Poster Presentation RACI Biomolecular Division Conference 2013

The Bifurcation of Desferrioxamine B for Increasing Molecular Diversity of Iron Chelators (#95)

Thomas Telfer 1 , Rachel Codd 1
  1. The University of Sydney, NSW, Australia

The death of dopaminergic neurons is a major pathological hallmark of Parkinson’s disease (PD). An elevated iron concentration within the substantia nigra of the PD brain catalyses this neuronal death though hydroxyl radical-derived oxidative damage. Removal of this excess iron from the PD brain provides a potential therapeutic strategy. Desferrioxamine B (DFOB) is a high affinity iron(III) chelator used clinically to manage iron overload disease. Although DFOB is highly hydrophilic, adamantyl-based semi-synthetic derivatives of DFOB have been designed with improved lipid solubility to enable blood-brain barrier (BBB) and cell membrane penetration1 . In in vitro PD models, these compounds displayed 65-fold greater performance over native DFOB2 . This project aimed to increase diversity within this group of potential PD therapeutics using an innovative semi-synthetic strategy. Whereas the first generation compounds were unidirectional, these second-generation compounds are bidirectional, allowing greater control of physicochemical properties. Using solution-phase peptide coupling reactions, DFOB was initially bifurcated to allow two sites for chemical attachment. The promising adamantyl derivatives were conserved on one arm, while a range of alternative ancillary fragments can be appended to the second. Conjugation of PEGylated reagents of different monomer lengths, vitamin E and lipoic acid derivatives, and adamantyl- and 8-hydroxyquinoline-based ancillary groups are expected to allow tuning of plasma residence time, the introduction of additional anti-oxidant properties, and the imparting BBB carrier properties, respectively. This project has enabled a deeper understanding of the boundaries of DFOB semi-synthesis, and has designed an operating framework for the preparation of bifurcated adamantyl-based DFOB derivatives.

  1. Liu, J., Obando, D., Schipanski, L., Groebler, L., Witting, P., Kalinowski, D., Richardson, D., Codd, R. (2010). Conjugates of desferrioxamine B (DFOB) with derivatives of adamantane or with orally available chelators as potential agents for treating iron overload. Journal of Medicinal Chemistry 53(3): 1370-82.
  2. Liddell, J., Obando, D., Liu, J., Ganio, G., Volitakis, I., Mok, S., Crouch, P., White, A., Codd, R. (2013). Lipophilic adamantyl- or deferasirox-based conjugates of desferrioxamine B have enhanced neuroprotective capacity: implications for Parkinson disease. Free Radical Biology and Medicine 60: 147-156.