A Detailed Investigation on Conformation, Permeability and PK Properties of Two Related Cyclohexapeptides

This contribution provides detailed insights regarding permeability properties of published cyclohexapeptides related to their conformation. The study includes data on oral bioavailability and PK parameters including application of a known enhancer. Interestingly, the latter did not show an effect, neither on the cyclic peptide exhibiting low oral uptake nor on the similar molecule showing a 30 % oral bioavailability in mice. These results are discussed in the context of exposed polar surface area for the preferred conformation and structural data obtained by NMR and X-ray crystallography. Graphical Abstract