise to a number of studies on the synthesis and chemical transformations of such units. The discussion below is confined to cyclols related to or arising from piperazine-2,5-diones. 

The proline-containing tricyclic system similar to the unit present in the ergot alkaloids, seems to be particularly efficient in stabilizing the cyclol structure. This is probably due to the conformational rigidity pro-... 

In addition to the effects noted above, the ergot alkaloids produce a variety of other central nervous system and peripheral effects. Detailed structure-activity analysis and appropriate semisynthetic modifications have yielded a large number of agents of interest. 

The photoaddition of water to the ergot alkaloids has been the subject of a number of studies,214,215 and the structures of the adducts have been elucidated. 

FIGURE 7 Structures of some ergot alkaloids used for the preparation of CSPs. (From Ref. 12.)... 

The tertiary members of these classes (Figure 8-2) are often used for their effects on the eye or the central nervous system. Many antihistaminic (see Chapter 16 Histamine, Serotonin, the Ergot Alkaloids), antipsychotic (see Chapter 29 Antipsychotic Agents Lithium), and antidepressant (see Chapter 30 Antidepressant Agents) drugs have similar structures and, predictably, significant antimuscarinic effects. 

Since the last review on ergot alkaloids, important new alkaloids from different sources, mostly from new ergot strains, have been discovered. Their proposed structure could in some cases be confirmed by synthesis. Some of them seem to be intermediates in the biogenetic pathway from tryptophan to the peptide alkaloids. Others are considered as end products of secondary plant metabolism. In any case we find many interesting structures among these recently discovered substances. 

The delicate structures as well as the interesting patterns of pharmacological activity of certain ergot alkaloids have received continuous attention among synthetic chemists. This is especially true of derivatives of lysergic acid, and this chapter will be devoted to the most remarkable developments in syntheses of this class of natural compounds. 

---