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Modeling the Preferred Shapes of Polyamine Transporter Ligands and Dihydromotuporamine-C Mimics:  Shovel versus Hoe

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journal contribution
posted on 20.04.2006 by Breitbeil, Navneet Kaur, Jean-Guy Delcros, Bénédicte Martin, Khalil A. Abboud, Phanstiel
Preferred conformers generated from motuporamine and anthracene−polyamine derivatives provided insight into the shapes associated with polyamine transporter (PAT) recognition and potentially dihydromotuporamine C (4a) bioactivity. Molecular modeling revealed that N-(anthracen-9-ylmethyl)-3,3-triamine (6a), N1-(anthracen-9-ylmethyl)-4,4-triamine (6b), N1-(anthracen-9-ylmethyl)-N1-ethyl-3,3-triamine (7a), N1-(anthracen-9-ylmethyl)-N1-ethyl-4,4-triamine (7b), and 4a all preferred a hoe motif. This hoe shape was defined by the all-anti polyamine shaft extending above the relatively flat, appended ring system. The hoe geometry was also inferred by the 1H NMR spectrum of the free amine of 7a (CDCl3), which showed a strong shielding effect of the anthracene ring on the chemical shifts associated with the appended polyamine chain. This shielding effect was found to be independent over a broad concentration range of 7a, which also supported an intramolecular phenomenon. The degree of substitution at the N1-position seems to be an important determinant of both the molecular shape preferences and biological activity of anthracenylmethyl−polyamine conjugates.