Alkaloid structures minor alkaloids

The minor alkaloid gelsedine, originally isolated from G. sempervirens in 1953 (3), has also been found in G. elegans (19). The structure of gelsedine (6) has been determined by means of H-NMR and mass spectral analysis (4,9)... 

Tabernanthe orientalis. This plant is now called Ervatamia orientalis, and is found in Western Australia. The leaves contain ibogaine, along with six minor alkaloids that are closely related, structurally. 

Dercitin (464) is a violet acridine alkaloid from a deepwater species of Dercitus with antitumour, antiviral and immunomodulatory properties in vitro [389] and with in vivo antitumour activity [390]. The structure was proposed on the basis of spectral properties. Cyclodercitin (465) was isolated as a minor alkaloid from a deepwater Dercitus species and three... 

Lobelia or Indian tobacco consists of the dried leaves and tops of Lobelia inflata (Campanulaceae), an annual herb from the USA and Canada. Lobelia contains about 0.2-0.4% of alkaloids, of which the piperidine derivative lobeline (Figure 6.23) is the chief constituent. Minor alkaloids identified include closely related structures, e.g. lobelanine (Figure 6.23). The North American Indians employed lobelia as an alternative or substitute for tobacco (Nicotiana tabacum Solanaceae), and it is found that lobeline stimulates nicotinic receptor sites in a similar way to nicotine, but with a weaker effect. Lobeline has been employed in preparations intended as smoking deterrents. The crude plant drug has also long been used to relieve asthma and bronchitis, though in large doses it can be quite toxic. 

Dehydrothalifaberine (473), Q H NjOg, amorphous, [a] ,4 +95.9° (c0.143, MeOH), is a minor alkaloid of Thalictrumfaberi. The structure was deduced by NMR, MS, and CD, and by partial synthesis of 473 by oxidation of the companion alkaloid thalifaberine (302) with DDQ. The dehydro base does not appear to be an artifact of air oxidation of302 during isolation (545). 

Natalinine (491), C25H23N05, amorphous, is a minor alkaloid of Berberis empetrifolia Lam. MS and high-resolution NMR established the skeletal structure, and CD indicated the (R) configuration (561). Natalinine may be derived biogenetically from catabolism of an aporphine-benzylisoquinoline dimer [such as pakistanine (92), a major co-occurring alkaloid] (561), or by rearrangement of a coyhaiquine (107)-type dimer (562). 

Carbon-13 n.m.r. assignments have been reported for a number of isomeric 3-butyl-5-methyloctahydroindolizines that were synthesized in studies of the trial pheromone of the Pharaoh ant, and for some closely related indolizidines. This work includes a detailed discussion of the preferred conformations of these compounds.15 Securinegine, a minor alkaloid from Securinega suffruticosa Rehd., is isomeric with securinine, and the structure (22) has been proposed.16... 

The structures of the major alkaloids of Stephanotis japonica were reported earlier.8 Two minor alkaloids, stephanthraniline B (7a) and dihydrogagaminin... 

During the structure elucidation work, cephalotaxine was shown to form a mono-O-acetate (106) (102), and this compound was later found as a minor alkaloid in C. fortunei (98). An impure sample of acetylcephalotaxine was also obtained from C. wilsoniana Hay. (90). 

In 1976, Lamberton and his colleagues reported (70) the isolation of two minor alkaloids, anopterimine and anopterimine TV-oxide, from the leaves of A. macleayanus F. Muell. These alkaloids were not encountered in the related species, A. glandulosus Labill. On the basis of extensive H- and 13C-NM R analyses, structures 70 and 71 were assigned to anopterimine and anopterimine TV-oxide, respectively. 

Dihydroatisine, a minor alkaloid of the roots of A. heterophyllum Wall, was isolated (SO) from the strong base fraction and its structure (78) was established by comparison with the sodium borohydride reduction product of atisine or isoatisine. Recently, an X-ray analysis of dihydroatisine confirmed (30) its structure and determined the absolute configuration as 45, 55, 87 , 107 , 127 , and 155. So far dihydroatisine has not been reported in any other plant. 

Hetisine (125) was isolated as a minor alkaloid from the roots of A. heterophyllum Wall (80) in 1942 by Jacobs and Craig (118, 119). Later it was also isolated from D. cardinale Hook (120). Several papers were published (121, 122) regarding the chemistry and structure elucidation of hetisine, but the structure of hetisine (125) was eventually established by an X-ray diffraction study (123, 124). Earlier work on the chemistry of hetisine has been reviewed in Volume XII of this treatise (6). 

Chromatography of the mother liquors of lythrancepine 102 afforded three minor alkaloids lythrancines 104, 105, and 106. The structure and stereochemistry of these bases was elucidated by analysis of NMR and mass spectra and by comparison with those of lythrancine 103. The assigned structure 104 for lythrancine-V was unequivocally confirmed by the previously described conversion of lythrancine 102 to this alkaloid via isomer 114 (61). 

Rhazinaline, one of the minor alkaloids of Rhazya stricta, has been formulated55 as (167), i.e. 16-formyl-16-epistrictamine, and may well be identical with the alkaloid of this structure isolated earlier from the same source by Smith and his collaborators.95 However, it has not yet proved possible to compare the two specimens directly. 

Alkaloids of Delphinium grandiflora.—Savchenko30 has reported the isolation of four alkaloids from D. grandiflora. The total alkaloid content of the plant was 0.71%. The major alkaloid, methyl-lycaconitine (36), was isolated as its perchlorate salt. Delpyrine (no structure indicated), anthranoyl-lycoctonine (14), and a minor alkaloid were isolated by counter-current distribution methods. 

Anopterimine, C25H33NO3, m.pt. 235—238 °C, and anopterimine N-oxide, C25H33NO4, m.pt. 233—235 °C, were isolated as minor alkaloids from the leaves of A. macleayanus42 These bases were assigned structures (91) and (92), respectively, from the spectral data. 

Monoterpenoid Alkaloids.—Aristotelia Alkaloids. Details of the elucidation of the structure of aristone by the X-ray method have been published.39" Aristoserratine, a new, minor alkaloid of A. serrata and A. peduncularis39b is 15-oxoaristoteline (59). Since aristoserratine could not be reduced to aristoteline, the absolute configuration expressed in (59) was deduced from its c.d. spectrum. 

There are recognized at present three naturally occurring members of this group, cinchonamine, quinamine, and conquinamine, all minor alkaloids of certain Cinchona and Memijia species. The elucidation of their structures led to the suggestion that the quinoline moiety of the major bases, e.g., cinchonine and quinine, of these plants was probably derived from tryptophan via an indolic precursor. It has since been demonstrated from the results of feeding experiments with isotopically labeled tryptophan that this amino acid really can serve as a precursor of various indole alkaloids (1) as well as of quinine (2). The details of these processes are not yet known but probably involve an intermediate(s) related to cinchonamine (2, 3, 6). 

In a reinvestigation of the minor alkaloids of A. quebrachoblanco, whose presence had already been indicated by Hesse (59) in 1882 (Vol. II), Biemann et al. (28, 51a) were able to isolate by a combination of alumina and gas chromatography about twenty compounds. The identification or structure determination of fifteen of these by mass spectrometry was described. Six belonged to the aspidospermine group and four of these were the known compounds, aspidospermine (II), deacetylaspido-spermine (VI), V.,-methyldeacetylaspidospermine (XLI), and (— )-pyri-folidine (XLVI). The three last-named had not previously been encountered in nature, VI and XLI having been prepared from aspidospermine (II) and vallesine (XXXVIII) (38, 39, 25). (— )-Pyrifolidine is identical with O-methylaspidocarpine (XLVI) which has been prepared... 

The typical fragmentations pattern of the alkaloid type (199) was very useful for the structural elucidation of some minor alkaloids occurring in the bark of Aspidosperma oblongum A. DC. They were shown to be methoxyl and dehydro derivatives of the parent molecule.95, 96... 

A minor alkaloid of the stem bark of O. nitida is inandenin-10,11-diol (64). Its reported structure was based on HCl-catalyzed hydrolysis of its N,N, 0.0 -tetraacety 1 derivative. In this reaction, which proceeds via a... 

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