Strychnos alkaloids numbering

Among the wide variety of unsaturated functionalities which participate in the cobalt-mediated [2+2+2] cycloaddition that has proved to be a powerful tool for the assembly of complex polycyclic molecules are a number of aromatic heterocyclic double bonds, such as those in pyrrole and indole <20000L2479, 2001JA9324 and references therein>. Indoles, including those substituted at C-3, can be cyclized, both intra- and intermolecularly, with a wide variety of alkynes to yield functionalized products in moderate to good yields. A stereoselective cobalt-mediated [2+2+2] cycloaddition reaction between the W(pent-2-en-4-ynoyl)indole moiety of tryptamine derivative 1093 (R = (CH2)2NHAc) and acetylene has been employed for the formal total synthesis of strychnine 1097, the most famous Strychnos alkaloid and a commonly used rodenticide and animal stimulant (Scheme 213). 

Pharmacology of Calabash-curare.f —Paralytic Activity. A number of Strychnos alkaloids have considerably greater paralytic action than any previously known natural or synthetic neuromuscular blocking agent. Unfortunately, frogs are not suitable for the evaluation of curare effects because they show sea-... 

The material first used by Wieland et al. was gourd curare from the middle Orinoco district, near Urbana, in Bolivar State, Venezuela, but in the fomth paper (1941) results are recorded for curares from Colombia and Venezuela, for which more precise details of origin are not available and there is considerable difference in the nature and quantity of the alkaloids in the various samples used. An examination has also been made of the bark of Strychnos toxifera, and one of the alkaloids (toxiferine II) it contains has been found in some of the curares examined. In all, ten alkaloids have been obtained and characterised and, with the exception of curine, they are all of quaternary type. They are named toxiferine, dihydrotoxiferine, or calabash-curarine (shortened to C-curarine in practice) according to type, and the variants within the type are distinguished by numbers, or numbers and letters, e.g., toxiferine I, toxiferine Ilb. 

Pauridiantha appears, therefore, to be a genus in which the biosynthetic pathways are limited in number and are stopped at primitive alkaloids. It follows a lack of structural specificity, permitting chemotaxonomic correlations with other plants characterized by the same features. From this point of view, the genus Pauridiantha resembles not only many Nauclea, but also a number of Strychnos. 

Introduction and Interrelationships.—Calabash-curare is prepared from the bark of South American Strychnos of the family Loganiaceae. From the curare and the Strychnos species, along with a large number of monomeric indole alkaloids, fifteen structurally classified bisindole alkaloids have been isolated. Their structures are all based on one CjgN skeleton. Only the N h N h fdimetho-salts exhibit high curare-activity. 

In their studies on the biosynthesis of terpenoid indole alkaloids, De Silva and co-workers have carried out a screening of some indole alkaloid producing plants of Sri Lanka for the occurrence of the first nitrogenous monoterpenoid precursor (70,71). In this survey, Rauvolfia serpentina, Strychnos nux-vomica, Cinchona ledgeriana, and a number of Mitragyna and Vinca species were tested for the presence of vincoside and 5a-carboxyvincoside. Although these two proposed bio-intermediates (at the time) were not detected, macroisolation techniques revealed the occurrence of 5a-carboxystrictosidine (78), an isomer of 5a-carboxyvincoside, in all plants tested, and strictosidine (79), an isomer of vincoside, only in... 

American poisonous mixture called curare. Curare is derived from certain members of the genus Strychnos, and contains a number of toxic alkaloids (strychnine being a famihar name for such an alkaloid). Thus, enzymes in glycolysis and the tricarboxylic cycle proper are of fundamental concern, for their blockage or inhibition could prove fatal. Inhibitors for enzymes involved in the carboxylic acid cycle are listed in Appendix B of Hoffman (1999). 

F.V.M., from the leaves, stems, and flowers of U. guaianensis (Aubl.) Gmel., from Strychnos camptoneura, and from the root bark of Nauclea latifolia Sm. Angustoline, and very probably (t.l.c. evidence) angustidine also, occur in U. rhynchophylla and U. homomallaand angustoline occurs in N. latifolia. Preliminary t.l.c. evidence was also obtained for the presence of angustine-type alkaloids in a number of other African and Asian Strychnos species. "... 

Calabash curare, prepared from plants of the genus Strychnos, is packed in hollow gourds. It contains a large number of alkaloids and is extremely poisonous. The alkaloids contain an indole ring system and can be divided into 3 types the yohimbine type (e.g. mavacur-ine), the strychnine type (e.g. Wieland-Gumlich aldehyde) andthehfrindole type (e. g. calabash toxiferin-I). 

Curare is a muscle relaxant drug, originally used as an arrow poison by Amazonian Indians. The traditional curare is prepared by a secret recipe thought to involve a number of plant species (Plotkin 1993). Plant sources of curare include Strychnos castelnaei and species in the Loganaceae family and Chondodendron tomentosum in the Menispermaceae family. Tubocurarine, a benzylisoquinoline dimer, is the major alkaloid in the curare plants. It exhibits paralysing effects on skeletal muscles, and is used as a muscle relaxant in surgical procedures. It controls convulsions caused by the toxic alkaloid strychnine. 

James (1950) cites a number of examples of seeds containing no alkaloids (Nicotiana tabacum), scant alkaloids (Atropa belladona), and abundant alkaloids (Strychnos nox-vomica). Thus it becomes very important to have a method capable of distinguishing between the static and dynamic constituents of a plant such as Vinca rosea, which at maturity contains about 100 alkaloids, whereas the seeds of V. rosea are essentially devoid of material (Scott, 1970). Figure 6.1 (Scott et al., 1973 Scott, 1974) shows the incorporation of OL-tryptophan by the seedlings. From the figure... 

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