Inter-individual Variability in Activity of the Major Drug Metabolizing Enzymes in Liver Homogenates of 20 Individuals

Title:Inter-individual Variability in Activity of the Major Drug Metabolizing Enzymes in Liver Homogenates of 20 Individuals

Volume: 19 Issue: 4

Author(s): Shalenie P. den Braver-Sewradj, Michiel W. den Braver, Marc van Dijk, Yongjie Zhang, Stefan J. Dekker, Lukas Wijaya, Nico P.E. Vermeulen, Lysiane Richert, Jan N.M. Commandeur and J. Chris Vos*

Affiliation:

• AIMMS-Division of Molecular Toxicology, Department of Chemistry and Pharmaceutical sciences, Vrije Universiteit, De Boelelaan 1108, 1081 HZ Amsterdam,Netherlands

Keywords: Inter-individual variability, drug metabolizing enzymes, correlations, phase I metabolism, phase II metabolism, reaction phenotyping.

Abstract: Background: Inter-individual variability in hepatic drug metabolizing enzyme (DME) activity is a major contributor to heterogeneity in drug clearance and safety. Accurate data on expression levels and activities of DMEs is an important prerequisite for in vitro-in vivo extrapolation and in silico based predictions. Characterization and assessment of inter-correlations of the major DMEs cytochrome P450s (CYPs) and UDP-glucuronosyltransferases (UGTs) have been extensively documented, but simultaneous quantification including other major DMEs has been lacking.

Objective: Assessment of inter-donor variability and inter-correlations of CYPs, UGTs, sulfotransferases (SULTs), glutathione S-transferases (GSTs), NAD(P)H:quinone oxidoreductase 1 (NQO1) and NRH: quinone oxidoreductase 2 (NQO2) in a set of 20 individual liver homogenates.

Method: The main drug metabolizing isoforms of CYP and UGT have been reaction phenotype in individual liver microsomes and NQO1, NQO2, GSTT1 and GSTT2 in corresponding cytosol. In addition, we assessed overall SULT activity in liver cytosol using acetaminophen and 7-hydroxycoumarin as non-selective substrates and cytosolic GST activity using the non-selective substrate 1-chloro-2,4-dinitrobenzene (CDNB). Expression of GST isoforms was also assessed.

Results and Conclusion: While hepatic NQO1 activity was highly variable, NQO2 activity was more conserved. In addition, we found that of the hepatic GST isoforms, the variation in GSTM3 levels, which is poorly studied, was highest. The majority of significant correlations were found amongst CYP and UGT enzyme activities. The dataset presented provides the absolute quantification of the largest number of hepatic DME activities so far and constitute an essential resource for in silico toxicokinetic and metabolic modelling studies.

Cite this article as:

den Braver-Sewradj P. Shalenie, den Braver W. Michiel, van Dijk Marc, Zhang Yongjie , Dekker J. Stefan , Wijaya Lukas , Vermeulen P.E. Nico , Richert Lysiane , Commandeur N.M. Jan and Vos Chris J. *, Inter-individual Variability in Activity of the Major Drug Metabolizing Enzymes in Liver Homogenates of 20 Individuals, Current Drug Metabolism 2018; 19 (4) . https://dx.doi.org/10.2174/1389200219666180108160046