Poster Presentation 8th Modern Solid Phase Peptide Synthesis & Its Applications Symposium 2022

Using chirality to induce permeability in somatostatin analogues (#119)

Travis Lay 1 , Philip E Thompson 1 , Colin Pouton 1 , David K Chalmers 1
  1. Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria , Australia

Peptides have proven to be effective pharmaceutical agents. However, their inherent lack of permeability results in low oral bioavailability, inhibiting their therapeutic potential. Despite this, there are cyclic peptide structures that exist which have proven orally bioavailable peptides are a possibility, such as Cyclosporine A1 and the peptide library developed by Lokey et al.2

Somatostatin (SRIF) is a peptide hormone that acts as a regulator for hormone secretion3. While peptide-based drugs for SRIF are on the market, for the treatment diseases such as acromegaly, none are orally administered, which leads to low patient compliance. In our current work, we aim to synthesise a library of SRIF analogues integrated with moieties that favour permeability.

The usual approach for peptide permeability involves increasing hydrophobicity while reducing hydrogen bonding potential. However, another important factor for peptide permeability is the three-dimensional shape they adopt, which is strongly affected by the chirality of the amino acids present in the peptide chain. In this work, we are investigating head-to-tail cyclic analogues of SRIF, by applying a chirality scan as well as modulating the size of the macrocycles, to investigate how small conformational changes can have a profound impact on permeability and potentially activity.

  1. Ahlbach, C. L.; Lexa, K. W.; Bockus, A. T.; Chen, V.; Crews, P.; Jacobson, M. P.; Lokey, R. S. Beyond cyclosporine A: conformation-dependent passive membrane permeabilities of cyclic peptide natural products. Future Med Chem 2015, 7, 2121-2130.
  2. White, T. R.; Renzelman, C. M.; Rand, A. C.; Rezai, T.; McEwen, C. M.; Gelev, V. M.; Turner, R. A.; Linington, R. G.; Leung, S. S. F.; Kalgutkar, A. S.; Bauman, J. N.; Zhang, Y.; Liras, S.; Price, D. A.; Mathiowetz, A. M.; Jacobson, M. P.; Lokey, R. S. On-resin N-methylation of cyclic peptides for discovery of orally bioavailable scaffolds. Nat Chem Biol 2011, 7, 810-817.
  3. Günther, T.; Tulipano, G.; Dournaud, P.; Bousquet, C.; Csaba, Z.; Kreienkamp, H.-J.; Lupp, A.; Korbonits, M.; Castaño, J. P.; Wester, H.-J.; Culler, M.; Melmed, S.; Schulz, S. International union of basic and clinical pharmacology. CV. Somatostatin receptors: Structure, function, ligands, and new nomenclature. Pharmacol Rev 2018, 70, 763-835.