Methyl lycaconitine

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). 

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 ... 

Alkaloids of Delphinium oreophilum 14-Acetylbrowniine.— From the aerial parts of this species, total alkaloids were obtained in a yield of 0.8%.Two bases were isolated from this material. One was identified as methyl-lycaconitine (41) by comparison of its perchlorate salt with an authentic sample (see diagram on p. 224). 

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