Evidence that nicotine acetylcholine receptors are not the main targets of cotinine toxicity

The toxicity of nicotine, cotinine and their mixtures was studied in Mus musculus mice as well their effects on growth after repetitive administration to young mice. The affinity constants of the two alkaloids for the nicotinic acetylcholine receptors (nAChRs) of Torpedo and rat brain membranes were determined. The administration of these alkaloids produced distinct symptoms of intoxication. Nicotine was 100-fold more toxic than cotinine and 10-fold more rapid than cotinine at producing respiratory arrest. The affinity of nicotine for both subtypes of nAChRs was > 100-fold higher than that of cotinine. Repetitive administrations of nicotine caused weight loss, whereas that of cotinine caused weight gain (P < 0.01). The administration of the two alkaloids as mixtures to mice caused significantly (P < 0.01) higher mortality than theoretically expected. Furthermore, hexamethonium pretreatment reduced by 2-fold (P < 0.01) the toxicity of nicotine but enhanced by 1.6-fold (P < 0.01) that of cotinine and was without effects on toxicity of mixtures. We suggest that nAChRs are not the main targets of cotinine toxicity.

Antipoliovirus structure-activity relationships of some aporphine alkaloids

A series of 18 aporphinoids have been tested in vitro against human poliovirus. The aporphines (+)-glaucine fumarate (1), (+)-N-methyllaurotetanine (4), (+)-isoboldine (7), and (-)-nuciferine, HCl (10) were found to be active with selectivity indices > 14. The nature of the 1, 2-substituents of the isoquinoline moiety appeared to be critical for antipoliovirus activity. An SAR study demonstrated the importance of a methoxyl group at C-2 on the tetrahydroisoquinoline ring for the induction of antipoliovirus activity. Molecular modeling of some compounds in this series revealed the close similarities between the three-dimensional conformational features of the inactive 1,2-substituted derivatives (+)-boldine (6) and (+)-laurolitsine (5) with derivatives containing the 1,2-(methylenedioxy) moiety, which were generally found to be inactive as exemplified by (+)-cassythicine (9).

[Diethyl benzylpiperazinomethyl and benzylpiperazinomethylbenzyl phosphonates as calcium inhibitors]

Two sets of phosphonic diethylester including a substituted benzylpiperazine moiety are synthesized. In spite of the spasmolytic or the calcium antagonistic potentialities of benzylpiperazine and phosphonic moieties, none of the six compounds, tested in vitro, exhibit any calcium antagonistic profile.

[The beta-adrenolytic activity of new arylmethyloxypropanolamine analogs of dioxadilol]

A series of arylmethyloxypropanolamines structurally related to Dioxadilol has been synthesized and tested for their beta adrenolytic activity. Only one compound, the benzofuranic derivative 3c, exhibited a similar activity as Dioxadilol but was less potent than propranolol.

Influence of the vinyl group on the calcium antagonistic activity of analogues of Fostedil

Four aryl vinyl diethyl benzylphosphonates related to Fostedil were synthesized and evaluated for their in vitro calcium-inhibitory activity. None of these compounds exhibited any calcium antagonistic profile. Unlike a series of diethyl-styryl benzylphosphonates, previously described, the presence of two aromatic rings linked by a vinyl group did not improve the calcium antagonistic activity.

[Hydroxyiminoacetone-like reactivators of phosphorylated cholinesterases. Structure-activity relationships via molecular modelling]

A structure-activity relationships (S.A.R.) is performed on a series of iminocetones acting like reactivators of phosphorylated cholinesterases. The structural and electronic molecular characteristics are computed using a molecular modelling system (Moldesign). A multidimensional statistical analysis point out the role of MEP's which are representative of the whole molecular electronic distribution.