Metabolism and disposition of the novel antileukaemic drug, benzamide riboside, in the isolated perfused rat liver

Alexandra Salamon, Birgit Hagenauer, Therese Thalhammer, Thomas Szekeres, Karsten Krohn, Hiremagalur N. Jayaram, Walter Jäger

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Abstract

Benzamide riboside (BR) is a novel anticancer agent exhibiting pronounced activity against several human tumor cells, however, little is known about its biotransformation. To analyze for BR and its metabolites, livers of Wistar and mutant TR- rats were perfused with BR in a single pass system. In bile, native BR and its deamination product, benzene carboxylic acid riboside (BR-COOH) was quantified by HPLC. Total excretion of BR and BR-COOH into bile of Wistar rats was low (< 0.2%) whereas cumulative efflux of BR and its metabolite BR-COOH was high, representing 79% and 1.6% of infused BR, respectively. Biliary excretion of BR and BR-COOH in TR- rats, deficient in canalicular multispecific organic anion transporter, a membrane protein identical to MRP2 in tumor cells, was only slightly lower than in Wistar rats, indicating that BR and BR-COOH are non-substrates of MRP2. Experiments using rat hepatocytes incubated with BR did show a linear uptake of BR and a subsequent metabolism to BR-COOH that was largely excreted into the cellular supernatant. Examination of the cytotoxic activity against the human HL60 and K562 leukemia cells in a clonogenic assay demonstrated an IC50 of 619 μM and 1013 μM for BR-COOH compared to the IC50 of 0.21 μM and 0.46 μM for BR, suggesting the inertness of the metabolite. In summary, we found that deamination of BR to BR-COOH is the main metabolic pathway in rat liver. BR-COOH formation should also be considered in human liver during cancer therapy.

Original languageEnglish (US)
Pages (from-to)2489-2502
Number of pages14
JournalLife Sciences
Volume69
Issue number21
DOIs
StatePublished - Oct 12 2001

Keywords

  • Benzamide riboside
  • IMP-dehydrogenase inhibitor
  • Isolated perfused rat liver
  • Metabolism

ASJC Scopus subject areas

  • Pharmacology

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    Salamon, A., Hagenauer, B., Thalhammer, T., Szekeres, T., Krohn, K., Jayaram, H. N., & Jäger, W. (2001). Metabolism and disposition of the novel antileukaemic drug, benzamide riboside, in the isolated perfused rat liver. Life Sciences, 69(21), 2489-2502. https://doi.org/10.1016/S0024-3205(01)01329-7