Metabolism of the calmodulin antagonist DY-9760e in animals and humans

• Published in: Xenobiotica Vol. 35; no. 5; pp. 499 - 517
• Main Authors: Tachibana, S., Tanaka, M., Fujimaki, Y., Suzuki, W., Ookuma, T., Ohori, Y., Hayashi, K.-I., Iwata, H., Okazaki, O., Sudo, K.-I.
• Format: Journal Article
• Language: English
• Published: England Informa UK Ltd 01.05.2005; Taylor & Francis
• Subjects: Animals; Biotransformation; Calmodulin - antagonists & inhibitors; Calmodulin antagonist; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme System - metabolism; DY-9760e; Escherichia coli; Escherichia coli - enzymology; Escherichia coli - genetics; glucuronidation; Humans; imidazole; imidazole oxidation; in vitro-in vivo comparison; Indazoles - chemistry; Indazoles - pharmacokinetics; Macaca fascicularis; Magnetic Resonance Spectroscopy; Male; metabolism; Microsomes, Liver - enzymology; NADPH-Ferrihemoprotein Reductase - metabolism; Rats; Rats, Wistar; Recombinant Proteins; ring opening
• ISSN: 0049-8254; 1366-5928
• DOI: 10.1080/00498250500136692

The in vitro metabolism of the calmodulin antagonist DY-9760e was investigated using liver microsomes from humans and three other animal species and compared with the in vivo metabolism in rats after intravenous administration of DY-9760e. Seven major metabolites were produced by human liver microsomes by the following metabolic pathways: N-dealkylation, phenyl hydroxylation, O-demethylation and imidazole oxidation. These metabolites were also produced by liver microsomes from monkeys, dogs and rats; additionally, a hydroxylated derivative of the indazole moiety was produced only by rat microsomes. To identify the structures of two imidazole ring metabolites whose authentic compounds could not be obtained, Escherichia coli co-expressing human cytochrome P450 CYP3A4 and NADPH-P450 reductase was used to biosynthesize these metabolites. NMR spectra elucidated the precise structures; oxidation occurred at the imidazole ring, and the subsequent ring-opening resulted in the generation of amide and formylamine groups. Glucuronide conjugates of the hydroxylated and O-demethylated derivatives were major components in rat bile. Therefore, DY-9760e metabolites generated in vitro correspond to the aglycones of the major metabolites observed in rat bile.