Lycaconitine

Aconitum lycoctonum. From the roots of this species Hiibschmann isolated the amorphous alkaloids acolyctine and lycoctonine. Dragen-dorff and Spohn showed that Hiibschmann s alkaloids were probably decomposition products of lycaconitine, C2,H3403N2. 2H2O, which they isolated along with myoctonine, 27 30 8 2 - 5H2O. These results liave been considerably extended by Schulze and Bierling, and more recently by Marion and Manske, for lycoctonine. 

Myoctonine, (C3sH420ioN2)2, [a] + 44 7° (EtOH), is amorphous on hydrolysis it furnishes the same products as lycaconitine. 

CggHjgOjN. HjO, m.p. 143°, [a] ° + 53-2° (EtOH), apparently identical with the basic hydrolytic product of lycaconitine (p. 686) from which methyllycaconitine differs in yielding methylsuccinic acid in place of succinic acid on hydrolysis. This established for the first time similarity in constitution between alkaloids of the two closely related Ranunculaceous... 

The pattern of data on the role of al receptors (pentamers of the al subunit) is far from clear. Nomikos et al. (1999) reported sharply reduced locomotor activity in nicotine-dependent rats injected with the selective al antagonist methyl-lycaconitine (MLA). Barik and Wonnacott (2006) found increased al sensitivity in the hippocampus of rats during nicotine withdrawal, as evidence by increased norepinephrine release in response to an al agonist. On the other hand, Markou and Paterson (2001) reported that systemically administered ML A failed to precipitate either somatically expressed withdrawal behaviors or altered ICSS thresholds. 

Herbivores possibly regulate the amount eaten from toxic plants and thus avoid ill effects. Cattle cycle between consuming large and small amounts of tall larkspur, D. harbeyi. The principal toxic alkaloid in tall larkspur is methyl-lycaconitine (Pfister etcj/., 1997). 

Studies of the arrhythmogenic effects and the effects on heart rate of aconitine (14), X-desacetyl-lappaconitine (7), lappaconitine (6), lycoctonal (13), lycoctonine (12), lappaconine (15), avadharidine (9), lycaconitine (10), anthranoyl-lycoctonine (8), and cashmiradelphine (septentriodine) (11) were also reported.8 The alkaloids (6), (7), and (15) were found to be arrhythmogenic... 

Alkaloids of Aconitum umbrosum Umbrosine.—From roots of Aconitum umbrosum, workers at Tashkent have isolated lycaconitine (13), anthranoyl-lycoc-tonine (14), ajacine (15), and a new alkaloid, umbrosine (16), C24H39N06, m.pt. 150—151 °C.21... 

Methyl-lycaconitine (36), anthranoyl-lycoctonine (14), and a new alkaloid, C24H39NO7, m.pt. 98—100 °C, were isolated from the alkaloid fraction of the roots of D. dictyocarpum collected in the Kuyandysa region.27 The i.r., n.m.r., and mass spectral data indicate that the new alkaloid is most probably demethylenedeltamine (37). This conclusion was confirmed by comparison with the demethylene derivative of deltamine (eldelidine) (38). 

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. 

Alkaloid A , which forms lycoctonine on mild alkaline hydrolysis, was identified as methyl-lycaconitine (36) from 13C n.m.r. data. Alkaloid B also forms lycoctonine on similar hydrolysis. However, the 13C n.m.r. spectrum of Alkaloid B ... 

It is probable that avadharidine is formed from lycaconitine by reacting with ammonia during the extraction of the alkaloids from the plant in the same way that delsemine is formed from methyllycaconitine. The esterifying acid of lycaconitine is XXIXb, and therefore the structure of lycaconitine is XXXIV. 

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