Strychnos species

Curare is a generic term for various South American arrow poisons. Curare has been used for centuries by the Indians along the Amazon and Orinoco rivers for immobilizing and paralyzing wild animals used for food. Preparations of curare are derived from Strychnos species, which contain quaternary neuromuscular alkaloids like tubocurarine. Tubocurarine is a potent antagonist at the nicotinic acetylcholine receptor. 

Philippe G, Angenot L, Tits M, Frederich M. About the toxicity of some Strychnos species and their alkaloids. Toxicon 2004 44 405-416. 

Figure 86. Some alkaloids from Strychnos species.

Frederich, M., Tits, M. and Angenot, L. 2003. Indole alkaloids from Strychnos species and their antiplasmodial and cytotoxic activities. Chemistry of Natural Compounds, 39(6) 513-519. 

Activity of some alkaloids on Gram-positive and Gram-negative bacteria. Some alkaloids from Strychnos species. 

Constituent of symphoricarpos albus (L.) and of several lonicera and strychnos species [3]... 

Strychnine was used in its impure powder form centuries before it was isolated. The nuts that yielded the seeds were given names such as poison nut or vomit nuts. Natives prepared poison arrows using the seeds and excretions of Strychnos species, and Europeans... 

Quetin-Leclercq J, Angenot L and Bisset NG (1990) South American Strychnos species. Ethnobotany (except curare) and alkaloid screening. J Ethnophar-macol 28, 1-52. 

Only a few of the quaternary alkaloids so far isolated have high curare-activity, and these are responsible for the toxicity of the curares and bark extracts the majority of the pure alkaloids are inactive or only weakly active. At present there is no evidence against the view that all the toxic alkaloids of calabash curare are derived from Strychnos species it is probable that the same also holds true for most of the nontoxic curare alkaloids. 

Venezuelan 8. toxifera bark (30), and they have been detected chromato-graphically in extracts from the barks of several Strychnos species (20, 25, 43-45). A study of these two alkaloids gave a first insight into the structures of alkaloids from calabash curare and commenced with a demonstration that they are interrelated. 

Melinonine H, formulated as C20H21-23N2O+ from analyses of the picrate, mp 290°-292°, and perchlorate, has one A-methyl and one O-methyl group. Its UV-spectrum shows that this alkaloid is the only quinoline derivative so far isolated from calabash curare or Strychnos species. It is not identical with the quaternary Ab-metho derivatives of cinchonine or cinchonidine (40). 

This pale-yellow quaternary alkaloid, picrate mp 189°, [a]D of chloride — 930° (in water), was first isolated from a calabash curare (12) it was subsequently isolated from other calabash curare preparations (34, 35) and has been identified chromatographically in extracts from the bark of S. mitscherlichii (33) and other Strychnos species (7). The identification of C-fluorocurarine is greatly helped by its deep-blue fluorescence in UV-light. Analyses of the crystalline iodide and anthraquinone sulfonate showed its molecular formula to be C2oH23N20+ (12), which is in agreement with all subsequent work. The properties of C-fluorocurarine, particularly its low toxicity and high Rc values, suggest that it is a C20 alkaloid rather than a double molecule. This was confirmed (102) by application of the partial quaternization method to one of its derivatives (see subsequent discussion) the method cannot be applied to C-fluorocurarine itself, since on pyrolysis it is not smoothly demethylated to the... 

Alkaloids of Unknown Structure from Calabash Curajre and Strychnos Species... 

Bi snordi hydrotoxi feri ne,bi snor--C-alkaloid H.caracurine V Isolation from strychnos species uPorasil 300x3.9 EtOAc-MeOH-25% NH.0H(90 10 1), (80 25 2) 33, 41,44... 

Indole alkaloids from Strychnos species and their anti-plasmodial and cytotoxic activities 03KPS425. 

In this chapter, alkaloids isolated from Strychnos species are presented in tabular form (see Table II). Most recent papers on these subjects simply describe the structures of new alkaloids as determined primarily by spectral methods. Therefore, detailed description concerning structure elucidation of individual alkaloids seems unnecessary. Coverage of the literature starts from around 1965. In line with this principle, the Strychnos alkaloids tabulated by M. Hesse (7,8) are included only when they were reported to be newly found in other species of Strychnos. Thus,... 

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. 

C-Curarine (54) is formed by oxidation of C-dihydrotoxiferine (46) under very mild conditions. The alkaloid has, however, repeatedly been isolated from South American Strychnos species under conditions which do not suggest that it is an artefact. The same applies to C-alkaloid E (51) formed from C-toxiferine (38). 

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