Evaluation of Synthetic Cytochrome P-Mimetic Metalloporphyrins To Facilitate "Biomimetic" Biotransformation of a Series of mGlu Allosteric Ligands.

Allosteric ligands within a given chemotype can have the propensity to display a wide range of pharmacology, as well as unexpected changes in GPCR subtype selectivity, typically mediated by single-atom modifications to the ligand. Due to the unexpected nature of these "molecular switches", chemotypes with this property are typically abandoned in lead optimization. Recently, we have found that in vivo oxidative metabolism by CYPs can also engender molecular switches within allosteric ligands, changing the mode of pharmacology and leading to unwanted toxicity. We required a higher-throughput approach to assess in vivo metabolic molecular switches, and we turned to a "synthetic liver", a 96 well kit of biomimetic catalysts (e.g., metalloporphyrins) to rapidly survey a broad panel of synthetic CYPs' ability to oxidize/"metabolize" an mGlu PAM (VU0403602) known to undergo an in vivo CYP-mediated molecular switch. While the synthetic CYPs did generate a number of oxidative "metabolites" at known "hot spots", several of which proved to be pure mGlu PAMs comparable in potency to the parent, the known CYP-mediated in vivo ago-PAM metabolite, namely, VU0453103, was not formed. Thus, this technology platform has potential to identify hot spots for oxidative metabolism and produce active metabolites of small-molecule ligands in a high-throughput, scalable manner.