University of Oulu

Juha Jyrkäs, Toni Lassila, Ari Tolonen, Extrahepatic in vitro metabolism of peptides; comparison of human kidney and intestinal S9 fraction, human plasma and proximal tubule cells, using cyclosporine A, leuprorelin, and cetrorelix as model compounds, Journal of Pharmaceutical and Biomedical Analysis, Volume 225, 2023, 115219, ISSN 0731-7085,

Extrahepatic in vitro metabolism of peptides : comparison of human kidney and intestinal S9 fraction, human plasma and proximal tubule cells, using cyclosporine A, leuprorelin, and cetrorelix as model compounds

Saved in:
Author: Jyrkäs, Juha1,2; Lassila, Toni1; Tolonen, Ari1
Organizations: 1Admescope Ltd, Typpitie 1, 90620 Oulu, Finland
2Research Unit of Sustainable Chemistry, Faculty of Technology, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.8 MB)
Persistent link:
Language: English
Published: Elsevier, 2022
Publish Date: 2023-01-18


Peptide therapeutics showcase number of advantages compared to the traditional small molecule drugs, e,g. they usually have higher affinity to target and lower toxicity profiles. Endogenous peptides are mostly cleared from the body through renal clearance or proteolytic hydrolysis. As a part of drug discovery, metabolite identification is an important part in their development to identify metabolic hot spots and to further improve their stability. As the catabolism of the peptides and peptide-like drugs is often considered to be extrahepatic, the use of in vitro systems derived from these organs might be beneficial. In this study, multiple extrahepatic metabolic systems were evaluated for the applicability for peptide metabolism studies. Three peptide drugs (leuprorelin, cetrorelix, cyclosporin) were incubated in kidney and intestinal S9 fraction ( ± NADPH), fresh plasma (anticoagulants EDTA and heparin separately), and plated proximal tubule cells. Additionally, leuprorelin was also incubated with human kidney microsomes and cytosol to further investigate the NADPH-dependent metabolism detected in kidney S9 fraction. Both substrate disappearance and metabolite formation were monitored, using UPLC/HR-MS analysis of the collected samples. Overall, the largest number of metabolites was formed in the incubation with kidney S9 fraction, followed by intestinal S9, while incubations with proximal tubule cells produced lower number of metabolites All investigated peptides were stable in plasma and only a few metabolites were detected, likely because the studied peptide drugs have been optimized to be stable in plasma. Leuprorelin showed NADPH-dependent metabolite formation in kidney S9 fraction, while the metabolism of cetrorelix was more NADPH independent. As expected, formation of cytochrome P450 (CYP) catalyzed metabolism of cyclosporine was not observed with the employed extrahepatic systems. The NADPH-dependent metabolism of leuprorelin was detected also in the incubation with kidney cytosol, but not with kidney microsomes, and was thus not caused by CYPs or FMOs, but with cytosolic NADPH-dependent drug metabolizing enzymes. These enzymes could, in principle, activate the amide bond via reductive or oxidative metabolism outside the amide bond. The identity of the involved drug metabolizing enzymes in this process is still unknown.

see all

Series: Journal of pharmaceutical and biomedical analysis
ISSN: 0731-7085
ISSN-E: 1873-264X
ISSN-L: 0731-7085
Volume: 225
Article number: 115219
DOI: 10.1016/j.jpba.2022.115219
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
Funding: Admescope Ltd provided funding for the study. All experiments were conducted in the laboratory of Admescope Ltd and authors designed and conducted the study.
Copyright information: © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (