Erythrina alkaloid isolation

Combined Erythrina Alkaloids. The sources of the liberated alkaloids (see above) are now known to be, at least in two cases, the sulphur-containing alkaloids erysothiopine and erysothiovine, which are esters of sulphoacetic acid, HOOC. CHj. SOj. OH, identified as the aniline salt, m.p. 187-9° with erj sopine and erysovine respectively. The sources of erysodine and erysonine have not yet been isolated. These combined alkaloids arc believed to be sulphonic esters, of the type HO. OC. CHj. SOj. 0. R, where R is the alkaloidal residue. ... 

Demethoxyerythratidinone (10), one of the simplest of the erythrina alkaloids, was isolated in 1973 by Barton et al. from Erythrina lithosperma [14]. A concise approach to such Erythrina alkaloids using a disfavored 5-endo-trig radical cyclization mediated by nickel powder was described by Zard and coworkers [15]. A-Alkenyl trichloroacetamide 7 was... 

In the Erythrina series, the total synthesis of ( )-erysotramidine (10), an oxo-erythrinan alkaloid, isolated from Erythrina arborescens Roxb.,13 has been... 

Erysophorine (13) was isolated from the water-soluble extract of the seeds of E. arborescens Roxb. (37). The molecular formula C32H38N304.CI was established by analysis. The mass spectrum of 13 gave no molecular ion but exhibited fragments consistent with a 1,6-diene Erythrina alkaloid and a carboxylated indole-3-alkylamine. Erysophorine appeared to be a combined alkaloid, and its UV spectrum was similar to that of an equimolar mixture... 

Cocculine (C17H21N02) and cocculidine (ClgH23N04) were isolated from C. laurifolius in 1950 (77) but escaped mention in previous reviews of this treatise because only a partial structure, unrelated to the Erythrina alkaloids, had been advanced (78). On the basis of the spectroscopic properties of the alkaloids and their Hofmann degradation products, structures 56 and 54 (without stereochemistry) were proposed for cocculine and cocculidine, respectively (79) however, a different group (80) proposed structures 69 and 70, respectively, on the basis of similar evidence. The... 

A related alkaloid coccutrine (C18H23N03) was isolated from C. trilobus (60) and structure 52 established spectroscopically, with the positions of the aromatic hydroxyl and methoxyl groups being defined by X-ray analysis. Coccutrine is the only example of an Erythrina alkaloid containing an oxygen function at C-17. 

Continued examination of the pharmacologically interesting species C. laurifolius, particularly by Singh et al. (55, 56, 70- 72, 74) has led to the isolation of more Erythrina alkaloids that have structures related to cocculine (56) and cocculidine (54). Coccuvine (C17H19N02) and coccuvinine (C18H2IN02) were found to be of the 1,6-diene type (56, 72) and the structures 16 and 14, respectively, were established on the basis of spectroscopic evidence and chemical interconversions. Methylation of coccuvine (16) (see... 

Only two normal Erythrina alkaloids have been isolated from Cocculus species, dihydroerysodine (47) (75) and dihydroerysovine (44), the latter recently from C. trilobus (57). Neither alkaloid has been found in Erythrina species. The structure 44 for dihydroerysovine was deduced from the spectroscopic evidence and by methylation using diazomethane to give the known dihydroerysotrine (38). The positions of the aromatic substituents were determined by detailed NMR experiments using NOE and INDOR techniques (see Section II,C,2d). 

Cocculolidine, an alkaloid with striking insecticidal properties isolated from the leaves of Cocculus trilohus DC, has recently been isolated and assigned the structure (XCIV) of a lower homolog of -erythroidine 50). The degradation reactions reported closely parallel those of /3-erythroidine. This makes the second report of Erythrina alkaloids in Cocculus species, dihydroerysodine having been isolated earlier from C. laurifolius 51). 

The enol-lactam (30), which has occupied a central role in the synthesis of Erythrina alkaloids, has been converted in an unprecedented reaction into the dimeric isomers [31 C(6)-a-0] and [31 C(6)-/ -OJ.15 This reaction may be effected in benzene, pyridine, or acetic acid solution in the presence of lead tetra-acetate. The structures of the products were elucidated by spectral and chemical means. As enol ethers, these compounds were found to exhibit surprising stability to mineral acids. However, catalytic reduction of [31 C(6)-a-OJ under neutral conditions gave the starting enol-lactam (30) and the 7/Miydroxylactam (32 RJ = OH, R2 = R3 = H). The dimer [3 l C(6)-/i-0] yielded only compound (32 R1 = OH, R2 = R3 = H). Similarly, sodium borohydride reduction of the dimer mixture in hot isopropanol led to cleavage products (32 R1 = OH, R2 = R3 = H)and(32 RJ = R3 = H, R2 = OH). Besides the dimeric products, compound (32 R1 + R2 = O, R3 = OAc) was also isolated from the lead tetraacetate oxidation in low yields. Attempts to discover conditions for the formation of preparative amounts of (32 R1 + R2 = O, R3 = OAc), a compound of more potential usefulness for alkaloid synthesis, were fruitless. The other question of interest, whether or not the trans-dimer [31 C(6)-/i-0] could be converted into a monomeric trans-erythrinane system, remains to be answered. 

Although the first of the Erythrina alkaloids was isolated in 1937 (12), it is only recently that the exact ring-systems and the relationship between the aromatic and erythroidine types have been elucidated. Prelog and collaborators (95, 96) proved that the aromatic Erythrina alkaloids are represented by XIX. This is probably the basic ring-system for all of the... 

Erysodienone (1 R = H), a compound previously unknown in Nature, has been isolated from Erythrina lithosperma. The isolation of erybidine (2) from E. xbidwilli Lindl. is of biogenetic interest. Its structure was determined by spectral studies, Hofmann degradation, and synthesis from erysodienone (1 R = H). This species has been shown previously to elaborate Erythrina alkaloids. 

The Erythrina alkaloids represent a group of natural products isolated from various species of plants of the same name and found in tropical and sub-tropical regions of the world. They are all spirocyclic isoquinoline alkaloids and found in all parts of... 

The present contribution will give a brief classification of the Erythrina alkaloids, a compilation of new alkaloids isolated from 1997 to 2004 covering source, structure, analytical/spectral data, a new pathway of their biosynthesis, an overview of all the synthesis strategies hitherto known for the erythrinane alkaloids including several approaches to the homoerythrinane group, and finally a short review of their biological activities. 

Between 1940 and 1950 the systematic examination of more than fifty Erythrina species showed that all the alkaloids isolated produce effects similar to curare alkaloids 116, 119), which had been used as adjuvant in surgical anaesthesia (720). 

Folkers K, Koniuszy F (1940) Erythrina Alkaloids. VIL Isolation and Characterization of the New Alkaloids, Erythraline and Erythratine. J Am Chem Soc 62 436... 

Erythrina Alkaloids Recent Advances in THEIR Synthesis, Isolation and Pharmacology... 

The methanol extract of E. herbacea flowers was subjected to the conventional extraction and isolation procedures for alkaloids. A new Erythrina alkaloid, 10-hydroxy-ll-oxoerysotrine (29), was isolated together with five known compounds. The structure of the new compound was elucidated on the basis of its spectral data, including 2-D NMR and mass spectra (MS). The new compound is a rare C-10 ox ygenated Erythrina alkaloid [49]. 

Flausino, O. de Avila Santos, L. Verli, H. Pereira, A. M. da Silva, V. Nunes, R. Effects of Erythrinian alkaloids isolated from Erythrina mulungu (Papilionaceae) in mice submitted to animal models of anxiety. Biol Pharm. Bull, 2007,30,375-378. 

A group of alkaloids with a unique skeleton known as the Erythrina alkaloids have been isolated from the seeds of Erythrina plants examples include erythraline and erysodienone obtained from the seeds of E. indica [1,2]. The relative and absolute stereochemistry of these alkaloids was determined by X-ray crystallography and chemical degradation studies [3].The chemical synthesis of the Erythrina alkaloid nucleus was achieved biomi-metically through phenol oxidative coupling [4]. 

Many Erythrina alkaloids possess curare-like action and interact with acetylcholine receptors. Extracts of many Erythrina species are used in indigenous medicine, particularly in India. Cocculine and cocculidine nitrates have been reported to show hypotensive action in dogs (Dyke and Quessy, 1981). The insecticidal alkaloid cocculolidine (109) has been isolated from Cocculus trilobus and C. carolinus... 

It is of chemotaxonomic interest that the bases cocculine and cocculidine, which closely resemble some of the Erythrina alkaloids, have been isolated from Cocculus species (Menispermaceae). The recent isolation from C. trilobus of coccutrine, an apparent relative of protostephanine, as reflected by the ring-A oxygenation pattern, suggests that the dibenzazonines are not an end point in alkaloid biosynthesis. 

From Erythrina crystagalli cv. Maruba deiko, erythraline, erythrinine, and ery-thratine were isolated (77). Examination by TLC demonstrated that these alkaloids are present in all heartwood, bark, and roots. Many other Erythrina alkaloids have been isolated from plants of the genus Erythrina (Leguminosae), but most have been obtained from leaves and fruits. 

It is interesting to note that a member of the Erythrina alkaloids, dihydroery-sodine, was isolated (0.003%) from a Menispermaceae, Cocculus laurifolius (158). 

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). 

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