Micro- and nanoplastics – current state of knowledge with the focus on oral uptake and toxicity

This review focuses on micro- and nanoplastic particles with the main focus on oral uptake and transport at the intestinal epithelium and potential toxic consequences.

Pyridyl-Ala Modified Cyclic Hexapeptides: In-Vitro and In-Vivo Profiling for Oral Bioavailability

We and others have been aiming at modifications to maintain or to enhance solubility while enabling permeability for cyclic hexapeptides. Especially, the 2-pyridyl-Ala modification was investigated, since in this case, the pyridyl-nitrogen is able to form an H-bond to the NH of the same residue. The hypothesis of a backbone side-chain interaction was demonstrated by NMR experiments, and further results obtained on a variety of pyridyl-Ala derivatives, studied systematically in the context of permeability, are presented in this contribution. Thus, this study sheds some more light on the pyridyl-Ala modification, which had been reported earlier. In addition to the in vitro profiling, the extent of oral bioavailability was assessed in rats. In principle, the pyridyl-Ala residue can be considered as an amino acid supporting oral uptake. Graphic Abstract

Modelling oral up-take of hydrophobic and super-hydrophobic chemicals in fish

PbTk simulations with hydrophobic chemicals have revealed that diffusive transport through aqueous boundary layers in the gastro-intestinal tract and in the blood is the limiting process for oral uptake scenarios. This process can only be modelled correctly if transport facilitated by albumin and bile micelles through these boundary layers is accounted for.