Alkaloids erythrina family

The Erythrina Family. The final alkaloid family we will consider presents another novel feature, a spiro carbon (meaning from a single carbon two rings are formed). The best example is the alkaloid beta-er) oidine (3.26). It has found use as a muscle relaxant. 

It has become customary to call the principal members of this group the lupin alkaloids, but in view of their wide distribution in the Papilionaceae, a better title is that suggested above, since they appear to be the characteristic alkaloids of this leguminous sub-family. This is not the only type of alkaloid found in the Leguminosae other types occur, e.g., in Acacia (p. 631), Crotalaria (p. 601), Erythrina (p. 386), Mimosa (p. 4) and Pentaclethra (p. 776). 

The beanlike seeds of the trees and shrubs of the genus Erythrina, a member of the legume family, contain substances that possess curare-like activity. The plants are widely distributed in the tropical and subtropical areas of the American continent, Asia, Africa, and Australia, but apparently they are not used by the natives in the preparation of arrow poisons. Of 105 known species, the seeds from more than 50 have been tested, and all were found to contain alkaloids with curariform properties. Erythroidine, from E. americana, was the first crystalline alkaloid of the group to be isolated. It consists of at least two isomeric alkaloids, a and P-erythroidine both are dextrorotatory. Most experimental and clinical study has centered on the b form because it is more readily obtainable in pure state. P-Erythroidine is a tertiary nitrogenous base. Several hydrogenated derivatives of p-erythroidine have been prepared of these, dihydro-P-erythroidine has been studied most carefully and subjected to clinical trial. Conversion of P-erythroidine into the quaternary metho salt (p-erythroidine methiodide) does not enhance, but rather almost entirely, abolishes its curariform activity this constitutes a notable exception to the rule that conversion of many alkaloids into quaternary metho salts results in the appearance of curare-like action. 

Desmaele and co-workers have developed a sequence involving attack onto a jr-allylPd complex followed by an intramolecular Michael addition leading to functionalized cyclohexane derivatives [95]. This useful transformation was used as a key step in the total synthesis of racemic dihydroery-thramine 110, a biologically active compound of the Erythrina alkaloids family [96] (Scheme 42). 

Gercideae. (a) The occurrence of alkaloids. Key to branches leading to families that accumulate quinolizidines, pyrrolizidines (No. 1 see arrows) Erythrina (No. 3) indolizidines (No. 4) p-carbolines (No. 5) or simple indoles (No. 2) are marked. The rbcl sequences used (1400 bp) derived from Kass and Wink, 1997a,b Wink and Mohamed (2003). Trees were reconstructed with maximum parsimony. 

Erythrina alkaloids, which are known to arise biogenetically from benzyl-tetrahydroisoquinolines, are found to occur in numerous Erythrina species of the family Fabaceae (Leguminosae), the only exception being their presence in the genus Cocculus (Menispermaceae) (55). Erythrina alkaloids are of wide interest because of their remarkable physiological action. 

Johns SR, Kowala C, Lamberton JA, Sioumis AA, Wunderlich JA (1968) Homo-erythrina Alkaloids from Schelhammera pedunculata F.Muell. (Family Liliaceae). J Chem Soc Chem Commun 1102... 

Benzylisoquinollne alkaloids a group of alkaloids found mainly in members of the poppy family (Papaveraceae). The benzyl substituent on Cl of the isoquinoline radical can enter various secondary cycli-zations through phenol oxidation. The ring structures of the medically important Papaveraceae alkaloids (see), Erythrina alkaloids (see) and the fcisbenzyliso-quinoline Curare alkaloids (see) arise in this way. Biosynthetically, papaverine is derived from 2 molecules of dopa, one being converted to dopamine, the other to 3,4-dihydroxyphenylacetaldehyde. Mannich condensation of these two leads first to norlaudano-sine, which is dehydrated to papaverine (Fig. 1). 

Actually there are no good definitions of alkaloids (Bate-Smith and Swain, 1966) since each one is either too narrow or too broad. Even in the restricted Winterstein and Trier definition, at least five alkaloid families exist that can be derived from different amino acids consequently, there is a need to establish the proper biosynthetic pathways to permit the application of the alkaloid character to chemotaxonomy, It has been mentioned above that canadine (berberidine) may be found in plants of six partially unrelated botanical families. This fact is not surprising when considered in relation to the biochemical investigations of canadine biosynthesis. Many reactions are necessary to convert tyrosine into canadine consequently, one might even wonder why the distribution of this alkaloid is so limited. In contrast, other plants (and even some that produce canadine) can produce many alkaloids that are derived from tyrosine but have a marked difference in structure. Tyrosine serves as the key precursor of alkaloids of the isoquinoline type, but other types of alkaloids, such as colchicine and the Amaryllidaceae and the Erythrina alkaloids, may be synthesized from this amino acid. The nucleus of an alkaloid molecule can arise from different precursors thus the indole nucleus in Erythrina alkaloids arises from tyrosine, while in brucine it comes from tryptophan (Figure 1.5). The alkaloids cinchonamine and cinchonine differ in that cinchonamine has an indole nucleus, while cinchonine (like quinine) has a quinoline nucleus however, they exist in a precursor-product relationship (that is, the quinoline type is derived from the indole type in a one-step reaction). 

The isolation of these new 8-oxo-alkaloids adds two further examples to a growing family of 8-oxo-erythrina alkaloids, other examples being erythrabine (Id) and erysotramidine (If) (Ito et al. 1973) isolated from E.arborescens and crystamidine (In) from E.crysta-galli (Ito et al. 1973) whilst two other oxo-alkaloids have been found in Cocculus laurifolius (Uprety and Bhakuni 1975), (Bhakuni and Jain 1980). 

The family Annonaceae comprises some 2000 species and only about 150 have been investigated for their chemical constituents. Studies during the past decade have indicated that this family can perform biosynthetic sequences which yield an array of isoquinolines. As examples of the more unique types of isoquinolines, Erythrina alkaloids and the cularines form the subjects of two separate chapters. Relatively little information exists on the pharmacology of the cularines. There are now about 225 bisbenzyl-... 

The erythrina alkaloids form a widely distributed family that lately has received considerable attention as a result of their unique tetracychc skeleton and biological activities. Erythrocarine (46) [27, 28], erythravine (50) [29], and (-l-)-jS-erythroidine (59) [30] are three members of this family that have been synthesized with metathesis as a key step. The molecular structures of erythrocarine, found in the seeds of Erythrina carihaea, and erythravine, isolated from Erythrina cochleata, are related. As a result, the total syntheses independently proposed by, respectively, Mori et al. and Hatakeyama et al. proceeded via the comparable intermediates 45 and 49, respectively, as shown in Scheme 2.11. Ene-yne 45 was synthesized in a number of steps. This substrate was subjected to HCl, followed by [Ru]-I catalyst (10mol%) to induce a tandem enyne-RCM process to yield the acetylated natural product in a quantitative conversion as a 1 1 mixture of diastereoisomers. After... 

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