Both the D-(+) and L-(-) enantiomers of nicotine inhibit Abeta aggregation and cytotoxicity.
The underlying cause of Alzheimer's disease is thought to be the aggregation of monomeric beta-amyloid (Abeta), through a series of toxic oligomers, which forms the mature amyloid fibrils that accumulate at the center of senile plaques. It has been reported that L-(-)-nicotine prevents Abeta aggregation and toxicity, and inhibits senile plaque formation. Previous NMR studies have suggested that this could be due to the specific binding of L-(-)-nicotine to histidine residues (His6, His13, and His14) in the peptide. Here, we have looked at the effects of both of the L-(-) and D-(+) optical enantiomers of nicotine on the aggregation and cytotoxicity of Abeta(1-40). Surprisingly, both enantiomers inhibited aggregation of the peptide and reduced the toxic effects of the peptide on cells. In NMR studies with Abeta(1-40), both enantiomers of nicotine were seen to interact with the three histidine residues. Overall, our data indicate that nicotine can delay Abeta fibril formation and maintain a population of less toxic Abeta species. This effect cannot be due to a highly specific binding interaction between nicotine and Abeta, as previously thought, but could be due instead to weaker, relatively nonspecific binding, or to the antioxidant or metal chelating properties of nicotine. D-(+)-nicotine, being biologically much less active than L-(-)-nicotine, might be a useful therapeutic agent.
Moore
Susan A
SA
Department of Biological Sciences, University of Lancaster, Lancaster LA1 4YQ, UK.
Huckerby
Thomas N
TN
Gibson
Gillian L
GL
Fullwood
Nigel J
NJ
Turnbull
Stuart
S
Tabner
Brian J
BJ
El-Agnaf
Omar M A
OM
Allsop
David
D
D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000633:toxicity* / Q000648:ultrastructure; D045744:Cell Line, Tumor; D003497:Cyclic N-Oxides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D006131:Growth Inhibitors / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000633:toxicity*; D006801:Humans; D017665:Hydroxyl Radical / Q000037:antagonists & inhibitors; D009447:Neuroblastoma / Q000737:chemistry / Q000473:pathology; D009538:Nicotine / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000633:toxicity* / Q000648:ultrastructure; D013113:Spin Labels; D013237:Stereoisomerism; D013778:Tetrazolium Salts / Q000737:chemistry
D016229:Amyloid beta-Peptides; D003497:Cyclic N-Oxides; D006131:Growth Inhibitors; D010446:Peptide Fragments; D013113:Spin Labels; D013778:Tetrazolium Salts; C078592:amyloid beta-protein (1-40); D017665:Hydroxyl Radical; D009538:Nicotine; C017245:5,5-dimethyl-1-pyrroline-1-oxide