Synthesis and Pharmacokinetic Properties of Novel CPLAα Inhibitors with 1-(carboxyalkylpyrrolyl)-3-aryloxypropan-2-one Structure

Indole-5-carboxylic acids with 3-aryloxy-2‑oxopropyl residues in position 1 have been shown to be potent inhibitors of cytosolic phospholipase Aα (cPLAα), an enzyme involved in the formation of pro-inflammatory lipid mediators. Unfortunately, in animal experiments, only very low plasma concentrations could be achieved after peroral administration of this type of compound. Since insufficient metabolic stability was suspected as the cause, structural modifications were made to optimize this property. These included the conversion of the aromatic into an aliphatic carboxylic acid function as well as the rigidification of the lipophilic structural elements. A selected pyrrole-3-propionic acid was tested for its peroral in vivo bioavailability in mice. However, higher plasma concentrations could not be achieved also with this compound. Using the Caco2 cell permeation assay, substances investigated were found to be very good substrates for gastrointestinal efflux transporters, which explains their poor peroral absorption.