Structural analogues of thyronamines. Some aspects of the structure and bioactivity of the 4-[4-(2-aminoetoxy)benzyl]aniline

Tyronamines are endogenous compounds formed from L-thyroxine or its intermediate metabolites by deiodination and decarboxylation. The biological activity of thyronamines is associated with an effect on the central nervous system, cardiovascular system, and metabolism. In the central nervous system, thyronamines exhibit properties as a neuromodulator of adrenergic and histaminergic neurons. Structural features of thyronamines and their synthetic analogues in solutions can be investigated using the possibilities of complementary experimental and computational NMR spectroscopy.

Molecular modeling of the structure and evaluation of chemical shifts of ¹H and ¹³C nuclei were performed for the 4-[4-(2-aminoethoxy)benzyl]aniline, that is a structural analogue of thyronamines. The intramolecular dynamics of the key structural fragments of 4-[4-(2-aminoethoxy)benzyl]aniline was studied by the PM6-DH2 method as well as at B3LYP/6-31G(d,p) level of theory. Nonspecific solvation with dimethyl sulfoxide was taken into account within the polarized continuum model IEFPCM. Chemical shifts of the ¹H and ¹³C nuclei were estimated for the basic conformers of 4-[4-(2-aminoethoxy)benzyl]aniline. Calculated chemical shifts of the ¹H and ¹³C nuclei are in good agreement with the experimental ones obtained for 4-[4-(2-aminoethoxy)benzyl]aniline in DMSO-d₆ solution. In general, B3LYP/6-31G(d,p) level of theory can be recommended for further DFT-studies of the structure and properties of 4-[4-(2-aminoethoxy)benzyl]aniline as well as related compounds.

Some aspects of bioactivity of the 4-[4-(2-aminoethoxy)benzyl]aniline is discussed.