J8-Erythroidine

These syntheses of Hofmann degradation products established the structure of XV but left two possibilities for a-erythroidine itself, II or XIX. The correctness of II was demonstrated by showing that a- and j8-erythroidines could be interconverted by warming in aqueous alkali. 

An X-ray crystallographic study of dihydro-j8-erythroidine hydrobromide carried out by Hanson 18) not only confirmed the structures... 

A chemical determination of the absolute configuration at C-3 by Boekelheide and Wenzinger corroborated this conclusion 19). The di-hydropyran derivative (L) derived from tetrahydro-j8-erythroidine... 

XLIX) was degraded by Hofmann eliminations (Fig. 6) to a mixture of dienes which w as oxidized to X( — )-3-methoxyadipic acid. The absolute configuration of this acid was knowui from earlier work in which it had been a key intermediate in establishing the absolute configuration of sterols 20) and led to the 3 R configuration for j8-erythroidine. 

Other pharmacological studies of dihydro-j8-erythroidine in recent years include its effect on cholinergic transmission in the brain 44, 45) and spinal cord 46) and on Renshaw nerve cells 47-49). 

When it comes to heteromeric receptors, many antagonists have little useful selectivity. The exceptions are dihydro-j8-erythroidine and the rapidly growing family of the a-cono-toxins (see below). An important point is that many of the antagonists available have channel-blocking properties (see, for instance, mecamylamine and hexamethonium). 

Eight known bases were isolated from this plant, namely, erysopine, erythraline, erythramine, erysodine, erysotrine, erythratine, N,N-dimethyltryptophan, and hypaphorine. In addition three alkaloids, not previously known to occur naturally, were isolated, namely, N-norprotosinomenine (CigHaiO N hydrochloride, mp 242-244° [a] +18°) (74), protosinomenine (picrolonate, mp 172-174°) (75) which was methylated to laudanosine (mp 83-85°), and j8-erythroidine (76) (92). 

It has long been known that quaternary ammonium salts can exert a curare-like action, and in recent years much attention has been given to the synthesis and pharmacological testing of such products work on this subject up to 1936 has been reviewed by Ing, and more recently a theoretical discussion of the relationship between structure and action in drugs of this type has been provided by Holmes, Jenden and Taylor. " Chase, Lehmann and Yonkmann have compared the action of quaternary salts of quinine with that of j8-er5rthroidine hydrochloride and of dihydro-j8-erythroidine hydrobromide. Quinine ethochloride shows marked curariform action of short duration. ... 

As j8-erythroidine and its hydrides appear to be important curarising agents in the erythrina series it is convenient to tabulate at this stage the threshold curarising potencies of these alkaloids and to add for comparison the curarising potencies of the other free erythrina alkaloids. Similar tables are given later for the liberated and combined (p. 890) alkaloids. 

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