Synthesis of 3-hydroxy-4-pyridinone hexadentate chelators, and biophysical evaluation of their affinity towards lipid bilayers.

Iron is an essential micronutrient for almost every living organism, namely pathogenic bacteria. In an infection scenario, host-pathogen competitive relationships for the element are present and Fe withholding is a well known response of the host. Also, bacterial resistance is a major concern that can compromise public health and the WHO underlines an urgent need to search for new pharmaceutical ingredients or strategies to fight opportunistic bacteria. Iron metabolism, and in particular, deprivation is a strategy that currently constitutes another option to fight bacterial infection. In this work we report the synthesis of a new hexadentate chelator with enhanced hydrophilicity (MRHT) and the improved synthesis of two other chelators. The affinity towards charged and non-charged phospholipid bilayers was evaluated for three hexadentate chelators: MRHT, CP256 and RH8b using NMR and EPR spectroscopies. The results revealed that these structures, bearing 3,4-HPO units have a high affinity towards the hydrophilic region of the phospholipid bilayer. From the three hexadentate chelators, MRHT stood out, especially for liposomes with a charged surface, suggesting that this molecule could more efficiently compete with natural siderophores, creating an iron gradient near bacteria organisms.