Search tips
Search criteria

Results 1-3 (3)

Clipboard (0)
Year of Publication
Document Types
1.  N-n-alkylnicotinium analogs, a novel class of antagonists at α4β2* Nicotinic acetylcholine receptors: Inhibition of S(-)-nicotine-evoked 86Rb+Efflux from rat thalamic synaptosomes 
The AAPS Journal  2006;7(4):E922-E930.
PyridineN-n-alkylation of S(-)-nicotine (NIC) affordsN-n-alkylnicotinium analogs, previously shown to competitively inhibit [3H]NIC binding and interact with α4β2* nicotinic receptors (nAChRs). The present study determined the ability of the analogs to inhibit NIC-evoked86Rb+ efflux from rat thalamic synaptosomes to assess functional interaction with α4β2* nAChRs. In a concentration-dependent manner, NIC evoked86Rb+ efflux (EC50=170 nmol/L). Analoginduced inhibition of NIC-evoked86Rb+ efflux varied over a ≈450-fold range. Analogs with longn-alkyl chain lengths (C9−C12) inhibited efflux in the low nmol/L range (IC50=9–20 nmol/L), similar to dihydro-β-erythroidine (IC50=19 nmol/L). Compounds with shortern-alkyl chain lengths (C1−C8) produced inhibition in the low μmol/L range (IC50 =3–12 μmol/L). C10 and C12 analogs completely inhibited NIC-evoked efflux, whereas C1–9 analogs produced maximal inhibition of only 10% to 60%. While the C10 analogN-n-decylnicotiniumiodide (NDNI) did not produce significant inhibition of NIC-evoked dopamine release in previously reported studies, NDNI possesses high affinity for [3H]NIC binding sites (Ki=90 nmol/L) and is a potent and efficacious inhibitor of NIC-evoked86Rb+ efflux as demonstrated in the current studies. Thus, NDNI is a competitive, selective antagonist at α4β2* nAChRs.
PMCID: PMC2750962  PMID: 16594645
nicotine analogs; subtype-selectivity; neuronal nicotinic receptor
2.  A general procedure for the enantioselective synthesis of the minor tobacco alkaloids nornicotine, anabasine, and anatabine 
The AAPS Journal  2005;7(3):E752-E758.
The minor tobacco alkaloids nornicotine, anabasine, and anatabine fromNicotiana tobacum are known to possess nicotinic receptor agonist activity, although they are relatively less potent than S-(−)-nicotine, the principal tobacco alkaloid. Previous pharmacological investigations and structure-activity studies have been limited owing to the lack of availability of the optically pure forms of these minor alkaloids. We now report a 2-step synthetic procedure for the enantioselective synthesis of the optical isomers of nornicotine and anabasine, and a modified procedure for the synthesis of anatabine enantiomers. These procedures involve initial formation of the chiral ketimine resulting from the condensation of either 1R, 2R, 5R-(+)- or 1S, 2S, 5S-(−)-2-hydroxy-3-pinanonewith3-(aminomethyl)pyridine followed by enantioselective C-alkylation with an appropriate halogenoalkane or halogenoalkene species, N-deprotection, and base-catalyzed intramolecular ring closure, to form the appropriate, chirally pure minor tobacco alkaloid. Using this approach, theR-(+)-andS-(−)-enantiomers of the above minor tobacco alkaloids were obtained in good overall chemical yield and excellent enantomeric excess.
PMCID: PMC2751277  PMID: 16353951
Nicotiana alkaloids; tobacco; stereoselective synthesis
3.  Molecular modeling of mono- and bis-quaternary ammonium salts as ligands at the α4β2 nicotinic acetylcholine receptor subtype using nonlinear techniques 
The AAPS Journal  2005;7(3):E678-E685.
The neuronal nicotinic acetylcholine receptor (nAChR) has been a target for drug development studies for over a decade. A series ofmono- andbis-quaternary ammonium salts, known to be antagonists at nAChRs, were separated into 3 structural classes and evaluated using both self-organizing map (SOM) and genetic functional approximation (GFA) algorithm models. Descriptors from these compounds were used to create several nonlinear quantitative structure-activity relationships (QSARs). The SOM methodology was effective in appropriately grouping these compounds with diverse structures and activities. The GFA models were also able to predict the activities of these molecules. Charge distribution and the hydrophobic free energies were found to be important indicators of bioactivity for this particular class of molecules. These QSAR approaches may be a useful to screen and selectin silico new drug candidates from larger compound libraries to be further evaluated in in vitro biological assays.
PMCID: PMC2751270  PMID: 16353944
self-organizing map; genetic functional approximation; neuronal nicotinic acetylcholine receptor

Results 1-3 (3)